62
If a plant species with a diploid number of 32 is crossed with another plant species with a diploid number of 24, what will be the diploid number of the resulting first generation of offspring? After the zygote multiplies to form a mass of cells, what is the chromosome number of each cell?
  1. 32, 28
  2. 24, 24
  3. 28, 28
  4. 28, 32
63
Compare and contrast sex determination in birds and mammals.
  1. In mammals, sex is determined by the presence of XX (homozygous) in males and XY (heterozygous) in females, while in birds, sex is determined by the presence of ZZ (homozygous) in females and ZW (heterozygous) in males.
  2. In mammals, sex is determined by the presence of XX (homozygous) in males and XY (heterozygous) in females, while in birds, sex is determined by the presence of ZW (heterozygous) in females and ZZ (homozygous) in males.
  3. In mammals, sex is determined by the presence of XX (homozygous) in females and XY (heterozygous) in males, while in birds, sex is determined by the presence of ZZ (homozygous) in females and ZW (heterozygous) in males.
  4. In mammals, sex is determined by the presence of XX (homozygous) in females and XY (heterozygous) in males, while in birds, sex is determined by the presence of ZW (heterozygous) in females and ZZ (homozygous) in males.
64
What is the advantage of sexual reproduction?
  1. Sexual reproduction allows animals to conserve resources and reproduce only during optimal conditions.
  2. Sexual reproduction results in offspring with diverse phenotypes, which may enhance survival of a population in a changing environment.
  3. Sexual reproduction guarantees that both parents will provide parental care.
  4. Sexual reproduction yields more numerous offspring more rapidly than is possible with asexual reproduction.
65
In sexual reproduction, two cells of a species combine to form another cell. Why is this useful?
  1. It produces new combination of genes, which enables offspring to survive during environmental changes.
  2. It results in the production of many offspring in a short period of time.
  3. It does not involve gamete formation and requires less energy.
  4. It allows immobile organisms to reproduce in the absence of a mate.
66
Spawning is often triggered by a signal such as water temperature or day length. What is an advantage of using this type of signal versus using individual courtship behaviors?
  1. It allows many individuals to spawn simultaneously without males and females having to choose individual mates.
  2. It is the only way that males and females can time gamete release simultaneously.
  3. These are the only types of signals that can be used.
  4. It increases the distance that gametes can travel.
67
Which of the following statements about hormone regulation of the female reproductive cycle is true?
  1. LH and FSH are produced in the ovaries, and estradiol and progesterone are produced in the pituitary.
  2. Estradiol and progesterone secreted from the corpus luteum cause the myometrium to thicken.
  3. Progesterone is produced by the corpus luteum.
  4. Secretion of GnRH by the hypothalamus is inhibited by high levels of estradiol, but stimulated by low levels of estradiol.
68
Which of the following statements about the menstrual cycle is TRUE?
  1. Estrogen levels rise during the luteal phase of the ovarian cycle and the secretory phase of the uterine cycle.
  2. Menstruation occurs much before LH and FSH levels peak.
  3. Menstruation occurs after progesterone levels rise.
  4. Progesterone levels rise before ovulation, while estrogen levels rise after.
69
What stimulates Leydig cells in the testes to produce testosterone?
  1. FSH
  2. LH
  3. inhibin
  4. estrogen
71
What is the nature of the oogonium and the secondary oocyte? Which process results in the formation of the secondary oocyte?
  1. A diploid oogonium forms a haploid oocyte by the process of mitosis.
  2. A haploid oogonium forms a diploid oocyte by the process of meiosis.
  3. A diploid oogonium forms a haploid oocyte by the process of meiosis.
  4. A haploid oogonium forms a haploid haploid oocyte by the process of meiosis.
72
Why are the diploid zygotes produced after fertilization of sperm cells produced by spermatogenesis not similar?
  1. Their chromosome numbers are not the same.
  2. The size of the sperm produced are different.
  3. Some sperm may have a tail, whereas others may not.
  4. Crossing over occurs during spermatogenesis.
73
The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following mechanisms demonstrates negative feedback by the reproductive system in mammals?
  1. Increasing levels of testosterone inhibit the production of GnRH, LH, and FSH by the hypothalamus and pituitary.
  2. LH and FSH stimulate the interstitial cells of Leydig to release testosterone.
  3. The growing follicle starts releasing estrogen in increasing amounts.
  4. The corpus luteum releases progesterone after ovulation.
74
Discuss the positive feedback mechanisms by LH and FSH during the follicular and ovulation phase of the ovarian cycle.
  1. The stimulation of the anterior pituitary by GHRH secretes the hormones LH and FSH. The increasing amounts of these hormones stimulate several follicles in the ovary to start growing, but only one of these matures to release the egg.
  2. The stimulation of the anterior pituitary by GnRH secretes the hormones LH and TSH. The increasing amounts of these hormones stimulate several follicles in the ovary to start growing, but only one of these matures to release the egg.
  3. The stimulation of the anterior pituitary by GnRH triggers the secretion of the hormones LH and FSH. The increasing amounts of these hormones stimulate several follicles in the ovary to start growing, but only one of these matures to release the egg.
