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Question
Carrier-mediated transport is necessary whenA) diffusion will not allow adequate amounts of a substance to enter the cell.
B) movement into the cell is against a concentration gradient.
C) the level of nutrients in nature is very low.
D) nutrient concentration is very low in the environment, is higher inside of the cell, or diffusion is not possible.
Answer
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Related questions
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Which of the following statements about chlamydial infections is TRUE?
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The Spanish flu of 1918 was caused by an ________ influenza virus.
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D) H2N2
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A) vectors can be controlled through other means.
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In just over a decade of efforts, the World Health Organization (WHO) eradicated smallpox by using worldwide
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In 2003, the majority of AIDS deaths occurred in
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B) prevalence / mortality
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A) has multiple wild animal reservoirs and is thus difficult to eradicate.
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C) is spread through direct contact and has only a human reservoir.
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Influenza pandemics occur cyclically because
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B) clonal deletion
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Q:
An individual usually expresses ________ structurally distinct allele(s) that encode class I MHC proteins.
A) one
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C) four
D) six