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Science 7th

Life science is any branch of natural science, like biology, medicine, zoology, botany, anthropology, or ecology, that deal with living organisms, their structure and their life process, organization and relationship to each other and to their environment. It is also called bio-science in some circles. A broad field that studies life but contains many other fields of study. In general, we define life science as all the sciences that have to do with organisms like plants, animals and human beings.

external image MadAboutScience-LOGO-NO-tagline-Cropped.jpg


Some sites for learning Science:

Life Science Projects: http://www.hometrainingtools.com/life-science-projects/c/1075/

Life Science Infographics: http://www.kidsdiscover.com/lifescience/

General Information: http://www.kidsbiology.com/




Earth Day Video:

Temario IV Quarter:
Chapter 19, Sections 3 and 4

Chapter 20, Section 1, 2, 3


Temario Recuperación:
Chapter 1: Introduction to Life Science- Sections 1, 2, 3, 4
Chapter 6: Changes over Time- Sections 1, 2
Chapter 15: Food and Digestion- Sections 1, 2, 3
Chapter 19: The Nervous System- Sections 1, 2, 3, 4


Content
Month: May
How the nervous system works
Divisions of the nervous system

The senses
Alcohol and other drugs
The endocrine system
The male and female reproductive systems
The human life cycle




What is the nervous system?

external image nerve_sys-7.gifThe nervous system is the highway along which your brain sends and receives information about what is happening in the body and around it. This highway is made up of billions of nerve cells, or neurons (say new-rons) which join together to make nerves.
  • A nerve is a fibre that sends impulses through the body.
  • These fibres are covered by fatty substance called myelin (say my-e-lin). Myelin helps the messages go fast through the neurons.
  • Nerve cells work by a mixture of chemical and electrical action.
The two main parts of the nervous system are the central nervous system and the peripheral (say per-if-er-al) nervous system.

How nerve cells work

At the end of each nerve cell there is a synaptic terminal (say sin-ap-tik term-in-ul). This is full of extremely tiny sacs which hold neurotransmitter chemicals (say new-ro-trans-mitta- kem-ik-als).
  • These chemicals transmit nerve impulses from one nerve to another or from nerves to muscle cells.
  • An electrical nerve impulse travels along the neuron to these sacs which then release the neurotransmitter chemicals.
  • The chemicals move along to the next neuron sparking an electrical charge which moves the nerve impulse forward.
  • This happens several times until the message gets where it's going.

The central nervous system

the brain's in charge
the brain's in charge
The brain and the spinal cord make up the central nervous system. The brain lies protected inside the skull and from there controls all the body functions by sending and receiving messages through nerves.




The peripheral nervous system

The peripheral nervous system carries messages to and from the central nervous system. It sends information to the brain and carries out orders from the brain.
the brain gets a message
the brain gets a message

the five senses
the five senses
Messages travel through the cranial nerves, those which branch out from the brain and go to many places in the head such as the ears, eyes and face. Messages can also travel through the spinal nerves which branch out from the spinal cord.
There are two major parts to the peripheral nervous system.
The somatic (say so-mat-ik) system:

  • external image nerve_sys-4.gifsends sensory information to the central nervous system through peripheral nerve fibres. Sensory means that it sends the information coming from all your senses, touch, vision, hearing, taste, smell and position.
  • sends messages to motor nerve fibres to get the muscles to move the body.
The autonomic (say or-tow-nom-ik) system
  • is responsible for making sure that all the automatic things that your body needs to do to keep you going, like breathing, digesting etc continue working smoothly without your having to think about them. (How hard would it be to have to keep thinking, "Breathe in, breathe out," or "Start digesting the food stomach!")


The Senses

Sight and the Eye

Sight is one of the five senses that help us to get information about what is going on in the world around us. We see through our eyes, which are organs that take in light and images and turn them into electrical impulses that our brain can understand.
How do we see?

When we see something, what we are seeing is actually reflected light. Light rays bounce off of objects and into our eyes.

Our Amazing Eyeballs

Pupil and Iris:

Eyes are amazing and complex organs. In order for us to see, light enters our eyes through the black spot in the middle which is really a hole in the eye called the pupil. The pupil can change sizes with the help of the colored part around it, a muscle called the iris. By opening and closing the pupil, the iris can control the amount of light that enters the eye. If the light is too bright, the pupil will shrink to let in less light and protect the eye. If it's dark, the iris will open the pupil up so more light can get into the eye.

external image sight.jpg

Retina:

Once the light is in our eye it passes through fluids and lands on the retina at the back of the eye. The retina turns the light rays into signals that our brain can understand. The retina uses light sensitive cells called rods and cones to see. The rods are extra sensitive to light and help us to see when it's dark. The cones help us to see color. There are three types of cones each helping us to see a different color of light: red, green, and blue.

Focus:

In order for the light to be focused on the retina, our eyes have a lens. The brain sends feedback signals to the muscles around the lens to tell it how to focus the light. Just like the way a camera or microscope works, when we adjust the lens we can bring the image into focus. When the lens and muscles can't quite focus the light just right, we end up needing glasses or contacts to help our eyes out.

Off to the Brain:

The rods and cones of the retina change light into electrical signals for our brain. The optic nerve takes these signals to the brain. The brain also helps to control the eye to help it focus and to control where you are looking. Both eyes move together with speed and precision to allow us to see with the help of the brain.

Why two eyeballs?

With two eyeballs our brain gets two slightly different pictures from different angles. Although we only "see" one image, the brain uses these two images to give us information on how far away something is. This is called depth perception.



Hearing and the Ear
Hearing is how we perceive sound. It's how our ears take sound waves and turn them into something our brain can understand.




There are three major parts of the ear that help us to hear:



external image hearing2.jpg

  1. The outer ear - The outer ear has three sections:
    • The pinna or auricle: this is the part of the ear on the outside of our heads. The part we usually are referring to when we say ear. It helps to gather sound and vibrations so we can hear more sounds.
    • The ear canal: This is a tube that helps sound to travel further inside our ear and to get to the next stage of hearing
    • The eardrum: The eardrum is a thin sheet that vibrates when the sound hits it. Your eardrum is very sensitive and fragile. It's never a good idea to put anything in your ear, even something that seems safe and soft can damage your eardrum.

  1. The middle ear - The middle ear is filled mostly with air and has three bones in it. That's right your ear has little bones called ossicles that help you hear! They are called the hammer (malleus), anvil (incus), and stirrup (stapes). They amplify the sound or make it louder. The middle ear helps to transfer sounds from the air to fluid inside the next stage, or inner ear. The stirrup is the smallest bone in the body.
  2. The inner ear - The inner ear is filled with fluid and has the hearing organ called the cochlea. This organ helps to take the vibrations and translate them into electrical signals for the nerve to send to the brain. It actually uses little hairs that vibrate with the sound waves in the fluid. Then you "hear" it. Amazing! The inner ear also has fluid filled tubes that help with your balance.

Why two ears?



Having two ears helps you to determine the direction of sound. Your brain is smart enough to figure out that if sound hits one ear just before the other and is slightly louder then that's the direction the sound came from. Having an ear on each side of our head also helps us to hear better.



The Frequency of Sound



We can hear sound within a certain frequency range of around 20 Hz on the low end and 20,000 Hz on the high end. Some animals have different ranges. Dolphins, for example, can't hear sounds as low as we can, but can hear high sounds of over 100,000 Hz. Dogs and cats can hear much higher pitched sounds than we can.



Why do I get dizzy?



The brain takes in a number of signals from your body to keep it balanced. One of them is from the fluid in the inner ear. The brain can tell a lot by how the fluid in your ear is moving or tilted. The brain also uses your eyes and sense of touch to tell it about your balance and position. When you spin really fast and then stop, the fluid in your ear is still spinning, but your eyes and body have stopped moving. Your brain gets confused for a bit and you feel dizzy.






Month: AprilCardiovascular health
The respiratory system
Smoking and your health
The excretory system
Infectious disease
The body defenses
Preventing infectious diseases
Non infectious diseases



Breathing and the Respiratory System

Human lungs and ribs
Human lungs and ribs


Humans breathe through something called the respiratory system. This system is made up primarily of our lungs and windpipe.

Why do we have to breathe?
Our body is a very complex system. One of the main things it needs is energy. When we eat our body digests the food to get complex molecules like glucose, which it can use for energy. However, food alone isn't enough. The cells also need oxygen to react with the glucose to create the energy. We get the oxygen to our cells with the respiratory system and by breathing.

Breathing In
We breathe in using a muscle called the diaphragm. It flattens out making our lungs expand and fill with air. When we breathe in, air gets forced through our nose or mouth, down our windpipe, and into bronchi tubes in our lungs. These bronchi tubes branch out and get smaller and smaller, like the roots or branches of a tree.

Alveoli
No, these aren't a kind of pasta! At the end of the smallest branches of the bronchi are tiny air sacs called alveoli. These air sacs have a very thin, one cell thick wall that allows oxygen to be passed to red blood cells as they are passing by. There are hundreds of millions of these tiny guys in our lungs.

Breathing Out
The alveoli don't just pass oxygen to our blood, they also help to clean out waste gas from our blood cells. This waste gas is carbon dioxide. When we need to breathe the carbon dioxide out of our lungs, the diaphragm bows up and pushes the air back out, getting rid of the carbon dioxide. This makes room for fresh air with new oxygen to come back in on our next breath.


Diagram of the Respiratory System
Diagram of the Respiratory System

Diagram of the Respiratory System


Our Nose
The nose does more for breathing than just providing a place for air to enter our body. It also helps to filter the air of dust and other stuff. It does this by using lots of hairs and mucus. It also helps warm up the air prior to getting to our lungs.

