Heredity and DNA Science Practice Questions

Updated on Sep 22, 2011

Review these concepts: Heredity and DNA Science Study Guide

Practice Questions

1. On paired chromosomes, when two alleles are identical, we say the pair is

a. heterozygous.

b. homozygous.

c. a tetrad.

d. binomial.

2. If a person with a phenotype of brown eyes reproduces with another person who exhibits the brown-eye phenotype, which possibility best describes the type of offspring that could be produced?

a. only brown-eyed children

b. only blue-eyed children

c. neither brown eyed or blue eyed

d. brown-eyed and blue-eyed children

3. Biology's Central Dogma states that

a. proteins produce RNA, which is translated into DNA.

b. DNA is transcribed into RNA, which is translated into proteins.

c. RNA codes for DNA, which codes for proteins.

d. DNA is translated into proteins that code for RNA.

4. Which of the following is NOT a nucleotide found in DNA?

a. uracil

b. guanine

c. cytosine

d. thymine

5. The phenotype describes an organism's

a. appearance.

b. genetic code.

c. type of DNA.

d. eye color only.

6. The shape of the DNA molecule is a

a. single spiral.

b. double spiral.

c. straight chain.

d. bent chain.


1. b. The pair of alleles is called homozygous, and an organism would be homozygous for the trait governed by those alleles.

2. d. Each parent exhibits the brown-eyed phenotype, so it is possible that only brown-eyed children would be produced. This would be the case if both parents were also homozygous for the brown-eye trait. However, because the brown-eye allele is dominant over the blue-eye allele, you cannot say for certain that the parents are each homozygous for brown eyes or if they are heterozygous. In other words, they may each have one brown-eye allele and one blue-eye allele. If that's the case, then they could end up producing a blue-eyed child if they each contribute a blue-eye gene. So the best answer is that they could produce both brown-eyed and blue-eyed children.

3. b. The Central Dogma of biology states that DNA in the cell's nucleus is transcribed into a messenger RNA molecule, which then leaves the nucleus and enters the cytoplasm. In the cell's cytoplasm, the RNA molecule is translated into a protein molecule.

4. a. Uracil is a nucleotide, but it is found in RNA, not in DNA. The nucleotides in DNA are anenine, guanine, cytosine, and thymine.

5. a. The phenotype is the expression of traits as determined by the genotype or genetic information contained in the organism's DNA.

6. b. DNA is in the shape of a double spiral or double helix

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