You had a cold last month and you caught another one this month from your brother. What is the most likely reason
for this happening?
a. Memory cells were not formed as a response to the first cold.
b. The antibodies formed as a response to the first cold were degraded.
c. The two cold viruses are different.
d. Your macrophages are unable to perform phagocytosis.
e. Your antigen-presenting cells do not recognize the second cold virus.
ANSWER: c
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What type of invertebrate hormone is ecdysone?
a. amino acid b. peptide c. protein d. steroid e. Its structure is unknown.
Which characteristics best describe earthworms?
a. polychaete; fluid filled coelom b. oligochaete; open circulatory system c. moves by only longitudinal muscle contraction and hydrostatic skeleton d. oligochaete; scavengers; closed circulatory system e. hermaphrodites that fertilize themselves; closed circulatory system
Pleiotropic genes
a. act on secondary sexual characteristics. b. influence more than one aspect of phenotype. c. are additive. d. produce lethal effects when homozygous. e. cannot be inherited.
You are the managing naturalist for a natural history museum that has just received a batch of fossils from one of the field paleontologists sponsored by the museum. The note in the box states the fossils all came from the same rock layer. The museum is organized according to geologic timescale, and its management needs you to tell them to which department (based on era) and period specialist (an individual with experience with life-forms of a particular geologic-timescale period) the fossils should go. You find fossils of fish and seed-bearing plants but no reptiles or higher animals and no flowering plants. To which era do these fossils belong?
A) Precambrian B) Paleozoic C) Mesozoic D) Cenozoic