Human Evolution Exam 1 Study Guide Solutions

Human Evolution Exam 1 Study Guide Solutions Natural Selection: - ANSWER-1. All species are capable of producing offspring at a faster rate than food supplies increase 2. Because in each generation more individuals are produced than can survive, there is a competition for limited resources 1. There is biological variation in all species 2. Some individuals in the population will possess traits that allow them to survive and reproduce more successfully than others in the same environment 3. Environmental conditions determine whether a trait is beneficial 4. Traits are inherited and passed on to the next generation. Individuals who possess favorable traits contribute more offspring to the next generation than do others, so these traits become more common. Those individuals that produce more offspring have greater reproductive success. ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/23 5. Over long periods of time, favorable traits accumulate in a population so that later generations are distinct from ancestral ones. In time, a new species appears 6. Geographic isolation may also lead to the formation of a new species • Natural selection causes evolutionary change • Evolution is the change in the genetic structure of a population over time - Changes in allele frequencies due to differential reproductive success - Systematic (not random) - Increases variation between populations - Decreases variation within populations Three types of natural selection: - ANSWER-- Directional selection - Stabilizing selection - Disruptive selection Unit of natural selection: - ANSWER-- Is the individual - Counter Lamarck ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/23 Unit of evolution: - ANSWER-- the population Gene Flow: - ANSWER-- use of codons to make certain proteins - some proteins can be created by several different nucleotide makeups, codons - redundancy helps protect against a mutation / mistake - we only need 20 amino acids, so we don't need a more complex system than three base codons / triplet codons • The exchange of alleles between populations • Migration • Systematic • Increases variation within populations • Decreases variation between populations Genetic Drift: - ANSWER-- Change in allele frequencies produced by random factors - Increases variation between populations ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 4/23 - It is unlikely every population will be fixed on the same allele (the other allele could go into fixation in other populations by random chance) - Decreases variation within populations (one allele will eventually disappear because eventually an entire population is fixed on a certain type of allele) Mutation: - ANSWER-- Change in DNA sequence - Point mutation: change in single base of DNA sequence - Most simple mutation - Ex: CTC CAC (glutamic acid valine) • The only source of new genetic variation • If in gametes creates evolutionary effect • Only source for new alleles • Shows evolution is an imperfect system - Random alternation in DNA sequence - Sources of mutation: radiation, chemicals ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 5/23 - If in gametes evolutionary effect - Creates NEW alleles - Random - Mutation rates are low - Increases variation both within and between populations - Most mutations are fatal because they're random, though every now and then a mutation may be beneficial and increase over time Characteristics of DNA: - ANSWER-1. code is universal 2. code is triplet 3. code is redundant Mendel's three "laws" of inheritance: - ANSWER-- Dominance, Segregation, Independent Assortment Dominance: - ANSWER-- The effects of some alleles will be inhibited by other (dominant) alleles - Dominant: alleles that are expressed (A) - Recessive: alleles that are masked when combined with a dominant allele (a) ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 6/23 Segregation: - ANSWER-- Allele pairs separate (segregate) during gamete formation and randomly unite at fertilization - Different expressions of a trait are controlled by discrete units of heredity - These units occur in pairs: one from each parent - Members of each pair segregate into gametes during meiosis (haploid) - Pair is formed again during fertilization - Alleles separate, you only have one or the other Independent Assortment: - ANSWER-- No relationship between traits for plant height and seed color - The expression of one trait is not influenced by the expression of another trait - Traits assort independently of each other during gamete formation - Linked genes, pleiotropic, and polygenetic traits (not distinct variations) are the exception to this principle Mitosis: - ANSWER-- ordinary cell division - mass majority of our cells go through this proce