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71 terms

CH 46 Animal Reproduction

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Regeneration, the regrowth of lost body parts, normally follows
fragmentation.
One of the evolutionary ʺenigmas,ʺ or unsolved puzzles, of sexual reproduction is due to the fact that
only half of the offspring from sexually reproducing females are also females.
An advantage of asexual reproduction is that
asexual reproduction enables the species to rapidly colonize habitats that are favorable to that species.
Genetic mutations in asexually reproducing organisms lead to more evolutionary change than do genetic mutations in sexually reproducing ones because
asexually reproducing organisms, but not sexually reproducing organisms, pass all mutations to their offspring.
Asexual reproduction results in greater reproductive success than does sexual reproduction
when a species is in stable and favorable environments.
Sexual reproduction patterns include the example of
hermaphroditism.
If you observe vertebrate organisms with parthenogenetic reproduction, internal development of embryos, and the lack of parental care for its young, you should categorize these organisms as
lizards.
Sexual reproduction
can produce diverse phenotypes that may enhance survival of a population in a changing environment.
Environmental cues that influence the timing of reproduction generally do so by
direct effects on hormonal control mechanisms.
For water fleas of the genus Daphnia, switching from a pattern of asexual reproduction to sexual reproduction coincides with
periods of temperature or food stresses.
All individuals of a particular species of whiptail lizards are females. Their reproductive efforts depend on
meiosis followed by a doubling of the chromosomes in eggs.
Evidence that parthenogenic whiptail lizards are derived from sexually reproducing ancestors includes
the requirement for male-like behaviors in some females before their partners will ovulate.
Like many other fishes, bluehead wrasses utilize harem mating as they reproduce sexually, but unlike most fish,
large females morph into reproductively competent males.
Animals with reproduction dependent on internal fertilization need not have
internal development of embryos.
In close comparisons, external fertilization often yields more offspring than does internal fertilization, but internal fertilization offers the advantage that
the smaller number of offspring produced often receive a greater amount of parental investment.
Internal and external fertilization both
produce zygotes.
Organisms with a reproductive pattern that produce shelled amniotic eggs generally
invest most of their reproductive energy in the embryonic and early postnatal development of their offspring.
Which statement is false concerning reproduction in invertebrate animals?
None of the invertebrates have structures that store sperm.
A cloaca is an anatomical structure found in many nonmammalian vertebrates, which functions as
a common exit for the digestive, excretory, and reproductive systems.
Chemical signals exchanged between potential reproductive partners are called
pheromones.
Females of many insect species, including honeybee queens, can store gametes shed by their mating partners in
the spermatheca.
Most flatworms, including parasitic liver flukes, are hermaphrodites where zygotes form as the result of
internal fertilization.
When female fruit flies mate with two different males on the same day,
the second maleʹs sperm fertilizes most of the eggs.
An oocyte released from a human ovary enters the oviduct as a result of
the wavelike beating of cilia lining the oviduct.
The junction of the upper vagina and the uterus is called the
cervix.
In humans, the follicular cells that remain behind in the ovary following ovulation become
a steroid-hormone synthesizing structure called the corpus luteum.
The male and female structures that consist mostly of erectile tissue include
penis and clitoris.
Testosterone is synthesized primarily by the
Leydig cells
Sperm cells are stored within human males in the
epididymis.
Among human males, both semen and urine normally travel along the
urethra.
31) Human sperm cells first arise in the
C) seminiferous tubules.
32) The surgical removal of the seminal vesicles would likely
C) greatly reduce the volume of semen.
33) Most of the noncellular fluid in ejaculated human semen is composed of
C) the secretions of the seminal vesicles.
34) Increasing and holding the temperature of the scrotum by 2°C, near the normal body-core temperature, would
B) reduce the fertility of the man by impairing spermatogenesis.
35) During human heterosexual (mutual) excitement, vasocongestion
E) occurs in the clitoris, vagina, and penis.
