Mutation rates:
A) are equal in all species; this is why we can accurately calibrate a molecular clock.
B) can be synonymous or non-synonymous.
C) tend to be higher in E. coli than in Homo sapiens.
D) can be affected by environmental factors.
E) are generally unimportant in evolution.
D) can be affected by environmental factors.
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A researcher decides to test the scientific validity of the common phrase “An apple a day keeps the doctor away.” What would be a valid hypothesis to investigate this specific question?
A. Eating apples decreases the frequency of contracting a cold. B. The daily consumption of a single apple does not change the number of visits to the doctor. C. Eating one apple every day is good for you. D. Apples are high in vitamin C. E. Those who consume apples have longer lifespans than those who do not consume apples.
In medicine, agriculture, and conservation applications of biotechnology, the common genetic unit used is the
A. allele. B. gene. C. centromere. D. nucleotide (nitrogen base). E. chromatid.
Why are most food chains limited to three to five trophic levels?
A) The higher the trophic level, the larger the organism; the larger the organism, the less likely it will be prey. B) The nutritional quality of existing biomass decreases with increasing trophic level. C) Most ecosystems have insufficient space to support the increased number of organisms that more trophic levels would require. D) There is insufficient energy to support more trophic levels.
Gastrulation ________
A) produces a solid ball of cells B) changes the blastocyst into an embryo that has three tissue layers C) changes the fertilized egg into a blastocyst D) changes a gastrula into a blastocyst