How do researchers use gene trees, species trees, and rates of nonsynonymous versus synonymous nucleotide substitution, to explore the evolutionary history of gene families?
What will be an ideal response?
By comparing gene trees and species trees, researchers can infer whether specific major duplication events occurred before or after particular species separated into different lineages. This allows researchers to identify the historical timing of gene family evolution and conclude whether the gene family is an ancient or recently evolved phenomenon. Rates of nonsynonymous versus synonymous substitution are used to test for positive selection to infer whether gene family expansion was favored by natural selection.
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The birds that are most highly adapted to marine life are the:
a. tubenoses. b. gulls. c. penguins. d. pelicans. e. sandpipers.
Engelmann concluded that chlorophyll in the chloroplasts is responsible for photosynthesis based on
the following results:a. Spirogyra cells each contain a long, spiral-shaped, emerald-green chloroplast embedded in the cytoplasm. b. The action spectrum of photosynthesis matched the maximum production of oxygen by Spirogyra, observed by the greatest accumulation of bacteria in the blue and red regions of the spectrum. c. Bacteria exposed to the action spectrum for photosynthesis showed no preference to any particular color of light. d. Accessory pigments transfer some of the energy of excitation produced by green light to chlorophyll molecules. e. Protons flow through the ATP synthase complex.
In the Hardy-Weinberg equation, the term q2 refers to the frequency of:
a. the recessive allele at a given locus. b. the homozygous recessive genotype at a given locus. c. the recessive alleles in a given population. d. the heterozygotes in a population. e. the total alleles in a gene pool.
Which of the following serves as both reactant in photosynthesis and product in cellular respiration?
a. O2 b. CO2 c. H2O d. a and b e. b and c