Question 1

Which is a major drawback of asexual reproduction?

Accepted Answer

A major drawback of asexual reproduction is that it leads to low genetic diversity among offspring. Since there is no genetic recombination, the offspring are genetically identical to the parent, and there is no opportunity for the creation of new combinations of genes that could lead to increased adaptation to changing environments or resistance to diseases or parasites. This lack of genetic diversity can make a population more vulnerable to changes in the environment and reduce its ability to evolve in response to new challenges.

Question 2

Which statement about sexual and asexual reproduction is true?

Accepted Answer

Parthenogenesis is a form of asexual reproduction where an egg develops into an offspring without being fertilized by a sperm. The other options are incorrect. Budding is a form of asexual reproduction, not sexual reproduction (option A). Not every member of a sexually reproducing population can convert resources into offspring as reproduction requires the fusion of gametes (option B). Asexual reproduction is more common among invertebrates than vertebrates (option D). Regeneration is also a form of asexual reproduction, not sexual reproduction (option E).

Question 3

Whereas luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are produced by the _______ and act on the _______, estrogen and progesterone are produced by _______ and act on the _______.

Accepted Answer

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are produced by the anterior pituitary gland and act on the ovaries to stimulate ovulation and the production of estrogen and progesterone. Estrogen and progesterone, in turn, are produced by the ovaries and act on the uterus to regulate the menstrual cycle and prepare the uterus for pregnancy.

Question 4

A person eating undercooked pork ingests a single tapeworm larva.Several months later, the person's feces contain tapeworm proglottids, which contain thousands of tapeworm embryos.What is the most likely explanation for this?

Accepted Answer

The adult tapeworm that developed from the ingested larva is capable of producing both eggs and sperm, allowing it to reproduce by self-fertilization, which explains the presence of tapeworm proglottids containing thousands of embryos in the person's feces.

Question 5

Which structure(s) contribute(s) the greatest volume of material to semen?

Accepted Answer

The seminal vesicles contribute the greatest volume of material to semen, accounting for approximately 60% of the total volume. The prostate gland contributes about 30% and the bulbourethral glands and vasa deferentia contribute a small amount. The seminiferous tubules are not directly involved in semen production but are responsible for the production of sperm.

Question 6

A physician examines a couple seeking to conceive and discovers that the man's sperm count is sufficient and his sperm can penetrate eggs, but that the woman has scar tissue blocking both of her oviducts.Which procedure would the physician most likely recommend to this couple?

Accepted Answer

With scar tissue blocking both oviducts, the eggs cannot be fertilized naturally. In vitro fertilization (IVF) is a process where eggs are extracted from the woman's ovaries and fertilized with sperm in a laboratory. The resulting embryos are then transferred to the woman's uterus. This procedure bypasses the oviducts and allows fertilization to occur outside the body.

Question 7

Mammalian spermatocytes remain in cytoplasmic contact throughout their development

Accepted Answer

This is because during the first meiotic division, primary spermatocytes divide into two secondary spermatocytes. One of these will have two X chromosomes, and the other will have none. Therefore, the cytoplasmic contact allows the sharing of gene products from the X chromosome-containing secondary spermatocyte with the other one. This helps to ensure equal expression of genes on the X chromosome in all sperm cells produced.

Question 8

If you examined histological sections of adult human gonads under the microscope, you would conclude that

Accepted Answer

The answer of If you examined histological sections of adult...

Question 9

If a person develops an estrogen-secreting Leydig cell tumor, that person most likely will

Accepted Answer

Leydig cell tumors originate in the testes, which are located in the scrotum. Therefore, a palpable lump in the scrotum is a likely symptom. This tumor secretes estrogen, which does not directly relate to the ovaries, nurse cells, masculinization, or menopause.

Question 10

You discover a mutation in sea urchins that causes females to produce eggs lacking bindin receptors on the vitelline envelope.What would you expect to see if you exposed these eggs to normal sea urchin sperm?