36) The moment of orgasm is characterized by
C) rhythmic contraction of many parts of the reproductive system.
37) At the time of fertilization, the complete maturation of each oogonium has resulted in
A) one secondary oocyte.
38) In vertebrate animals, spermatogenesis and oogenesis differ, in that
C) cytokinesis is unequal in oogenesis, whereas it is equal in spermatogenesis.
39) Mature human sperm and ova are similar in that
A) they both have the same number of chromosomes.
40) A maleʹs ʺprimaryʺ sex characteristics include
B) embryonic differentiation of the seminal vesicles.
41) The primary difference between estrous and menstrual cycles is that
the endometrium shed by the uterus during the estrous cycle is reabsorbed but the shed endometrium is
excreted from the body during the menstrual cycle.
42) The breakdown and discharge of the soft uterine tissues that occurs if no egg is fertilized is called
A) menstruation.
43) In correct chronological order, the three phases of the ovarian cycle are
D) follicular → ovulation → luteal
44) In correct chronological order, the three phases of the uterine cycle are
C) menstrual → proliferative → secretory
45) A contraceptive pill that continuously inhibits the release of GnRH from the hypothalamus will
C) reduce the secretion of gonadotropins from the anterior pituitary gland.
A primary response by the Leydig cells in the testes to the presence of luteinizing hormone is an increase in the synthesis and secretion of
testosterone.
47) This hormone is secreted directly from a structure in the brain:
E) gonadotropin-releasing hormone
48) The primary function of the corpus luteum is to
C) maintain progesterone and estrogen synthesis after ovulation has occurred.
) For the 10 days following ovulation in a nonpregnant menstrual cycle, the main source of progesterone is the
corpus luteum.
Ovulation is the follicular response to a burst of secretion of
LH.
Prior to ovulation, the steroid hormone secreted by the growing follicle is
estradiol.
The hypothalamic hormone that stimulates hormone secretion by the anterior pituitary gland is
GnRH.
The hormone progesterone is produced
in the ovary and acts directly on the uterus.
A function-disrupting mutation in the progesterone receptor gene would likely result in
the inability of the uterus to support pregnancy.
Menopause is caused by
reduced synthesis of ovarian steroids despite high levels of gonadotropin hormones.
For normal human fertilization to occur,
only one sperm need penetrate one egg.
Fertilization of human eggs usually takes place in the
oviduct
This embryonic hormone maintains progesterone and estrogen secretion by the corpus luteum through the first trimester of pregnancy:
human chorionic gonadotropin (HCG)
Which hypothalamic hormone triggers the secretion of FSH?
gonadotropin-releasing hormone (GnRH)
A reliable ʺmarkerʺ that a pregnancy has initiated, and that is detectable in excreted urine, is
chorionic gonadotropin.
Labor contractions would be increased by the use of a synthetic drug that mimics the action of
oxytocin.
A high rate of metabolic activity is maintained in the pregnant uterus by
E) progesterone.
The secretion of follicle stimulating hormone from the pituitary is reduced by
) inhibin.
A thin layer of the developing embryo that secretes the hormone that keeps the corpus luteum functioning is
chorion.
A woman in the final week of pregnancy who is given an injection of oxytocin would likely
undergo vigorous contractions of her uterine muscles.
The ʺimmunotoleranceʺ of a pregnant woman toward her unborn child is the result of
the relative quiescence of a pregnant womanʹs immune system compared to when she was not pregnant.
Among these contraception methods, which has the highest risk of accidental pregnancy?
coitus interruptus
The use of birth-control pills (oral contraceptives)
) reduces the incidence of ovulation.
Which pair includes two contraceptive methods that are generally irreversible means to block gametes from moving to a site where fertilization can occur?
vasectomy and tubal ligation
Tubal ligation
prevents oocytes from entering the uterus.
For lactation to take place, __________ stimulates the synthesis of breast milk and __________ causes milk expulsion.
prolactin; oxytocin