A mutation in mice leads to overgrowth of the Sertoli cells, so they span across the diameter of the seminiferous tubules. What phenotype would you expect to see?
A. infertility due to lack of mature sperm entering the epididymis
B. infertility due to lack of mature oocytes
C. overproduction of sperm, so they clog the bulbourethral gland
D. overproduction of testosterone
Answer: A
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The formation of the bivalent during meiosis
A. is required for the pairing of homologous chromosomes. B. contributes to the genetic diversity of a species. C. ensures that the resulting haploid cells will have the same combination of homologous chromosomes as the original diploid cell. D. aids the alignment of sister chromatids in a single row along the metaphase plate. E. occurs during meiosis I and meiosis II.
The role of a tumor suppressor protein in a cell is to ____
a. promote cell division of healthy cells b. inhibit cell growth and division c. promote cell division of abnormal cells d. trigger DNA replication in preparation for cell division e. serve as a cell receptor for growth factors
____ in the figure diagram above represent consumers.
A. Only the plants
B. Only the insects
C. Everything except trees
D. Spiders, frogs, fish, and humans
Which of the following is NOT an adhesion mechanism that bacteria use to attach to a host?
A) fimbriae attach to epithelium of host B) glycocalyx anchors the microbe to the host C) dextran slime layer glues the microbe to the host surface D) envelope spikes puncture cells for entry