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. Who is known as the father of genetics?

Gregor Mendel

Charles Darwin

James Watson

Louis Pasteur

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2. A male with hemophilia inherits the gene from:

His father

Both parents

His mother

Grandparents

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3. In humans, sex is determined by:

Number of genes

X and Y chromosomes

Environment

Autosomes

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

Eye color

Hemophilia

Tongue rolling

Blood type

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5. Which term describes having identical alleles?

Genotypic

Dominant

Homozygous

Heterozygous

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

XXY

XY

YY

XX

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

Yellow seeds

Tall plants

Green pods

Wrinkled seeds

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8. Which generation did Mendel refer to as F1?

Second parental

First parental

Final

First filial

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

Microscope

PCR

Electrophoresis

Pedigree chart

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10. Which genotype represents a carrier female for hemophilia?

XhXh

XHXH

XHXh

XHY

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11. Which blood type is considered the universal donor?

O+

AB+

O−

AB−

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

Thermometer

Graph paper

Punnett square

Spectrophotometer

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

Sickle cell anemia

Thalassemia

Color blindness

Hemophilia

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14. How many chromosomes do human gametes contain?

46

23

22

44

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15. What is the law of segregation?

Alleles for a trait separate during gamete formation

All traits blend in offspring

Genes exist only in pairs

Dominant traits are always expressed

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16. What is the result of crossing over?

No change

Clones

Genetic variation

Identical gametes

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

One allele may mask the effect of another

Both alleles are equally expressed

The recessive allele is always expressed

Alleles blend to form an intermediate trait

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18. What does gene linkage refer to?

Genes with no effect on phenotype

Genes located close together on the same chromosome

Genes with multiple alleles

Genes found on different chromosomes

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19. 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?

All white-eyed offspring

50% white-eyed males

All red-eyed offspring

50% white-eyed females

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

Mouse

Pea plant

Drosophila melanogaster

Bacteria

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

Neither

Males

Females

Both equally

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22. What is meant by codominance?

Both alleles are fully expressed

Traits blend in offspring

One trait is hidden

One allele is completely dominant

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23. Which of the following represents multiple alleles?

XY

Tt

Rr

IA, IB, i (blood groups)

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

RR

Rr

Rr and rr

rr

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

3

2

1

4

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26. What is a test cross used for?

Predict phenotype

Determine age

Alter DNA

Determine unknown genotype

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27. What are sex chromosomes also known as?

Allosomes

Somatic chromosomes

Autosomes

Gametes

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28. What are alternative forms of a gene called?

Loci

Genotypes

Traits

Alleles

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

2:2

1:1

9:3:3:1

3:1

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

Hemophilia

Down syndrome

Sickle cell anemia

Huntington’s disease

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31. A genotype of “Tt” represents a:

Homozygous recessive

Heterozygous

Homozygous dominant

Incomplete dominance

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32. What does the law of independent assortment state?

Traits are always inherited together

Dominant traits skip generations

Gene pairs separate independently in gametes

All alleles blend equally

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33. What does a Punnett square help predict?

Genotypic and phenotypic outcomes

Chromosome numbers

Blood pressure levels

Evolution rate

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

100%

25%

50%

75%

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

Gene linkage

Monohybrid cross

Dihybrid cross

Co-dominance

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

Huntington’s disease

Cystic fibrosis

Hemophilia

Blood groups

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

2

3

5

4

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

Corn

Pea plants

Mice

Fruit flies

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

Mutation

Translocation

Nondisjunction

Inversion

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

Allele

Genotype

Trait

Phenotype

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

Type of chromosome

Type of mutation

Physical location of a gene on a chromosome

Type of allele

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

Genotype

Gene

Phenotype

Chromosome

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

Watson and Crick

Hugo de Vries, Carl Correns, Erich von Tschermak

Charles Darwin

Thomas Morgan

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44. Crossing over occurs during which phase of meiosis?

Prophase I

Anaphase I

Telophase II

Metaphase I

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

3:1

1:2:1

1:1

9:3:3:1

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

X-linked inheritance

Polygenic inheritance

Autosomal inheritance

Dominant-recessive on Y

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47. Which is an example of incomplete dominance?

AB blood group

Red and white flower making a pink flower

Hemophilia

Eye color in humans

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

75%

50%

25%

100%

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49. What causes variation in sexually reproducing organisms?

All of the above

Independent assortment and crossing over

Random fertilization

Mutation only

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

3

2

4

16

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