What is a gene? How are genes involved in the evolutionary process?
What will be an ideal response?
Genes are regions on chromosomes that are composed of double-stranded DNA molecules. A particular gene is determined by the sequence of DNA that composes it. Genes determine the genotypic, and hence phenotypic, characteristics of an individual. These genetically determined characteristics are not the same in all the individuals in a population. It is this variation in a population that is acted upon by natural selection, which brings about evolution.
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Which of the following items will not help treat or eliminate the symptoms of genetic disorders?
a. Dietary controls b. Hormone replacement therapy c. Exposure to carcinogens d. Prescription drugs e. Surgery
Suppose that you examine a vial of 100 flies that are all offspring from a single genetic cross, and you find only red-eyed females and red-eyed males present. You allow these flies to interbreed, and in the next generation you find all the females are red-eyed, but you find both red-eyed and white-eyed males. The allele for red eye colour (Xw+) is dominant over the allele for white eye colour (Xw). Which of the following best describes the genotypes of the original parents?
a. Xw+Xw+; XwY b. Xw+Xw; Xw+Y c. Xw+Xw; XwY d. XwXw; Xw+Y
How does the loop of Henle enable the mammalian kidney to produce hypertonic urine?I-The ascending limb of the loop actively extrudes Na+.II-The descending limb interacts with the ascending limb to raise the osmolarity of the extracellular fluid in the renal medulla.III-The concentration is further enhanced by the presence of urea, which draws water out of the collecting ducts by osmosis.
A. II and III B. just III C. just I D. I and II E. I, II, and III
Chromosomes are aligned at the middle of the
cell during
a. anaphase. b. metaphase. c. interphase. d. prophase. e. telophase