Biology Variation and Genetics Online Test MCQs

Malik TahirLast Updated: October 14, 2025

Important Biology Variation and Genetics Question and Answer

Total Questions:	50
Time Allowed:	25 Minutes
Total Marks:	50
How to Attempt Test:	Please choose the right Option in MCQ-type question.
Test Helpful For:	Biology Test MDCAT Test FPSC/PPSC/SPSC/KPPSC/BPSC/AJKPSC/NTS Biology Interview Question Answer Universities Entrance Test

Biology Variation and Genetics Practice Test Online With Explanation

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1. In a dihybrid cross, what phenotypic ratio is expected in the F2 generation?
3:1
2:2
1:1
9:3:3:1

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

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3. Which term describes the failure of chromosomes to separate properly during meiosis?
Nondisjunction
Translocation
Inversion
Mutation

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4. A male with hemophilia inherits the gene from:
Grandparents
Both parents
His mother
His father

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5. Which term refers to the physical appearance of a trait?
Phenotype
Genotype
Gene
Chromosome

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6. Which organism is commonly used to study sex linkage?
Pea plant
Bacteria
Mouse
Drosophila melanogaster

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7. Crossing over occurs during which phase of meiosis?
Prophase I
Telophase II
Anaphase I
Metaphase I

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8. A genotype of “Tt” represents a:
Homozygous dominant
Heterozygous
Homozygous recessive
Incomplete dominance

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9. In humans, sex is determined by:
Number of genes
X and Y chromosomes
Autosomes
Environment

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10. 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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11. How many chromosomes do human gametes contain?
44
46
23
22

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12. Which genotype represents a carrier female for hemophilia?
XhXh
XHXh
XHXH
XHY

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13. What organism did Mendel use in his inheritance experiments?
Mice
Pea plants
Corn
Fruit flies

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14. What are alternative forms of a gene called?
Traits
Genotypes
Loci
Alleles

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15. Which of the following conditions is caused by multiple alleles?
Blood groups
Hemophilia
Cystic fibrosis
Huntington’s disease

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16. How many alleles control the ABO blood group system?
1
3
4
2

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17. 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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18. How many phenotypes are possible in ABO blood group inheritance?
3
5
2
4

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19. Which of the following is a statistical tool used to predict inheritance?
Punnett square
Spectrophotometer
Thermometer
Graph paper

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20. In Mendel's experiment, round seeds were dominant over:
Green pods
Yellow seeds
Tall plants
Wrinkled seeds

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21. What is the genotype of a male in terms of sex chromosomes?
XXY
XY
YY
XX

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22. What is the law of segregation?
Genes exist only in pairs
All traits blend in offspring
Alleles for a trait separate during gamete formation
Dominant traits are always expressed

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23. Which of the following statements best explains Mendel’s principle of dominance?
Both alleles are equally expressed
Alleles blend to form an intermediate trait
One allele may mask the effect of another
The recessive allele is always expressed

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24. Which of the following is an example of a sex-linked trait?
Hemophilia
Blood type
Tongue rolling
Eye color

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25. Which term refers to the genetic makeup of an organism?
Phenotype
Genotype
Trait
Allele

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26. What is the result of crossing over?
Genetic variation
Clones
Identical gametes
No change

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27. What does a Punnett square help predict?
Genotypic and phenotypic outcomes
Blood pressure levels
Evolution rate
Chromosome numbers

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28. In a dihybrid cross, how many different phenotypes can be produced?
4
3
16
2

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29. Who is known as the father of genetics?
Louis Pasteur
James Watson
Gregor Mendel
Charles Darwin

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30. What is meant by codominance?
One allele is completely dominant
One trait is hidden
Both alleles are fully expressed
Traits blend in offspring

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31. Which of the following disorders is caused by a recessive gene on the X chromosome?
Hemophilia
Down syndrome
Huntington’s disease
Sickle cell anemia

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32. What does the term "locus" refer to?
Type of mutation
Type of chromosome
Type of allele
Physical location of a gene on a chromosome

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33. 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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34. 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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35. If both parents are heterozygous for a trait, what is the chance their child will be homozygous recessive?
100%
25%
75%
50%

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36. Which blood type is considered the universal donor?
O−
AB+
O+
AB−

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37. What are sex chromosomes also known as?
Autosomes
Somatic chromosomes
Gametes
Allosomes

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38. Which term describes having identical alleles?
Homozygous
Dominant
Genotypic
Heterozygous

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39. If a trait is X-linked and recessive, who is more likely to express it?
Females
Neither
Both equally
Males

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40. What is the expected phenotypic ratio in a monohybrid cross?
1:2:1
3:1
1:1
9:3:3:1

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41. 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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42. What causes variation in sexually reproducing organisms?
Independent assortment and crossing over
All of the above
Mutation only
Random fertilization

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43. What is a test cross used for?
Determine age
Alter DNA
Predict phenotype
Determine unknown genotype

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44. What does gene linkage refer to?
Genes found on different chromosomes
Genes with no effect on phenotype
Genes located close together on the same chromosome
Genes with multiple alleles

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45. What tool is used to trace inheritance patterns in families?
Microscope
Electrophoresis
PCR
Pedigree chart

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46. Which of the following is a genetic disorder related to blood clotting?
Sickle cell anemia
Thalassemia
Color blindness
Hemophilia

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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. 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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49. Which of the following represents multiple alleles?
IA, IB, i (blood groups)
Rr
Tt
XY

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50. Which generation did Mendel refer to as F1?
First filial
First parental
Second parental
Final

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Malik TahirLast Updated: October 14, 2025

5 Comments

Qandeel says:

October 2, 2021 at 12:28 pm

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Qandeel says:

October 2, 2021 at 12:28 pm

This is very help full. Allah pak give peace the owner of this app???

Qandeel says:

October 2, 2021 at 12:28 pm

This is very help full. Allah pak give peace the owner of this app???

Naaz says:

August 28, 2021 at 5:27 am

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ame says:

October 1, 2020 at 4:33 pm

many of your mcqs are wrong. kindly check them

Important Biology Variation and Genetics Question and Answer

Biology Variation and Genetics Practice Test Online With Explanation

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