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Chapter 5: Principles of Inheritance

NCERT Solutions for CBSE Class 10 Biology — 32 solved questions with detailed explanations.

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Solved Questions

Q1. Mendel's law of segregation states that:

Genes blend
Alleles separate during gamete formation
Linked genes always stay together
Only dominant alleles are expressed

Difficulty: Easy · Topic: Mendel's Laws

Solution

Law of segregation: two alleles of a gene separate during gamete formation, each gamete receiving one allele.

Q2. The phenotypic ratio in a dihybrid cross (F₂) is:

3:1
1:2:1
9:3:3:1
1:1:1:1

Difficulty: Easy · Topic: Dihybrid Cross

Solution

Dihybrid cross F₂ ratio: 9:3:3:1 (9 dominant for both, 3:3 dominant for one, 1 recessive for both).

Q3. Incomplete dominance produces:

recessive phenotype
intermediate phenotype
dominant phenotype
no phenotype

Difficulty: Easy · Topic: Principles of Inheritance

Solution

intermediate phenotype.

Q4. Codominance means:

blending
both alleles express equally
neither expresses
one dominates

Difficulty: Easy · Topic: Principles of Inheritance

Solution

both alleles express equally.

Q5. Epistasis is:

codominance
one gene masking another gene
linkage
incomplete dominance

Difficulty: Easy · Topic: Principles of Inheritance

Solution

one gene masking another gene.

Q6. Test cross is crossing with:

homozygous dominant
heterozygous
homozygous recessive
any individual

Difficulty: Easy · Topic: Principles of Inheritance

Solution

homozygous recessive.

Q7. Down syndrome has:

trisomy 18
trisomy 21 (47 chromosomes)
monosomy X
monosomy 21

Difficulty: Easy · Topic: Principles of Inheritance

Solution

trisomy 21 (47 chromosomes).

Q8. Turner syndrome has:

45,X (monosomy X)
47,XXY
47,XXX
45,Y

Difficulty: Easy · Topic: Principles of Inheritance

Solution

45,X (monosomy X).

Q9. Klinefelter syndrome has:

47,XXY
45,X
47,XXX
46,XY

Difficulty: Easy · Topic: Principles of Inheritance

Solution

47,XXY.

Q10. Pleiotropy is when:

no genes affect traits
one gene affects multiple traits
genes are linked
multiple genes affect one trait

Difficulty: Easy · Topic: Principles of Inheritance

Solution

one gene affects multiple traits.

Q11. Polygenic inheritance involves:

no genes
linked genes only
one gene for multiple traits
multiple genes for one trait

Difficulty: Easy · Topic: Principles of Inheritance

Solution

multiple genes for one trait.

Q12. Multiple alleles means:

only 2 alleles
no alleles
linked alleles
more than 2 alleles for a gene in population

Difficulty: Easy · Topic: Principles of Inheritance

Solution

more than 2 alleles for a gene in population.

Q13. Pedigree analysis is used to:

count chromosomes
sequence DNA
clone genes
trace inheritance patterns in families

Difficulty: Easy · Topic: Principles of Inheritance

Solution

trace inheritance patterns in families.

Q14. Pleiotropy: one gene affects:

no trait
one trait only
linked traits
multiple traits

Difficulty: Easy · Topic: Principles of Inheritance

Solution

multiple traits.

Q15. Polygenic: multiple genes for:

no trait
one trait
one gene
multiple traits

Difficulty: Easy · Topic: Principles of Inheritance

Solution

one trait.

Q16. Multiple alleles: >2 alleles for:

one gene in population
linked genes
no gene
two genes

Difficulty: Easy · Topic: Principles of Inheritance

Solution

one gene in population.

Q17. Pedigree analysis traces:

DNA sequence
protein structure
inheritance in families
cell division

Difficulty: Easy · Topic: Principles of Inheritance

Solution

inheritance in families.

Q18. Complementary genes give ratio:

1:2:1
9:3:3:1
15:1
9:7

Difficulty: Easy · Topic: Principles of Inheritance

Solution

9:7.

Q19. Color blindness in humans is:

Autosomal dominant
Autosomal recessive
X-linked recessive
Y-linked

Difficulty: Easy-Medium · Topic: Sex-linked Traits

Solution

Color blindness is X-linked recessive. More common in males (XY) who need only one affected X.

Q20. Blood group AB shows:

epistasis
codominance
incomplete dominance
complete dominance

Difficulty: Easy-Medium · Topic: Principles of Inheritance

Solution

codominance.

Q21. Hemophilia is:

Y-linked
autosomal recessive
X-linked recessive
autosomal dominant

Difficulty: Easy-Medium · Topic: Principles of Inheritance

Solution

X-linked recessive.

Q22. Sickle cell anemia shows:

Y-linkage
codominance at molecular level
complete dominance
X-linkage

Difficulty: Easy-Medium · Topic: Principles of Inheritance

Solution

codominance at molecular level.

Q23. Monohybrid F2 phenotypic ratio is:

9:3:3:1
3:1
1:1
1:2:1

Difficulty: Easy-Medium · Topic: Genetics

Solution

3:1.

Q24. Monohybrid F2 genotypic ratio is:

3:1
1:1
9:3:3:1
1:2:1

Difficulty: Easy-Medium · Topic: Genetics

Solution

1:2:1.

Q25. Dihybrid F2 phenotypic ratio is:

9:3:3:1
1:1:1:1
3:1
1:2:1

Difficulty: Easy-Medium · Topic: Genetics

Solution

9:3:3:1.

Q26. Test cross ratio for heterozygous is:

1:2:1
3:1
1:1
all dominant

Difficulty: Easy-Medium · Topic: Genetics

Solution

1:1.

Q27. Linked genes show:

no inheritance
lower recombination frequency
equal segregation
independent assortment

Difficulty: Easy-Medium · Topic: Genetics

Solution

lower recombination frequency.

Q28. Crossing over frequency is measured in:

centimorgans (cM)
nucleotides
chromosomes
kilobases

Difficulty: Easy-Medium · Topic: Genetics

Solution

centimorgans (cM).

Q29. Sex determination in humans is:

haplodiploidy
XX-XY system
XO system
ZW-ZZ system

Difficulty: Easy-Medium · Topic: Genetics

Solution

XX-XY system.

Q30. Sex determination in birds is:

haplodiploidy
XO system
XX-XY system
ZW-ZZ system

Difficulty: Easy-Medium · Topic: Genetics

Solution

ZW-ZZ system.

Q31. Sex determination in bees is:

XX-XY
ZW-ZZ
XO
haplodiploidy

Difficulty: Easy-Medium · Topic: Genetics

Solution

haplodiploidy.

Q32. ABO blood groups are controlled by:

gene I with 3 alleles (Iᴬ, Iᴮ, i)
X-linked gene
2 genes
3 genes

Difficulty: Easy-Medium · Topic: Genetics

Solution

gene I with 3 alleles (Iᴬ, Iᴮ, i).

Other Chapters in Biology

Ch 1: Reproduction in Organisms Ch 2: Sexual Reproduction in Plants Ch 3: Human Reproduction Ch 4: Reproductive Health Ch 6: Molecular Basis of Inheritance Ch 7: Evolution Ch 8: Human Health & Disease Ch 9: Strategies for Enhancement Ch 10: Microbes in Human Welfare Ch 11: Biotechnology Principles Ch 12: Biotechnology Applications Ch 13: Organisms & Populations Ch 14: Ecosystem Ch 15: Biodiversity & Conservation Ch 16: Environmental Issues

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