Genetics1

What is a phenotype?

• The expression of a trait; physical appearance.
• refers to the genetic makeup of an individual
• An organism that has the same genes for a trait (ex. TT or tt)
• the passing of traits from parent to offspring

What does heterozygous mean?

• An organism that has the same genes for a trait (TT or tt)
• An organism that has different genes for a trait (Tt)
• When neither gene is fully dominant; offspring is a mixture of both
• the different forms of a trait (hair color--> brown, blonde, red

An allele whose trait only shows up when no dominant allele is present.

• hidden allele
• dominant allele
• recessive allele
• present allele

What type of chromosomal abnormality do people with Down Syndrome have? 

• trisomy 21
• monosomy 21
• recessive inheritance
• dominant inheritance

Two brown eyed parents (Bb) have a baby. What is the chance the baby is blue eyed?

• 0 %
• 25%
• 50%
• 75%

W=white hair
w= non-white hair
If you cross a horse with WW and a horse with ww what fraction of the offspring would be expected to have white hair?

• none
• 3/4
• 1/2
• all

R=round seed
r=wrinkled seed.
Cross a homozygous round with a wrinkled. Which statement predicts the results?

• offspring will be Rr
• offspring will be RR
• round seeds will be recessive to wrinkled
• Wrinkled will be observed in half of offspring

A human usually has _____ total chromosomes.

• 6
• 22
• 4
• 46

Which of the following alleles is homozygous recessive?

• Tt
• tt
• TT
• T

Pea plants can have green or yellow seeds. In a pea plant that is heterozygous for seed color, the allele for yellow seeds masks the effects of the allele of green seeds. Which of the following terms best describes the allele for yellow seeds?

• codominant
• recessive
• dominant
• sex-linked