The appearance of _____ on Earth due to the action of photosynthetic bacteria occurred about 2.7 billion years ago
a. water
b. carbon dioxide
c. ATP
d. oxygen
e. iron
ANSWER: d
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The pathway of metabolism that involves a series of electron transfers from reduced carrier molecules such as NADH2 and NADPH2 to a terminal electron acceptor is:
a. substrate-level phosphorylation. b. fermentative metabolism. c. oxidative phosphorylation. d. aerobic respiration.
What characteristic is unlikely to be associated with arctic tundra?
a. a perpetually waterlogged soil b. rapid nutrient recycling c. one of the world's greatest store of carbon d. permafrost e. cool, anaerobic conditions
When a volume of air expands against the environment and no heat enters or leaves, the air temperature will
What will be an ideal response?
Normal diploid somatic (body) cells of the mosquito Culex pipiens contain six chromosomes. Assign the symbols AmAp, BmBp, and CmCp to the three homologous chromosomal pairs
The "m" superscript indicates that the homolog is maternally derived; the "p" indicates a paternally derived homolog. Assume that in the genus Culex, the sex chromosomes are morphologically identical. (a) For each of the cell types given below, draw and label (with reference to the symbols defined above) an expected chromosomal configuration. mitotic metaphase metaphase of meiosis I metaphase of meiosis II (b) The stage at which "sister chromatids go to opposite poles" immediately follows which of the stages listed in (a)? (c) Assuming that all nuclear DNA is restricted to chromosomes and that the amount of nuclear DNA essentially doubles during the S phase of interphase, how much nuclear DNA would be present in each cell listed in part (a)? Note: Assume that the G1 nucleus of a mosquito cell contains 3.0 × 10-12 grams of DNA. (d) Given that the sex of Culex is determined by alleles of one gene-males heterozygous, Mm, and females homozygous, mm–illustrate a labeled chromosomal configuration (involving the symbols AmAp, BmBp, and CmCp and the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is on the AmAp chromosome and that crossing over has not occurred between the M locus and the centromere.