Question

What makes some people resistant to infection with HIV?

Mutations in a cell surface receptor that is bound by the virus

Production of a greater amount of antibodies against the virus

Greater than normal activation of the complement system after exposure to the virus

Absence of T cells, which are the target of the virus

Enhanced innate immunity

A biologist analyzes the DNA sequences in three different primates. The biologist finds that primates A and B have almost identical DNA sequences. The DNA sequences in primate C are significantly different from those of primates A and B. This information allows the biologist to conclude that:

primates A and B are more closely related to each other than either is to primate C.

all three primates appeared on Earth at about the same time.

either primate A or primate B must be a direct ancestor of primate C.

primate C must have been the ancestor of both primate A and B.

primate C is more closely related to primate A than to primate B.

What is the basis for a molecular clock?

Constant mutation rates for specific genes

Duplicated genes in the human genome

The fossil record

Genetic drift

Chromosome banding patterns

Answer 1

*Mutation in a cell surface receptor that is bound by the virus* makes some people resistant to infection with HIV.

A biologist analyzes the DNA sequences in three different primates. The biologist finds that primates A and B have almost identical DNA sequences. The DNA sequences in primate C are significantly different from those of primates A and B. This information allows the biologist to conclude that:all three primates appeared on Earth at about the same time.

The fossil record is the basis for a molecular clock