Biology Genetics & Evolution Flashcards

Which type of RNA carries amino acids to the ribosome during translation?

Answer: tRNA

Transfer RNA (tRNA) carries specific amino acids to the ribosome, matching anticodons to mRNA codons.

A cell has the genotype AaBb. If the two genes assort independently, what fraction of offspring from self-fertilization will be AABB?

Answer: 1/16

Each locus independently gives a 1/4 chance of AA, so the combined probability for AABB is 1/4 × 1/4 = 1/16.

What is a frameshift mutation?

Answer: An insertion or deletion that alters the reading frame

Frameshift mutations result from insertions or deletions of nucleotides that are not multiples of three, disrupting the reading frame.

Natural selection acting on quantitative traits toward an intermediate phenotype is called:

Answer: Stabilizing selection

Stabilizing selection favors intermediate phenotypes and reduces variation in a population over time.

Which enzyme unwinds the DNA double helix during replication?

Answer: Helicase

Helicase breaks hydrogen bonds between complementary base pairs to unwind the double helix at the replication fork.

In incomplete dominance, two red snapdragons (RR) crossed with white snapdragons (WW) produce pink offspring. What is the phenotype ratio when two pink plants are crossed?

Answer: 1 red : 2 pink : 1 white

A cross between two pink (RW) plants yields RR : RW : WW in a 1:2:1 ratio, giving red, pink, and white phenotypes.

Which of the following best describes allopatric speciation?

Answer: Geographic isolation separates populations until they become reproductively isolated

Allopatric speciation occurs when geographic barriers physically separate populations, allowing them to diverge until reproductive isolation is complete.