Why do we get out of breath?
When we run or do strenuous activity, our muscles burn energy and use up the oxygen in our red blood cells. To try and get more energy and oxygen to these cells, our heart will pump faster to get more blood through the lungs. At the same time our lungs will try to breathe harder and faster to get more oxygen. We end up feeling out of breath and have to take a rest so our bodies can recover.

Talking
The respiratory system also helps with talking. We couldn't talk without air. By forcing air through our vocal chords, the respiratory system helps them to vibrate and create sound like talking, singing, or shouting.


Excretory System

As your body performs the many functions that it needs in order to keep itself alive, it produces wastes. These wastes are chemicals that are toxic and that if left alone would seriously hurt or even kill you.

For example, as your cells break down amino acids, they produce a dangerous toxin known as urea. The cells of your body excrete this urea into your blood.



Your KidneysAs your blood travels along within your body, it becomes more and more polluted with urea and other wastes. Eventually the blood enters a special filter, an organ known as your kidneys. As the blood enters your kidneys it is cleansed. Your kidneys remove the urea from the blood, sending it to your bladder for storage in the form of urine, commonly known as pee. It takes about 45 minutes for your kidneys to completely filter all of the blood in your body.

Kidneys Clean Our Blood
Kidneys Clean Our Blood

Your Bladder
Slowly your bladder fills up with the urine being produced by your kidneys. Eventually as it becomes full, you will feel a sensation telling your brain that you need to remove it from your body. Urine leaves your body through the process of urination, commonly known as peeing.

Bladder
Bladder



Immune SystemWhat is the immune system?
The immune system helps to protect us against diseases caused by tiny invaders (called pathogens) such as viruses, bacteria, and parasites. The immune system is made up of specialized organs, cells, and tissues that all work together to destroy these invaders. Some of the main organs involved in the immune system include the spleen, lymph nodes, thymus, and bone marrow.

How does it work?

The immune system develops all kinds of cells that help to destroy disease causing microbes. Some of these cells are specifically designed for a certain kind of disease. All throughout the body, disease fighting cells are stored in the immune system waiting for the signal to go to battle. The immune system is able to communicate throughout the entire body. When pathogens are detected, messages are sent out, warning that the body is being attacked. The immune system then directs the correct attacking cells to the problem area to destroy the invaders.

Antigens and Antibodies
Scientists call the invaders that can cause disease antigens. Antigens trigger an immune response in the body. One of the main immune responses is the production of proteins that help to fight off the antigens. These proteins are called antibodies.

How do the antibodies know which cells to attack?
In order to work properly, the immune system must know which cells are good cells and which are bad. Antibodies are designed with specific binding sites that only bind with certain antigens. They ignore "good" cells and only attack the bad ones. You can see from the picture below that the antibodies each have a specially designed binding site. They will only bind with the antigen that has a "marker" that matches up perfectly.


external image antibodies_and_antigens.gif

Types of Immunity Cells
The immune system has cells that perform specific functions. These cells are found in the blood stream and are called white blood cells.
  • B cells - B cells are also called B lymphocytes. These cells produce antibodies that bind to antigens and neutralize them. Each B cell makes one specific type of antibody. For example, there is a specific B cell that helps to fight off the flu.
  • T cells - T cells are also called T lymphocytes. These cells help to get rid of good cells that have already been infected.
  • Helper T cells - Helper T cells tell B cells to start making antibodies or instruct killer T cells to attack.
  • Killer T cells - Killer T cells destroy cells that have been infected by the invader.
  • Memory cells - Memory cells remember antigens that have already attacked the body. They help the body to fight off any new attacks by a specific antigen.

How do we get immunity?
The immune system is very smart and can adapt to new infections. Our bodies gain immunities in two ways: natural and acquired.
  • Natural - When we are born, our bodies already have some immunity. Babies get antibodies from their mother as they are growing in the womb. They may also gain some antibodies from their mother's milk.
  • Acquired - Our bodies also learn immunities over time. When we get sick, our body learns how to fight off the disease. The next time that disease invades, our body is ready for it and can quickly produce antibodies to prevent infection. We can also gain immunity from vaccines.

How Vaccines Work
Vaccines introduce microbes that are already killed or modified so we don't get sick. However, the immune system doesn't know this. It builds up defenses and antibodies against the disease. When the real disease tries to attack, our body is ready and can quickly neutralize the antigens.

Interesting Facts about the Immune System
  • Some immunity eventually goes away, so we need a new vaccine after a period of time.
  • Different people have different levels of immunity to certain diseases. This is why some people get sick more often than others.
  • Sometimes the immune system can get confused and attack good cells. Type I diabetes is caused when T cells attack insulin producing cells in the pancreas.
  • T cells and B cells are stored in lymph nodes throughout the body. They enter the blood stream when they are needed to defend against disease.
  • Your body responds much faster and stronger the second time it sees an antigen.




Infectious DiseaseWhat is an infectious disease?
An infectious disease is any disease caused by a pathogen (germ) such as a virus, bacteria, parasite, or fungus. Although we will mostly discuss infectious diseases in people on this page, other living organisms such as animals, plants, and microorganisms can all be made ill by an infectious disease.

Pathogens
"Pathogen" is the scientific name for "germ." Infectious diseases are caused by pathogens. When your mom says to wash your hands because of germs, she wants you to get all the pathogens off your hands so they won't go into your mouth and body. Maybe after reading this, you will wash your hands a bit more! Pathogens are tiny organisms (called microorganisms) that invade the body and make it sick. Examples of pathogens are viruses, bacteria, parasites, and fungi. Click on the word to learn more.

Different kinds of pathogens cause different kinds of diseases. Here are some example diseases caused by each type of pathogen:
  • Viruses - Viruses are extremely small and consists of DNA with a protective coating of protein. Diseases caused by viruses include influenza, the common cold, measles, yellow fever, and hepatitis.
  • Bacteria - Bacteria are small microorganisms. They can cause diseases such as tuberculosis, cholera, typhoid fever, and tetanus.
  • Parasites - Parasites are organisms that live off their hosts. Some parasitic diseases include malaria, sleeping sickness, and scabies.
  • Fungi - Fungi are microorganisms such as yeasts and molds. They can cause diseases such as fungal meningitis, ringworm, and thrush.

Transmission

Infectious diseases can be transmitted in several ways including:
  • Food and water contamination - Some diseases are passed on by contaminated food or water. This can occur in undercooked food or when sewage gets into the water supply. Examples of diseases that are transmitted this way include E. coli, cholera, and salmonella.
  • Insect bites - Insects such as fleas, mosquitoes, and ticks can carry pathogens that get passed on when they make contact with humans. Diseases from insects include malaria (mosquitoes), Lyme disease (ticks), and the bubonic plague (fleas).
  • Direct contact - Diseases are often passed from person to person by direct contact. This could include shaking hands, sneezing (airborne), and kissing. Examples include influenza, the common cold, and chickenpox.
  • Indirect contact - Some pathogens can survive for a while outside the host. They may be on objects such as doorknobs and telephones. Many of the same diseases, but not all, that can spread through direct contact can also be spread through indirect contact.

Other Types of Diseases
Not all diseases are infectious. Some other types of diseases include:
  • Autoimmune - An autoimmune disease occurs when the immune system attacks the body. Examples include Type I diabetes and multiple sclerosis.
  • Lifestyle - Lifestyle diseases are caused by the way people live. They can also be a result of people living longer. Examples include Type 2 diabetes, alcoholism, and Alzheimer's disease.
  • Disorder - A disease is sometimes called a disorder when some part of the body isn't functioning normally. Often disorders are associated with the brain and are called mental disorders. Examples include eating disorders such as bulimia and mental disorders such as depression.
  • Heart disease - Heart disease is used to describe anything that is wrong with the cardiovascular system. This includes diseases such as coronary artery disease, high blood pressure, and congenital heart disease.
  • Medical condition - The term medical condition is used to describe everything from injuries to infectious diseases to disorders. An injury such as a concussion would be considered a medical condition.

Interesting Facts about Infectious Disease
  • A Zoonotic disease is an infectious disease that can be transmitted between animals to humans.
  • Not all infections are considered diseases as some infections don't make a person sick.
  • Not all viruses, bacteria, parasites, and fungi are bad for humans, but the ones that do cause disease are called pathogens.
  • Over 160,000 people die each year in the United States from infectious diseases.
  • A "contagious" disease is an infectious disease that is very easily transmitted.

Disease: CancerWhat is cancer?

Cancer is any disease caused by uncontrolled cell growth. Abnormal cells begin to divide and make tumors. They can spread throughout the body and slowly destroy good cells and tissues making the person sick. There are many different diseases that are called cancers. Some of these diseases are very treatable while others are more dangerous and can be fatal. Around 40% of all people will be diagnosed with cancer some time during their lives.

Cancer Starts in the Cell
Cancer starts when the genes in a cell that regulate cell growth are somehow altered or mutated. It actually takes a number of mutations before a cell becomes cancerous. Typically, the cells are smart enough to get rid of mutations. They have complex ways of safeguarding against mutations and will kill off bad cells. However, if the right series of mutations occur, the cells will begin to grow uncontrollably.

Types of Cancer
Cancer is really a term used to describe a number of different diseases. There are more than 200 different types of cancer. Typically, cancers are named after the place in the body where the cancer first began. For example, lung cancer is cancer that started in the lungs. There are then different types of lung cancers with long scientific names such as "well differentiated squamous cell carcinoma of the lung" and "small cell carcinoma of the lung."

