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Science · 2025 · 3 marks
CBSE 2025 · Region 1 · Set 1 · Q30
(a) What are chromosomes? (b) Explain in brief how stability of DNA content of a species is ensured in sexually reproducing organisms?
(a)
What are chromosomes ?
(b)
Explain in brief how stability of DNA content of a species is ensured in sexually reproducing organisms ?
Marking-scheme solution
(a)
Chromosomes carry genes which control the traits of an organism/chromosomes contain information for inheritance of features from parents to next generation in the form of DNA(Deoxy ribonucleic acid) molecule.
(b)
Each cell has two copies of each chromosome, one from male and the other from female parents which get halved during the formation of germ cells/gametes.
After fusion of the germ cells zygote is formed which restores the normal number of chromosomes and the same amount of DNA in the progeny.
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CBSE Class 10 Science past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.