Genetics Review

The speed that a person can move their muscles is controlled by the "athlete gene." A typical human muscle cell has...

• Two copies of the athlete gene.

• One copy of the athlete gene.

• Three copies of the athlete gene.

• Four copies of the athlete gene.

Tags

HS-LS3-3

HS-LS3-1

Match each genotype with their correct symbols.

• RR

• HETEROZYGOUS

• Rr

• Homozygous DOMINANT

• rr

• Homozygous recessive

Tags

HS-LS3-3

R = FAST MUSCLES, r = slow muscles

DOMINANT-recessive inheritance

A homozygous man with FAST MUSCLES (RR) mates with a homozygous woman with slow muscles (rr). What are the possible phenotypes that their children could have?

• All children will have FAST MUSCLES.

• All children will have slow muscles.

• All children will have muscles that are IN BETWEEN FAST AND SLOW.

• Some children will have FAST MUSCLES and some will have slow muscles.

Tags

HS-LS3-3

R = FAST MUSCLES, r = slow muscles

DOMINANT-recessive inheritance

What is the probability that a HETEROZYGOUS man (Rr) and a homozygous recessive woman (rr) will have a child with slow muscles?

• 25%
• 50%
• 100%
• 75%

Tags

HS-LS3-3

R = FAST MUSCLES, r = slow muscles

DOMINANT-recessive inheritance

What BEST explains why a HETEROZYGOUS person (Rr) can have children with slow muscles, but a homozygous DOMINANT person (RR) cannot?

• The HETEROZYGOUS person can pass down a DOMINANT allele to the offspring.

• HETEROZYGOUS people (Rr) cannot have children with slow muscles.

• Homozygous DOMINANT people (AA) do not mate with people with slow muscles.

• HETEROZYGOUS people can pass down a recessive allele to the offspring.

Tags

HS-LS3-3

R = FAST MUSCLES, r = slow muscles

E = DARK HAIR, e = red hair

Tim has DARK HAIR (Ee).  Beth has red hair (ee).  If their baby has slow muscles like Beth (rr), is the baby guaranteed to have red hair?

• No, alleles are inherited independently from each other.

• Yes, you either inherit all of a parent's DOMINANT alleles or all of their recessive alleles.

• No, if you inherit one recessive allele you will always inherit a DOMINANT allele to balance it out.

• Yes, a person either only has DOMINANT alleles or recessive alleles.

Tags

HS-LS3-3