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Science · 2024 · 5 marks
CBSE 2024 · Region 3 · Set 1 · Q35
(a) (i) What are spores? On which structures are they formed? How do they overcome unfavourable conditions? Name the organism which multiplies with…
(a)(i)
What are spores ? On which structures are they formed ? How do they overcome unfavourable conditions ? Name the organism which multiplies with the help of these structures.
(ii)
Give two reasons why some plants are grown by the method of vegetative propagation. List two methods used to grow plants vegetatively.
OR 35. (b) (i) Study the diagram given below and name the parts marked as A, B and C. What happens when B reaches C in the ovary ? Mention its significance.
(ii)
Write the post fertilisation changes that occur in a flower.
Marking-scheme solution
(i) • Spores are reproductive structures that detach from the parent and give rise to a new individual.
Sporangium / Sporangia
Covered by thick walls to protect them from unfavourable conditions.
Rhizopus
(ii)
Plants which have lost the capacity to produce seeds.
Plants bear flowers and fruits earlier so as to reduce time.
To get genetically similar plants.
Methods
Layering and Grafting
(i)
A - Male Germ Cell/Male Gamete; B - Pollen tube; C - Female Germ Cell / Female Gamete.
B carries A (male germ cell) and this germ cell fuses with C (female germ cell) to form a zygote.
Significance: Zygote is capable of growing into a new plant.
(ii) Post fertilisation changes: -
Zygote divides many times to form an embryo within ovule.
Ovule is converted into seed
Ovary ripens into fruit.
Petals, Sepals, Stamens, Style and Stigma may shrivel/dry and may fall off.
All How do Organisms Reproduce? questions2024 question paperNCERT solutions: How do Organisms Reproduce?Practice How do Organisms Reproduce? →
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CBSE Class 10 Science past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.