In gene regulation and control, repression is defined as the:
a. internal change in the original nucleotide sequence of a gene or genes within an or-ganism's genome.
b. mechanism of genetic control in which genes are induced only when the substrate to be degraded by enzymatic action is present.
c. change of the bacterial genotypes through the exchange of DNA from one cell to another.
d. mechanism of genetic control in which genes are not transcribed and therefore are not expressed in the presence of those target products in sufficient supply.
D
To avoid waste and overproduction of enzymes in the cell, some genes are turned off by the presence of the product of that gene expression.
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What is the advantage of radial symmetry in cnidarians? a. It allows for larger availability of food
b. It can be cut multiple ways. c. It allows for the growth of protective tentacles. d. It allows for cnidarians to respond to their environment from all sides, equally.
The systolic pressure for a normal young adult would be under
a. 60 mm Hg. b. 80 mm Hg. c. 100 mm Hg. d. 120 mm Hg. e. 140 mm Hg.
Currently, much commercial lumber and wood products come from which biome?
a. tundra b. temperate rain forest c. savanna d. tropical rain forest e. temperate deciduous forest
Why is the ratio of male to female births roughly 50:50?
a. half of all sperm cells carry a Y chromosome b. all eggs carry an X chromosome c. half of all egg cells carry a Y chromosome d. all sperm cells carry an X chromosome