The majority of nitrogen in soil and marine environments is fixed by
a. free-living bacteria and archaea
b. symbionts
c. E. coli
d. biofilm organisms
e. UV light
Answer: a. free-living bacteria and archaea
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Specific proteins produced by cells of the immune system in response to the presence of foreign molecules that circulate in the serum and are present in secretions such as saliva are called:
a. antigens. b. immunoglobulins. c. cytokines. d. phagogens.
Which of the following hormones stimulates ovulation?
a. gonadotropin-releasing hormone b. luteinizing hormone c. follicle-stimulating hormone d. estrogen e. progesterone
A tidal wave wipes out the entire population of mice living on an island. This is an example of
A) Type III survivorship. B) a density-dependent effect. C) the effects of abiotic factors. D) the interaction between density-dependent and abiotic factors.
R codes for right-handed and r codes for left-handed. You check the handedness of 20 classmates and find that 15 are right-handed and 5 are left-handed. Which of the following do you know from this information?
a. p^2 b. 2pq c. q^2 d. p