CK-12 Foundation
Ck 12: Life Science: Terrestrial Biomes
[Free Registration/Login may be required to access all resource tools.] A terrestrial biome is an area of land with a similar climate that includes similar communities of plants and animals. Different terrestrial biomes are usually...
CK-12 Foundation
Ck 12: Life Science: Translation of Rna to Protein
[Free Registration/Login may be required to access all resource tools.] The mRNA, which is transcribed from the DNA in the nucleus, carries the directions for the protein-making process. mRNA tells the ribosome how to create a specific...
CK-12 Foundation
Ck 12: Life Science: Carbon Cycle
[Free Registration/Login may be required to access all resource tools.] Carbon is one of the most common elements found in living organisms. Chains of carbon molecules form the backbones of many molecules, such as carbohydrates,...
CK-12 Foundation
Ck 12: Life Science: Human Genome Project
[Free Registration/Login may be required to access all resource tools.] A person's genome is all of his or her genetic information. In other words, the human genome is all the information that makes us human. Learn more about the human...
CK-12 Foundation
Ck 12: Life Science: Animal Communication
[Free Registration/Login may be required to access all resource tools.] What does the word "communication" make you think of? Talking on a cell phone? Texting? Writing? Those are just a few of the ways in which human beings communicate....
CK-12 Foundation
Ck 12: Life Science: Transcription of Dna to Rna
[Free Registration/Login may be required to access all resource tools.] DNA is located in the nucleus. Proteins are made on ribosomes in the cytoplasm. Remember that information in a gene is converted into mRNA, which carries the...
CK-12 Foundation
Ck 12: Life Science: Blood Diseases
[Free Registration/Login may be required to access all resource tools.] Problems can occur with red blood cells, white blood cells, platelets, and other parts of the blood. Many blood disorders are genetic, meaning they are inherited...
CK-12 Foundation
Ck 12: Life Science: Hardy Weinberg Theorem
[Free Registration/Login may be required to access all resource tools.] Sometimes understanding how common a gene is within a population is necessary. Or, more specifically, you may want to know how common a certain form of that gene is...
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Ck 12: Life Science: Nitrogen Cycle
[Free Registration/Login may be required to access all resource tools.] Like water and carbon, nitrogen is also repeatedly recycled through the biosphere. This process is called the nitrogen cycle. Learn more about the nitrogen cycle in...
CK-12 Foundation
Ck 12: Life Science: Urinary System
[Free Registration/Login may be required to access all resource tools.] Sometimes, the urinary system is called the excretory system. But the urinary system is only one part of the excretory system. Recall that the excretory system is...
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Ck 12: Life Science: Recombinant Dna
[Free Registration/Login may be required to access all resource tools.] Recombinant DNA is the combination of DNA from two different sources. For example, it is possible to place a human gene into bacterial DNA. Recombinant DNA...
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Ck 12: Life Science: Learned Behavior of Animals
[Free Registration/Login may be required to access all resource tools.] Just about all human behaviors are learned. Learned behavior is behavior that occurs only after experience or practice. Learned behavior has an advantage over innate...
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Ck 12: Life Science: Polygenic Traits
[Free Registration/Login may be required to access all resource tools.] Another exception to Mendel's rules is polygenic inheritance, which occurs when a trait is controlled by more than one gene. This means that each dominant allele...
CK-12 Foundation
Ck 12: Life Science: Evolution Acts on the Phenotype
[Free Registration/Login may be required to access all resource tools.] Natural selection acts on the phenotype (traits or characteristics) of an individual. On the other hand, natural selection does not act on the underlying genotype...
CK-12 Foundation
Ck 12: Life Science: Habitat Destruction
[Free Registration/Login may be required to access all resource tools.] From a human point of view, a habitat is where you live, go to school, and go to have fun. Your habitat can be altered, and you can easily adapt. Most people live in...
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Ck 12: Life Science: Preventing Infectious Diseases
[Free Registration/Login may be required to access all resource tools.] Infectious diseases are diseases that spread from person to person. What can you do to avoid infectious diseases? Eating right and getting plenty of sleep are a good...
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Ck 12: Life Science: Habitat and Niche
[Free Registration/Login may be required to access all resource tools.] Are you on the basketball team? Are you a cheerleader? Do you play an instrument in the band? Your niche would be your role or place in the school. Organisms also...
CK-12 Foundation
Ck 12: Life Science: Active Transport
[Free Registration/Login may be required to access all resource tools.] During active transport, molecules move from an area of low concentration to an area of high concentration. This is the opposite of diffusion, and these molecules...
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Ck 12: Life Science: Passive Transport
[Free Registration/Login may be required to access all resource tools.] The cell membrane is semi-permeable. Sometimes molecules need the help of special transport proteins or an input of energy to help them move across it. When an input...
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Ck 12: Life Science: Cell Division
[Free Registration/Login may be required to access all resource tools.] Cells do eventually wear out. At that point, they need to be replaced. This is one reason that your cells divide. New cells that result after cells divide are also...
CK-12 Foundation
Ck 12: Life Science: Modern Genetics
[Free Registration/Login may be required to access all resource tools.] Mendel laid the foundation for modern genetics, but there were still a lot of questions he left unanswered. What exactly are the dominant and recessive factors that...
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Ck 12: Life Science: Genetic Disorders
[Free Registration/Login may be required to access all resource tools.] Some human genetic disorders are also X-linked or Y-linked, which means the faulty gene is carried on these sex chromosomes. Other genetic disorders are carried on...
CK-12 Foundation
Ck 12: Life Science: Cell Transport
[Free Registration/Login may be required to access all resource tools.] Cells are found in all different types of environments, and these environments are constantly changing. For example, one-celled organisms, like bacteria, can be...
CK-12 Foundation
Ck 12: Life Science: Cell Membrane
[Free Registration/Login may be required to access all resource tools.] All cells have a barrier around them that separates them from the environment and from other cells. This barrier is called the plasma membrane, or cell membrane....