Monohybrid Crosses Review

The physical expression of a genetic trait is called a

• mutation

• genotype

• crossing over

• phenotype

The following items are examples of __________.

Items: eye color, hair color, height

• homozygous alleles

• genotype

• heterozygous alleles

• phenotype

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

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

Which of the following genotypes would be considered heterozygous?

• BB
• gg
• Ff
• TT

In cacti, long arms (A) are dominant to short arms (a).  Suppose 2 heterozygous cacti are crossed.  What percentage of their offspring are expected to have short arms?

• 0%
• 25%
• 75%
• 100%

One of the two forms of a gene is called a(n)

• genotype
• allele
• hybrid
• trait

A genotype is

• the listing of the alleles for the trait
• the physical appearance of the trait
• the separation of the chromosomes
• the letters seen on the outside of the Punnett square

Why is crossing over important?

• Increases the number of genes that can be inherited
• Increases genetic variation
• Decreases the occurrence of genetic diseases
• Decreases the number of genes that can be inherited

A __________ allele always shows up in an organism when the it is present.

• dominant
• hybrid

In guinea pigs, short hair is dominant to long hair. What would be the genotype of a guinea pig that is heterozygous for short hair?

• s

• SS

• ss

• Ss