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Genetics and Heredity Practice Tests

These Grade 9 Biology practice tests explain how DNA, genes, chromosomes, and alleles carry information from one generation to the next. Questions cover Mendelian inheritance, Punnett squares, meiosis, mutations, pedigrees, genetic variation, and basic biotechnology.

Skills covered

  • Distinguishing DNA, genes, chromosomes, alleles, genotype, and phenotype
  • Applying dominant, recessive, homozygous, heterozygous, incomplete dominance, codominance, and sex-linked inheritance concepts
  • Using Punnett squares and probability to predict possible offspring genotypes and phenotypes
  • Connecting meiosis, crossing over, independent assortment, fertilization, and chromosome number to genetic variation
  • Interpreting mutations, pedigrees, karyotypes, natural selection, and introductory genetic engineering

How to use these practice tests

Start by identifying the gene, allele, chromosome, or inheritance pattern involved. For crosses, write the parental alleles and list the possible gametes before calculating the probability. Review each explanation to strengthen genetics vocabulary and evidence-based reasoning.

For more Grade 9 Science practice, return to the Grade 9 Science category.

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Grade 9 Genetics and Heredity Practice Tests

Practice Grade 9 Science questions about DNA, genes, chromosomes, alleles, Mendelian inheritance, Punnett squares, meiosis, mutations, pedigrees, and genetic variation.

Choose the best answer. Identify the genetic information or inheritance pattern, apply the relevant rule, and use probabilities carefully when interpreting crosses.

10 Questions
0/10 Questions0 %
Correct 0
Incorrect 0
Unanswered 10
1. QuestionMultiple choice

What is the main purpose of meiosis?

Please select an answer first.

Correct answer: A

The correct answer is To produce haploid gametes with half the usual chromosome number..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Meiosis reduces chromosome number and produces gametes for sexual reproduction.
  3. Check the answer: The correct answer is To produce haploid gametes with half the usual chromosome number..

Meiosis reduces chromosome number and produces gametes for sexual reproduction.

2. QuestionMultiple choice

What is the usual result of mitosis?

Please select an answer first.

Correct answer: B

The correct answer is Two genetically similar diploid daughter cells..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Mitosis supports growth and repair by producing two daughter cells that usually have the same chromosome number and genetic information.
  3. Check the answer: The correct answer is Two genetically similar diploid daughter cells..

Mitosis supports growth and repair by producing two daughter cells that usually have the same chromosome number and genetic information.

3. QuestionMultiple choice

How does crossing over increase genetic variation?

Please select an answer first.

Correct answer: C

The correct answer is It exchanges DNA between homologous chromosomes during meiosis..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Crossing over creates new combinations of alleles by exchanging corresponding DNA segments between homologous chromosomes.
  3. Check the answer: The correct answer is It exchanges DNA between homologous chromosomes during meiosis..

Crossing over creates new combinations of alleles by exchanging corresponding DNA segments between homologous chromosomes.

4. QuestionMultiple choice

What are homologous chromosomes?

Please select an answer first.

Correct answer: D

The correct answer is A pair of chromosomes with the same general genes, one from each parent..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Homologous chromosomes carry the same types of genes at corresponding locations, although their alleles may differ.
  3. Check the answer: The correct answer is A pair of chromosomes with the same general genes, one from each parent..

Homologous chromosomes carry the same types of genes at corresponding locations, although their alleles may differ.

5. QuestionMultiple choice

What are sister chromatids?

Please select an answer first.

Correct answer: A

The correct answer is Identical copies of a chromosome joined after DNA replication..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: After DNA replication, each chromosome consists of two identical sister chromatids joined at a centromere.
  3. Check the answer: The correct answer is Identical copies of a chromosome joined after DNA replication..

After DNA replication, each chromosome consists of two identical sister chromatids joined at a centromere.

6. QuestionMultiple choice

What happens to chromosome number during fertilization?

Please select an answer first.

Correct answer: B

The correct answer is Two haploid gametes combine to restore the diploid number..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Fertilization joins two haploid gametes, restoring a diploid zygote with one chromosome set from each parent.
  3. Check the answer: The correct answer is Two haploid gametes combine to restore the diploid number..

Fertilization joins two haploid gametes, restoring a diploid zygote with one chromosome set from each parent.

7. QuestionMultiple choice

What is nondisjunction?

Please select an answer first.

Correct answer: C

The correct answer is Failure of chromosomes to separate correctly during cell division..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Nondisjunction can create gametes with too many or too few chromosomes when chromosomes do not separate properly.
  3. Check the answer: The correct answer is Failure of chromosomes to separate correctly during cell division..

Nondisjunction can create gametes with too many or too few chromosomes when chromosomes do not separate properly.

8. QuestionMultiple choice

During meiosis I, what separates?

Please select an answer first.

Correct answer: D

The correct answer is Homologous chromosome pairs..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Meiosis I separates homologous chromosomes, while sister chromatids separate during meiosis II.
  3. Check the answer: The correct answer is Homologous chromosome pairs..

Meiosis I separates homologous chromosomes, while sister chromatids separate during meiosis II.

9. QuestionMultiple choice

How many chromosomes are in a typical human gamete?

Please select an answer first.

Correct answer: A

The correct answer is 23..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: Human gametes are haploid and contain 23 chromosomes; fertilization restores 46 in the zygote.
  3. Check the answer: The correct answer is 23..

Human gametes are haploid and contain 23 chromosomes; fertilization restores 46 in the zygote.

10. QuestionMultiple choice

What is a zygote?

Please select an answer first.

Correct answer: B

The correct answer is The diploid cell formed when two gametes fuse..

  1. Identify the genetics concept: Determine whether the question asks about DNA, alleles, inheritance, meiosis, variation, or genetic evidence.
  2. Apply the inheritance principle: A zygote is the first diploid cell of a new organism after fertilization.
  3. Check the answer: The correct answer is The diploid cell formed when two gametes fuse..

A zygote is the first diploid cell of a new organism after fertilization.

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