Natural selection can alter gene frequencies in a population because
A) carriers of inherited disease rarely survive to reproduce.
B) it maintains alleles that improve survival to sexual maturity.
C) it compensates for defects caused by deleterious alleles.
D) individuals with deleterious alleles selectively interbreed.
B) it maintains alleles that improve survival to sexual maturity.
You might also like to view...
Which is not a density-dependent, growth-limiting factor?
a. predation b. drought c. parasitism d. competition e. disease
When first used in medicine in the 1940s, penicillin was uniformly effective in killing the bacterium Staphyloccocus aureus. Today, ____________________ has led to an increase in antibiotic-resistant alleles, and humans are increasingly at risk from untreatable Staphyloccocus aureus infections.
a) uncleanliness in hospitals b) natural selection in Staphyloccocus aureus populations c) natural selection in human populations d) the substitution of methicillin for penicillin e) molecular genetics
You discover a fungus that contains a strange star-shaped organelle not found in any other eukaryotic cell you have seen. On further investigation, you find the following
1. The organelle possesses a small genome in its interior. 2. The organelle is surrounded by two membranes. 3. Vesicles do not pinch off from the organelle membrane. 4. The interior of the organelle contains proteins similar to those of many bacteria. 5. The interior of the organelle contains ribosomes. How might this organelle have arisen?
Your friend claims that phloem always carries sugars down a plant. What, if anything, is wrong with that statement?
a. Phloem can carry sugars down a plant, but it can carry sugars up as well (e.g., if sugars are moving to flowers or fruits). b. Phloem can carry sugars down a plant, but it can also carry sugars to the left or to the right from its location (e.g. sugars can move to leaves). c. The statement is completely true. d. Phloem is responsible for carrying sugars down a plant while xylem carries them up.