Photosynthesis In Higher Plants(12th Grade > Biology ) Questions and answers for exam Preparation

12th Grade > Biology

PHOTOSYNTHESIS IN HIGHER PLANTS MCQs

Total Questions : 59 | Page 6 of 6 pages

Question 51. During what stage of photosynthesis is O

_{2}

produced?

cyclic photophosphorylation
the light-dependent reactions involving photosystems I and II
carbon fixation
the Krebs cycle

Discuss Question

Answer: Option B. -> the light-dependent reactions involving photosystems I and II
:
B
This is due to the splitting of the water molecule during the non-cyclic photophosphorylation.

Question 52. Select the wrongly matched pair with regard to C4 cycle.

Primary CO2 fixation – PGA product
Site of initial carboxylation – mesophyll cells
Primary CO2 acceptor – PEP
C4 plant – Maize

Discuss Question

Answer: Option A. -> Primary CO2 fixation – PGA product
:
A
The primary CO₂fixation product in C4 cycle is oxaloacetic acid (OAA) in mesophyll cells. It then forms other 4 – carbon compounds like malic acid or aspartic acid in the mesophyll cells itself, which are transferred to the bundle sheath cells.

Question 53. Light energy in photosynthesis is utilised in

H2O converted into H2
ADP converted into ATP
ATP converted into ADP
None of the above.

Discuss Question

Answer: Option B. -> ADP converted into ATP
:
B
During downhill movement, the electrons release energy, which converted ADP into ATP.

Question 54. In the thylakoid membranes, what is the main role of the antenna pigment molecules?

split water and release oxygen to the reaction-center chlorophyll
harvest photons and transfer light energy to the reaction-center chlorophyll
synthesize ATP from ADP and Pi
transfer electrons to ferredoxin and then NADPH

Discuss Question

Answer: Option B. -> harvest photons and transfer light energy to the reaction-center chlorophyll
:
B
These are also called as the accessory pigments.

Question 55. Which of the following statements is true with regard to the light reaction of photosynthesis?

In PS – II reaction centre, chlorophyll – a has an absorption peak of 700 nm, hence called p700
In PS – I, the reaction centre chlorophyll –a has an absorption maxima at 680 nm and is called p680
The splitting of water molecule is associated with PS – I
Photo systems – I and II are involved in Z – scheme.

Discuss Question

Answer: Option D. -> Photo systems – I and II are involved in Z – scheme.
:
D
Photophosphorylation is the synthesis of ATP from ADP and inorganic phosphate in the presence of sunlight. When the two photo systems, work in a series, first PS – II and then the PS – I, a process called non-cyclic phosphorylation occurs in the two photosystems that are connected through an electron transport chain in Z - scheme. (due to the shape of path of electrons flow). Both ATP and NADH + H⁺ are synthesized by this kind of electron flow.

Question 56. Consider the following statements. I. The portion of the spectrum between 300-500 nm is also referred to as photosynthetically active radiation (PAR) II. Magnesium, calcium and chloride ions play prominent roles in the photolysis of water. III. In cyclic phosphorylation, oxygen is not released (as there is no photolysis of water) and NADPH is also not produced.

I is true, but II and III are false
I and II are true; but III is false
II is true; but I and III are false
I, II and III are true

Discuss Question

Answer: Option D. -> I, II and III are true
:
D
The portion of thespectrum between 400 – 700 nm is referred to as photosynthetically active radiation. Manganese and chloride ions play a prominent role in thephotolysis of water. Oxygen is released because of photolysis of waterand NADPH is produced in non-cyclic photophosphorylation.

Question 57. Which statement describes the functioning of photosystem II?

Light energy excites electrons in the electron transport chain in a photosynthetic unit.
The excitation is passed along to a molecule of P700 chlorophyll in the photosynthetic unit.
The P680 chlorophyll donates a pair of protons to NADPH, which is thus converted to NADP+
The electron vacancies in P680 are filled by electrons derived from water.

Discuss Question

Answer: Option D. -> The electron vacancies in P680 are filled by electrons derived from water.
:
D
When light falls in photosystem II, electrons get excited and are transported through an electron transport chain to photosystem I. Water is split, oxygen is released and electrons are transferred to photosystem II.

Question 58. Which of the following sequences correctly represents the flow of electrons during photosynthesis?

NADP+→ O2 → CO2
H2O → NADP+ → Calvin cycle
NADP+ → chlorophyll → Calvin cycle
H2O → photosystem I → photosystem II

Discuss Question

Answer: Option B. -> H2O → NADP+ → Calvin cycle
:
B
Electrons flow from water through the photosystem II, electron transport chain, and photosystem I to NADP

^{+}

. The electrons of NADPH thus formed are then used in the Calvin cycle.

Question 59. Solar energy is passed from one pigment to the other until it is concentrated into one particular ______ molecule, the reaction-center chlorophyll.