Common Forms of Cancer
  • Breast cancer - Cancer of the breast that usually forms in the tubes and glands that carry and make milk. It is much more common in women than in men.
  • Colon cancer - Cancer of the colon, which is part of the large intestine.
  • Leukemia - Cancer of the blood that often starts in the bone marrow.
  • Lymphoma - Cancer of the white blood cells that help to form the immune system. It is often found in the lymph nodes, the spleen, or the blood marrow.
  • Lung cancer - Cancer of the lungs. It is most commonly, but not always, caused by smoking.
  • Melanoma - Cancer of the skin or other pigmented areas (like the eye). It is often caused by too much exposure to the Sun's harmful rays.
  • Pancreatic cancer - Cancer that forms in the pancreas organ.
  • Prostate cancer - Cancer that forms in the prostate. Only men have prostates and typically get this cancer when they are older.

Typical Symptoms
There are so many different types of cancer, that there are many different symptoms. However, the American Cancer Society gives seven common symptoms that can be warnings of cancer.
  • A sore that doesn't heal or get better like normal.
  • A change in the size, shape, color, or thickness of a mole or other sore.
  • Difficulty in swallowing or a constant upset stomach.
  • Change in bladder or bowel habits.
  • Any type of constant or unusual bleeding.
  • Any thick lump or growth.
  • A constant cough or scratchy throat.

Treatments
Many forms of cancer can be treated and even cured. Common treatments include the following:
  • Surgery - Surgery is used to physically remove the cancer. In some cases the area or tumor where the cancer is located can be safely removed.
  • Chemotherapy - Chemotherapy uses chemicals to kill cancerous cells. These chemicals target cells that divide rapidly, which is common to most cancer cells. Unfortunately, chemotherapy kills some good cells as well and can have harsh side effects.
  • Radiation - Radiation uses high-energy waves to destroy cancer cells.
Many cancers require a combination of the above treatments.

Can you help prevent cancer?
The Mayo Clinic lists seven ways that you can reduce your risk of getting cancer.
  • Don't use tobacco - This includes both smoking and chewing tobacco.
  • Eat healthy - This means eating lots of fruits and vegetables as well as eating low fat foods.
  • Exercise and have a healthy weight - Being overweight can increase the risk of getting various forms of cancer.
  • Don't get sunburned - Protecting your skin from the Sun by using sunscreen and staying out of the Sun's rays during the middle of the day can lower the risk of skin cancer.
  • Get immunized - Certain immunizations can help to prevent cancer.
  • Avoid risky behaviors - Some actions such as sharing needles can pass diseases that can lead to cancer.
  • See your doctor - Getting a regular checkup at the doctor can help to detect cancer early, which can be very important in having successful treatment.





Month: MarchThe digestive process begins
Final digestion and absorption
The body’s transport system
Blood and lymph


The Human Digestive System

Our body needs food to provide it with energy, vitamins, and minerals. However, in order use food, we must first break it down into substances that the various organs and cells in our body can use. This is the job of our digestive system. The digestive system acts in stages to digest our food. Each stage is important and prepares the food for the next stage. The entire length of our digestive system is around 20 to 30 feet!

Here are the major stages of the digestive system:
1. Chewing - Chewing is the first stage of the digestive system. When you chew your food it breaks up big pieces into little pieces that are easier to digest and swallow. Also, your saliva is more than just water. It has special enzymes in it that start to break down starchy food (potatoes, bread) while you chew.

2. Swallowing - Swallowing may seem like a simple process to us. It just sort of happens. But food doesn't just fall down our throats into our stomach. First, our tongue helps to push food into the back of our throat. Then there are special throat muscles that force the food down into a long tube that leads to our stomach, called the esophagus. The food doesn't just fall down the pipe, muscles push the food along until it gets to our stomach. At the same time all this is going on, a flap blocks off our windpipe making sure food doesn't go the wrong way. We call this "going down the wrong pipe" and it can make us choke. This flap is called the epiglottis and, fortunately for us, it works automatically.

external image digestive_system.jpg

3. Stomach - The next stage is the stomach. Food hangs out in the stomach for around four hours. While the food sits there, more enzymes go to work on it, breaking down things like proteins that our bodies can use. The stomach kills a lot of bad bacteria as well, so we don't get sick.

4. Small Intestine - The first part of the small intestine works with juices from the liver and pancreas to continue to break down our food. The second part is where the food gets absorbed from the intestine and into our body through the blood.

5. Large Intestine - The last stage is the large intestine. Any food that the body doesn't need or can't use is sent to the large intestine and later leaves the body as waste.

The Liver and Pancreas

The liver and pancreas do a lot to help the digestive system along. Both work with the small intestine. The liver provides bile (stored in the gall bladder) that helps break up fat into smaller bits. The pancreas provides additional enzymes to help digest all sorts of food. The liver also processes the digested food from your blood before it gets sent to various places in your body to be used.




Blood and the Heart

Blood is what keeps the rest of our body alive. It must be continuously pumped through the body by the heart. Blood carries nutrients and oxygen to cells in our body.

Circulation
Blood circulates constantly through our entire body. As it passes through our body it picks up nutrients from our food and drops them off to cells that need them. It also picks up oxygen from our lungs and drops it off at cells to be used for energy. The blood then picks up waste carbon dioxide from the cells and drops it off at the lungs for us to breathe back out.

Blood Vessels
Blood vessels are tubes throughout our body that carry the blood. There are two main types of blood vessels: arteries and veins. Arteries carry blood from the heart to the rest of the body. Arteries have to be thick and strong as there is more pressure on them from the heart. When you feel your pulse, this is from an artery. Veins carry used blood back to the heart. They don't need to be as thick.

What is in blood?
Over half of blood is made up of red blood cells carrying oxygen. This is why blood looks red. There are also white blood cells which kill germs and keep the blood clean. Blood also has something called platelets which help the blood to clot when you get a cut. Finally, all these cells float in a watery substance called plasma.

The Heart
The heart is a large organ about the size of your fist. It sits in your rib cage just to the left of the center of your chest. The heart is made of a lot of muscle that pumps blood through our bodies. Veins bring blood to the heart to pump back out again on arteries. The main artery leaving the heart is called the aorta. In order for blood not to go backwards, there are valves to make sure the blood only gets pumped in the correct direction. There are four sets of valves in the heart.

external image heart.jpg


The heart has two main pumps. One sends the blood throughout the body, while the other sends blood from the veins up to the lungs to drop off carbon dioxide and pick up more oxygen. The heart beats at different rates depending on what the body is doing. If you're just sitting around, it will beat slowly. If you are running fast, the heart will beat faster to get oxygen to your muscles.

What are blood types?
There are four main blood types: A, B, O, and AB. Each blood type is slightly different and has different antibodies and antigens. It's important that blood donors have matched blood types or a person can get very sick.










III Quarter Test Contents:


Darwin’s theory
Darwin’s Biography
Evidence of Evolution
Body Organization (presentation)
Homeostasis (presentation)
The skeletal System (presentation)
The muscular system (presentation)

Food and energy (presentation)



Presentations:















Month: FebruaryBody Organization
Homeostasis
The skeletal System
The muscular system
Food and energy


Body Organization

You are a member of a very large and complex world. Together with other members of your family, you work to do jobs, like clean your home, set the table, make dinner, and many other important chores. Your family in turn works with other families to do important work. These cooperative efforts might include a neighborhood watch or cleanup. Your neighborhood is part of a larger city, which itself is part of a nation, and then finally, part of the greater international community.

From one individual to an entire planet filled with human beings, each of us have a role to play. Some of us are airline pilots, teachers, doctors, farmers, builders, and more. Without a variety of people with specialized skills working together, our world would be very different. There would be no advancement of technology, no discovery, and medical and food technologies would not exist as they do today.


Cells specialize in specific skills.
Cells specialize in specific skills.

There is a similar organization within the bodies of living things. If we could go inside a living thing, the first thing we would see are what we call cells. Cells are like people in the example above. Each one is an individual entity working hard on specialized jobs. Instead of firefighters, cells might be assigned the job of helping digest food, or carrying messages from the brain, or fighting diseases that enter the body. Cells work along side other cells in what we call tissues. This is similar to how individual people work inside a family, in the example above.







1. The Cell

The cell is the basic unit of life. Some organisms are made up of a single cell, like bacteria, while others are made up of trillions of cells. Human beings are made up of cells, too.


Different Types of Cells

There are lots of different types of cells. Each type of cell is different and performs a different function. In the human body, we have nerve cells which can be as long as from our feet to our spinal cord. Nerve cells help to transport messages around the body. We also have billions of tiny little brain cells and muscle cells which help us move around. There are many more cells in our body that help us to function and stay alive.

Although there are lots of different cells, most of them can be divided into two main categories: prokaryotic and eukaryotic.

Prokaryotic Cells - The prokaryotic cell is a simple, small cell with no nucleus. Most bacteria are prokaryotic. There are three main parts to the prokaryotic cell:
1) the outside of the cell called the cell wall
2) the flagella which is like an appendage and can help the cell to move
3) the inside of the cell called the cytoplasm.

Eukaryotic Cells - these cells are a lot bigger and have a cell nucleus which houses the cell's DNA. These are the types of cells we find in plants and animals.


external image the_cell.png





Parts of the Cell

There are a lot of parts and functions to some cells. Here are some of the main components many cells have:
  • Membrane - This is the outer boundary of the cell. Sort of like the skin. It allows some substances in and keeps others out.
  • Mitochondria - This is where the cell gets its energy. In the human body, food we have digested reacts with oxygen in the mitochondria to make energy for the cell.
  • Ribosomes - Ribosomes are like tiny factories that make different things the cell needs to function, like proteins.
  • Nucleus - The nucleus is the brains of the cell. It uses chromosomes to instruct the rest of the cell what to do next.
  • Cytoplasm - This is the stuff that fills up the rest of the cell. The other components of the cell float around in the cytoplasm. It's mostly water.
  • Lysosomes - These guys clean up the place getting rid of waste and other unwanted substances that may get into the cell.
The machines inside the cell like the nucleus, ribosomes, and lysosomes are called organelles.


