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

How many chromosomes are found in human egg and sperm cells?

• 20
• 23
• 26
• 46

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

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

• 25%
• 50%
• 75%
• 100%

Purebred is another word for __________, while hybrid is another word for __________.

• dominant; recessive
• recessive; dominant
• homozygous; heterozygous
• heterozygous; homozygous

The two different forms of a gene are called _________.

• zygotes
• traits
• phenotypes
• alleles

What word describes how traits are passed from parent to offspring?

• Alleles
• Dominance
• Probability
• Heredity

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

How many cycles of cell division occur in meiosis?

• 1
• 2
• 3
• 4