Biology Test Biology Genetics & Evolution 5

Question 1

What is the bottleneck effect in evolutionary biology?

Accepted Answer

A drastic reduction in population size followed by recovery, reducing genetic diversity

Answer

The bottleneck effect occurs when a population is greatly reduced in size, causing random loss of alleles and reduced genetic diversity in the surviving population.

Question 2

How does a testcross help determine whether an organism showing a dominant phenotype is homozygous or heterozygous?

Accepted Answer

Cross it with a homozygous recessive organism and observe offspring

Answer

Crossing with a homozygous recessive (aa) reveals the unknown genotype: if any offspring show the recessive phenotype, the parent is heterozygous.

Question 3

Which process allows bacteria to rapidly acquire new genes, including antibiotic resistance genes, from other bacteria?

Accepted Answer

Horizontal gene transfer

Answer

Horizontal gene transfer, including conjugation, transformation, and transduction, allows bacteria to acquire genes from other organisms outside of vertical inheritance.

Question 4

What distinguishes homologous structures from analogous structures in evolution?

Accepted Answer

Homologous structures share common ancestry; analogous structures are functionally similar but evolved independently

Answer

Homologous structures reflect shared common ancestry (e.g., vertebrate forelimbs), while analogous structures result from convergent evolution in unrelated lineages.

Question 5

Which of the following describes pleiotropy?

Accepted Answer

One gene controls multiple phenotypic traits

Answer

Pleiotropy occurs when a single gene influences two or more seemingly unrelated phenotypic traits, such as the PKU gene affecting brain and pigment development.

Biology Practice Test

Biology Practice Test

Biology Test Biology Genetics & Evolution 5