Chapter 49

Asexual reproduction is most successful in: a. changing environments. b. sessile animals. c. densely settled populations. d. land animals. e. genetically varied individuals.

Which of the following processes does not increase genetic diversity? a. parthenogenesis b. random DNA mutations c. genetic recombination d. independent assortment e. random combinations of paternal and maternal chromosomes

Gametogenesis has parallel stages in egg and sperm formation. The stage in eggs that is equivalent to spermatids is the: a. primary oocyte. b. oogonium. c. ovum. d. ootid and polar bodies. e. secondary oocyte and polar body.

Some placental animals provide nutrients to their embryos from an attached membranous yolk-containing sac. They are called: a. oviparous animals. b. ovoviviparous animals. c. metatherians. d. eutherians. e. hermaphrodites.

During spermatogenesis in mammals, sperm travels from the: a. Sertoli cells past the epididymis and urethra, through the vas deferens to the prepuce. b. seminal vesicles past the prostate gland, through the glans and prepuce to the bulbourethral glands. c. vestibular glands past the Leydig cells, through the accessory glands and epididymis to the vas deferens. d. labia past the bulbourethral glands, through the vas deferens and urethra to the epididymis. e. seminiferous tubules past the Sertoli cells, through the epididymis and vas deferens to the urethra.

The secondary oocyte in humans is fertilized in the: a. uterus. b. vagina. c. oviduct. d. cervical canal. e. ovary.

The most effective method to prevent fertilization is: a. the oral contraceptive. b. the IUD. c. the morning-after pill. d. vasectomy in men and tubal ligation in women. e. the rhythm method.

How would an "antipregnancy vaccine" that stimulates a woman's immune system to develop antibodies against human chorionic gonadotropin (hCG) prevent pregnancy?

Men sometimes have reduced fertility because of testicular varicoceles, varicose veins in the testes in which blood pools. Based on what you now know of the conditions under which sperm develop properly, how do you think this condition might impair sperm development?

Sertoli cells protect spermatocytes from attack by antibodies during their development in the human male. What structures might protect the oocyte and egg from attack by antibodies in the human female?

Compare the advantages and disadvantages of sexual and asexual reproduction for an aphid and a parasitic worm.

It may be possible to develop a birth control drug that would prevent conception by interfering with fertilization. Outline the design for such a drug and explain exactly how it would work. (There may be more than one design that, in theory, would be effective.)

The nematodes Caenorhabditis elegans and Caenorhabditis briggsae are both hermaphroditic. Phylogenetic evidence indicates that the last common ancestor of these two species had a normal malefemale mechanism of reproduction. What does this evidence suggest about their hermaphroditism?