8th Grade Genetics March 14, 2025

What is the basic unit of DNA called?

• gene

• nucleotide

• chromosome

• protein

What are the four nitrogenous bases found in DNA?

• adenine, uracil, cytosine, guanine

• adenine, thymine, cytosine, guanine

• adenine, thymine, uracil, guanine

• cytosine, thymine, guanine, uracil

Describe the shape of a DNA molecule.

• Single strand

• Triple helix

• Circular loop

• Double helix

How many chromosomes do humans typically have?

• 48

• 50

• 46

• 44

What is the difference between a gene and a chromosome?

• A gene is a complete set of chromosomes found in a cell.

• A chromosome is a single DNA molecule that does not contain genes.

• A gene is a segment of DNA that codes for a protein, while a chromosome is a structure that contains many genes.

• A gene is a type of chromosome that contains multiple proteins.

What is the process by which DNA is copied called?

• Replication

• Translation

• Transcription

• Mutation

What is a dominant allele?

• A dominant allele is an allele that expresses its trait in the presence of another allele.

• An allele that only expresses its trait when paired with another dominant allele.

• An allele that does not affect the phenotype of an organism.

• An allele that is always recessive regardless of other alleles.

What is a recessive allele?

• A recessive allele is always expressed in the phenotype.

• A recessive allele is dominant over other alleles.

• A recessive allele is an allele that only expresses its trait when two copies are present.

• A recessive allele requires only one copy to show its trait.

What inheritance pattern is shown when a trait is expressed in the offspring even if only one parent contributes the allele?

• Recessive inheritance

• Dominant inheritance

• Incomplete dominance

• Codominant inheritance

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

• Chromosome

• Phenotype

• Allele

• Genotype