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

Blood type

Eye color

Hemophilia

Tongue rolling

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

Green pods

Yellow seeds

Wrinkled seeds

Tall plants

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3. What is the result of crossing over?

Genetic variation

No change

Identical gametes

Clones

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4. How many chromosomes do human gametes contain?

44

46

23

22

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

Co-dominance

Monohybrid cross

Dihybrid cross

Gene linkage

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6. Which term describes having identical alleles?

Heterozygous

Genotypic

Dominant

Homozygous

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

Electrophoresis

PCR

Pedigree chart

Microscope

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8. Which genotype represents a carrier female for hemophilia?

XhXh

XHY

XHXh

XHXH

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

Gene

Chromosome

Genotype

Phenotype

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10. Which is an example of incomplete dominance?

Red and white flower making a pink flower

Hemophilia

Eye color in humans

AB blood group

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11. What causes variation in sexually reproducing organisms?

All of the above

Mutation only

Random fertilization

Independent assortment and crossing over

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

Fruit flies

Mice

Corn

Pea plants

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13. What does a Punnett square help predict?

Evolution rate

Chromosome numbers

Blood pressure levels

Genotypic and phenotypic outcomes

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14. Who is known as the father of genetics?

Gregor Mendel

James Watson

Charles Darwin

Louis Pasteur

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

Neither

Females

Both equally

Males

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16. 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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17. Which organism is commonly used to study sex linkage?

Mouse

Drosophila melanogaster

Pea plant

Bacteria

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

Watson and Crick

Charles Darwin

Hugo de Vries, Carl Correns, Erich von Tschermak

Thomas Morgan

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19. What is a test cross used for?

Alter DNA

Determine unknown genotype

Determine age

Predict phenotype

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

Translocation

Nondisjunction

Mutation

Inversion

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21. What does the law of independent assortment state?

Gene pairs separate independently in gametes

All alleles blend equally

Dominant traits skip generations

Traits are always inherited together

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

3

4

5

2

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23. What is the law of segregation?

Alleles for a trait separate during gamete formation

Genes exist only in pairs

Dominant traits are always expressed

All traits blend in offspring

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24. Which blood type is considered the universal donor?

O−

AB+

O+

AB−

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

RR

rr

Rr and rr

Rr

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27. 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 red-eyed offspring

All white-eyed offspring

50% white-eyed males

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

Color blindness

Thalassemia

Hemophilia

Sickle cell anemia

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

9:3:3:1

3:1

1:2:1

1:1

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31. What is meant by codominance?

One allele is completely dominant

One trait is hidden

Traits blend in offspring

Both alleles are fully expressed

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

2

3

16

4

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

XY

YY

XXY

XX

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

Genotype

Trait

Phenotype

Allele

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35. A genotype of “Tt” represents a:

Homozygous dominant

Homozygous recessive

Heterozygous

Incomplete dominance

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36. Crossing over occurs during which phase of meiosis?

Prophase I

Telophase II

Metaphase I

Anaphase I

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37. What are alternative forms of a gene called?

Alleles

Traits

Genotypes

Loci

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

Autosomal inheritance

Dominant-recessive on Y

Polygenic inheritance

X-linked inheritance

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

Blood groups

Cystic fibrosis

Huntington’s disease

Hemophilia

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

Punnett square

Graph paper

Thermometer

Spectrophotometer

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

Physical location of a gene on a chromosome

Type of allele

Type of mutation

Type of chromosome

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42. Which generation did Mendel refer to as F1?

Second parental

First filial

First parental

Final

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43. What are sex chromosomes also known as?

Somatic chromosomes

Autosomes

Allosomes

Gametes

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

Sickle cell anemia

Huntington’s disease

Down syndrome

Hemophilia

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45. Which of the following represents multiple alleles?

Tt

IA, IB, i (blood groups)

XY

Rr

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

The recessive allele is always expressed

Both alleles are equally expressed

One allele may mask the effect of another

Alleles blend to form an intermediate trait

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

4

3

1

2

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48. In humans, sex is determined by:

Autosomes

Number of genes

Environment

X and Y chromosomes

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49. A male with hemophilia inherits the gene from:

His mother

Both parents

Grandparents

His father

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

2:2

9:3:3:1

3:1

1:1

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