72) Suppose a researcher claims to be able to make a hybrid animal that is a cross between a human and a rhesus monkey. The normal diploid number for humans is 46, and the normal diploid number for rhesus monkeys is 48. Based on normal meiosis, how many chromosomes would the human gamete have, and how many chromosomes would the rhesus monkey have? Given these numbers, how many chromosomes would you expect the hybrid embryo to contain?

73) Errors in meiosis can be one mechanism of evolution. A change in the number of chromosomes can lead to the production of new species. Some plant species may have originated from errors during cell division, which led to them having more than two sets of chromosomes, a condition called polyploidy. Hypothesize what kind of error during meiosis might occur to cause a normally diploid plant to generate tetraploid offspring, in which the offspring have four sets of chromosomes.

74) Different species can sometimes interbreed to produce hybrid offspring. For example, the breeding of a horse with a donkey produces a mule. However, these hybrids are usually sterile. A horse will produce gametes with 32 chromosomes, and a donkey will produce gametes with 31 chromosomes, resulting in a mule with 63 chromosomes. Using your understanding of meiosis, propose a reason why mules are sterile.

75) In meiosis, X and Y chromosomes will pair as homologous chromosomes, but they will recombine only in a few limited regions, at the ends. Explain why recombination is limited in this situation.

76) Describe how sperm and egg cells are different from somatic cells in number of chromosomes (in humans), the cell division processes they undergo and the process that generates them, and the process they undergo to generate a zygote.