question

Which of these is NOT a carcinogen?

answer

fat testosterone cigarette smoke UV light all of the above are carcinogens

question

_____ is a carcinogen that promotes colon cancer.

answer

fat (A diet high in fat increases the risk of both colon and breast cancer.)

question

Which of the following would be most likely to lead to cancer?

answer

amplification of a proto-oncogene and inactivation of a tumor-suppressor gene (Excess copies of the proto-oncogene could stimulate cell division abnormally, and the inactivation of a tumor-suppressor gene would eliminate a brake on cell division.)

question

All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs?

answer

Proto-oncogenes are necessary for the normal control of cell growth and division. (Proto-oncogenes can become oncogenes when a mutation or other genetic change increases the activity of the encoded protein.)

question

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?

answer

G1 (In mammalian cells, this checkpoint is termed the restriction point.)

question

Which of the following is true of benign tumors, but not malignant tumors?

answer

They remain confined to their original site (They remain confined to their original site)

question

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

answer

Proto-oncogenes normally help regulate cell division.

question

Of the two processes we learned about which is gong on in my hand right now?

answer

mitosis

question

If you look through a microscope and see chromosomes lined up two by two, what stage of cellular reproduction must you be looking at?

answer

meiosis I only

question

What structure is where sister chromatids are joined together?

answer

centromere (The centromere is the point of attachment between two sister chromatids of a duplicated chromosome.)

question

If the hypothetical organism has 5 chromosomes in one of its gametes, then it must have ______ chromosomes in a body cell just before mitosis

answer

10 (just before mitosis, the chromosomes in a body cell are duplicated, but the sister chromatids remain joined together. So you will see 10 (duplicated) chromosomes in a typical body cell.)

question

Chromosomes are duplicated and lined up by homologous pair _________________.

answer

at the start of meiosis I

question

What name is given to this process (budding)?

answer

asexual reproduction

question

Human gametes are produced by _____.

answer

meiosis (Meiosis produces haploid gametes from a diploid parental cell.)

question

Normal human gametes carry _____ chromosomes.

answer

23

question

Which of these cells is (are) haploid? The figure shows the process of meiosis. Initially, chromosomes are scattered all over the cell. This stage is labeled A. During interphase, they become replicated and arranged in pairs with homologous chromosomes. This stage is labeled B. During meiosis 1, which is labeled C, the cell divides into 2 and each cell has 1 chromosome. During meiosis 2, which is labeled D, the cells from meiosis 1 divide into 2 once again. The resulting cells all have 1 chromatid.

answer

C and D (Once meiosis I is completed, cells are haploid.)

question

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

answer

16

question

Meiosis I produces _____ cells, each of which is _____.

answer

two ... haploid

question

Meiosis II typically produces _____ cells, each of which is _____.

answer

four ... haploid

question

During _____ sister chromatids separate.

answer

anaphase II (Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.)

question

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

answer

telophase I

question

Synapsis occurs during _____.

answer

prophase I

question

Synapsis

answer

the pairing of homologous chromosomes, occurs during prophase I

question

Homologous chromosomes migrate to opposite poles during _____.

answer

anaphase I

question

During _____ chromosomes align single file along the equator of a haploid cell.

answer

metaphase II

question

At the end of _____ and cytokinesis there are four haploid cells.

answer

telophase II

question

During _____ a spindle forms in a haploid cell.

answer

prophase II

question

Select the statement that accurately describes gametes.

answer

Gametes, such as eggs and sperm, are haploid reproductive cells that fuse during fertilization in sexual life cycles.

question

Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

answer

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. (During anaphase of both meiosis I and meiosis II, the DNA content (number of copies of chromosomes) in a cell is halved. However, the ploidy level changes only when the number of unique chromosome sets in the cell changes. This occurs only in meiosis I (where separation of homologous chromosomes decreases the ploidy level from 2n to n and produces daughter cells with a single chromosome set).)

question

Heredity.

answer

The transmission of traits from parents to offspring

question

The following processes are associated with meiosis and the sexual life cycle: DNA replication before meiosis crossing over chromosome alignment in metaphase I and separation in anaphase I chromosome alignment in metaphase II and separation in anaphase II fertilization Sort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both. (Note that a bin may be left empty.)

answer

Both: DNA replication before meiosis crossing over chromosome alignment in metaphase I and separation in anaphase I chromosome alignment in metaphase II and separation in anaphase II fertilization

question

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

answer

There would be less genetic variation among gametes.

question

True or false? Humans form gametes by a process called gametogenesis.

answer

True

question

What role do germ cells play in gametogenesis?

answer

They produce cells that divide by mitosis and then undergo meiosis to form gametes.

question

What products are formed when a diploid cell undergoes meiosis?

answer

Four haploid cells.

question

Which of the following statements about oogenesis in humans is true?

answer

Beginning at puberty, a primary oocyte completes its first meiotic division to form a secondary oocyte and a polar body approximately every month. (This secondary oocyte is released into the oviduct during ovulation and then begins meiosis II, which is not complete unless the oocyte is fertilized by a sperm cell.)

question

Which diploid cells are produced by an embryonic germ cell?

