Solved Examples on Photosynthesis in Higher Plants
Question1: In the leaves of C4 plants, malic acid formation during CO2 fixation occurs in the cells of [CBSE PMT’2007]
(a) bundle sheath
(b) phloem
(c) epidermis
(d) mesophyll
Answer: d
Solution:
In C4 plants, C4 cycle occurs in mesophyll cells and C3 cycle occurs in bundle sheath.
Question2: Electrons from excited chlorophyll molecule of photosystem II are accepted first by: [CBSE PMT’2008]
(a) Cytochrome-b
(b) Cytochrome-f
(c) Quinone
(d) Ferredoxin
Answer: c
Solution:
Electrons from excited chlorophyll molecules of photosystem II are accepted first by quinine. Photosystem II is a photosynthetic pigment system along with some electron carriers that is located in the appressed part of the grana thyllakoids. Photosystem II has chlorophyll a, b and carotenoids. Other components of PS II are phaeophytin, plastoquinone (PQ), cytochrome complex and blue coloured copper containing plastocyanin.
Question3: Importance of day length in flowering parts of plants was first shown in [CBSE PMT’2008]
(a) Lemna
(b) tobacco
(c) cotton
(d) Petunia
Answer: b
Solution:
Photoperiodism was first studied by Garner and Allard (1920). They observed that “Maryland Mammoth” variety of tobacco could be made to flower in summer by reducing the light hours with artificial darkening. It could be made to remain vegetative in winter by providing extra light.