High School Biology : Cell Division

Study concepts, example questions & explanations for High School Biology

varsity tutors app store varsity tutors android store

Example Questions

Example Question #71 : Cell Division

In human females, an ovum is released into the fallopian tube approximately how often?

Possible Answers:

Every 28 days

All the eggs are released at birth

Only after fertilization

Once a year

Once a day

Correct answer:

Every 28 days

Explanation:

Normally, one ovum is released every 28 days in human females. These 28 days constitute the menstrual cycle, which may vary in length, but on average, the cycle takes 28 days. A female is born with all the eggs she will ever have, and after the initiation of menstruation, one egg is released every 28 days until menopause.

Example Question #71 : Cell Division

What hormone stimulates primary oocytes to resume meiosis?  

Possible Answers:

Thyroid-stimulating hormone

Follicle-stimulating hormone

Luteinizing hormone

Estrogen

Human chorionic gonadotropin

Correct answer:

Follicle-stimulating hormone

Explanation:

At the beginning of the menstrual cycle, elevated follicle-stimulating hormone (FSH) stimulates primary oocytes to resume meiosis. A spike in luteinizing hormone (LH) triggers ovulation. Thyroid-stimulating hormone (TSH) and human chorionic gonadotropin (hCG) are involved in thyroid hormone secretion, and in maintenance of the corpus luteum during pregnancy, respectively. Estrogen is a female sex hormone, and has an indirect regulatory role in meiotic divisions of ova.

Example Question #11 : Understanding Oogenesis

Where does oocyte development occur in humans?

Possible Answers:

Placenta

Fallopian tubes

Uterus

Ovaries

Cervix

Correct answer:

Ovaries

Explanation:

An oocyte develops in the ovaries during female gametogenesis. If the oocyte eventually becomes an ovum and is fertilized in the fallopian tubes, the resulting gamete will be implanted in the uterus. The placenta is an organ that connects the developing fetus to the uterine wall, and the cervix is the lower portion of the uterus that separates the vagina from the uterus.

Example Question #231 : Cell Biology

How many chromosomes does a normal human gamete have?

Possible Answers:

Correct answer:

Explanation:

When gametes join they form a cell called a zygote. Human sperm and eggs contain 23 chromosomes. Human zygotes contain 46 chromosomes. The type of cell division that produces gametes with half the normal chromosomes is called meiosis.  

Example Question #231 : Cell Biology

Spermatogenesis produces four viable spermatozoa. What is produced during oogenesis?

Possible Answers:

Four mature ova

Four mature polar bodies

One mature ovum and three polar bodies

Three mature ova and one polar body

Correct answer:

One mature ovum and three polar bodies

Explanation:

During oogenesis—at the end of meiosis and cytokinesis—an oogonium divides into one mature ovum capable of being fertilized and three polar bodies that are reabsorbed, while a spermatogonium divides into four viable spermatozoa capable of fertilization.

Example Question #41 : Meiosis

How many chromosomes and how many chromatids are contained in one spermatid?

Possible Answers:

46 chromosomes composed of 92 chromatids

23 chromosomes composed of 46 chromatids

46 chromosomes composed of 46 chromatids

46 chromosomes composed of 23 chromatids

23 chromosomes composed of 23 chromatids

Correct answer:

23 chromosomes composed of 23 chromatids

Explanation:

A spermatid is the final product of spermatogenesis. It is a haploid cell, meaning it has only one copy of each allele (one of each chromosome instead of two). Normal diploid cells have two copies of each chromosome, for a total of 46. Spermatids have half this number, for a total of 23 chromosomes. Each chromosome is composed of only a single chromatid following division, for a total of 23 chromatids.

When the zygote is formed during the fusion of the sperm and egg cells, the final cell is diploid, containing 46 chromosomes (23 from each gamete).

An outline of spermatogenesis is given here for further understanding.

Spermatogenesis Timeline:

1) Spermatogonium (46 chromosomes, 92 chromatids)

- Has a pair of each chromosome, and each individual chromosome has two chromatids.

- Undergoes mitosis (normal cell division) to produce a primary speratocyte.

2) Primary spermatocyte (46 chromosomes, 46 chromatids)

- Has a pair of each chromosome and each individual chromosome has one chromatid.

