Biology Genetics & Biological Diversity Flashcards

In a dihybrid cross between two organisms heterozygous for both traits (AaBb × AaBb), what fraction of offspring will express both dominant phenotypes?

Answer: 9/16

The 9:3:3:1 ratio means 9/16 offspring express both dominant phenotypes.

Which of the following best describes incomplete dominance?

Answer: The heterozygote shows a blended intermediate phenotype

In incomplete dominance, the heterozygote phenotype is intermediate between the two homozygous phenotypes (e.g., red × white = pink).

A bacterium that can synthesize all needed amino acids is best described as a:

Answer: Prototroph

A prototroph is a wild-type microorganism capable of synthesizing all required organic compounds from inorganic precursors.

Which domain includes organisms with peptidoglycan in their cell walls and no membrane-bound nucleus?

Answer: Bacteria

Bacteria have cell walls containing peptidoglycan and lack a membrane-bound nucleus.

During meiosis, genetic variation is increased by crossing over, which occurs during:

Answer: Prophase I

Crossing over (recombination) between homologous chromosomes occurs during Prophase I of meiosis.

The biological species concept defines a species primarily by:

Answer: Reproductive isolation

The biological species concept defines a species as a group of populations whose members can interbreed and produce fertile offspring, separated from other groups by reproductive isolation.

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

Answer: tRNA

Transfer RNA (tRNA) carries specific amino acids to the ribosome, where it base-pairs with the mRNA codon via its anticodon.