13. (02.04 MC) Which statement best describes the difference between primary and secondary succession? (4 points)

In primary succession, the pioneer community contains nutrient-poor soil, whereas in secondary succession, the pioneer community contains nutrient-rich soil.

In primary succession, the pioneer community changes relatively quickly, whereas in secondary succession, the pioneer community changes relatively slowly.

In primary succession, the pioneer community changes as a result of natural forces, whereas in secondary succession, the pioneer community changes as a result of human
actions.

In primary succession, there is a progression of growth that develops on newly formed land, whereas
disturbed by an event.
secondary succession, it is the redevelopment of a habitat that has been

Considering the yellow and green pea color phenotypes studied by gregor mendel: a. what is the biochemical function of the protein that is specified by the gene responsible for the pea color phenotype? (1 point) b. a null allele of a gene is an allele that does not specify (or encode) any of the biochemical function that the gene normally provides (in other words, either no protein at all or only non-functional protein is produced from it). of the two alleles, y and y, which is more likely to be a null allele? (1 point) c. in terms of the underlying biochemistry, why is the y allele dominant to the y allele? (2 points) d. why are peas that are yy homozygotes green? (1 point) e. the amount of protein produced from a gene is roughly proportional to the number of functional copies of the gene carried by a cell or individual. what do the phenotypes of yy homozygotes, yy heterozygotes, and yy homozygotes tell us about the amount of sgr enzyme needed to produce a yellow color? explain your reasoning. (2 points)

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -