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18.E: Animal Reproduction and Development (Exercises)

  • Page ID
    8096
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    18.1: How Animals Reproduce

    Review Questions

    In which group is parthenogenesis a normal event?

    A. chickens
    B. bees
    C. rabbits
    D. sea stars

    Answer

    B

    Genetically unique individuals are produced through ________.

    A. sexual reproduction
    B. parthenogenesis
    C. budding
    D. fragmentation

    Answer

    A

    External fertilization occurs in which type of environment?

    A. aquatic
    B. forested
    C. savanna
    D. steppe

    Answer

    A

    Free Response

    What might be a disadvantage to temperature-dependent sex determination?

    Answer

    Temperatures can vary from year to year and an unusually cold or hot year might produce offspring all of one sex, making it hard for individuals to find mates.

    Compared to separate sexes and assuming self-fertilizing is not possible, what might be one advantage and one disadvantage to hermaphroditism?

    Answer

    A possible advantage of hermaphroditism might be that anytime an individual of the same species is encountered a mating is possible, unlike separate sexes that must find an individual of the right sex to mate. (Also, every individual in a hermaphrodite population is able to produce offspring, which is not the case in populations with separate sexes.) A disadvantage might be that hermaphrodite populations are less efficient because they do not specialize in one sex or another, which means a hermaphrodite does not produce as many offspring through eggs or sperm as do species with separate sexes. (Other answers are possible.)

    18.2: Development and Organogenesis

    Review Questions

    The process of gastrulation forms the _______.

    A. blastula
    B. zygote
    C. organs
    D. germ layers

    Answer

    D

    Which of the following gives rise to the skin cells?

    A. ectoderm
    B. endoderm
    C. mesoderm
    D. none of the above

    Answer

    A

    Free Response

    What do you think would happen if multiple sperm fused with one egg?

    Answer

    If multiple sperm fused with one egg, a zygote with a multiple ploidy level (multiple copies of the chromosomes) would form, and then would die.

    18.3: Human Reproduction

    Review Questions

    Sperm are produced in the ________.

    A. scrotum
    B. seminal vesicles
    C. seminiferous tubules
    D. prostate gland

    Answer

    C

    Which female organ has an endometrial lining that will support a developing baby?

    A. labia minora
    B. breast
    C. ovaries
    D. uterus

    Answer

    D

    Which hormone causes FSH and LH to be released?

    A. testosterone
    B. estrogen
    C. GnRH
    D. progesterone

    Answer

    C

    Nutrient and waste requirements for the developing fetus are handled during the first few weeks by ________.

    A. the placenta
    B. diffusion through the endometrium
    C. the chorion
    D. the blastocyst

    Answer

    B

    Which hormone is primarily responsible for the contractions during labor?

    A. oxytocin
    B. estrogen
    C. β-HCG
    D. progesterone

    Answer

    A

    Free Response

    Compare spermatogenesis and oogenesis as to timing of the processes, and the number and type of cells finally produced.

    Answer

    Stem cells are laid down in the male during gestation and lie dormant until adolescence. Stem cells in the female increase to one to two million and enter the first meiotic division and are arrested in prophase. At adolescence, spermatogenesis begins and continues until death, producing the maximum number of sperm with each meiotic division. Oogenesis continues again at adolescence in batches of eggs with each menstrual cycle. These primary oocytes finish the first meiotic division, producing a viable egg with most of the cytoplasm and its contents, and a second cell called a polar body containing 23 chromosomes. The second meiotic division is initiated and arrested in metaphase. At ovulation, one egg is released. If this egg is fertilized, it finishes the second meiotic division. This is a diploid, fertilized egg.

    Describe the events in the ovarian cycle leading up to ovulation.

    Answer

    Low levels of progesterone allow the hypothalamus to send GnRH to the anterior pituitary and cause the release of FSH and LH. FSH stimulates follicles on the ovary to grow and prepare the eggs for ovulation. As the follicles increase in size, they begin to release estrogen and a low level of progesterone into the blood. The level of estrogen rises to a peak, causing a spike in the concentration of LH. This causes the most mature follicle to rupture and ovulation occurs.

    Describe the stages of labor.

    Answer

    Stage one of labor results in uterine contractions, which thin the cervix and dilate the cervical opening. Stage two delivers the baby, and stage three delivers the placenta.


    This page titled 18.E: Animal Reproduction and Development (Exercises) is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax.

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