Chapter 46

Question 1

Regeneration, the regrowth of lost body parts, normally follows

Answer 1

fragmentation.

Question 2

One of the evolutionary “enigmas,” or unsolved puzzles, of sexual reproduction is that

Answer 2

only half of the offspring from sexually reproducing females are also females.

Question 3

Asexual reproduction results in greater reproductive success than does sexual reproduction when

Answer 3

a species is in stable and favorable environments.

Question 4

Sexual reproduction

Answer 4

can produce diverse phenotypes that may enhance survival of a population in a changing environment.

Question 5

Environmental cues that influence the timing of reproduction generally do so by

Answer 5

direct effects on hormonal control mechanisms.

Question 6

All individuals of a particular species of whiptail lizards are females. Their reproductive efforts depend on

Answer 6

meiosis followed by a doubling of the chromosomes in eggs.

Question 7

Evidence that parthenogenic whiptail lizards are derived from sexually reproducing ancestors includes

Answer 7

the requirement for male-like behaviors in some females before their partners will ovulate

Question 8

Which of the following patterns of reproduction are found only among invertebrate animals?

Answer 8

fission and budding

Question 9

Animals with reproduction dependent on internal fertilization need not have

Answer 9

internal development of embryos.

Question 10

In close comparisons, external fertilization often yields more offspring than does internal fertilization. However, internal fertilization offers the advantage that

Answer 10

the smaller number of offspring produced often receive a greater amount of parental investment.

Question 11

Internal and external fertilization both

Answer 11

produce single-celled zygotes.

Question 12

Organisms with a reproductive pattern that produces shelled amniotic eggs generally

Answer 12

invest most of their reproductive energy in the embryonic and early postnatal development of their offspring.

Question 13

External chemical signals that coordinate potential reproductive partners are called

Answer 13

pheromones.

Question 14

Females of many insect species, including honeybee queens, can store gametes shed by their mating partners in

Answer 14

the spermatheca.

Question 15

An oocyte released from a human ovary enters the oviduct as a result of

Answer 15

the wavelike beating of cilia lining the oviduct.

Question 16

The junction of the upper vagina and the uterus is called the

Answer 16

cervix.

Question 17

In humans, the follicular cells that remain behind in the ovary following ovulation become

Answer 17

a steroid-hormone synthesizing structure called the corpus luteum.

Question 18

Testosterone is synthesized primarily by the

Answer 18

Leydig cells.

Question 19

Sperm cells are stored within human males in the

Answer 19

epididymis.

Question 20

Among human males, both semen and urine normally travel along the

Answer 20

urethra.

Question 21

Human sperm cells first arise in the

Answer 21

seminiferous tubules.

Question 22

Mature human sperm and ova are similar in that

Answer 22

they both have the same number of chromosomes.

Question 23

The primary difference between estrous and menstrual cycles is that

Answer 23

the endometrium shed by the uterus during the estrous cycle is reabsorbed, whereas the shed endometrium of menstrual cycles is excreted from the body.

Question 24

At the end of a nonpregnant ovarian cycle, the breakdown and discharge of the soft uterine tissues is called

Answer 24

menstruation.

Question 25

In correct chronological order, the three phases of the human ovarian cycle are

Answer 25

follicular → ovulation → luteal.

Question 26

In correct chronological order, the three phases of the human uterine cycle are

Answer 26

menstrual → proliferative → secretory.

Question 27

A reproductive hormone that is secreted directly from a structure in the brain is

Answer 27

gonadotropin-releasing hormone.

Question 28

The primary function of the corpus luteum is to

Answer 28

maintain progesterone and estrogen synthesis after ovulation has occurred.

Question 29

Prior to ovulation, the primary steroid hormone secreted by the growing follicle is

Answer 29

estradiol.

Question 30

The hypothalamic hormone that stimulates hormone secretion by the anterior pituitary gland is

Answer 30

GnRH.

Question 31

Menopause is characterized by

Answer 31

reduced synthesis of ovarian steroids despite high levels of gonadotropin hormones.

Question 32

Fertilization of human eggs usually takes place in the

Answer 32

oviduct.

Question 33

What is the embryo-produced hormone that maintains progesterone and estrogen secretion by the corpus luteum through the first trimester of pregnancy?

Answer 33

human chorionic gonadotropin (HCG)

Question 34

The hypothalamic hormone that triggers the secretion of FSH is

Answer 34

gonadotropin-releasing hormone (GnRH).

Question 35

Labor contractions can be increased by the medical use of a synthetic drug that mimics the action of

Answer 35

oxytocin.