High School Biology : Understanding Oogenesis

Study concepts, example questions & explanations for High School Biology

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Example Questions

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Example Question #31 : Meiosis

Fraternal twins or triplets may be born as a result of __________.

Possible Answers:

two or more sperm fertilizing a single ovum

failure of the oocyte to complete meiosis

ovulating before the follicular phase of the menstrual cycle

more than one follicle maturing in a single menstrual cycle

an oocyte entering metaphase before fertilization

Correct answer:

more than one follicle maturing in a single menstrual cycle

Explanation:

During the menstrual cycle, typically only one follicle matures and is fertilized. The follicles that do not mature are called polar bodies and degenerate. However, sometimes multiple follicles remain and are available to be fertilized, resulting in genetically distinct embryos, known as fraternal twins.  

Example Question #11 : Understanding Oogenesis

After a primary oocyte divides meiotically, three haploid cells are produced. What is the term for the two smaller cells that typically disintegrate and are not fertilized?

Possible Answers:

Embryos

Fallopian tubes

Diploids

Polar bodies

Zygotes

Correct answer:

Polar bodies

Explanation:

Typically, each menstrual cycle produces three primary oocytes. Two of these primary oocytes are inevitably smaller than the third and usually disintegrate before maturation and fertilization. These two cells are known as polar bodies. Usually, meiosis results in four daughter cells that are all haploid. However, after meiosis I of oogenesis, there are two daughter cells, one primary oocyte, and a polar body. After meiosis II, the primary oocyte divides into a secondary oocyte and another polar body. However, the polar body that was a result of the first meiotic division usually does not complete meiosis, and thus does not divide again.

Example Question #32 : Meiosis

What must occur for a secondary oocyte to complete meiosis II?

Possible Answers:

Degeneration

Fertilization

Menstruation

Uterine contractions

Implantation

Correct answer:

Fertilization

Explanation:

The secondary oocyte completes meiosis II only when fertilized by a spermatozoan. After fertilization is initiated, the secondary oocyte begins its second meiotic division, resulting in the formation of a mature ovum and another polar body. At this point, the ovum is ready to fuse with the spermatozoan.

Example Question #31 : Meiosis

Where does fertilization of the ovum typically occur?

Possible Answers:

Follicle

Ovary

Cervix

Uterus

Fallopian tube

Correct answer:

Fallopian tube

Explanation:

Fertilization typically occurs in the fallopian tube. After fertilization, the diploid zygote will begin the process of implantation into the uterus, where it undergoes mitotic divisions. The resulting multicellular organism is called the embryo, which further develops in the uterus into a fetus.

Example Question #33 : Meiosis

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

Possible Answers:

Once a day

Only after fertilization

All the eggs are released at birth

Once a year

Every 28 days

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 #32 : Meiosis

What hormone stimulates primary oocytes to resume meiosis?  

Possible Answers:

Follicle-stimulating hormone

Human chorionic gonadotropin

Estrogen

Luteinizing hormone

Thyroid-stimulating hormone

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 #34 : Meiosis

Where does oocyte development occur in humans?

Possible Answers:

Cervix

Fallopian tubes

Ovaries

Uterus

Placenta

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 #11 : Understanding Oogenesis

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

Possible Answers:

Four mature polar bodies

One mature ovum and three polar bodies

Four mature ova

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.

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