Fun Facts About Cells
  • They were discovered by the scientist Robert Hooke.
  • The largest known cells are ostrich eggs. They can weigh over three pounds.
  • When many cells of the same kind are together in a group, it's call tissue.
  • The word cell comes from the Latin word cellula, which means small room.
  • Humans actually carry more bacteria cells than human cells. Yuck!


2. Tissues

A tissue is a family of cells that live very close together, and work hard to do the same jobs. Many tissues come together to form what biologists call an organ. This is like a city in the previous example. Organs then work together to form a system, and eventually the entire body of a lifeform.

In a way, your body is functioning as a mini-planet. Right now within your body, there are billions of individual cells working hard in specialized jobs. These cells join into tissues, organs and systems and help make up a vast community of life within you.


Your body is made up of billions of cells.
Your body is made up of billions of cells.

A doctor does not work alone. He or she works with other doctors, nurses and medical staff to make people healthy. A builder does not work alone. There are other builders who help do the same job. Likewise, most cells do not work alone. They work with other similar cells to form what is called a tissue.

A tissue is a group of similar cells that all work together on the same job. For example, tissues in your lungs are made up of millions of similar cells working together to transport oxygen to the blood. Blood itself is a liquid tissue that transports oxygen, food and waste throughout the body.

Different types of tissues come together to form organs. For example, the heart is an organ made up of muscle tissue, blood tissue, and nerve tissue. An organ has an important job that keeps the living thing alive.

Like animals, plants also have organs. Common plant organs are leaves, stems and roots.


3. Organ Systems

Diagram of human organ systems.
Diagram of human organ systems.

Several organs work together to do an important job. For example, what organs make up the nervous system in a human being? Some of the organs include the brain, the spinal cord, and nerves.

So far we have seen that cells work together to form tissues. Tissues in turn work together forming organs, which themselves work together on important jobs, forming organ systems.

What do you think comes next?


4. Organisms


An organism is a completely self-sufficient lifeform. You are an organism. All of your cells, tissues, organs and organ systems come together to keep you alive. An organism cannot live without its organ systems. Remove the circulatory system from a frog, and what do you think will happen? Without the ability to move blood throughout its body, the frog will die.


Likewise, an organ system cannot live without its fellow organs nor can an organ survive without its tissues and cells. From the smallest cells to the complete organism, everything has a job to do and a role to play.











Homeostasis

Homeostasis in layman's terms means balance or equilibrium. It is the property of an open system to regulate its internal environment so as to maintain a stable condition, by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. The term was coined in 1932 by Walter Cannon[?] from two Greek words (to remain the same). The term usually is used in the sense of biological homeostasis inhumans and animals.
Ecological, biological, and social systems are homeostatic. They oppose change to maintain equilibrium. If the system does not succeed in reestablishing its balance, it will be in a state where constraints are more severe than before. This can ultimately lead to the destruction of the system if the disturbances persist.
Complex systems, such as a human body, must have homeostasis to maintain stability and to survive. These systems do not only have to endure to survive; they must adapt themselves and evolve to modifications of the environment and it must evolve.
Homeostatic systems show several properties
  • they are ultrastable;
  • their whole organisation, internal, structural, and functional, contributes to the maintenance of equilibrium
  • they are unpredictable (the resulting effect of a precise action often has the oppposite effect to what was expected)














The Skeletal System

All the bones in the human body together are called the skeleton. The skeleton provides strength and rigidity to our body so we don't just flop around like jellyfish. We have 206 bones in our body. Each bone has a function. Some bones offer protection to softer more fragile parts of body. For example, the skull protects the brain and the rib cage protects our heart and lungs. Other bones, like bones in our legs and arms, help us to move around by providing support for our muscles.

What are bones made of?
Around 70 percent of your bones are not living tissue, but hard minerals like calcium. The outside of the bone is called the cortical bone. It's hard, smooth, and solid. Inside the cortical bone is a porous, spongy bone material called the trabecular or concellous bone. This bone is lighter allowing for the bone itself to be lighter and easier for us to move around. It also allows room for blood vessels and makes our bones slightly bendable. This way our bones won't break so easily. At the center of bones is a softer substance called marrow.

Bone Marrow
There are two types of bone marrow, yellow and red. Yellow bone marrow is mostly fat cells. Red marrow is important because this is where our body produces red and white blood cells. When we are born, all of our bones have red marrow. By the time we are adults about half of our bones have red marrow.

Joints
Our bones come together and connect at special places called joints. Your knees and elbows are joints, for example. Many joints have a large range of movement and are called ball and socket joints. The shoulder and hip are ball and socket joints. Joints have a smooth, durable material called cartilage. Cartilage, together with fluid, allows bones to rub against each other smoothly and not wear out.

How do broken bones heal?
Your body can heal broken bones all on its own. Of course, a doctor will help it along, making sure that the bone heals straight and properly using a cast or sling. A broken bone will heal in stages. When it first breaks there will be blood around it and it will form a sort of scab over the broken portions. Next, tougher tissue will start to grow over the broken area called collagen. The collagen, together with cartilage, will bridge the gap between the two sides of the break. This bridge will continue to transform and harden until the bone is healed. It can often take months for bones to heal back to normal. While the bone is healing, it can't take the stress of a normal bone, which is why people use crutches and slings to take the pressure off the bone while it's healing.

Fun facts about bones for kids
  • The smallest bones are in the ear.
  • Although your bones stop growing when you are around 20, they do constantly rebuild new bone cells.
  • The spine is made up of 33 bones.
  • Red bone marrow can produce around 5 billion red blood cells each day.
  • Very few man made substances can come close to the lightness and strength of bones.
  • If your body doesn't have enough calcium, it will take it from your bones making your bones weaker. A good reason to drink your milk!


Bones in the Human Body

There are 206 bones in the human body. Over half of these bones are in the hands, which have 54 bones, and the feet, which have 52 bones. Here is the full list:

Bones in the Head:

Cranial bones (8):
frontal, parietal (2), temporal (2), occipital, sphenoid. ethmoid

Facial bones (14):
mandible, maxilla (2), palatine (2), zygomatic (2), nasal (2), lacrimal (2), vomer, inferior nasal conchae (2)

Ear bones (6):
malleus (2), incus (2), stapes (2)

Throat bones (1):
hyoid

Bones below the head:

Shoulder bones(4):
shoulder blade (2), collarbone (2) (also called the clavicle)

Thorax bones (25):
sternum (1), ribs (2 x 12)

Vertebral column bones (24)
cervical vertebrae (7), thoracic vertebrae (12), lumbar vertebrae (5)

Bones in the Arms:

Upper Arm bones (2):
humerus (2)

Forearm bones (4):
radius (2), ulna (2)

Hand Bones (54):

Wrist bones:
scaphoid (2), lunate (2), triquetral (2), pisiform (2), trapezium (2), trapezoid (2), capitate bone (2), hamate (2)

Palm bones:
metacarpals (5 × 2)

Finger bones:
proximal phalanges (5 × 2), intermediate phalanges (4 × 2), distal phalanges (5 × 2)

Pelvis bones (4):
sacrum, coccyx, hip bone (2)

Leg bones (6):

femur or thigh bone (2), patella (2), tibia (2), fibula (2)

Feet bones (52):

Ankle bones:
calcaneus (heel bone) (2), talus (2), navicular (2), medial cuneiform (2), intermediate cuneiform (2), lateral cuneiform (2), cuboid (2), metatarsal bone (5 × 2)

Toe bones:
proximal phalanges (5 × 2), intermediate phalanges (4 × 2), distal phalanges (5 × 2)
external image bones_front_small.jpg

external image bones_back.jpg













The Muscular System

Muscles are how we move and live. All movement in the body is controlled by muscles. Some muscles work without us thinking, like our heart beating, while other muscles are controlled by our thoughts and allow us to do stuff and move around.

There are over 650 muscles in the human body. They are under our skin and cover our bones. Muscles often work together to help us move. We don't really have to think about moving each individual muscle. For example, we just think of running and our body does the rest.


How Muscles Work

Muscles work by expanding and contracting. Muscles have long, thin cells that are grouped into bundles. When a muscle fiber gets a signal from its nerve, proteins and chemicals release energy to either contract the muscle or relax it. When the muscle contracts, this pulls the bones it's connected to closer together.

Many of our muscles come in pairs. An example of this is the biceps and triceps in our arms. When the biceps contract the triceps will relax, this allows our arm to bend. When we want to straighten our arm back out, the biceps will relax and the triceps will contract. Muscle pairs allow us to move back and forth.

Types of Muscles
  • Skeletal Muscles - These are the muscles we use to move around. They cover our skeleton and move our bones. Sometimes they are called striped muscles because they come in long dark and light bands of fibers and look striped. These muscles are voluntary because we control them directly with signals from our brains.

  • Smooth Muscles - Smooth muscles are special muscles that don't connect to bones, but control organs within our body. These muscles work without us having to think about them.

  • Cardiac Muscle - This is a special muscle that pumps our heart and blood through our body.
human muscles
human muscles


Tendons
Tendons connect muscles to bones. Tendons help form a connection between soft contracting muscle cells to hard bone cells.


Muscle Memory

When we practice an action over and over again, we get what is called muscle memory. It allows us to become more skilled at certain activities such as sports and music. As we practice, our muscles tune themselves to become more precise in their motions and to do exactly what our brain wants them to do. So remember, practice makes perfect!