- Then replicates its DNA, resulting in 46 chromosomes with 92 chromatids.

- Then undergoes meiosis I (homologous chromosome pairs separate), producing two secondary spermatocytes.

3) Secondary spermatocytes (23 chromosomes, 46 chromatids)

- Has one of each chromosome, and each individual chromosome has two chromatids.

- Each secondart spermatocyte undergoes meiosis II (chromatids of each chromosome separate, similar to mitosis), producing a total of four spermatids.

4) Spermatids (23 chromosomes, 23 chromatids).

- Has one of each chromosome, and each individual chromosome has one chromatid

 

Example Question #1 : Understanding Spermatogenesis

Spermatogenesis is __________.

Possible Answers:

a process that occurs in both human males and females

the formation of genetically identical spermatids via meiosis

the formation of genetically identical spermatids via mitosis

the formation of genetically nonidentical spermatids via mitosis

the formation of genetically nonidentical spermatids via meiosis

Correct answer:

the formation of genetically nonidentical spermatids via meiosis

Explanation:

Spermatogenesis occurs only in human males (in the testes), not in females. It is the process by which spermatids are formed via meiosis. The process of meiosis contributes to genetic diversity. This is why siblings are not identical to each other or to their parents.

Example Question #1 : Understanding Spermatogenesis

Where does spermatogenesis occur?

Possible Answers:

Lumen

Prostate gland

Seminiferous tubules

Seminal vesicle

Ampulla

Correct answer:

Seminiferous tubules

Explanation:

Spermatogenesis is the process of producing the male gametes, spermatozoa (sperm). The spermatogonia in the seminiferous tubules of the testes mature into spermatocytes, which undergo meiosis to form spermatozoa. The spermatozoa complete their maturation process in the epididymas, then they are ready to enter the vas deferens before ejaculation. Lumen is a general term that means "an opening." Although spermatogenesis does occur in the lumen of the seminiferous tubules, the term lumen is too broad and is not the best answer. An ampulla is a general term that, in anatomy, means "the dilated end of a duct." There is an ampulla of the vas deferens before it enters the prostate gland, but spermatogenesis does not occur there. The prostate gland produces a milky, alkaline solution that comprises about 30% of semen. The seminal vesicles are glands that produce the majority of the solution that will become semen. Note the difference between semen (fluid) and sperm (cells).

Example Question #71 : Cell Division

Often, in animals that sexually reproduce, hormones or chemicals that are present during normal gametogenesis are not strictly necessary, allowing for a chance of reproduction even under difficult environmental circumstances.

Which of the following hormones/proteins, while normally present, may not be strictly necessary for the process of spermatogenesis in the human male?

Possible Answers:

Testosterone

Estradiol

Androgen-binding protein

Follicle Stimulating Hormone

Inhibin

Correct answer:

Follicle Stimulating Hormone

Explanation:

Follicle-stimulating hormone may help to sequester testosterone in the testes (the Sertoli cells can perform the same function by releasing androgen-binding protein), but the only hormone needed to maintain spermatogenesis is testosterone itself. FSH is not needed for in-vitro maturation of spermatozoa, and thus cannot be said to be required inside the body for the process of spermatogenesis.

Example Question #72 : Cell Division

What is the primary role of androgen-binding protein (ABP) in the process of spermatogenesis?

Possible Answers:

Stimulates phagocytosis of leftover cytoplasm from spermiogenesis, cleaning the testicular fluid of dead cellular material.

Regulates spermatid adhesion on the side of the blood-testis barrier towards the lumen.

Maintains the blood-testis barrier to prevent the body's immune system from attacking and destroying the developing spermatocytes.

Increases fertility in the reproductive tract by concentration of testosterone near the developing gametes.

Creates a pH-neutral environment for the rapid production of follicle stimulating hormone (FSH) in the testes.

Correct answer:

Increases fertility in the reproductive tract by concentration of testosterone near the developing gametes.

Explanation:

A very high level of testosterone (15-70 times greater than in the blood) is required for the initiation and maintenance of spermatogenesis, and androgen-binding protein's most direct role is ensuring this high concentration of testosterone by preventing absorption of testosterone back into the body across the blood-testis barrier.

Learning Tools by Varsity Tutors