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Ck 12: Life Science: Seasonal Changes in Plants
[Free Registration/Login may be required to access all resource tools.] Have you seen the leaves of plants change colors? During what time of year does this happen? What causes it to happen? Plants can sense changes in the seasons....
CK-12 Foundation
Ck 12: Life Science: Symbiotic Relationships of Fungi
[Free Registration/Login may be required to access all resource tools.] Fungi don't live in isolation. They often interact with other species. In fact, fungi can be dependent on another organism for survival. When two species live close...
CK-12 Foundation
Ck 12: Life Science: Types of Nutrients
[Free Registration/Login may be required to access all resource tools.] Carbohydrates, proteins, and lipids contain energy. When your body digests food, it breaks down the molecules of these nutrients. This releases the energy so your...
CK-12 Foundation
Ck 12: Life Science: Vascular Seedless Plants
[Free Registration/Login may be required to access all resource tools.] Vascular seedless plants have vascular tissue but do not have seeds. Most of the large vascular seedless plants from ancient times are now extinct, but their smaller...
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Ck 12: Life Science: Viruses
[Free Registration/Login may be required to access all resource tools.] We have all heard of viruses. The flu, the common cold, and many other diseases are caused by viruses. But what is a virus? Do you think viruses are living? Which...
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Ck 12: Life Science: Water Cycle
[Free Registration/Login may be required to access all resource tools.] Water and elements like carbon and nitrogen are constantly being recycled through the environment. This process is called a biogeochemical cycle because it involves...
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Ck 12: Life Science: Fish
[Free Registration/Login may be required to access all resource tools.] What exactly is a fish? You probably think the answer is obvious. You may say that a fish is an animal that swims in the ocean or a lake, using fins. But not all...
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Ck 12: Life Science: How the Eye Works
[Free Registration/Login may be required to access all resource tools.] The job of the eye is to focus light. The parts of the eye help it to carry out its job. Follow the path of light through the eye as you read about it. Learn more...
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Ck 12: Life Science: Skin
[Free Registration/Login may be required to access all resource tools.] Did you know that you see the largest organ in your body every day? You wash it, dry it, cover it up to stay warm, and uncover it to cool off. Yes, your skin is your...
CK-12 Foundation
Ck 12: Life Science: Birds
[Free Registration/Login may be required to access all resource tools.] There is an amazingly wide variety of birds. Birds are vertebrates. Almost all have forelimbs modified as wings, but not all birds can fly. Learn more about birds in...
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Ck 12: Life Science: Components of Blood
[Free Registration/Login may be required to access all resource tools.] Did you know that blood is a tissue? Blood is a fluid connective tissue that is made up of red blood cells, white blood cells, platelets, and plasma. Learn more...
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Ck 12: Life Science: Fungi
[Free Registration/Login may be required to access all resource tools.] Ever notice blue-green mold growing on a loaf of bread? Do you like your pizza with mushrooms? Has a physician ever prescribed an antibiotic for you? Learn more...
CK-12 Foundation
Ck 12: Life Science: Heart
[Free Registration/Login may be required to access all resource tools.] What does the heart look like? How does it pump blood? Learn more about the heart in this learning module produced by CK-12.
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Ck 12: Life Science: Human Sperm
[Free Registration/Login may be required to access all resource tools.] Sperm, the male reproductive cells, are tiny. In fact, they are the smallest cells in the human body. Some people think that they look like tadpoles. Learn more...
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Ck 12: Life Science: Domains of Life
[Free Registration/Login may be required to access all resource tools.] Humans are in the same domain as trees and algae. What could they possibly have in common? It is the location of their DNA inside their cells. Their cells all have a...
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Ck 12: Life Science: Human Vision
[Free Registration/Login may be required to access all resource tools.] Sight, or vision, is the ability to see light. It depends on the eyes detecting light and forming images. It also depends on the brain making sense of the images, so...
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Ck 12: Life Science: Skeletal System Joints
[Free Registration/Login may be required to access all resource tools.] As you age, you might start noticing pain in your knees or elbows. These are examples of joints. Joints are the part of the skeletal system that connect your bones....
CK-12 Foundation
Ck 12: Life Science: Aquatic Biomes
[Free Registration/Login may be required to access all resource tools.] Aquatic biomes can be generally classified based on the amount of salt in the water. Freshwater biomes have less than 1% salt and are typical of ponds and lakes,...
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Ck 12: Life Science: Hiv and Aids
[Free Registration/Login may be required to access all resource tools.] HIV, or human immunodeficiency virus, causes AIDS. AIDS stands for "acquired immune deficiency syndrome." It is a condition that causes death and does not have a...
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Ck 12: Life Science: Insects
[Free Registration/Login may be required to access all resource tools.] Insects, with over a million described species, are the most diverse group of animals on Earth. They may be found in nearly all environments on the planet. No matter...
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Ck 12: Life Science: Kidneys
[Free Registration/Login may be required to access all resource tools.] The kidneys are important organs in maintaining homeostasis, the ability of the body to maintain a stable internal environment despite a changing environment....
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Ck 12: Life Science: Mitosis and Cytokinesis
[Free Registration/Login may be required to access all resource tools.] During mitosis, the DNA in a nucleus must replicate. The copied DNA is divided into two genetically identical sets, so that after cytokinesis or cell division, each...
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Ck 12: Life Science: Sponges
[Free Registration/Login may be required to access all resource tools.] Sponges are classified in the phylum Porifera, from the Latin words meaning "having pores." Sponges are sessile, meaning they cannot move, so they filter water...
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Ck 12: Life Science: Turtles
[Free Registration/Login may be required to access all resource tools.] Turtles are reptiles in the order Testudines. Most turtle bodies are covered by a special shell developed from their ribs. About 300 species are alive today, and...