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Science · 2026 · 4 marks
CBSE 2026 · Region 1 · Set 1 · Q15
Mendel took garden pea plants with different characteristics, such as height to study the inheritance pattern of factors (genes). He crossed tall pea…
Mendel took garden pea plants with different characteristics, such as height to study the inheritance pattern of factors (genes). He crossed tall pea plant with short pea plant and obtained all the tall plants in the $\displaystyle \mathrm{F}_{1}$ generation. Answer the following questions :
(a)
Why only tall pea plants were observed in $\displaystyle \mathrm{F}_{1}$ progeny ?
(b)
By which method did Mendel obtain $\displaystyle \mathrm{F}_{2}$ progeny?
(c)
(i)
Write one difference between dominant and recessive trait.
OR
(ii)
Write two observations made by Mendel about $\displaystyle \mathrm{F}_{1}$ progeny.
Marking-scheme solution
(a) In \(\displaystyle \mathrm{F}_{1}\) progeny, pea plants have ' Tt ' where ' T ' is dominant over ' t ' so all the plants of \(\displaystyle \mathrm{F}_{1}\) progeny were tall. / Tall height is dominant trait over short height.
(b) Self-pollination
(c) (i)
OR
| Dominant trait | Recessive trait | |
| i) | Expresses itself over recessive trait. | i) Unable to express itself in presence of a dominant trait. |
| ii) | Expresses in both conditions-TT and Tt. | ii) Expresses itself only when it is 'tt' or in pure condition. |
(c) (ii) Mendel's observations:
All plants of \(\displaystyle \mathrm{F}_{1}\) progeny were tall.
No medium/ no short height plants observed in \(\displaystyle \mathrm{F}_{1}\) progeny.
F $\displaystyle 1$ progeny resembled one parent only.
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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.