Read the following passage and answer the questions that follow : Not all plants carry out photosynthesis by…
Read the following passage and answer the questions that follow :
Not all plants carry out photosynthesis by the same mechanism. In most plants, it depends directly on gaseous carbon dioxide that diffuses into the leaf. However, some plants can store carbon dioxide in the vacuole of the leaf cells as part of a complex carbon compound. This compound is transported to the chloroplast and releases carbon dioxide when required for photosynthesis. This special mechanism is believed to have evolved as an adaptation in such plants which do not open stomata during the daytime to conserve water for survival in dry conditions (desert conditions).
Attempt either (a) or (b) :
(a) (i) Which process in these plants is minimised to help the plants survive in dry conditions ?
(ii) Which part of the leaf is responsible for exchange of gases during photosynthesis ?
Solution
(a) (i) Opening of stomata during the day is minimised to prevent loss
of water by evaporation. / Transpiration (loss of water in the form
of water vapour) is minimised.
(ii) Stomata
OR
(b) (i)
• Absorption of light energy by Chlorophyll.
• Conversion of light energy to chemical energy and splitting of
water molecules into hydrogen and oxygen
• Reduction of Carbon Dioxide into Carbohydrates
(ii) At night.
(iii) Diagram of Open stomatal pore.
Diagram - 1 Mark
Labelling - 1 Mark
16 (a) (i)
• Structure: Bryophyllum leaf
• Type: Vegetative propagation / Asexual reproduction
(ii)
• Advantage: Genetically identical plants, maintaining
desirable traits of the parents. / Bear flowers and fruits
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earlier than those plants which are grown from seeds / Used
for the plants that have lost their capacity to produce seeds.
(any one)
• Disadvantage: No genetic variation.
(iii) As DNA of single parent is involved without gamete fusion. /
Offsprings are produced by mitosis hence similar genetic makeup
thus, no variation.
(iv) It creates genetic variation, enhances chances of survival in
changing environment and drives evolution.
OR
(b) (i) Name: Multiple Fission
Type: Asexual reproduction
(ii) In stage P, many daughter cells are produced by multiple fission /
Repeated nuclear divisions followed by cytoplasmic divisions.
(iii) Plasmodium (any other)
(iv)
• Vegetative propagation
Advantages –
• All the plants produced are genetically similar to the parent
plant
• Such plants can bear flowers and fruits earlier than those
produced from seeds.
( any other advantage)
SECTION – B
(Chemistry)