Unit 7- Genetics Review

Front

What is a phenotype?

Back

A phenotype is the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences. Example: Having freckles.

Front

What does homozygous dominant mean?

Back

Homozygous dominant refers to having two identical dominant alleles for a trait. Example: MM is homozygous dominant.

Front

What is incomplete dominance?

Back

Incomplete dominance is a genetic situation in which one allele does not completely dominate another allele, resulting in a new phenotype that is a blend of the two. Example: A red flower crossed with a white flower may produce pink flowers.

Front

In a Punnett square, what percentage of offspring will show the dominant trait if both parents are heterozygous?

Back

75% of the offspring will show the dominant trait.

Front

What does the genotypic cross PP x pp represent?

Back

This cross represents a mating between a purebred purple-flowered plant (PP) and a purebred white-flowered plant (pp). All offspring will be heterozygous (Pp) and display the dominant purple flower phenotype.

Front

What is the difference between homozygous and heterozygous?

Back

Homozygous means having two identical alleles for a trait (e.g., AA or aa), while heterozygous means having two different alleles for a trait (e.g., Aa).

Front

What is a genotype?

Back

A genotype is the genetic constitution of an individual, specifically the alleles present for a particular gene. Example: The genotype for a trait can be homozygous dominant (AA), homozygous recessive (aa), or heterozygous (Aa).

Front

What is a dominant trait?

Back

A dominant trait is a trait that is expressed in the phenotype even when only one copy of the allele is present. Example: In pea plants, the allele for purple flowers (P) is dominant over the allele for white flowers (p).

Front

What is a recessive trait?

Back

A recessive trait is a trait that is only expressed in the phenotype when two copies of the recessive allele are present. Example: The allele for white flowers (p) is recessive in pea plants.

Front

What is a Punnett square used for?

Back

A Punnett square is a diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents.