Genetics

B=brown eyes
b= blue eyes
What is true about two brothers that have brown eyes?
One has genotype BB the other Bb.

• they have same phenotype and genotype
• they have different genotypes and phenotypes
• they have same phenotype but different genotypes
• they have same genotype but different phenotypes

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

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

In mussels, the allele for brown coloring (B) is dominant, and the allele for blue coloring(b) is recessive. For which parental genotypes are 100% of the offspring expected to be blue?

• BbxBb
• bbxbb
• BBxbb
• BBxBB

In guinea pigs, the alleles for black hair(B) is dominant to the allele for brown hair(b). Two black-haired guinea pigs are crossed. One of the pigs is homozygous for black hair and one is heterozygous. What percentage of their offspring are expected to have black hair?

• 25%
• 50%
• 75%
• 100%

The genotype of an organism describes the

• codons that make up the genes
• number of gene's on the chromosmes
• genetic make-up of a trait
• type of chromosomes in the nucleus

In a Punnett square, a lower case letter stands for a ____________ allele.

• dominant

• recessive

• homozygous

• heterozygous

Hair color, height, eye color and freckles are examples of human traits. What do we call the physical expression of the genetic material of an organism?

• genetics

• heredity

• genotype

• phenotype

Heterozygous is when...

• the alleles are the same.

• the alleles are different.

• the alleles are absent.

• the alleles are present.

The blending of two traits is known as ---

• incomplete dominance

• codominance