Keystone Biology: Genetics and Evolution Questions and Answers

Question 1

A population of insects is sprayed with a new insecticide.
Most of the insects are killed, but a few individuals survive.
These survivors reproduce, and in the next generation, a significantly higher percentage of the population is resistant to the insecticide.
Which principle of evolution does this scenario best illustrate?

Accepted Answer

Natural selection

Answer

Gene flow

Answer

Genetic drift

Answer

Artificial selection

Question 2

Which of the following correctly describes the central dogma of molecular biology, representing the flow of genetic information to synthesize a protein?

Accepted Answer

DNA → RNA → Protein

Answer

Protein → RNA → DNA

Answer

RNA → DNA → Protein

Answer

DNA → Protein → RNA

Question 3

The wing of a bat, the flipper of a whale, and the arm of a human all share a similar underlying bone structure, despite being used for different functions (flying, swimming, and grasping). What term best describes these structures?

Accepted Answer

Homologous structures

Answer

Vestigial structures

Answer

Analogous structures

Answer

Convergent structures

Question 4

During the process of meiosis, homologous chromosomes can exchange segments of DNA. This process is known as crossing over. What is the most significant outcome of this event?

Accepted Answer

It increases genetic variation in the resulting gametes.

Answer

It ensures the daughter cells are identical to the parent cell.

Answer

It doubles the chromosome number for the new organism.

Answer

It repairs any DNA damage that occurred during replication.

Question 5

A frameshift mutation, caused by the insertion or deletion of a nucleotide, is often more damaging to the resulting protein than a point mutation (substitution). Which of the following best explains why?

Accepted Answer

It alters the reading frame of the genetic code, changing all codons downstream from the mutation.

Answer

It causes the DNA to become unstable and break apart.

Answer

It only affects the very last amino acid in the protein chain.

Answer

It is always corrected by repair enzymes before translation occurs.

Question 6

In pea plants, the allele for tall stems (T) is dominant to the allele for short stems (t). If a heterozygous tall plant (Tt) is crossed with a short plant (tt), what percentage of the offspring is expected to have a heterozygous genotype?

Accepted Answer

50%

Answer

0%

Answer

25%

Answer

75%