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. What is the law of segregation?

Dominant traits are always expressed

All traits blend in offspring

Genes exist only in pairs

Alleles for a trait separate during gamete formation

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

Wrinkled seeds

Green pods

Tall plants

Yellow seeds

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

The recessive allele is always expressed

Alleles blend to form an intermediate trait

One allele may mask the effect of another

Both alleles are equally expressed

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

YY

XX

XY

XXY

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5. What is meant by codominance?

Traits blend in offspring

Both alleles are fully expressed

One trait is hidden

One allele is completely dominant

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

Mutation

Nondisjunction

Translocation

Inversion

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7. What does gene linkage refer to?

Genes with multiple alleles

Genes located close together on the same chromosome

Genes with no effect on phenotype

Genes found on different chromosomes

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8. Which genotype represents a carrier female for hemophilia?

XHY

XHXH

XhXh

XHXh

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9. How many chromosomes do human gametes contain?

23

22

46

44

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

Type of mutation

Type of allele

Physical location of a gene on a chromosome

Type of chromosome

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

Pea plants

Corn

Mice

Fruit flies

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12. What is the result of crossing over?

No change

Identical gametes

Genetic variation

Clones

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

25%

100%

50%

75%

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

1:1

3:1

1:2:1

9:3:3:1

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15. Which generation did Mendel refer to as F1?

First parental

Final

Second parental

First filial

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

Cystic fibrosis

Huntington’s disease

Hemophilia

Blood groups

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

Electrophoresis

Pedigree chart

Microscope

PCR

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

Punnett square

Thermometer

Spectrophotometer

Graph paper

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

Huntington’s disease

Hemophilia

Down syndrome

Sickle cell anemia

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

Gene

Chromosome

Phenotype

Genotype

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21. What does a Punnett square help predict?

Chromosome numbers

Evolution rate

Genotypic and phenotypic outcomes

Blood pressure levels

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

Color blindness

Sickle cell anemia

Hemophilia

Thalassemia

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23. Which blood type is considered the universal donor?

AB−

O−

AB+

O+

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

Rr and rr

Rr

rr

RR

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25. What are sex chromosomes also known as?

Somatic chromosomes

Gametes

Allosomes

Autosomes

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26. Which term describes having identical alleles?

Genotypic

Heterozygous

Homozygous

Dominant

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

Charles Darwin

Thomas Morgan

Watson and Crick

Hugo de Vries, Carl Correns, Erich von Tschermak

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

3:1

1:1

2:2

9:3:3:1

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29. A genotype of “Tt” represents a:

Incomplete dominance

Homozygous recessive

Heterozygous

Homozygous dominant

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30. Which of the following represents multiple alleles?

XY

Tt

Rr

IA, IB, i (blood groups)

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31. What causes variation in sexually reproducing organisms?

Independent assortment and crossing over

Mutation only

All of the above

Random fertilization

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

16

2

4

3

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33. In humans, sex is determined by:

Number of genes

X and Y chromosomes

Environment

Autosomes

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34. What is a test cross used for?

Determine age

Determine unknown genotype

Alter DNA

Predict phenotype

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35. What does the law of independent assortment state?

Traits are always inherited together

Gene pairs separate independently in gametes

All alleles blend equally

Dominant traits skip generations

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36. Who is known as the father of genetics?

Gregor Mendel

Louis Pasteur

James Watson

Charles Darwin

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

Bacteria

Mouse

Pea plant

Drosophila melanogaster

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

4

3

5

2

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39. Which is an example of incomplete dominance?

Eye color in humans

AB blood group

Red and white flower making a pink flower

Hemophilia

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

Neither

Males

Females

Both equally

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41. 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 red-eyed offspring

All white-eyed offspring

50% white-eyed females

50% white-eyed males

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

25%

75%

50%

100%

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

Phenotype

Genotype

Allele

Trait

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44. Crossing over occurs during which phase of meiosis?

Telophase II

Prophase I

Anaphase I

Metaphase I

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

2

4

3

1

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46. What are alternative forms of a gene called?

Alleles

Loci

Genotypes

Traits

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

Co-dominance

Gene linkage

Dihybrid cross

Monohybrid cross

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

X-linked inheritance

Polygenic inheritance

Dominant-recessive on Y

Autosomal inheritance

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49. A male with hemophilia inherits the gene from:

His mother

His father

Both parents

Grandparents

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

Tongue rolling

Hemophilia

Blood type

Eye color

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