BMST - Basic Math and Science Genetics and Heredity Questions and Answers Flashcards

In incomplete dominance, a red-flowered plant (RR) is crossed with a white-flowered plant (WW). What color will the F1 flowers be?

Answer: Pink

In incomplete dominance, heterozygotes (RW) show an intermediate phenotype, producing pink flowers.

A mutation in a somatic cell (non-reproductive body cell) is:

Answer: Passed only through mitosis to daughter cells of that cell

Somatic mutations affect only the cells that descend from the mutant cell via mitosis; they are not transmitted to the next generation.

The law of independent assortment states that:

Answer: Alleles of different genes are distributed independently during gamete formation

Mendel's law of independent assortment states that alleles of different genes segregate independently of one another during gamete formation.

Which of the following best describes a test cross?

Answer: Crossing an organism of unknown genotype with a homozygous recessive individual

A test cross reveals the unknown genotype by mating the organism with a homozygous recessive individual and analyzing the offspring.

Down syndrome (Trisomy 21) results from:

Answer: Three copies of chromosome 21 due to nondisjunction

Down syndrome occurs when nondisjunction during meiosis results in an egg or sperm with two copies of chromosome 21, giving the offspring a total of three.

If a trait is controlled by multiple genes (polygenic inheritance), you would expect the distribution of phenotypes in a large population to be:

Answer: A continuous bell-shaped curve

Polygenic traits, such as height and skin color, produce a continuous range of phenotypes that form a normal (bell-shaped) distribution in a population.

In a dihybrid cross between two organisms that are both BbGg, what fraction of offspring are expected to be homozygous recessive for both traits (bbgg)?

Answer: 1/16

For each trait, the probability of a homozygous recessive offspring is 1/4; multiplying gives 1/4 × 1/4 = 1/16.