answer

Spermatogonia.

question

True or false? The production of sperm begins at puberty when spermatogonia undergo meiosis I to form primary spermatocytes, which then undergo meiosis II to form secondary spermatocytes. These secondary spermatocytes go on to form spermatids, which mature into sperm cells.

answer

False (Spermatogonia divide by mitosis and differentiate into primary spermatocytes. Starting at puberty, hormones stimulate the primary spermatocytes to undergo meiosis I to form secondary spermatocytes, which then undergo meiosis II to form spermatids.)

question

How does spermatogenesis differ from oogenesis?

answer

Diploid cells give rise to four functional gametes in spermatogenesis.

question

Which processes lead to most genetic variation in sexually reproducing organisms? Select all that apply.

answer

crossing over independent assortment of chromosomes in meiosis random fertilization

question

Which of these gametes contains one or more recombinant chromosomes? The figure shows 2 cells which undergo meiosis. A cell on the left has 4 chromosomes (from left to right and from top to bottom): large blue, large red, small blue, and small red. After two meiotic divisions, 4 cells labeled A to D are formed. Cell A contains 1 large blue and 1 small blue chromatid. Cell B contains 1 large blue and 1 small blue chromatid. Their ends of arms were replaced with parts of the homologous red chromosomes. Cell C contains, vice versa, 1 large red and 1 small red chromatid partially replaced with blue DNA. Cell D contains 1 large red and 1 small red chromatid. The other parental cell (on the right) has 4 chromosomes as well (from left to right and from top to bottom): large red, large blue, small blue, and small red. After two meiotic divisions, 4 cells are formed, one of which is labeled E. This cell contains 1 large red and one small blue chromatid.

answer

B and C

question

Suppose you wanted to start an animal-breeding business. For most of the following animals, you could start out with just a single animal. Which of the animals below would require that you start with at least two individuals?

answer

frogs

question

Sexual reproduction includes a reproductive pattern called _____.

answer

hermaphroditism (In hermaphroditism a single individual produces both sperm and ova; although some individuals fertilize themselves, most must mate with another member of the same species.)

question

The "reproductive handicap" for sexual reproduction refers to _____.

answer

have only half the offspring are females (A female undergoing asexual reproduction would have offspring that have 100% of her genes, whereas a sexually reproducing female typically passes only 50% of her genetic material to her offspring.)

question

Salamander and insect populations consisting only of genetically identical females lack males because _____.

answer

sperm do not fuse with eggs during reproduction, but the eggs develop into embryos anyway

question

Which of the following correctly traces the path of sperm from their site of production to their exit from a man's body?

answer

seminiferous tubule → epididymis → vas deferens → urethra (Sperm are produced in the seminiferous tubules, mature in the epididymis, and during ejaculation pass through the vas deferens into the urethra.)

question

In humans, oogenesis in comparison to spermatogenesis is different in that _____.

answer

oogenesis does not complete meiosis until after fertilization, but spermatogenesis is complete before the sperm leave the body

question

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

answer

cervix

question

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

answer

the wavelike beating of cilia lining the oviduct.

question

A surge in which hormone(s) immediately precedes ovulation?

answer

LH and FSH

question

Based on the graph, elevated levels of which hormone(s) most likely stimulate the LH/FSH surge just before ovulation?

answer

estradiol

question

The levels of pituitary hormones never increase above 10 grams/L of blood.

answer

Cannot be determined from the graph

question

A surge in estradiol levels correlates with a surge in progesterone levels.

answer

Not supported

question

Which characteristic of the male reproductive system is not variable among animal species that reproduce sexually?

answer

Presence of genitalia.

question

True or false? The basic functions of the human female reproductive system are to produce eggs, develop offspring, and make hormones.

answer

True (Eggs are produced in the ovaries and transported to the uterus, the site of embryonic development.)

question

Which function is not performed by the male reproductive system?

answer

Production and storage of oogonia. (Oogonia are produced bythe female reproductive system.)

question

Which hormone spikes midway through the menstrual cycle and triggers ovulation?

answer

Luteinizing hormone (LH). (Luteinizing hormone (LH) secreted by the pituitary gland causes the mature ovarian follicle to rupture, a process called ovulation.)

question

Which male reproductive structures are responsible for the transport and delivery of sperm?

answer

Vas deferens, urethra, and penis. (The vas deferens transports sperm from the epididymis to the ejaculatory duct, which empties into the urethra; the urethra carries sperm through the penis to the outside of the body and into the female reproductive tract.)

question

Where does a human fetus develop?

answer

Uterus. (The uterus is the site of implantation and embryonic development.)

question

Which of the following events occurs at the onset of the luteal phase of the menstrual cycle?

answer

Development of the corpus luteum. (The corpus luteum develops from the ruptured follicle during the luteal phase after ovulation.)

question

A fertilized egg usually implants itself and develops in the _____.

answer

uterus

question

A rapid increase in the _____ level stimulates ovulation.

answer

luteinizing hormone

question

After ovulation, high levels of _____ inhibit _____ secretion.

answer

estrogen and progesterone ... FSH and LH

question

Developing ovarian follicles primarily secrete _____.

