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Science — CBSE Class 10 board question

Q1. [1]
Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds were crossed with each other which produced F1 progeny that have only round yellow (RrYy) seeds. When F1 plants are self-pollinated, the F2 progeny will have which new combination of characters, as compared to the parents : (i) Round, yellow (ii) Round, green (iii) Wrinkled, yellow (iv) Wrinkled, green Correct options are :
  1. (A) (i) and (ii)
  2. (B) (i) and (iv)
  3. (C) (ii) and (iv)
  4. (D) (i) and (iii)
Previously asked in CBSE board exam
2026 31/4/1 Q6
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer

(D) (i) and (iii)

The parental combinations were round green (RRyy) and wrinkled yellow (rrYY). The new combinations appearing in F2 are round yellow and wrinkled yellow — wait, re-checking: parents had round green and wrinkled yellow; new combinations are round yellow (RrYy / RRYY) and wrinkled green (rryy). So the answer is (B) (i) and (iv).

(B) (ii) and (iii)

The correct answer is (D) (ii) and (iii) — No.

Correct Answer: (B)

The parents were round green and wrinkled yellow. New combinations (not seen in parents) in F2 are (i) round yellow and (iv) wrinkled green.

Explanation

The parents are RRyy (round, green) and rrYY (wrinkled, yellow). So the parental phenotypes are "round green" and "wrinkled yellow." In F2 (from Fig. 8.5), all four combinations appear: round yellow, round green, wrinkled yellow, and wrinkled green. The new combinations — those not present in the original parents — are round yellow and wrinkled green, making option (B) correct. Students must carefully distinguish "new combinations" from the parental phenotypes.

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Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.