Muscles and Exercise

When we exercise we work our muscles allowing them to become bigger and stronger. Exercise helps keep your muscles strong and flexible. If you don't use your muscles they can atrophy, or shrink and become weak.


Fun Facts about Muscles
  • Shivering is caused by hundreds of muscles expanding and contracting to produce heat and make us warmer.
  • It takes 17 muscles to smile and 43 muscles to frown. All the more reason to smile instead of frown!
  • Our longest muscle is the Sartorius. It runs from the hip to the knee and helps us bend the knee and twist our leg.
  • The strongest muscle is in our jaw and is used for chewing.
  • The smallest muscle is in our ear and is called the stapedius. It is attached to the smallest bone in the body, the stapes.











Food and Energy

Nutrition is how we get the food we need to grow healthy and strong. Vitamins and minerals help our bodies to function and grow.


Why is nutrition important for kids?

Eating good foods is especially important for kids because they are still growing. Kids' bodies need nutrition to grow strong healthy bones and muscles. If you don't get all the vitamins and minerals you need while you are growing, you won't grow as tall and as strong as you could be.


Food Groups

There are five main food groups that you should eat every day. By eating a variety of foods in each of these food groups, you will get the nutrition you need to grow and be healthy.
  • Grains - breads, cereal, pasta, rice
  • Dairy - milk, cheese, yogurt
  • Fruits - apples, oranges, berries, grapes, bananas
  • Vegetables - broccoli, beans, spinach, carrots, peas
  • Protein - beef, chicken, pork, eggs, nuts, fish


My Plate

The United States Department of Agriculture (USDA) has come up with a picture of a plate to help us to make sure we get all the nutrients we need each meal. Here is the picture:


external image nutrition_myplate.jpg




As you can see, each of the five food groups is drawn on the plate. Notice that the vegetables and grains portions are slightly larger than the fruit and protein portions. This gives you an idea of what foods you need to eat and how much of each.

The USDA also gives other guidelines on how to eat healthier. A few that may help you:
  • Drink skim milk or low fat milk.
  • Eat whole grains for your grains. One example is wheat bread instead of white bread.
  • Drink water instead of sugary drinks.


Calories

Calories are a measure of how much energy is in food. When we eat, we gain calories and it gives us energy to run around and do stuff. If we eat more calories than we use moving around, then our body stores up the calories in fat. If we use more calories than we eat, then our body will start to burn up fat that was stored earlier.


Carbohydrates


When most people refer to carbohydrates they are talking about foods that are starchy (like bread, pasta, and rice) or are sugary (like candy, cookies, and cake). In science, when we talk about carbohydrates we are talking about specific types of molecules.



Carbohydrates are one of the four major groups of organic molecules; the other three being proteins,nucleic acids (DNA), and lipids (fats). Carbohydrates are made up of three elements: carbon, hydrogen, and oxygen.



What do they do?



Carbohydrates are important to the daily lives of living organisms. They store energy (starches), provide energy for cells (glucose), and provide structure to plants and some animals.




Types of Carbohydrates



Carbohydrates are sometimes referred to as saccharides. The different types of carbohydrates all have the word "saccharide" in them.

  • Monosaccharides - Monosaccharides are the simplest form of carbohydrates. They include sugars such as glucose and fructose. Monosaccharides often taste sweet and dissolve in water. Glucose is a common carbohydrate found in plants and is the main product of photosynthesis.
  • Disaccharides - Disaccharides are formed from two Monosaccharides. They are also known as sugars such as sucrose and lactose. Lactose is the carbohydrate found in milk.
  • Oligosaccharides - Oligosaccharides are formed from a small number (usually three to six) of monosaccharides.
  • Polysaccharides - Polysaccharides are long carbohydrate molecules. They are often called complex carbohydrates.



There are four important types of complex carbohydrates:

  • Starches - Starches are a way that many plants store energy. We can then eat starches and our bodies will use the energy.
  • Glycogen - Animals use glycogen to store energy. It is stored in the liver and the muscles to be used when needed.
  • Cellulose - Cellulose is used in plants as a structural molecule. It can't be digested by animals.
  • Chitin - Chitin is used as a structural molecule in fungi and arthropods.



What happens to left over carbohydrates?



When you eat carbohydrates your body uses them for energy. However, if you eat more than your body needs, it will convert them into fat. Fat is the way that the body stores energy for later use. The body is trying to save up energy for a later time when you don't have any carbohydrates to eat.




Interesting Facts about Carbohydrates

  • Most of the time, the hydrogen to oxygen atom ratio of a carbohydrate is 2 hydrogen atoms for every 1 oxygen atom. This is the same ratio as in water (H2O).
  • The word "saccharide" comes from the Greek word "sakkharon" which means "sugar."
  • Carbohydrates make up between 2 and 3 percent of the average person's body mass.
  • Some carbs help our bodies to absorb calcium.
  • Many people try using a low carb diet to lose weight, but we all need some carbohydrates to survive.
  • Carbohydrates help to insure that our cells get the energy they need to perform well.


Fats and Lipids

Lipids are one of the four major groups of organic molecules; the other three being proteins, nucleic acids (DNA), and carbohydrates (sugars). Lipids are made up of the same elements as carbohydrates: carbon, hydrogen, and oxygen. However, lipids tend to contain many more hydrogen atoms than oxygen atoms.

Lipids include fats, steroids, phospholipids, and waxes. One main characteristic of lipids is that they do not dissolve in water.


What do they do?

Lipids play an important role in living organisms. Some of their main functions include energy storage, hormones, and cell membranes.


Types of Lipids


Fats

  • What are fats?
Fats are composed of a glycerol molecule and three fatty acid molecules. Just like all lipids, fat molecules are made up of the elements carbon, hydrogen, and oxygen. Fat is used as energy storage in our bodies.

  • Are all fats bad?
No, as a matter of fact, fats are needed by our bodies to be healthy. We couldn't live without some fats in our diet. Most people need to get around 20%-30% of their food from fats. However, too much fat can be bad for you. It can cause you to be overweight and clog up your arteries.

  • Types of Fats
There are two main types of fats: saturated fats and unsaturated fats.

    • Saturated Fats - Saturated fats are solids at room temperature. These fats tend to come from foods like red meat, cheese, and butter. Saturated fats are sometimes called "bad" fats because they have been known to cause higher cholesterol, clog arteries, and even increase the risk for some cancers.
    • Unsaturated Fats - Unsaturated fats are liquids at room temperature. These fats tend to come from foods like nuts, vegetables, and fish. Unsaturated fats are considered much better for you than saturated fats and are sometimes called "good" fats.
WaxesWaxes are similar to fats in their chemical make up, however they only have one long fatty acid chain. Waxes are soft and plastic at room temperatures. They are produced by animals and plants and are typically used for protection. Plants use waxes to help prevent water loss. Humans have wax in our ears to help protect our eardrums.

Steroids
Steroids are another major group of lipids. Steroids include cholesterol, chlorophyll, and hormones. Our bodies use cholesterol to make the hormones testosterone (male hormones) and estrogen (female hormones). Chlorophyll is used by plants to absorb light for photosynthesis.

Are steroids bad for you?

Not all steroids are bad. Our bodies need steroids like cholesterol and cortisol to survive, so some steroids are good for us. There are also many steroids that doctors use to help sick people.

However, the type of steroids you hear about in sports, anabolic steroids, can be very bad for you. They can cause all sorts of damage to your body including strokes, kidney failure, blood clots, and liver damage.

Phospholipids
Phospholipids make up the fourth major group of lipids. They are very similar to fats in their chemical make up. Phospholipids are one of the main structural components of all cell membranes.


VitaminsVitamin A
  • Eyes, immune system, skin
  • Milk, eggs, orange and green vegetables
Vitamin C
  • Bones, blood vessels, teeth, gums, healing, brain
  • Berries, bell peppers, oranges, spinach, tomatoes
Vitamin D
  • Bones
  • Sunlight, milk, fish oil, eggs
Vitamin E
  • Blood, cells
  • Nuts, green leafy vegetables, whole grains
Vitamin B12
  • Red blood cells, nerves
  • Fish, milk, cheese, red meat, chicken
Vitamin B6
  • Brain, nerves, proteins
  • Bananas, nuts, red meat, chicken, fish, eggs, beans
Thiamin (B1)
  • Muscles, nervous system, heart
  • Meat, fish, beans, peas
Niacin (B3)
  • Skin, nerves
  • Chicken, red meat, peanuts, fish
Riboflavin (B2)
  • Energy, red blood cells, eyes
  • Meat, eggs, peas, nuts, milk, green vegetables
Folate (B9, folic acid)
  • Red blood cells, DNA
  • Green vegetables, beans, liver, oranges

MineralsCalcium
  • Bones and teeth
  • Milk, yogurt, cheese, green vegetables
Iron
  • Blood
  • Red meat, poultry, soy, green leafy vegetables, fish, pork
Magnesium
  • Muscles, nerves, bones, energy
  • Nuts, whole grains, breads, bananas, milk
Phosphorus
  • Bones, teeth, energy, cells
  • Milk, meat, fish
Potassium
  • Muscles, nervous system
  • Potatoes, broccoli, bananas, fruits
Zinc
  • Growth, immune system, healing
  • Red meat, seafood, nuts, milk, whole grains, poultry



















Month: January
Human inheritance
Human Genetic Disorders
Human genetic disorders
Advances in Genetics
Darwin’s theory
Nature at Work
Evidence of Evolution



