Every Book Back multiple-choice question from Genetics (10th Standard Science, Samacheer Kalvi) — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
According to Mendel alleles have the following character
A. Pair of genesCorrect
B. Responsible for character
C. Production of gametes
D. Recessive factors
Explanation. Every pea plant carries two factors for a particular trait, and that pair of genes is what Mendel called an allele. The word therefore names a pair, not a single factor.
Q2
9 : 3 : 3 : 1 ratio is due to
A. Segregation
B. Crossing over
C. Independent assortmentCorrect
D. Recessiveness
Explanation. The dihybrid ratio appears because the two pairs of alleles separate independently of each other during gamete formation. That is Mendel's law of independent assortment.
Q3
The region of the chromosome where the spindle fibres get attached during cell division
A. Chromomere
B. Centrosome
C. CentromereCorrect
D. Chromonema
Explanation. The centromere is the primary constriction of the chromosome, and it is the point to which spindle fibres attach. The centrosome is a separate structure outside the nucleus.
Q4
The centromere is found at the centre of the ________________ chromosome.
A. Telocentric
B. MetacentricCorrect
C. Sub-metacentric
D. Acrocentric
Explanation. Chromosomes are classified by where the centromere lies. A metacentric chromosome has it exactly at the centre, giving two arms of equal length.
Q5
The _____________ units form the backbone of the DNA.
A. 5 carbon sugar
B. Phosphate
C. Nitrogenous bases
D. Sugar phosphateCorrect
Explanation. Alternating deoxyribose sugar and phosphate groups form the two strands that run along the outside of the molecule. The nitrogenous bases project inward and pair across.
Q6
Okasaki fragments are joined together by ___________________ .
A. Helicase
B. DNA polymerase
C. RNA primer
D. DNA ligaseCorrect
Explanation. Okazaki fragments are the short pieces made on the lagging strand during replication. DNA ligase seals the gaps between them. Helicase only unwinds the double helix.
Q7
The number of chromosomes found in human beings are ___________________ .
A. 22 pairs of autosomes and 1 pair of allosomes.Correct
B. 22 autosomes and 1 allosome
C. 46 autosomes
D. 46 pairs autosomes and 1 pair of allosomes.
Explanation. Each human cell contains 23 pairs of chromosomes. Of these, 22 pairs are autosomes and the remaining pair are the allosomes or sex chromosomes.
Q8
The loss of one or more chromosome in a ploidy is called ___________ .
A. Tetraploidy
B. AneuploidyCorrect
C. Euploidy
D. polyploidy
Explanation. Aneuploidy is the gain or loss of one or a few individual chromosomes. Euploidy and polyploidy involve whole extra sets of chromosomes rather than single ones.
These are the Book Back 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 8 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.
