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

Mutation

Nondisjunction

Translocation

Inversion

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

100%

50%

75%

25%

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3. 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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4. What is meant by codominance?

Traits blend in offspring

Both alleles are fully expressed

One allele is completely dominant

One trait is hidden

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

Tongue rolling

Eye color

Hemophilia

Blood type

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

Phenotype

Genotype

Gene

Chromosome

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7. What are sex chromosomes also known as?

Gametes

Allosomes

Autosomes

Somatic chromosomes

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8. 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 females

50% white-eyed males

All red-eyed offspring

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9. What are alternative forms of a gene called?

Loci

Genotypes

Traits

Alleles

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10. What does gene linkage refer to?

Genes located close together on the same chromosome

Genes with no effect on phenotype

Genes with multiple alleles

Genes found on different chromosomes

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

5

3

2

4

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

Fruit flies

Corn

Mice

Pea plants

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

Alleles blend to form an intermediate trait

Both alleles are equally expressed

One allele may mask the effect of another

The recessive allele is always expressed

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

Type of allele

Physical location of a gene on a chromosome

Type of chromosome

Type of mutation

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15. Which of the following represents multiple alleles?

IA, IB, i (blood groups)

Rr

XY

Tt

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

Yellow seeds

Wrinkled seeds

Tall plants

Green pods

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17. Which generation did Mendel refer to as F1?

Final

First filial

Second parental

First parental

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

9:3:3:1

2:2

3:1

1:1

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19. What does a Punnett square help predict?

Blood pressure levels

Evolution rate

Chromosome numbers

Genotypic and phenotypic outcomes

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20. Crossing over occurs during which phase of meiosis?

Anaphase I

Prophase I

Metaphase I

Telophase II

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

Watson and Crick

Hugo de Vries, Carl Correns, Erich von Tschermak

Thomas Morgan

Charles Darwin

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

50%

25%

100%

75%

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

Blood groups

Hemophilia

Cystic fibrosis

Huntington’s disease

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24. What causes variation in sexually reproducing organisms?

Mutation only

All of the above

Random fertilization

Independent assortment and crossing over

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

Autosomal inheritance

Dominant-recessive on Y

X-linked inheritance

Polygenic inheritance

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26. What is the result of crossing over?

No change

Identical gametes

Genetic variation

Clones

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

Neither

Males

Both equally

Females

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28. Which term describes having identical alleles?

Genotypic

Homozygous

Heterozygous

Dominant

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

Drosophila melanogaster

Mouse

Pea plant

Bacteria

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30. 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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31. Which is an example of incomplete dominance?

Red and white flower making a pink flower

AB blood group

Hemophilia

Eye color in humans

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

Hemophilia

Huntington’s disease

Down syndrome

Sickle cell anemia

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33. In humans, sex is determined by:

Autosomes

Environment

X and Y chromosomes

Number of genes

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34. Which blood type is considered the universal donor?

AB−

AB+

O+

O−

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35. A male with hemophilia inherits the gene from:

His father

Both parents

His mother

Grandparents

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

2

3

4

16

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

Spectrophotometer

Thermometer

Punnett square

Graph paper

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38. What is a test cross used for?

Predict phenotype

Determine age

Determine unknown genotype

Alter DNA

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

XX

XY

YY

XXY

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

Electrophoresis

Microscope

PCR

Pedigree chart

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41. How many chromosomes do human gametes contain?

22

46

44

23

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42. Who is known as the father of genetics?

Gregor Mendel

James Watson

Charles Darwin

Louis Pasteur

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43. What does the law of independent assortment state?

Dominant traits skip generations

Gene pairs separate independently in gametes

Traits are always inherited together

All alleles blend equally

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

Trait

Allele

Genotype

Phenotype

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

Monohybrid cross

Dihybrid cross

Co-dominance

Gene linkage

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

rr

RR

Rr and rr

Rr

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47. Which genotype represents a carrier female for hemophilia?

XHXh

XHXH

XHY

XhXh

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

4

3

1

2

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49. A genotype of “Tt” represents a:

Homozygous recessive

Incomplete dominance

Heterozygous

Homozygous dominant

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

Hemophilia

Thalassemia

Sickle cell anemia

Color blindness

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