15 extra multiple-choice questions for Genetics (10th Standard Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
The scientist regarded as the father of genetics is
- A. Charles Darwin
- B. Gregor Johann MendelCorrect
- C. Hugo de Vries
- D. Thomas Hunt Morgan
Explanation. Gregor Johann Mendel worked out the rules of inheritance from his experiments on the garden pea, and the chapter opens with his work.
Q2
How many pairs of contrasting traits did Mendel choose for his experiments?
- A. Five
- B. Six
- C. SevenCorrect
- D. Eight
Explanation. Mendel selected seven pairs of distinguishing traits, including flower colour and position, seed colour and shape, pod colour and shape, and stem length.
Q3
The process of acquiring characters or traits from parents is called
- A. Variation
- B. HeredityCorrect
- C. Mutation
- D. Evolution
Explanation. Heredity is the transmission of characters from parents to offspring. Variation is the difference between related organisms, and mutation is a change in the genetic material.
Q4
The monohybrid phenotypic ratio obtained in the F2 generation is
- A. 3 : 1Correct
- B. 1 : 2 : 1
- C. 9 : 3 : 3 : 1
- D. 1 : 1
Explanation. A cross involving a single pair of contrasting traits gives three dominant to one recessive in the second filial generation. The 1:2:1 ratio is genotypic, not phenotypic.
Q5
Chromosomes bearing an elongated knob-like appendage are said to carry a
- A. Centromere
- B. Telomere
- C. SatelliteCorrect
- D. Chromomere
Explanation. A satellite is the elongated knob-like appendage found on some chromosomes. A telomere is the terminal end of the chromosome, not a knob.
Q6
The terminal end of a chromosome is called the
- A. Centromere
- B. TelomereCorrect
- C. Satellite
- D. Secondary constriction
Explanation. A chromosome consists of the primary constriction, centromere, secondary constriction, telomere and satellite. The telomere is the terminal end of the structure.
Q7
A chromosome with the centromere at one end, so that it appears rod shaped, is
- A. Metacentric
- B. Sub-metacentric
- C. Acrocentric
- D. TelocentricCorrect
Explanation. Chromosomes are classified as telocentric, acrocentric, sub metacentric and metacentric according to the position of the centromere. In a telocentric chromosome it lies at one end.
Q8
Each nucleotide of DNA consists of a phosphate group, a nitrogenous base and
- A. a deoxyribose sugarCorrect
- B. a ribose sugar
- C. an amino acid
- D. a fatty acid
Explanation. The three components of a DNA nucleotide are a deoxyribose sugar, a nitrogenous base and a phosphate group. Ribose sugar belongs to RNA instead.
Q9
In the DNA molecule base pairing always occurs between
- A. two purines
- B. two pyrimidines
- C. a purine and a pyrimidineCorrect
- D. a sugar and a phosphate
Explanation. Pairing is always between a purine and a pyrimidine, which keeps the width of the double helix constant along its whole length.
Q10
The double helix model of DNA was proposed by
- A. Mendel and Morgan
- B. Watson and CrickCorrect
- C. Darwin and Wallace
- D. Hugo de Vries and Correns
Explanation. The chapter presents the structure of DNA through the Watson and Crick model, in which two strands wind around each other as a double helix.
Q11
The enzyme that unwinds the two strands of DNA during replication is
- A. HelicaseCorrect
- B. DNA ligase
- C. RNA primase
- D. DNA polymerase
Explanation. Helicase separates the two strands so that each can serve as a template. Polymerase then adds new nucleotides and ligase seals the remaining gaps.
Q12
New nucleotides are added to form the complementary strand of DNA with the help of
- A. DNA ligase
- B. Helicase
- C. DNA polymeraseCorrect
- D. Amylase
Explanation. DNA polymerase adds the new nucleotides so that a new complementary strand is formed against each template strand during replication.
Q13
The sex of a child is determined by
- A. the ovum produced by the mother
- B. the sperm produced by the fatherCorrect
- C. both parents equally
- D. the number of autosomes
Explanation. The sperm produced by the father carries either an X or a Y chromosome and so decides the sex of the child. The mother is not responsible for determining it.
Q14
An inheritable change in the genetic material of an organism is called
- A. Heredity
- B. Variation
- C. MutationCorrect
- D. Karyotype
Explanation. Mutation is an inheritable change in the amount or the structure of a gene or a chromosome, and therefore a change in the genetic material itself.
Q15
The number and appearance of the complete set of chromosomes of a cell is known as its
- A. Genotype
- B. Phenotype
- C. KaryotypeCorrect
- D. Allele
Explanation. Karyotype describes the complete set of chromosomes of a cell by number and appearance. Genotype refers to the genetic constitution and phenotype to the visible expression.
About these Genetics questions
These are the Additional multiple-choice questions for Genetics from the Tamil Nadu State Board (Samacheer Kalvi) 10th Standard Science syllabus. Each question shows the correct option and an original, step-by-step explanation so you understand the method, not just the answer. Use the answer key above to jump to any question, then take the practice test to check yourself under exam-like conditions.
Frequently asked questions
How many MCQs are there in Genetics?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 10th Standard Science MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Genetics book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
