The cells of the immune system that are responsible for attacking cells that have become cancerous are the:
a. B-cells
b. cytotoxic T-cells
c. helper T cells
d. suppressor T cells (T regulatory cells)
Ans: b. cytotoxic T-cells
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The most common method of transfer of antimicrobial resistance is through the use of
A. viruses. B. R plasmids. C. introns. D. exons.
What happens during nondisjunction?
a. Cells enter a brief interphase between meiosis I and meiosis II. b. Pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. c. Cells divide evenly during meiosis. d. One segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome.
If you cross two pea plants, one with green peas and the other with yellow peas, you find all of the offspring have yellow peas. You conclude the yellow parent was
A. homozygous for the recessive allele. B. heterozygous. C. homozygous for the dominant gene. D. homozygous for the dominant allele. E. homozygous for the recessive gene.
Some members of the species D. bifasciata produce mostly female offspring if reared at or below 21°C. The causative agent of this condition (called sex ratio) is a protozoan infection that is lethal to most male larvae
How can you demonstrate that it is both inherited and extrachromosomal? A) Inject ooplasm of affected females into normal females and then mate these with normal males. B) Inject cytoplasm from somatic cells of an affected female into normal females and then mate them with normal males. C) Mate affected females with normal males and assess daughter somatic cells for presence of the protozoan. D) Perform reciprocal crosses of affected and normal individuals and examine the offspring for infection. E) Perform reciprocal crosses of affected and normal individuals and look for affected male offspring.