answer

estrogens

question

If there is fertilization, secretion of _____ by the early embryo maintains the corpus luteum.

answer

human chorionic gonadotropin (HCG, secreted by the early embryo, maintains the corpus luteum. The corpus luteum secretes estrogen and progesterone, which maintain the endometrium for implantation.)

question

If there is no fertilization, degeneration of the corpus luteum results in a drop in _____, which results in the sloughing off of the uterus's endometrium.

answer

estrogen and progesterone (Estrogen and progesterone are responsible for maintaining the endometrium in the event that the egg has been fertilized.)

question

Ovulation usually occurs on or about day _____ of a 28-day ovarian cycle.

answer

14

question

What is the usual site of the fertilization of an egg cell?

answer

oviduct

question

Sperm become capable of movement while in the _____.

answer

epididymis

question

Sperm exit a male's body via the _____.

answer

urethra

question

The secretion of androgens is regulated by a _____ feedback mechanism involving the _____ and _____.

answer

negative ... hypothalamus ... pituitary gland (An increase in androgens inhibits the secretion of releasing hormones by the hypothalamus and LH secretion by the pituitary gland. A decrease in androgens stimulates the secretion of releasing hormones by the hypothalamus and LH secretion by the pituitary gland.)

question

Which hormone(s) is(are) directly responsible for triggering the development of the secondary sex characteristics of males, such as beard growth?

answer

androgens (Androgens, such as testosterone, are responsible for both sperm production and the secondary sex characteristics of males.)

question

Which pituitary secretion stimulates sperm production?

answer

FSH (In males, follicle-stimulating hormone (FSH) stimulates sperm production.)

question

Which pituitary secretion stimulates the testes to secrete androgens?

answer

LH (In males, luteinizing hormone (LH) stimulates the testes to secrete androgens.)

question

Sperm develop in the _____.

answer

seminiferous tubules

question

Secondary Sex Characteristics of Males

answer

deep voice, male hair growth pattern, increased muscle size, increased aggressiveness

question

Secondary Sex Characteristics of Females

answer

enlarged breasts, fat deposition in hips and breasts, water retention, changes in calcium metabolism and bone deposition

question

The increased levels of ____________________ in the second half of the cycle inhibit secretion of FSH and LH and promote maintenance of the endometrium.

answer

progesterone

question

A peak in _______________ levels causes a surge in LH secretion, leading to ovulation.

answer

estradiol

question

__________ stimulates the development of ovarian follicles.

answer

FSH

question

An increase in ________ concentration triggers ovulation.

answer

LH

question

Which statements correctly explain how the hormone-based contraceptives affect the female reproductive cycle?

answer

The progestin in the progestin-only pill causes changes in the endometrium that prevent implantation. The low doses of progestin and estradiol in the combination pill have a negative feedback effect on the hypothalamus, blocking ovulation. The low dose of estradiol in the combination pill prevents the surge in LH production.

question

The anatomical location for the typical union of a sperm and an egg (conception) is the _____.

answer

oviducts (Ovulation releases the eggs into the abdominal cavity, where they are swept into the oviduct.)

question

Human pregnancy is indicated by the presence of chorionic-gonadotropin metabolites in the urine until _____.

answer

the placenta takes over for the ovaries in producing the steroid hormones needed during pregnancy (Prior to the full development of the placenta at the end of the first trimester, chorionic gonadotropin is needed to stimulate steroid hormone production in the ovaries.)

question

Which of the following characterizes parthenogenesis?

answer

An egg develops without being fertilized.

question

In male mammals, excretory and reproductive systems share

answer

the urethra.

question

Which of the following is not properly paired?

answer

seminiferous tubule-cervix (testosterone-estradiol vas deferens-oviduct scrotum-labia majora Sertoli cells-follicle cells all are paired correctly)

question

Peaks of LH and FSH production occur during

answer

the period just before ovulation

question

During human gestation, rudiments of all organs develop

answer

in the first trimester.

question

Which of the following is a true statement?

answer

The endometrial lining is shed in menstrual cycles but reabsorbed in estrous cycles

question

For which of the following is the number the same in spermatogenesis and oogenesis?

answer

meiotic divisions required to produce each gamete

question

Which statement about human reproduction is false?

answer

The earliest stages of spermatogenesis occur closest to the lumen of the seminiferous tubules. (Spermatogenesis and oogenesis require different temperatures. An oocyte completes meiosis after a sperm penetrates it. Fertilization occurs in the oviduct. Effective hormonal contraceptives are currently available only for females. Are all true)

question

Which of these is true of the cytoplasm of an unfertilized egg?

answer

It is an unevenly distributed mixture of mRNA, proteins, organelles, and other substances. (Many proteins are found concentrated at one end of the cell or another and provide positional information to the developing embryo.)

question

Which hormone's secretion is controlled by a positive feedback mechanism?

answer

Oxytocin

question

Identify the role(s) of follicle-stimulating hormone (FSH) in human reproduction. Select all that apply.

answer

FSH stimulates the growth of new follicles in the ovary. FSH promotes the activity of Sertoli cells, which nourish sperm developing within seminiferous tubules.

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