Human males have _______ sex chromosomes.
a. XX
b. XY
c. XO
d. three types of
e. 23
Answer: b. XY
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How does inefficient transfer of energy among trophic levels result in the typically high endangerment status of many top-level predators?
A) Top-level predators are destined to have small populations that are sparsely distributed. B) Predators have relatively large population sizes. C) Predators are more disease-prone than animals at lower trophic levels. D) Predators have short life spans and short reproductive periods. E) Top-level predators are more likely to be stricken with parasites.
Which of the following is not a function of the IgG antibodies? a. Bind to pathogens
b. Attack invading bacteria through phagocytosis. c. Activates compliments. d. Neutralize toxins. e. Protection of the fetus.
Which of the following is likely to have the most toxic side effects to humans?
A. Inhibitors of protein synthesis B. Inhibitors of cell wall synthesis C. Disrupters of cell membrane structure D. Inhibitors of DNA synthesis
The umbilical cord of a mammal connects the
A) amnion and the chorion. B) maternal and fetal bloodstreams. C) yolk sac and the allantois. D) fetus and the placenta. E) embryo and the amnion.