Genetics intro

Which term describes an allele that masks the effect of another allele?

• Recessive

• Dominant

• Hybrid

• Purebred

Answer explanation

The term 'dominant' describes an allele that masks the effect of another allele, known as the recessive allele. In a heterozygous genotype, the dominant allele's trait will be expressed.

What is the term for an organism with two identical alleles for a trait?

• Heterozygous

• Hybrid

• Homozygous

• Dominant

Answer explanation

An organism with two identical alleles for a trait is called homozygous. In contrast, heterozygous refers to having two different alleles, while hybrid typically describes a mix of species. Dominant refers to allele expression.

Match each description with the correct type of trait.

• Recessive trait

• Is when 2 alleles are different

• Homozygous

• It is always expressed

• Dominant trait

• It is masked by a dominant trait

• Heterozygous

• Is when 2 alleles are the same

Answer explanation

A recessive trait is not expressed when a dominant trait is present; it is masked by the dominant trait. Therefore, the correct description is that it is masked by a dominant trait.

What does a Punnett square help predict?

• The age of an organism

• The possible genetic outcomes of a cross

• The number of chromosomes

• The color of an organism

Answer explanation

A Punnett square is a tool used in genetics to predict the possible genetic outcomes of a cross between two organisms. It helps visualize how alleles combine, making it clear which traits may be inherited.

Tags

NGSS.MS-LS3-2

Which term refers to an organism with two different alleles for a trait?

• Homozygous

• Purebred

• Heterozygous

• Dominant

Answer explanation

The term 'heterozygous' refers to an organism that has two different alleles for a specific trait, distinguishing it from 'homozygous,' which has identical alleles. Thus, the correct answer is 'heterozygous.'

What is an allele?

• A type of cell

• A form of a gene

• A chromosome

• A Punnett square

Answer explanation

An allele is a specific version of a gene that can vary between individuals. It determines traits and characteristics, making "a form of a gene" the correct choice, while the other options refer to different biological concepts.

Match each genetic term with its correct description.

• A trait that is masked in the presence of a dominant allele.

• Hybrid

• An organism produced by crossing parents with different traits.

• Purebred

• An organism that is the offspring of parents with the same traits.

• Recessive

• An organism with two different alleles for a trait.

• Heterozygous

Answer explanation

A purebred organism is the offspring of parents with the same traits, ensuring uniformity in characteristics. In contrast, a hybrid results from different traits, while heterozygous and recessive refer to genetic variations.

What does the term "hybrid" mean in genetics?

• An organism with two identical alleles

• An organism with two different alleles

• An organism with no alleles

• An organism with only dominant alleles

Answer explanation

In genetics, a "hybrid" refers to an organism that has two different alleles for a specific gene. This contrasts with homozygous organisms, which have identical alleles. Therefore, the correct choice is an organism with two different alleles.

Which of the following is NOT a genetic term?

• Allele

• Hybrid

• Homozygous

• Photosynthesis

Answer explanation

Photosynthesis is a process by which plants convert light energy into chemical energy, not a genetic term. In contrast, allele, hybrid, and homozygous are all terms related to genetics.

• Hybrid
• Heterozygous
• Homozygous
• Recessive

Answer explanation

The genotype TT indicates that both alleles are the same (dominant), making it homozygous. A hybrid refers to different alleles, and heterozygous means having one of each allele. Recessive describes an allele that is masked by a dominant one.