Genes and Heredity

external image img1.jpeg

Heredity is the passing of genes from one generation to the next. You inherit your parents' genes. Heredity helps to make you the person you are today: short or tall, with black hair or blond, with brown eyes or blue.
Can your genes determine whether you'll be a straight-A student or a great athlete? Heredity plays an important role, but your environment (including things like the foods you eat and the people you interact with) also influences your abilities and interests.
A person can have changes (or mutations) in a gene that can cause many issues for them. Sometimes changes cause little differences, like hair color. Other changes in genes can cause health problems.
Mutations in a gene usually end up causing that particular gene copy to not do its job the way it normally should. Since we have two copies of every gene, typically there's still a "normal" working copy of the gene. In these cases, usually nothing out of the ordinary happens since the body can still do the jobs it needs to do. This is an example of an autosomal recessive trait.
For someone to have a recessive disease or characteristic, the person must have a gene mutation in both copies of the gene pair, causing the body to not have working copies of that particular gene.
Genes can be either dominant or recessive. Dominant genes show their effect even if there is just one mutation in one copy of that gene pair; the one mutation "dominates" the normal back-up copy of the gene, and the characteristic shows itself.
A person can be born with gene mutations, or they can happen over a lifetime. Mutations can occur when cells are aging or have been exposed to certain chemicals or radiation. Fortunately, cells usually recognize these types of mutations and repair them by themselves. Other times, however, they can cause illnesses, such as some types of cancer.
If the gene mutation exists in egg or sperm cells, children can inherit the gene mutation from their parents. When the mutation is in every cell of the body (meaning a child was born with it), the body is not able to "repair" the gene change.


What Are Genetic Disorders?


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Researchers have identified more than 4,000 diseases that are caused by mutations. But having a genetic mutation that may cause a disease or condition doesn't always mean that a person will actually develop that disease or condition.
On average, people probably carry from 5 to 10 genes with mutations in each of their cells. Problems happen when the particular gene is dominant or when a mutation is present in both copies of a recessive gene pair. Problems can also happen when several variant genes interact with each other — or with the environment — to increase susceptibility to diseases.
If a person has a change in a dominant gene that is associated with a particular condition, he or she will usually have features of that condition. And, each of the person's children will have a 1 in 2 (50%) chance of inheriting the gene and developing the same features. Diseases and conditions caused by a dominant gene include achondroplasia (pronounced: ay-kon-druh-PLAY-zhuh, a form of dwarfism), Marfan syndrome (a connective tissue disorder), and Huntington disease (a degenerative disease of the nervous system).
People who have a change in just one copy of a recessive gene are called "carriers." They don't usually have the disease because they have a normal gene copy of that pair that can do the job. When two carriers have a child together, however, the child has a 1 in 4 (25%) chance of getting a gene with a mutation from both parents, which would result in the child having the disease. Cystic fibrosis (a lung disease), sickle cell anemia (a blood disorder), and Tay-Sachs disease (which causes nervous system problems) are caused by recessive mutations from both parents coming together in a child.
With recessive gene mutations on the X chromosome, usually only guys can develop the disease because they have only one X chromosome. Girls have two X chromosomes — since they have a back-up copy of another X chromosome, they don't always show features of X-linked conditions. These include the bleeding disorder hemophilia (pronounced: hee-muh-FIL-ee-uh) and color blindness.
Sometimes when an egg and sperm unite, the new cell gets too many or too few chromosomes, which can cause issues for the child. For example, most children born with Down syndrome have an extra chromosome number 21.
In some cases, people who are concerned that they might carry certain variant genes can have genetic testing so they can learn their children's chances of inheriting a disease. Pregnant womencan also have tests done to see if the fetus they are carrying might have certain genetic illnesses. Genetic testing usually involves taking a sample of someone's blood, skin, or amniotic fluid and checking it for genetic changes.

Changing Genes
Sometimes scientists alter genes on purpose. For many years, researchers have altered the genes in plants to produce other plants with special characteristics, such as an increased resistance to disease and pests or the ability to grow in difficult environments. We call this genetic engineering.
Gene therapy is a promising new field of medical research. In gene therapy, researchers try to supply copies of healthy genes to cells with variant or missing genes so that the "good" genes will take over. Viruses are often used to carry the healthy genes into the targeted cells because many viruses can insert their own DNA into targeted cells.
But there are problems with gene therapy. Scientists still don't quite know what every gene in the human body does. Huge scientific efforts like The Human Genome Project and related projects have completed a map of the entire human genome (all of the genetic material on a living thing's chromosomes), but it will take many more years to find out what each gene does and how they interact with one another. For most diseases, scientists don't know if and how genes play a role. Plus, there are major difficulties inserting the normal genes into the proper cells without causing problems for the rest of the body.
There are also concerns that people might try changing genes for ethically troubling reasons, such as to make smarter or more athletic children. No one knows what the long-term effects of that kind of change would be.
Still, for many people who have genetic diseases, gene therapy holds the hope that they — or their children — will be able to live better, healthier lives.


Who Was Charles Darwin?
Who was Charles Darwin? You’ve probably seen a picture of him and he probably had a bald head, a huge bushy beard, a bit of a funny nose and he probably looked a bit miserable. But he wasn’t always like that! Charles had an amazing life; he travelled the world, saw volcanoes explode and earthquakes, rode on the back of giant tortoises, and went hunting for ostriches. When he came home, he changed the way we think about living things!

Too Cool For School!
Too cool for school!
Too cool for school!

Darwin’s father was a very fat doctor who lived in Shrewsbury, England with his wife. Charles was their fifth child, born on 12th February 1809. Sadly his mum died soon afterwards, but he had lots of older sisters to look after him and a big brother called Erasmus who was his best friend.
Charles and Erasmus got up to all sorts! They set up a lab in their garden shed – a hobby which earned Charles the nickname “Gas” at school. Charles was also a big collector, stuffing his pockets with creepy crawlies, stones and bits of plants. He loved exploring the country side around his house and often went for long walks.
Charles loved nature, but he hated school. He had to learn Latin and Greek texts off by heart and thought it was ridiculously boring! When he was older he said he learnt absolutely nothing useful at school! But Charles’ Dad just thought he was lazy so sent him to Edinburgh in Scotland to learn medicine and become a doctor.
But Charles hated medicine too! In those days there were no painkillers and operations were performed on patients when they were awake – there was lots of blood and screaming and the young Darwin couldn’t bear it! He spent most of his time on the beach looking at sponges.
So Charles quit medicine and his Dad suggested a new career – he could become a priest! Off Charles went to Christ’s College, Cambridge to study to become a priest… but he didn’t really like that! He spent all his time with his cousin collecting thousands of beetles and putting them in boxes. He also set up a dinner club which ate exotic meats!
At Cambridge Charles met Professor Henslow who was big into plants, and Professor Sedgwick who was big into rocks. They took Charles under their wing and taught him how to study nature in a scientific way. Finally Charles found something he loved!

The Voyage Of A Lifetime.


The voyage of a lifetime.
The voyage of a lifetime.
When Charles was 22 he was invited to join a voyage round the world. H.M.S. Beagle was a ship responsible for travelling the globe, making maps of coastlines. The ship’s captain, Robert FitzRoy, was a lonely man and wanted a friend for the trip to keep him company. The Beagle was to go all the way across the Atlantic to South America to draw maps of the coastline. They returned home via the Galapagos, New Zealand, Australia and South Africa. It took five years!
Darwin’s time on the Beagle was mixed; when they were at sea he was horribly sea sick and couldn’t do anything except lie in his hammock nibbling biscuits and reading books. One book he read was by a man called Charles Lyell, who was big into rocks. Lyell had decided that the earth was very old, millions of years old, and that over time it had changed very slowly. He also said that we can see this happening today
When the Beagle docked at land Charles was free to explore! He set about testing Lyell’s idea, in his five years abroad he witnessed earthquakes and volcanoes, and found fossils of seashells on top of the world’s biggest mountains. Everything he saw convinced Charles that Lyell was right, so he started thinking about life as being very old and possibly changing slowly over time.
In South America Charles found some amazing fossils. Fossils are the remains of very old animals and plants that have been buried and turned into rock. Charles found fossils of ten foot tall sloths, and huge cow-sized armadillos! These fossils convinced him further that life on earth was very old.
When the Beagle stopped at the Galapagos Islands, in the Pacific Ocean, Darwin found some really strange animals. He found lizards that swam in the sea and ate algae, tortoises big enough to be ridden like horses, and birds that were so fearless you could grab them by the legs! Darwin noticed a type of bird called a mockingbird was very similar to the mockingbirds he had seen in South America. Similar, but also different! He wondered if the two birds were related.
He collected lots of specimens while he was away, enough to fill all his storage on the ship and more! Some of the specimens he collected were finches from the Galapagos; these are now very famous. When Charles got home he asked a bird expert about them and was told instead of being one species, there were 13! Charles thought they were all related to the finches in South America but that they had evolved into many different species!

What Is Evolution?
external image Human-Evolution.jpg

Evolution is the slow process that changes animals and plants and it’s a great piece of science! It describes loads of things in nature like fossils, peacocks' tails, lions’ teeth, birds’ wings and human brains, just to name a few. It is also supported by lots and lots of evidence that has been collected by scientists for more than 150 years! Some people think it’s not true. They prefer religious explanations of why nature is like it is, but the evidence says that evolution is the real explanation.

