Understanding Genetics and Heredity

What does it mean for an organism to be heterozygous for a trait?

• It has two identical alleles for a trait.

• It has two different alleles for a trait.

• It has no alleles for a trait.

• It has more than two alleles for a trait.

Which of the following describes a homozygous organism?

• It has two different alleles for a trait.

• It has two identical alleles for a trait.

• It has one dominant and one recessive allele.

• It has no alleles for a trait.

What is a genotype?

• The physical appearance of an organism.

• The genetic makeup of an organism.

• The environment in which an organism lives.

• The diet of an organism.

Tags

NGSS.HS-LS3-2

What is a phenotype?

• The genetic makeup of an organism.

• The physical appearance or traits of an organism.

• The number of chromosomes in an organism.

• The habitat of an organism.

• It is homozygous dominant.

• It is homozygous recessive.

• It is heterozygous.

• It has no alleles.

Which of the following is an example of a dominant trait?

• A trait that is only expressed when two recessive alleles are present.

• A trait that is expressed when at least one dominant allele is present.

• A trait that is never expressed.

• A trait that is expressed only in the absence of alleles.

If an organism's phenotype is tall and the tall trait is dominant, what could be its genotype?

• tt

• Tt

• TT

• Both B and C

What does it mean if a trait is recessive?

• It is always expressed in the phenotype.

• It is expressed only when two recessive alleles are present.

• It is expressed when at least one dominant allele is present.

• It is never expressed in the phenotype.

Which of the following genotypes is homozygous recessive?

• TT

• Tt

• tt

• TTT

• White flowers

• Red flowers

• Pink flowers

• No flowers

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2