12. which of the following typically occurs in the biosphere?
a. continuous circulation of hot and cold oceanic currents
b. regulation of the rate at which thermal energy leaves the planet
c. the interaction of plants and animals within specific climate regions
d. the recycling of the continental crust in subduction zones

Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. they identify the gene responsible for toxin production. the dominant allele (t) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. heterozygotes produce an intermediate amount of toxin. the genotypes of all individuals in the population are determined (see chart) and used to determine the actual allele frequencies in the population. is this population in hardy-weinberg equilibrium? a) yes. b) no; there are more homozygotes than expected. c) no; there are more heterozygotes than expected. d) more information is needed to answer this question.