Heredity and Punnett Squares

Front

What are genes?

Back

Segments of DNA that carry traits for offspring.

Front

What is it called when an organism has two identical alleles for a trait?

Back

Homozygous (purebred).

Front

What is the probability of offspring having short tusks when a heterozygous long-tusked elephant is crossed with a homozygous recessive short-tusked elephant?

Back

50%.

Front

What trait always shows up in an organism when the allele is present?

Back

Dominant allele.

Front

What is a chart that shows all the possible combinations of alleles from a genetic cross?

Back

Punnett square.

Front

What do we call an organism with two different alleles for a trait?

Back

Heterozygous.

Front

What is the term for the physical expression of a trait?

Back

Phenotype.

Front

What is the genetic makeup of an organism called?

Back

Genotype.

Front

What is a recessive allele?

Back

An allele that is masked by a dominant allele and only shows up when two copies are present.

Front

What is codominance?

Back

A situation where both alleles in a heterozygote are fully expressed.