Accepted Answer

The bindin receptors are necessary for sperm to recognize and bind to the egg's vitelline envelope. Without them, normal sperm would not be able to fertilize the egg, resulting in the inability of normal sperm to fertilize the eggs.

Question 11

Tay-Sachs disease is an autosomal recessive genetic disorder that causes deterioration of nerves during the early months of life and usually death by the age of 4 years.A man and woman who are both carriers of the Tay-Sachs allele want to have a child that is unaffected by the disease.To assure this outcome, their best approach would be to use _______ combined with genetic analysis of the embryos, which are two assisted reproductive technologies available in medical clinics.

Accepted Answer

The answer of Tay-Sachs disease is an autosomal recessive genetic...

Question 12

Which birth control method prevents implantation rather than fertilization?

Accepted Answer

The intrauterine device (IUD) works by preventing implantation of a fertilized egg in the uterus, rather than preventing fertilization itself.

Question 13

If a woman gives birth to fraternal (non-identical) twins, then she ovulated more than one egg prior to conception.This could occur if, during that ovarian cycle,

Accepted Answer

Fraternal twins result from the fertilization of two different eggs released during the same menstrual cycle. This can happen if the granulosa cells of two follicles develop the highest amounts of FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone) receptors. These receptors allow the follicles to respond more effectively to these hormones, promoting their growth and development, leading to the release of more than one egg.

Question 14

In honeybees, males are produced from unfertilized eggs and are haploid.This mode of asexual reproduction has advantages over budding or regeneration because

Accepted Answer

While honeybees produce male drones through a form of asexual reproduction, they are still produced through meiosis which contributes to genetic diversity. This can be advantageous for the population as it allows for adaptation to changing environments and can promote resilience against disease or other stressors.

Question 15

After visiting his doctor for erectile dysfunction, a man is prescribed sildenafil, a drug that prevents cGMP from being degraded.This drug is most likely to help this man's condition by

Accepted Answer

Sildenafil prevents cGMP from being degraded, which promotes the accumulation of cGMP in smooth muscle cells associated with penile arteries. This leads to relaxation of the smooth muscle cells and increased blood flow to the penis, resulting in an erection.

Question 16

One of the first indications that a woman is pregnant is that she misses her monthly menstrual period.This is the result of

Accepted Answer

The secretion of human chorionic gonadotropin (hCG) by the blastocyst once it implants is the basis for pregnancy tests. This hormone maintains the corpus luteum, which then continues to produce estrogen and progesterone to support the developing embryo. The rise in hCG levels also signals to the ovary to stop releasing eggs, leading to the cessation of menstruation.

Question 17

When collecting sea urchins for an experiment on fertilization that you will conduct back in your lab, you carefully put each sea urchin into a separate container of seawater on a bed of seaweed.The main reason for isolating the individuals is that, if carried together in a single container,

Accepted Answer

When sea urchins are in close proximity, one individual spawning can cause a chain reaction that induces the others to spawn as well. This can interfere with the experimenter's ability to control and manipulate the timing of fertilization events. Therefore, isolating each individual in a separate container helps to prevent this problem. The other answer choices are not applicable to the situation described.

Question 18

Which statement about events during childbirth is true?

Accepted Answer

The onset of labor is indeed marked by increased oxytocin secretion by the pituitaries of both the mother and the fetus, which stimulates the uterine contractions necessary for childbirth.

Question 19

A prepubertal boy develops an androgen-secreting Leydig cell tumor and experiences precocious puberty.The most likely reason for this is that the

Accepted Answer

The Leydig cell tumor is producing excessive amounts of testosterone, which is leading to precocious puberty. This is due to a premature increase in testosterone caused by the tumor.

Question 20

Of the contraceptive methods listed, which has the lowest failure rate?

Accepted Answer

The hormone containing vaginal ring has a failure rate of less than 1%, making it the most effective contraceptive method listed. The rhythm method, diaphragm, coitus interruptus, and condom all have higher failure rates.

Quiz 42: Animal Reproduction