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- This graph plots the rise and fall of pituitary and ovarian hormones during the human ovarian cycle. Identify each hormone (A–D) and the reproductive events with which each one is associated (P–S). For A–D, choose from estrogen, LH, FSH, and progesterone. For P–S, choose from ovulation, growth of follicle, menstruation, and development of corpus luteum. How would the right-hand side of this graph be altered if pregnancy occurred? What other hormone is responsible for triggering this change?
Problem 1
Problem 2
Match each function with the correct structure.
2. Turns into the corpus luteum
3. Female gonad
4. Site of spermatogenesis
5. Site of fertilization in humans
6. Site of human gestation
7. Sperm duct
8. Secretes seminal fluid
9. Lining of uterus
a. vas deferens
b. prostate gland
c. endometrium
d. testis
e. follicle
f. uterus
g. ovary
h. oviduct
Problem 10
After a sperm penetrates an egg, it is important that the vitelline layer separate from the egg so that it can
a. Secrete important hormones.
b. Enable the fertilized egg to implant in the uterus.
c. Prevent more than one sperm from entering the egg.
d. Attract additional sperm to the egg.
Problem 11
In an experiment, a researcher colored a bit of tissue on the outside of a frog gastrula with an orange fluorescent dye. The embryo developed normally. When the tadpole was placed under an ultraviolet light, which of the following glowed bright orange? (Explain your answer.)
a. The heart
b. The pancreas
c. The brain
d. The stomach
Problem 12
How does a zygote differ from a mature egg?
a. A zygote has more chromosomes.
b. A zygote is smaller.
c. A zygote consists of more than one cell.
d. A zygote divides by meiosis.
Problem 13
A woman had several miscarriages. Her doctor suspected that a hormonal insufficiency was causing the lining of the uterus to break down, as it does during menstruation, terminating her pregnancies. Treatment with which of the following might help her remain pregnant?
a. Oxytocin
b. Follicle-stimulating hormone
c. Luteinizing hormone
d. Prolactin
- The embryos of reptiles (including birds) and mammals have systems of extraembryonic membranes. What are the functions of these membranes, and how do fish and frog embryos survive without them?
Problem 14
- Compare sperm formation with egg formation. In what ways are the processes similar? In what ways are they different?
Problem 15
- In an embryo, nerve cells grow out from the spinal cord and form connections with the muscles they will eventually control. What mechanisms described in this chapter might explain how these cells 'know' where to go and which cells to connect with?
Problem 16
- As a frog embryo develops, the neural tube forms from ectoderm along what will be the frog's back, directly above the notochord. To study this process, a researcher extracted a bit of notochord tissue and inserted it under the ectoderm where the frog's belly would normally develop. What can the researcher hope to learn from this experiment? Predict the possible outcomes. What experimental control would you suggest?
Problem 17
Problem 18
Should parents undergoing in vitro fertilization have the right to choose which embryos to implant based on genetic criteria, such as the presence or absence of disease-causing genes? Should they be able to choose based on the sex of the embryo? How could you distinguish acceptable from unacceptable criteria? Do you think such options should be legislated?
Problem 19
There are difficulties inherent in testing hypotheses involving human health. Imagine that you have developed a potential vaccine against AIDS. Given the nature of the disease, all testing must be conducted in humans. Can you design an ethical but effective experiment?