Genetics Review

An organism's phenotype describes its __________.

• genetic makeup
• physical appearance

What do you call a section of DNA that codes for a specific trait?

• nucleus
• chromosome
• gene
• DNA

A dominant trait shows up __________.

• only when two dominant alleles are present
• only when one dominant allele is present
• when at least one recessive allele is present
• when at least one dominant allele is present

A recessive trait only shows up when __________.

• two dominant alleles are present
• one dominant allele is present
• two recessive alleles are present
• at least one dominant allele is present

If you cross two parents, both with genotype Bb, what percentage of children will have brown eyes?

• 25%
• 50%
• 75%
• 100%

If you cross the genotype GG with genotype Gg, what is the ratio of purebred to hybrid?

• 2:2
• 3:1
• 4:0
• 1:3

The two different forms of a gene are called _________.

• zygotes
• traits
• phenotypes
• alleles

Plant height is T = tall and t = short. Flower color is P = purple and p = white. Which genotype is NOT possible for a tall plant with purple flowers?

• TtPp
• TTPP
• TTPp
• ttpp

------is the combination of two alleles that are different from one another.

• homozygous
• heterzygous
• phenotype
• trait

---- Is the combination of two alleles that are the same

• genotype
• homozygous
• phenotype
• trait