Recombinant DNA Test Review

The transfer of genes from parents to their offspring is known as

• differentiation

• heredity

• immunity

• evolution

A cross between two mice with long tails and brown fur produced the four types of offspring listed below: long tailed with brown fur long tailed with white fur short tailed with brown fur short tailed with white fur Which genetic mechanism best explains the results of this cross?

• intermediate inheritance

• gene linkage

• independent assortment

• crossing-over

Answer explanation

The correct genetic mechanism is independent assortment, where genes for tail length and fur color are on different chromosomes and assort independently during gamete formation.

In rats, black coat color is dominant over white coat color. If some of the offspring of a cross between a black rat and a white rat are white, the black rat must have been

• a polyploid

• homozygous

• heterozygous

• a mutation

Answer explanation

If some offspring are white, the black rat must carry the recessive white gene, making it heterozygous for coat color.

F represents the gene for brown coat color and f represents the gene for white coat color. In the cross Ff x ff all the offspring have a brown coat. Which genetic principle is illustrated by this cross?

• crossing-over

• multiple alleles

• codominance

• dominance

Answer explanation

The cross Ff x ff results in all offspring having a brown coat color, indicating that the dominant gene F for brown coat color is expressed over the recessive gene f for white coat color, illustrating the genetic principle of dominance.

Crosses between white-coated cattle (C^WC^W) and red-coated cattle (C^RC^R) produce roan offspring (C^RC^W). This type of inheritance pattern is known as

• multiple allele inheritance

• crossing-over

• sex linkage

• codominance

Answer explanation

The correct choice is codominance because roan offspring exhibit both white and red coat colors, showing equal expression of both alleles from the parents.

In a particular variety of corn, the kernels turn red when exposed to sunlight. In the absence of sunlight, the kernels remain yellow. Based on this information, it can be concluded that the color of these corn kernels is due to

• a different type of DNA that is produced when sunlight is present

• a different species of corn that is produced in sunlight

• the effect of sunlight on the number of chromosomes inherited

• the effect of environment on gene expression

Answer explanation

The color change in corn kernels from yellow to red is due to the effect of environment on gene expression.

Hereditary information for most traits is generally located in

• genes found on chromosomes

• chromosomes found on genes

• the mitochondria of gametes

• the lysosomes in the cytoplasm

Answer explanation

Hereditary information for most traits is generally located in genes found on chromosomes, as genes carry the instructions for specific traits and are organized on chromosomes within the cell.

Two genes for two different traits located on the same chromosome are said to be

• homozygous

• independently assorted

• mutagenic agents

• linked

Answer explanation

Two genes for two different traits located on the same chromosome are said to be linked, meaning they are close together on the chromosome and tend to be inherited together.

The diagram below represents a change in composition of homologous chromosomes during synapsis. This is called...

• nondisjunction

• gene linkage

• crossing-over

• polyploidy

Answer explanation

The correct choice is crossing-over, which refers to the exchange of genetic material between homologous chromosomes during synapsis.

Which change involves the loss of part of a chromosome?

• deletion

• addition

• base substitution

• gene mutation

Answer explanation

Deletion involves the loss of part of a chromosome, leading to the removal of a segment of DNA. This is the correct choice among the options provided.