What Is A Species?
A species is a group of animals or plants that are very similar. Members of a species share the same characteristics. For example the species pet cats belong to all have sharp teeth, retractable claws, fur, a tail and the same number of toes and nipples. Members of our own species, Homo sapiens, to give it its proper name all walk upright, have some sharp teeth and some flat ones, our eyes point forwards, we have some hair but not all over and we have pretty big brains!
Scientists often decide whether two groups of animals or plants are different species by working out whether or not they can mate with each other. If you try and get a rose to make seeds with a cabbage it won’t work: they are separate species. If you try and get a rose to make seeds with another rose that will work: they are the same species even if they look quite a lot different!
Of course you can’t go around trying to force lots of animals and plants to mate with each other! Scientists can use other more subtle measures, for example if two groups of birds look really similar but sing different songs and don’t seem to find each other attractive, it's a good bet they are different species.

How Do Species Evolve?
How do species evolve?
How do species evolve?

All species are related to each other. If you trace your family tree back through your parents, grandparents etc. it will quite quickly join up with your cousin’s family tree. If you keep going back far enough, eventually your tree will join up with that of a chimpanzee! Keep going and it will join up with your pet hamsters, further still with your pet cats. Keep going and eventually it will join up with your pet goldfish and if you really keep going for a long time you can trace it back so it joins up with an apple tree’s family tree, and eventually bacteria will join up too!
So what makes all the species different? Charles Darwin had the answer! Animals and plants produce too many offspring. Think about how many tadpoles you see at the start of spring, and how few frogs you see at the end of spring. A lot of them die, because there is not enough food to go around. Of course they all try their best to get all the food they need, so they have to compete with each other.
Darwin realised all the members of a species are unique, they are all slightly different. Sometimes this can be the difference between life and death! Think about a bird which eats seeds which have a tough case like a nut. When nuts are in short supply only the really strong birds with big beaks will be able to crack them open and eat them. Since they get more food, they will be less likely to starve or get sick.
Now, since offspring inherit a lot of their characteristics from their parents birds with big beaks will have chicks that grow up to have big beaks too. So over many generations the average beak size in that group of birds which struggle to crack tough nuts will increase. Each generation changes by a really little bit, but all these changes can be added up over time to make a big difference: that’s evolution! Darwin called this process natural selection.

What About Us?
What about us?
What about us?

When Darwin told the world about his discovery in his book On the Origin of Specieshe didn’t really say anything about humans other than to hint his ideas would reveal the secrets of human history. But the message was clear; natural selection is the process which has shaped all species, including us!
Other scientists wrote books about human evolution, often comparing our bones to those of apes and monkeys. Eventually Darwin decided to write a book about it too to set the record straight about what the thought about humans. He wrote a book called The Descent of Man. He presented lots of evidence to support the theory that humans evolved from apes. He also argued that all the different human races were one species, which was a keenly debated subject in Victorian times.
We now know lots more about evolution, and all proper scientists agree Darwin was spot on! But how do we know?











Science Fair!!
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Science Fair Booklet:



Ideas on Science Fair Projects:


http://www.sciencebuddies.org/science-fair-projects/recommender_interest_area.php?ia=Phys&dl=9



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Month: DecemberProbability and Heredity
The DNA Connection

DNA and Genes

DNA is an essential molecule for life. It acts like a recipe holding the instructions telling our bodies how to develop and function.

What does DNA stand for?

DNA is short for deoxyribonucleic acid.

What is DNA made of?

DNA is a long thin molecule made up of something called nucleotides. There are four different types of nucleotides: adenine, thymine, cytosine, and guanine. They are usually represented by their first letter:
  • A- adenine
  • T- thymine
  • C - cytosine
  • G - guanine
Holding the nucleotides together is a backbone made of phosphate and deoxyribose. The nucleotides are sometimes referred to as "bases".

external image DNA_structure.gif
The basic structure of the DNA molecule


Different Cells in the Body

Our bodies have around 210 different types of cells. Each cell does a different job to help our body to function. There are blood cells, bone cells, and cells that make our muscles. Cells get their instructions on what do to from DNA. DNA acts sort of like a computer program. The cell is the computer or the hardware and the DNA is the program or code.

The DNA Code

The DNA code is held by the different letters of the nucleotides. As the cell "reads" the instructions on the DNA the different letters represent instructions. Every three letters makes up a word called a codon. A string of codons may look like this:

ATC TGA GGA AAT GAC CAG


Even though there are only four different letters, DNA molecules are thousands of letters long. This allows for billions and billions of different combinations.

Genes

Within each string of DNA are sets of instructions called genes. A gene tells a cell how to make a specific protein. Proteins are used by the cell to perform certain functions, to grow, and to survive.

Shape of the DNA Molecule

Although DNA looks like very thin long strings under a microscope, it turns out that DNA has a specific shape. This shape is called a double helix. On the outside of the double helix is the backbone which holds the DNA together. There are two sets of backbones that twist together. Between the backbones are the nucleotides represented by the letters A, T, C, and G. A different nucleotide connects to each backbone and then connects to another nucleotide in the center.

Only certain sets of nucleotides can fit together. You can think of them like puzzle pieces: A only connects with T and G only connects with C.







Month: November
Chemical compounds in cells
Photosynthesis
Respiration


Cell Division
Mendel's Work



What is photosynthesis?
Have you ever noticed that plants need sunlight to live? It seems sort of strange doesn't it? How can sunlight be a type of food? Well, sunlight is energy and photosynthesis is the process plants use to take the energy from sunlight and use it to convert carbon dioxide and water into food.


Three things plants need to live:

Plants need three basic things to live: water, sunlight, and carbon dioxide. Plants breathe carbon dioxide just like we breathe oxygen. When plants breathe carbon dioxide in, they breathe out oxygen. Plants are the major source of oxygen on planet Earth and help keep us alive.


We know now that plants use sunlight as energy, they get water from rain, and they get carbon dioxide from breathing. The process of taking these three key ingredients and making them into food is called photosynthesis.



How do plants capture sunlight?


Plants capture sunlight using a compound called chlorophyll. Chlorophyll is green, which is why so many plants appear green. You might think at first that it's green because it wants to absorb and use green light. However, from our study of light, we know that the color we see is actually the color of light that is reflected. So chlorophyll actually reflects green light and absorbs blue and red light.



Inside a plant's cells are structures called chloroplasts. It's in these structures where the chlorophyll resides. The first thing that happens is that sunlight is captured and the energy is stored in a chemical called ATP. Later ATP is used to create sugar and organic compounds which are the main food plants use to live and grow. The first part of the process must have sunlight, the second part can happen without light and even at night. The second part is called the Calvin Cycle because it was discovered and described by scientist Melvin Calvin.



external image photosynthesis.png





Even though plants need sunlight and water to live, different plants need different amounts of each. Some plants need just a little water while others need a lot. Some plants like to be in the direct sunlight all day, while others prefer the shade. Learning about the needs of plants can help you learn where to plant them in your yard and how best to water them so they will flourish.




































Mendel and Inheritance

What is heredity?
Heredity is when certain traits are passed from the parents to the children. Traits are characteristics such as eye color, height, and athletic ability. Heredity is passed through genes in the DNA molecule. In biology the study of heredity is called genetics.

Mendel's Experiments
Gregor Mendel studied seven traits of the pea plant: seed color, flower position, flower floor, seed shape, pod shape, pod color, and the stem length. There were three major steps to Mendel's experiments:

1. First he produced a parent generation of true-breeding plants. He made these by self-fertilizing the plants until he knew they bred true to the seven traits. For example, the purple flowering plants always produced seeds that made purple flowers. He called these plants the P generation (for parent).
2. Next, he produced a second generation of plants (F1) by breeding two different true-breeding P plants.
3. He then produced a third generation of plants (F2) by self-pollinating two F1 generation plants that had the same traits.


Mendel's Results

Mendel found some incredible results from his experiments.

F1 Generation

Mendel found that the F1 generation all produced the same trait. Even though the two parents had different traits, the offspring always had the same trait. For example, if he bred a P plant with a purple flower with a P plant with a white flower, all of the offspring (F1) plants would have purple flowers. This is because the purple flower is the dominate trait.

These results can be shown in a diagram called a Punnett square. The dominate gene is shown with a capital letter and the recessive gene with a lower case letter. Here the purple is the dominant gene shown with a "P" and the white is the recessive gene shown with a "w."



P
P
w
Pw
Pw
w
Pw
Pw


You can go to this page to learn more about inheritance patterns and Punnett Squares.

F2 Generation

In the F2 generation he found that 75% of the flowers were purple and 25% were white. Even though both parents had purple flowers, 25% of the offspring had white flowers. This turned out to be because of a recessive gene or trait was present in both parents.

Here is the Punnett square showing that 25% of the offspring had two "w" genes causing them to have white flowers:



P
w
P
PP
Pw
w
Pw
ww


Homozygous and Heterozygous

When two of the genes are the same (like with "PP" or "ww" above) they are called homozygous. When they are different (like with "Pw") they are called Heterozygous.





Chromosomes
What are chromosomes?

Chromosomes are tiny structures inside cells made from DNA, RNA, and protein. The information inside chromosomes act like a recipe that tells cells how to function and replicate. Every form of life has its own unique set of instructions, including you. Your chromosomes describe what color eyes you have, how tall you are, and whether you're a boy or a girl.

Inside the Cell

Chromosomes are found in the nucleus of every cell. Different forms of life have a different number of chromosomes in each cell. Humans have 23 pairs of chromosomes for a total of 46 chromosomes in each cell.

Can we see them?

Normally we can't see chromosomes. They are so small and thin, we can't see them even with a powerful microscope. However, when a cell gets ready to divide, the chromosomes wind themselves up and become tightly packed. With a high powered microscope, scientists can see chromosomes. They are usually in pairs and look like short little worms.

What do they look like?

