Von Baer proposed that diagnostic traits for distinguishing species among vertebrates appear at the:
a. earliest stages of development.
b. latest stages of development.
c. earliest and latest stages of development.
d. middle stages of development.
B
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In most fungi, karyogamy does not immediately follow plasmogamy, which consequently _____
A) means that sexual reproduction can occur in specialized structures B) results in multiple diploid nuclei per cell C) allows fungi to reproduce asexually most of the time D) results in heterokaryotic or dikaryotic cells E) is strong support for the claim that fungi are not truly eukaryotic
More than half the world's human population lives in rural poverty. Which of the following environmental issues is most likely to be associated with these populations?
A) desertification B) acid rain C) oil pollution D) smog E) ozone depletion
Aortic and carotid bodies are
Select one: a. the same as the SA and AV nodes. b. types of valves in the heart. c. present in the lungs. d. sensitive to changes in CO2 and H+ in the blood. e. sensitive to oxygen changes.
Which of the following statements is TRUE of exogenous antigens?
A. All cells except red blood cells process exogenous antigens. B. Exogenous antigens are presented on class I MHC proteins. C. Only B cells can recognize exogenous antigens. D. Exogenous antigens are produced by cells infected with intracellular pathogens. E. Dendritic cells and macrophages process exogenous antigens.