MDCAT Biology Variation and Genetics Online Test MCQs

MDCAT Biology Variation and Genetics Test

Prepare for your MDCAT Biology exam with this online MCQ test on Variation and Genetics. This quiz includes key concepts such as types of variation, causes of genetic differences, and the role of mutations and meiosis, all aligned with the MDCAT 2025 syllabus.

MDCAT Biology Variation and Genetics Chaper Online Test

MDCAT Biology Variation and Genetics MCQS Online Test

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1. Which type of inheritance does not follow Mendel’s law of independent assortment?

Dihybrid cross

Monohybrid cross

Co-dominance

Gene linkage

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2. What does the term "locus" refer to?

Type of allele

Type of mutation

Type of chromosome

Physical location of a gene on a chromosome

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3. What is the result of crossing over?

Clones

Identical gametes

No change

Genetic variation

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4. What organism did Mendel use in his inheritance experiments?

Mice

Pea plants

Fruit flies

Corn

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5. Which term describes having identical alleles?

Dominant

Heterozygous

Homozygous

Genotypic

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6. Which of the following statements best explains Mendel’s principle of dominance?

Alleles blend to form an intermediate trait

One allele may mask the effect of another

Both alleles are equally expressed

The recessive allele is always expressed

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7. What is the genotype of a male in terms of sex chromosomes?

XX

XXY

YY

XY

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8. A cross between RR and rr individuals will result in which genotype in F1?

Rr

Rr and rr

RR

rr

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9. How many chromosomes do human gametes contain?

46

44

23

22

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10. Which of the following is a genetic disorder related to blood clotting?

Hemophilia

Sickle cell anemia

Thalassemia

Color blindness

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11. Which of the following conditions is caused by multiple alleles?

Huntington’s disease

Blood groups

Cystic fibrosis

Hemophilia

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12. If both parents are heterozygous for a trait, what is the chance their child will be homozygous recessive?

75%

100%

50%

25%

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13. Which term describes the failure of chromosomes to separate properly during meiosis?

Translocation

Mutation

Inversion

Nondisjunction

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14. What is a test cross used for?

Alter DNA

Determine age

Predict phenotype

Determine unknown genotype

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15. Which term refers to the physical appearance of a trait?

Chromosome

Genotype

Gene

Phenotype

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16. What does the law of independent assortment state?

Dominant traits skip generations

Traits are always inherited together

All alleles blend equally

Gene pairs separate independently in gametes

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17. What are sex chromosomes also known as?

Gametes

Allosomes

Somatic chromosomes

Autosomes

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18. Which term refers to the genetic makeup of an organism?

Trait

Genotype

Allele

Phenotype

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19. If a trait is X-linked and recessive, who is more likely to express it?

Females

Both equally

Neither

Males

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20. A male with hemophilia inherits the gene from:

Grandparents

Both parents

His father

His mother

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21. What is the probability of producing a tall pea plant (Tt × Tt), assuming tall (T) is dominant?

75%

25%

50%

100%

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22. How many alleles control the ABO blood group system?

3

4

2

1

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23. Which genotype represents a carrier female for hemophilia?

XHXH

XHY

XHXh

XhXh

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24. Who is known as the father of genetics?

Charles Darwin

Gregor Mendel

James Watson

Louis Pasteur

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25. A genotype of “Tt” represents a:

Heterozygous

Homozygous recessive

Incomplete dominance

Homozygous dominant

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26. What is meant by codominance?

Both alleles are fully expressed

One trait is hidden

One allele is completely dominant

Traits blend in offspring

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27. What causes variation in sexually reproducing organisms?

Mutation only

Independent assortment and crossing over

All of the above

Random fertilization

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28. What are alternative forms of a gene called?

Alleles

Traits

Loci

Genotypes

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29. In a dihybrid cross, what phenotypic ratio is expected in the F2 generation?

3:1

1:1

9:3:3:1

2:2

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30. What tool is used to trace inheritance patterns in families?

Microscope

Pedigree chart

Electrophoresis

PCR

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31. Which of the following is a statistical tool used to predict inheritance?

Punnett square

Spectrophotometer

Graph paper

Thermometer

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32. How many phenotypes are possible in ABO blood group inheritance?

3

4

2

5

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33. In Drosophila, red eyes are dominant over white eyes. What is the expected outcome of crossing a red-eyed female (carrier) with a white-eyed male?

50% white-eyed females

All white-eyed offspring

50% white-eyed males

All red-eyed offspring

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34. Which is an example of incomplete dominance?

AB blood group

Hemophilia

Red and white flower making a pink flower

Eye color in humans

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35. In humans, sex is determined by:

Number of genes

Environment

X and Y chromosomes

Autosomes

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36. Crossing over occurs during which phase of meiosis?

Telophase II

Prophase I

Metaphase I

Anaphase I

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37. What does gene linkage refer to?

Genes found on different chromosomes

Genes with multiple alleles

Genes located close together on the same chromosome

Genes with no effect on phenotype

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38. What is the law of segregation?

All traits blend in offspring

Genes exist only in pairs

Alleles for a trait separate during gamete formation

Dominant traits are always expressed

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39. In Mendel's experiment, round seeds were dominant over:

Yellow seeds

Green pods

Tall plants

Wrinkled seeds

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40. Which of the following disorders is caused by a recessive gene on the X chromosome?

Sickle cell anemia

Huntington’s disease

Hemophilia

Down syndrome

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41. Which of the following is an example of a sex-linked trait?

Tongue rolling

Eye color

Blood type

Hemophilia

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42. What is the expected phenotypic ratio in a monohybrid cross?

1:1

9:3:3:1

3:1

1:2:1

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43. Which generation did Mendel refer to as F1?

Second parental

First parental

Final

First filial

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44. Who rediscovered Mendel’s work in the early 1900s?

Hugo de Vries, Carl Correns, Erich von Tschermak

Watson and Crick

Charles Darwin

Thomas Morgan

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45. Which blood type is considered the universal donor?

AB+

AB−

O+

O−

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46. Which of the following represents multiple alleles?

XY

IA, IB, i (blood groups)

Rr

Tt

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47. The red-white eye color in Drosophila is an example of:

X-linked inheritance

Autosomal inheritance

Dominant-recessive on Y

Polygenic inheritance

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48. What does a Punnett square help predict?

Blood pressure levels

Genotypic and phenotypic outcomes

Evolution rate

Chromosome numbers

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49. In a dihybrid cross, how many different phenotypes can be produced?

16

3

2

4

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50. Which organism is commonly used to study sex linkage?

Pea plant

Drosophila melanogaster

Mouse

Bacteria

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