Ch 13.1: Meiosis and Sexual Life Cycles

Question 1

Why don’t more animals reproduce asexually?

Answer 1

less genetic variation

Question 2

How does genetic variation occur in sexual life cycles?

Answer 2

mutations create different versions of genes called alleles and the reshuffling of alleles during sexual reproduction produces genetic variation

Question 3

What three mechanisms contribute to genetic variation?

Answer 3

independent assortment of chromosomes, crossing over, and random fertilization

Question 4

What is independent assortment?

Answer 4

each pair of chromosomes sorts maternal and paternal homologs into daughter cells independently of the other pairs

Question 5

How do you determine the number of combinations possible when chromosomes assort independently into gametes?

Answer 5

2^n, where n is the haploid number (humans = 8 million or 2^23)

Question 6

What does crossing over produce?

Answer 6

recombinant chromosomes

Question 7

What are recombinant chomosomes?

Answer 7

the combination of DNA from two parents into a single chromosome

Question 8

What is natural selection?

Answer 8

natural environment consistently “selects” for certain traits among naturally occurring variation in the population