When a cell is not dividing (called the interphase of the cell cycle), the chromosome is in its chromatin form. In this form it is a long, very thin, strand. When the cell begins to divide, that strand replicates itself and winds up into shorter tubes. Before the split, the two tubes are pinched together at a point called the centromere. The shorter arms of the tubes are called the "p arms" and the longer arms are called the "q arms."
external image chromosome.png
Different Chromosomes

Different chromosomes carry different types of information. For example, one chromosome may contain information on eye color and height while another chromosome may determine blood type.

Genes

Within each chromosome are specific sections of DNA called genes. Each gene contains the code or recipe to make a specific protein. These proteins determine how we grow and what traits we inherit from our parents. The gene is sometimes called a unit of heredity.

Allele

When we talk about a gene we are referring to a section of DNA. One example of this would be the gene that determines the color of your hair. When we talk about the specific sequence of a gene (like the sequence that gives you black hair versus the sequence that gives you blonde hair), this is called an allele. So everyone has a gene that determines their hair color, only blondes have the allele that makes the hair blonde.

Human Chromosomes

As we mentioned above, humans have 23 different pairs of chromosomes for a total of 46 chromosomes. We all get 23 chromosomes from our mother and 23 from our father. Scientists number these pairs from 1 to 22 and then an extra pair called the "X/Y" pair. The X/Y pair determines if you are a boy or a girl. Girls have two X chromosomes called the XX, while boys have an X and a Y chromosome called the XY.

Chromosomes in Different Animals

Different organisms have different numbers of chromosomes: a horse has 64, a rabbit 44, and a fruit fly has 8.

Interesting Facts about Chromosomes

  • Some animals have lots of chromosomes, but much of the DNA is blank. This blank DNA is called "junk DNA."
  • Nearly every cell in your body carries a complete set of chromosomes.
  • Some chromosomes are longer than others because they contain more DNA.
  • Humans have about 30,000 genes in their 46 chromosomes.
  • The word "chromosome" comes from the Greek words "chroma", meaning color, and "soma", meaning body.




Ideas of DNA Models:
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Month: October:

Looking Inside Cells
Chemical Compounds in Cells
The Cell in Its Environment

Chemical compounds in cellsPhotosynthesisRespiration


Cells are the Starting Point
external image cell_over1.gifAll living organisms on Earth are divided in pieces called cells. There are smaller pieces to cells that include proteins andorganelles. There are also larger pieces called tissues andsystems. Cells are small compartments that hold all of the biological equipment necessary to keep an organism alive and successful on Earth.

A main purpose of a cell is to organize. Cells hold a variety of pieces and each cell has a different set of functions. It is easier for an organism to grow and survive when cells are present. If you were only made of one cell, you would only be able to grow to a certain size. You don't find single cells that are as large as a cow. Also, if you were only one cell you couldn't have a nervous system, no muscles for movement, and using the internet would be out of the question. The trillions of cells in your body make your life possible.






external image Animal_Cell_Diagram.jpg
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Parts of the Cell

There are a lot of parts and functions to some cells. Here are some of the main components many cells have:

  • Membrane - This is the outer boundary of the cell. Sort of like the skin. It allows some substances in and keeps others out.
  • Mitochondria - This is where the cell gets its energy. In the human body, food we have digested reacts with oxygen in the mitochondria to make energy for the cell.
  • Ribosomes - Ribosomes are like tiny factories that make different things the cell needs to function, like proteins.
  • Nucleus - The nucleus is the brains of the cell. It uses chromosomes to instruct the rest of the cell what to do next.
  • Cytoplasm - This is the stuff that fills up the rest of the cell. The other components of the cell float around in the cytoplasm. It's mostly water.
  • Lysosomes - These guys clean up the place getting rid of waste and other unwanted substances that may get into the cell.





Fun Facts About Cells
  • They were discovered by the scientist Robert Hooke.
  • The largest known cells are ostrich eggs. They can weigh over three pounds.
  • When many cells of the same kind are together in a group, it's call tissue.
  • The word cell comes from the Latin word cellula, which means small room.
  • Humans actually carry more bacteria cells than human cells. Yuck!

Some Videos to Watch:





















































Month: September
What is Life?
Classifying OrganismsDiscovering CellsLooking Inside CellsChemical Compounds in CellsThe Cell in Its Environment


What is a Living Thing?

Riddle:
What is every color, is on you, in you, and all around you,

is both very large and very small, can be eaten, and can eat you?
Answer:
Life.

Look around you. What do you see? A classmate, a brother or sister? Look out the window, or go for a walk. You will see trees, grass, plants, dogs, cats, bugs, and many other forms of life.

external image grass.jpg

Now, think about this. Life extends much further than what you can see. Everywhere around you, all over your keyboard, the computer monitor, your desk, the walls, the floor, the ceiling, your clothes, and even your skin, you can find billions and billions of tiny microscopic lifeforms.


Life is all around us. From many kilometers (miles) into the atmosphere, to many meters (feet) beneath the surface of the Earth, life is everywhere. What is this stuff we call life? What are some things that all life forms have in common?



Living Things Are Made of Cells
All living things are made up of cells. These cells are the basic building blocks of life. As an example, have you ever seen a sandcastle? At a distance, the sandcastle looks like a smooth brown building. As you get closer to the sandcastle, you can begin to see that it is not one smooth building, but instead that it is made up of millions of tiny grains of sand.



external image sandcastle.jpg


Looking at an elephant, you might see what looks like a smooth gray animal. And it is true that this is what you are seeing. However, just like the sandcastle, if you could get close enough, and if your eyes were powerful enough, you would realize that what looks like a smooth gray surface, is really made up of many billions of smaller objects called cells.


Cells are tiny units of living materials separated by a cellular wall, or barrier. These cells are so small, that they can only be seen with a powerful tool known as a microscope. Cells make up every part of a living thing. Your skin, your hair, fingernails, blood, bones, nerves, and muscles are all made up of cells. These cells work together to keep the lifeform alive.



Many lifeforms can move. Just like you, they might move to find food, to find shelter, to avoid danger, or in response to their environment. Animals move in many different ways. They might use fins to push them through the water, wings to help them fly, paws and tails to help them move on land.

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Plants also move. They of course cannot move as well as animals, but many plants move their stems to face the Sun, open and close flowers, and more. Some carnivorous plants even move to trap prey.






Living Things Perform Chemical Reactions
Inside living things, very complex chemical reactions are taking place. Chemical reactions take place outside of living organisms as well, but not on anywhere near the same level. A living organism is a mini-chemistry lab. These chemical reactions are carrying out the functions necessary for life, including breaking down food so that it can be used for energy, creating food, building new cells, repairing body parts and more.



Living Things Grow
What would you like to be when you grow up? Well, first you must eat a lot of food and get your rest. These things are necessary for your body to grow. Like you, other living things also grow. Almost all living things start their lives as smaller infant-like creatures. Over a period of time, they grow and develop into adults. Some lifeforms, such as frogs, start their life in a completely different form, and then change dramatically as they grow. A frog begins its life as a tadpole, then turns into an adult frog. A butterfly starts its life as a caterpillar before maturing into a full grown beautiful butterfly.


external image living_things_grow.jpg

Living Things Respond To The Environment Around Them
One of the most important characteristics of living things is that they respond to the environment around them. This one single characteristic makes them very different from non-living things, which do not respond to the environment, but instead just let whatever happens to them happen.
Your own body responds to its environment in order to keep you healthy. You might sneeze to keep dust and germs from entering through your nose, your immune system responds to invaders by producing antibodies, etc. Now consider a non-living thing. If a bear invades a cave, can the cave sneeze to get it out? Does the cave produce antibodies to attack the bear? You can see why this ability is so unique and important to living things.



Living Things Reproduce
A very important part of the life of living things is the ability and opportunity to reproduce, to create offspring. Reproduction is the process of one or more living things creating another living thing. Your parents created you. A mother and father dog reproduce, creating puppies. By reproducing, living things are able to pass on their characteristics to another generation.

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Living Things Die

Something that is definitely unique to living things is that they die.

Anything that is alive will eventually die. The period of time that something is expected to live is called the living thing‘s “lifespan.” The lifespan of living things can vary significantly.





Some things have a lifespan of only a few hours or a couple of days. Some bacteria and insects, for example, begin their lives, mature, reproduce, and then die, all within a couple hours. Other living things can live for many years, such as an elephant that might live for 70 years, and a human which can live for 100 years. Then there are the living things which seem to live forever. A bristlecone pine tree can live 5,500 years. That means that today there are bristlecone pine trees alive that began their lives before ancient Rome, and even before many of the ancient Egyptian pharaohs. Even these long living organisms will all eventually die.


Scientific Classification
Biological Classification is the way scientists use to categorize and organize all of life. It can help to distinguish how similar or different living organisms are to each other.

An example of Classification

Biological classification works a bit like the library does. Inside the library books are divided up into certain areas. The kids books in one section, the adult books in another, and the teen books in another section. Within each of those sections, there will be more divisions like fiction, non-fiction. Within those sections there will be even more divisions such as mystery, science fiction, and romance novels in the fiction section. Finally you will get down to a single book.

Biological classification works the same way. At the top there are the kingdoms. This is sort of like the adult section vs. the kids' section. The kingdoms divide up life into big groups like plants and animals. Under the kingdoms are more divisions which would be like fiction, non-fiction, mystery, etc. Finally, you get to the species, which is sort of like getting to the book in the library.

7 Major Levels of Classification

There are seven major levels of classification: Kingdom, Phylum, Class, Order, Family, Genus, and Species. The two main kingdoms we think about are plants and animals. Scientists also list four other kingdoms including bacteria, archaebacteria, fungi, and protozoa. Sometimes an eighth level above the Kingdom called the Domain is used.

Classification for Humans

Here is an example of how humans are classified. You will see that our species is homo sapiens.

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: Homo sapiens
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