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

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

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

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

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

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

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

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

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9. Which is an example of incomplete dominance?
Eye color in humans
Hemophilia
Red and white flower making a pink flower
AB blood group

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

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

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

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

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14. 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 white-eyed offspring
All red-eyed offspring
50% white-eyed males

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

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

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

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18. Which type of inheritance does not follow Mendel’s law of independent assortment?
Co-dominance
Gene linkage
Monohybrid cross
Dihybrid cross

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

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

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

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

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

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

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

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

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

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

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29. Who rediscovered Mendel’s work in the early 1900s?
Charles Darwin
Thomas Morgan
Hugo de Vries, Carl Correns, Erich von Tschermak
Watson and Crick

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

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

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

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

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

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

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

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

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

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

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

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

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

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44. 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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45. The red-white eye color in Drosophila is an example of:
Polygenic inheritance
Dominant-recessive on Y
X-linked inheritance
Autosomal inheritance

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46. What does the law of independent assortment state?
Traits are always inherited together
All alleles blend equally
Gene pairs separate independently in gametes
Dominant traits skip generations

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

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

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

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

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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

That platform is good to preparation for entry test

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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