  4. The stimulation of the anterior pituitary by GHRH secretes the hormones LH and TSH. The increasing amounts of these hormones stimulate several follicles in the ovary to start growing, but only one of these matures to release the egg.
75
Describe the possible event that would occur if the corpus luteum did not produce increasing amounts of progesterone.
  1. The implanted zygote will not be able to derive sufficient nutrition from the endometrium.
  2. Even if fertilization is successful, the zygote may not be able to implant successfully. If it does manage to implant, it will not be able to derive sufficient nutrition from the myometrium.
  3. Even if fertilization is successful, the zygote may not be able to implant successfully. If it does manage to implant, it will not be able to derive sufficient nutrition from the endometrium.
  4. The contraction of the uterus during childbirth and lactation will not take place, causing problems and complications in the mother.
76
What does a female contraceptive pill that inhibits the release of GnRH from the hypothalamus do?
  1. reduce the secretion of FSH and LH from the anterior pituitary gland
  2. initiate ovulation
  3. increase the flow phase of the menstrual cycle
  4. increase the production of estrogen and progesterone by the ovaries
77
What do the rising levels of FSH and LH in the follicular phase cause?
  1. The follicles on the surface of the ovary start growing in preparation for ovulation.
  2. The endometrium starts to thicken.
  3. The corpus luteum starts secreting progesterone.
  4. One of the mature follicles bursts, releasing the egg.
78
A couple has been trying to conceive for some time and goes to an endocrinologist for advice. If the endocrinologist diagnoses an obstruction in the oviducts of the female, what type of treatment can she recommend?
  1. opting for in vivo fertilization or ligation of the fallopian tubes surgically so that the tubes are sealed
  2. opting for in vivofertilization or removal of the obstruction surgically and then re-ligation of the ends of the fallopian tubes
  3. opting for in vitro fertilization or ligation of the fallopian tubes surgically so that the tubes are sealed
  4. opting for in vitro fertilization or removal of the obstruction surgically and then re-ligation of the ends of the fallopian tubes
79
How does a reproductive hormone that is secreted directly from the anterior pituitary stimulate the reproductive organs to produce hormones?
  1. by traveling through the blood to reach the target organs
  2. by binding with proteins to reach the reproductive organs
  3. by sending a chemical messenger to activate the reproductive organs
  4. by converting into an active form before targeting the reproductive organs
80
Explain the mechanisms by which hormones from the brain and ovaries interact, eventually leading to menstruation.
  1. After the release of the egg from the follicle, the corpus luteum is formed, which inhibits FSH and LH production, which then inhibits GnRH production, causing no other follicle to develop. When no fertilization takes place, the corpus luteum degenerates and the progesterone level declines, initiating the breakdown of the myometrium and the start of the menstrual cycle.
  2. After the release of the egg from the follicle, the corpus luteum is formed, which inhibits FSH and LH production, which then inhibits GnRH production, causing no other follicle to develop. When no fertilization takes place, the corpus luteum degenerates and the progesterone level declines, initiating the breakdown of the endometrium and the start of the menstrual cycle.
  3. After the release of the egg from the follicle, the corpus luteum is formed, which inhibits FSH and LH production, which then facilitates GnRH production, causing no other follicle to develop. When no fertilization takes place, the corpus luteum degenerates and the progesterone level declines, initiating the breakdown of the endometrium and the start of the menstrual cycle.
  4. After the release of the egg from the follicle, the corpus luteum is formed, which inhibits FSH and LH production, which then inhibits GnRH production, causing no other follicle to develop. When no fertilization takes place, the corpus luteum degenerates and the progesterone level rises, initiating the breakdown of the endometrium and the start of the menstrual cycle.
81
Multiple hormones work together to coordinate the female reproductive cycle. Which of these hormones is also responsible for the development of female secondary sexual characteristics, including breast development and hip widening?
  1. estrogen
  2. progesterone
  3. follicle stimulating hormone
  4. luteinizing hormone
82
Which hormone is released by the anterior pituitary as a part of the positive feedback loop between it and the ovary?
  1. Progesterone
  2. GnRH
  3. LH
  4. Estradiol
83
How does the feedback mechanism of hormones lead to muscular contractions during labor?
  1. A feedback relay occurs between the uterus, hypothalamus, and posterior pituitary to assure an adequate supply of oxytocin, which causes the contraction of smooth muscles of the uterus, leading to the birth of the baby.
  2. The posterior pituitary continuously produces oxytocin, which is sufficient for muscular contraction in the uterus, thereby causing the birth of the baby.
  3. A feedback relay occurs between the uterus, hypothalamus, and posterior pituitary to assure an adequate supply of prolactin, which causes the contraction of the smooth muscles of the uterus, leading to the birth of the baby.
  4. A feedback relay occurs between the uterus, hypothalamus, and posterior pituitary to assure an adequate supply of progesterone, which causes the contraction of the smooth muscles of the uterus, leading to the birth of the baby.
84
During childbirth, the hormone oxytocin causes contraction of the uterine wall muscles. As muscular contractions increase, more oxytocin is released from the pituitary, leading to more contractions. This is an example of which mechanism?
  1. end product inhibition
  2. negative feedback mechanism
  3. positive feedback mechanism
  4. feedback inhibition