Online Test — Principles of Inheritance and Variation
17 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 17
The Father of Genetics is:
Charles Darwin
Gregor Mendel
Louis Pasteur
Robert Hooke
Explanation: Mendel's pea experiments founded genetics.
Question 2 of 17
Alternative forms of a gene are called:
Alleles
Chromosomes
Nucleotides
Codons
Explanation: Alleles are alternative forms of a gene.
Question 3 of 17
An organism with identical alleles (TT or tt) is:
Heterozygous
Homozygous
Hybrid
Recessive only
Explanation: Identical alleles make it homozygous.
Question 4 of 17
The visible character of an organism is its:
Genotype
Phenotype
Allele
Gene
Explanation: The phenotype is the visible trait.
Question 5 of 17
The F1 of a tall (TT) × dwarf (tt) pea cross is:
All dwarf
All tall
Half tall half dwarf
All medium
Explanation: All F1 are tall (Tt) by the law of dominance.
Question 6 of 17
The F2 phenotypic ratio of a monohybrid cross is:
1:1
3:1
9:3:3:1
1:1:1:1
Explanation: Monohybrid F2 = 3:1.
Question 7 of 17
The genotypic ratio of a monohybrid F2 is:
3:1
1:2:1
9:3:3:1
1:1
Explanation: Genotypic ratio is 1 TT : 2 Tt : 1 tt.
Question 8 of 17
The reappearance of the recessive trait in F2 illustrates the Law of:
Segregation
Independent Assortment
Use and disuse
Limiting factors
Explanation: Segregation of alleles brings back the recessive trait.
Question 9 of 17
The F2 ratio of a dihybrid cross is:
3:1
1:2:1
9:3:3:1
1:1
Explanation: Dihybrid F2 = 9:3:3:1.
Question 10 of 17
Each trait pair being inherited independently is the Law of:
Dominance
Segregation
Independent Assortment
Linkage
Explanation: Independent assortment: traits separate independently.
Question 11 of 17
A blended phenotype like a pink snapdragon shows:
Complete dominance
Incomplete dominance
Co-dominance
Epistasis
Explanation: The intermediate (pink) heterozygote is incomplete dominance.
Question 12 of 17
Human blood group AB, where both antigens appear, is an example of:
Incomplete dominance
Co-dominance
Recessiveness
Linkage
Explanation: Both A and B alleles are fully expressed — co-dominance.
Question 13 of 17
The sex chromosomes of a human female are:
XY
XX
YY
XO
Explanation: Females are XX; males are XY.
Question 14 of 17
The sex of a human child is determined by the:
Mother's egg
Father's sperm (X or Y)
Grandparents
Diet
Explanation: The X- or Y-carrying sperm decides the child's sex.
Question 15 of 17
Down's syndrome is caused by an extra copy of chromosome:
21
X
Y
1
Explanation: Down's syndrome results from an extra chromosome 21.
Question 16 of 17
A single gene affecting many different traits at once shows:
Pleiotropy
Linkage
Co-dominance
Incomplete dominance
Explanation: Pleiotropy is one gene influencing multiple traits.
Question 17 of 17
In birds, the sex chromosomes of a female are:
XX
XY
ZW
ZZ
Explanation: In birds the female is ZW and the male is ZZ.