<p> BIOLOGY CONTENT STANDARDS REVIEW EVOLUTION</p><p>The frequency of an allele in a gene pool of a population depends on many factors and may be stable or unstable over time. As a basis for understanding this concept: </p><p>Students know why alleles that are lethal in a homozygous individual may be carried in a heterozygote and thus maintained in a gene pool.</p><p>1. Compare and contrast the terms homozygous and heterozygous. 2. Explain how lethal alleles are maintained in a gene pool (e.g., Tay Sachs disease).</p><p>Students know variation within a species increases the likelihood that at least some members of a species will survive under changed environmental conditions.</p><p>3. What is genetic variation? 4. Explain how genetic variation is essential when it comes to the survival of a population.</p><p>Evolution is the result of genetic changes that occur in constantly changing environments. As a basis for understanding this concept: </p><p>Students know how natural selection determines the differential survival of groups of organisms.</p><p>5. What is Natural Selection? How does Natural Selection work? 6. Does Natural Selection work on a phenotype or genotype? 7. What is selective pressure and how does it relate to Natural Selection?</p><p>Students know a great diversity of species increases the chance that at least some organisms survive major changes in the environment.</p><p>8. Explain how variation within a species increases the chance that some organisms would survive a major environmental change (i.e., selective pressure). Provide at least one example.</p><p>Students know the effects of genetic drift on the diversity of organisms in a population.</p><p>9. What is genetic drift? How does genetic drift relate to biological evolution?</p><p>Students know reproductive or geographic isolation affects speciation.</p><p>10. Define geographic isolation, reproductive isolation, species, and speciation. How do these terms/processes relate?</p><p>Students know how to analyze fossil evidence with regard to biological diversity, episodic speciation, and mass extinction</p><p>11. What is a fossil? How are fossils formed? 12. Explain how the fossil record provides evidence of biological diversity (that existed in the past), episodic speciation, and mass extinction.</p>