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Science · 2026 · 3 marks
CBSE 2026 · Region 4 · Set 1 · Q14
Study the given table and answer the following questions: (a) Depict the information given in the table in the form of a cross. (b) Deduce the F_2…
Study the given table and answer the following questions :
| Parents | $\displaystyle \mathrm{F}_{1}$ | $\displaystyle \mathrm{F}_{2}$ |
| A pea plant with red flowers was crossed with a pea plant with white flowers. | $\displaystyle 30$ seeds were sown and all bore plants with red flowers. | $\displaystyle 44$ seeds were sown, $\displaystyle 33$ plants bore red flowers and $\displaystyle 11$ plants bore white flowers. |
(a)
Depict the information given in the table in the form of a cross.
(b)
Deduce the $\displaystyle \mathrm{F}_{2}$ phenotypic ratio/ $\displaystyle \mathrm{F}_{2}$ ratio showing external look as well as genotypic /genetic makeup, ratio.
Marking-scheme solution
(a)
Parents: R R × rr
(Red flowers) (White flowers)
Gametes :
$\displaystyle \mathrm{F}_{1}$ :
(All red)
Rr × Rr
Gametes:
$\displaystyle \mathrm{F}_{2}$
(b)
Phenotypic ratio/ Showing external look of plants : $\displaystyle 33$ : $\displaystyle 11$
$\displaystyle 3$ : $\displaystyle 1$
(Red) (White)
Genotypic Ratio :
$\displaystyle 1$: $\displaystyle 2$: $\displaystyle 1$
RR: Rr: rr
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CBSE Class 10 Science past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.