Question 1

Which of the following determines genetic sex (male or female)in mammals?

Accepted Answer

The SRY gene on the Y chromosome is responsible for triggering the development of male characteristics in mammals. This gene is only present on the Y chromosome, so an embryo with two X chromosomes will develop as female. The other options are incorrect - the Y chromosome is typically only contained in sperm, not eggs; temperature has no effect on genetic sex determination; and the genetic makeup of the parents only contributes to the likelihood of inheriting certain genes (such as the Y chromosome). The acrosome of the sperm is involved in fertilization, but not in determining genetic sex.

Question 2

Choose the correct statement regarding estrous and menstrual cycles.

Accepted Answer

Animals with estrous cycles are only sexually receptive during ovulation. In contrast, humans, great apes, and some bats have menstrual cycles in which sexual receptivity and fertility are not limited to a specific time during the cycle. B is incorrect because menstrual cycles tend to be shorter than estrous cycles, lasting around 28 days in humans compared to several months in some animals with estrous cycles. C is incorrect because copulation can occur outside of ovulation in menstrual cycles. D is partially correct, as the lining of the uterus is shed during menstruation but not estrous. E is incorrect because ovulation occurs in both estrous and menstrual cycles.

Question 3

-According to the figure,what is a likely day of implantation?

Accepted Answer

Implantation typically occurs around 6-10 days after ovulation, which is usually around day 14 of a menstrual cycle. Therefore, day 21 is a likely day for implantation.

Question 4

Which hormone prevents the corpus luteum from degenerating?

Accepted Answer

Human chorionic gonadotropin (hCG) is produced by the developing placenta and prevents the corpus luteum from degenerating. This allows the corpus luteum to continue producing progesterone, which is necessary to maintain the early stages of pregnancy.

Question 5

Choose the letter of the best match from the following:
-Sperm blockage.

Accepted Answer

The answer of Choose the letter of the best match...

Question 6

You notice that in your aquarium,previously full of undoubtedly male fish,one is laying eggs.Upon a bit of research,you find out that the species of fish you purchased is a sequential hermaphrodite.Which of the following is true?

Accepted Answer

The fact that a previously male fish is now laying eggs suggests that it has undergone protandry, the process of changing from male to female. This is a common occurrence in sequential hermaphrodites.

Question 7

Why did internal fertilization likely evolve?

Accepted Answer

Internal fertilization likely evolved as an adaptation to life in a terrestrial environment. With a terrestrial environment, eggs would dry out quickly and need to be protected from predators. Internal fertilization increases the chances of successful fertilization and allows for the protection and nourishment of the developing embryo before birth.

Question 8

-According to the figure,what is the only hormone that doesn't peak during ovulation?

Accepted Answer

Progesterone levels typically rise after ovulation, peaking during the luteal phase of the menstrual cycle. This hormone prepares the body for a potential pregnancy after ovulation has occurred, unlike LH, FSH, and estrogen, which peak around the time of ovulation to trigger and support the release of an egg.

Question 9

Choose the letter of the best match from the following:
-Sperm destruction.

Accepted Answer

Foams and jellies are spermicides, which are substances designed to destroy sperm, preventing them from fertilizing an egg.

Question 10

Even if utilized properly,what is the least effective means of birth control?

Accepted Answer

Foam is considered the least effective means of birth control when compared to the options listed. This is because its effectiveness heavily depends on proper use each time, and even with correct use, it has a higher failure rate than methods like oral contraceptives, IUDs, and implants.

Question 11

Vertebrates that practice internal fertilization employ three strategies for embryonic and fetal development.In one strategy,the female retains the eggs within her body and the young are fully developed when they hatch inside of her.What is this called?

Accepted Answer

This strategy is called ovoviviparity, where the fertilized eggs are retained within the female's body until they hatch, with the young being fully developed at the time of hatching.

Question 12

There are exceptions to the general rule that amphibians lay eggs that develop in the water.These exceptions show extreme variation but they do have one thing in common.What is it?

Accepted Answer

They all develop in some sort of pouch.

Question 13

-According to the figure,what is occurring during day 2?

Accepted Answer

During day 2 of the menstrual cycle, menstruation is occurring, which is the shedding of the uterine lining.

Question 14

What is an important benefit of using condoms?

Accepted Answer

Condoms help protect against sexually transmitted infections and diseases, making them an important tool for safe sex practices. They do not have a failure rate of 1% and do not have any proven benefits for preventing prostate cancer or osteoporosis.

Question 15

Vertebrates that practice internal fertilization employ three strategies for embryonic and fetal development.In one strategy,the female retains the young which develop and obtain nourishment from the female's blood.What is this called?

Accepted Answer

Viviparity is the reproductive strategy in which the female retains the embryos and nourishes them internally until birth. The young receive nutrients from the female's blood, either directly or through a placenta. Oviparity is the deposition of eggs outside the body, where they develop and receive nourishment from the yolk. Ovoviviparity is a combination of the two, where the eggs develop and hatch inside the female's body but receive no nourishment from her, relying solely on the yolk. Protogyny and protandry refer to sequential hermaphroditism, where an individual changes sex during its lifetime.

Question 16

Choose the letter of the best match from the following:
-Prevention of egg maturation and ovulation.

Accepted Answer

The birth control pill contains hormones that prevent the release of an egg and therefore ovulation.

Question 17

Which of the following have young which feed on milk?

Accepted Answer

All marsupials, monotremes, and placental mammals feed their young with milk. Marsupials, like kangaroos and koalas, carry their young in pouches. Monotremes, such as the platypus and echidna, are egg-laying mammals but still produce milk for their offspring. Placental mammals, which include humans, dogs, and whales, develop their young in the uterus and feed them with milk after birth.

Question 18

There are numerous fish genera that have individuals that can change their sex during their lifetime.What is this called?

Accepted Answer

This is known as sequential hermaphroditism, where an individual changes sex during its lifetime. It can be either protogyny (female to male) or protandry (male to female). It is commonly found in fish, amphibians, and some reptiles.

Question 19

Choose the letter of the best match from the following:
-Surgical intervention.

Accepted Answer

Vasectomy is the only option listed that involves surgical intervention. The other options are all non-surgical methods of birth control.

Question 20

Choose the letter of the best match from the following:
-Prevention of embryo implantation.

Accepted Answer

The intrauterine device (IUD) works by preventing the fertilized egg from implanting in the uterus. It is a long-acting, reversible form of birth control that is inserted into the uterus by a healthcare provider. It is highly effective and can prevent pregnancy for up to 10 years. The other options listed do not specifically prevent embryo implantation.

Quiz 51: The Reproductive System

Which of the following determines genetic sex (male or female) in mammals?