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mcqs of
,
1 : Green light gives:
1
:
Least photosynthesis
2
:
Maximum Photosynthesis
3
:
High absorption
4
:
No oxygen
2 : If NADPH is absent:
1
:
CO₂ is fixed
2
:
Glucose not formed
3
:
Light absorbed
4
:
O₂ released
3 : Heavy oxygen experiment proved:
1
:
CO₂ gives O₂
2
:
Water gives O₂
3
:
NADPH stores O₂
4
:
ATP releases O₂
4 : Why do plants appear green in color?
1
:
Green light is absorbed
2
:
Blue light is reflected
3
:
Green light is reflected
4
:
All colors are absorbed
5 : Which part of the Chlorophyll molecule is hydrophobic?
1
:
Pyrrole ring
2
:
Porphyrin
3
:
Hydrocarbon tail
4
:
Magnesium center
6 : What holds the pyrrole rings of chlorophyll together?
1
:
Iron atom
2
:
Nitrogen atoms
3
:
Magnesium atom
4
:
Carbon atoms
7 : What is primary function of accessory pigments?
1
:
Absorb red light
2
:
Release oxygen
3
:
Store glucose
4
:
Transfer energy to chlorophyll a
8 : Which pigment is present in the reaction center of both photosystems?
1
:
Chlorophyll b
2
:
Carotene
3
:
Chlorophyll a
4
:
Xanthophylls
9 : What provides energy in photosynthesis?
1
:
Light
2
:
Water
3
:
CO₂
4
:
Glucose
10 : Which structure contains photosynthesis pigments in plant cells?
1
:
Nucleus
2
:
Thylakoid
3
:
Cytoplasm
4
:
Mitochondria
11 : Which structure connects grana in chloroplasts?
1
:
Lamella
2
:
Stroma
3
:
Outer membrane
4
:
Thylakoid lumen
12 : CO₂ reduced by:
1
:
Oxygen
2
:
NADPH
3
:
Chlorophyll
4
:
Water
13 : NADPH acts as:
1
:
Enzyme
2
:
Pigment
3
:
Reducing agent
4
:
Light absorber
14 : Closed stomata reduce:
1
:
Light
2
:
Water loss
3
:
CO₂ entry
4
:
Pigment
15 : Role of water in photosynthesis:
1
:
Splits to release oxygen
2
:
Makes starch
3
:
Stores light
4
:
Fixes carbon
16 : Why is the electron transport chain important in photosynthesis?
1
:
It absorbs light
2
:
It generates NADPH and ATP
3
:
It fixes CO₂
4
:
It reflects green light
17 : Maximum photosynthesis occurs in:
1
:
Yellow light
2
:
Green light
3
:
Red and blue light
4
:
White light
18 : Rubisco fixes:
1
:
Hydrogen
2
:
Water
3
:
Carbon dioxide
4
:
Oxygen
19 : Which part of photosynthesis occurs on Thylakoid membrane?
1
:
Carbon fixation
2
:
Glucose production
3
:
Light dependent reactions
4
:
Calvin cycle
20 : Action spectrum shows:
1
:
CO₂ use
2
:
Light absorption
3
:
Water Transport
4
:
Heat loss
21 : CO₂ enters through:
1
:
Roots
2
:
Stem
3
:
Stomata
4
:
Veins
22 : Engelmann used:
1
:
Moss
2
:
Pine
3
:
Spirogyra
4
:
Algae
23 : Which photosystem absorbs light of 680 nm most efficiently?
1
:
PS-II
2
:
PS-I
3
:
ATP Synthase
4
:
Electron carrier
24 : Which pigment primarily participates in the reaction center of photosynthesis?
1
:
Carotene
2
:
Xanthophyll
3
:
Chlorophyll a
4
:
Chlorophyll b
25 : Which statement best differentiates cyclic from non-cyclic photophosphorylation?
1
:
Only PS-I works in cyclic
2
:
Oxygen is formed in cyclic
3
:
NADPH is not formed in cyclic
4
:
Forms Chlorophyll
26 : What would happen if the Calvin cycle were interrupted?
1
:
ATP production would increase
2
:
Glucose production would stop
3
:
Photosynthesis would be enhanced
4
:
Oxygen production would increase
27 : How does ATP formation occur during electron transport?
1
:
Through the light directly
2
:
Via chemiosmosis
3
:
Through water uptake
4
:
By glucose breakdown
28 : How is energy from light stored during photosynthesis?
1
:
As glucose
2
:
In CO₂
3
:
In water molecule
4
:
In ATP and NADPH
29 : What is ATP synthase's role in Photosynthesis?
1
:
Splits water
2
:
Synthesizes ATP
3
:
Absorbs water
4
:
Transfers electrons
30 : Why is photolysis of water essential in photosynthesis?
1
:
Forms NADP+
2
:
Releases carbon dioxide
3
:
Fills electron gap in P680
4
:
Forms Chlorophyll
31 : Why is the Calvin cycle important for life on Earth?
1
:
It produces ATP for plants
2
:
It converts CO₂ into glucose for energy
3
:
It produces oxygen for respiration
4
:
It absorbs light for photosynthesis
32 : How is Calvin cycle affected in absence of light?
1
:
The cycle stops immediately
2
:
The cycle continues using stored ATP and NADPH
3
:
The cycle produces glucose at a faster rate
4
:
The cycle uses light from other sources
33 : How does the Calvin Cycle contribute to glucose synthesis?
1
:
By formation of ATP
2
:
By converting G3P into glucose
3
:
By reducing CO₂ to glucose
4
:
By producing NADPH for glucose synthesis
34 : Difference between the reduction and regeneration phases of the Calvin cycle:
1
:
Reduction forms glucose, and regeneration uses RuBP
2
:
Reduction uses ATP, and regeneration uses NADPH
3
:
Reduction forms G3P, and regeneration forms RuBP
4
:
Reduction fixes CO₂, and regeneration forms glucose
35 : What happens if NADPH accumulates in chloroplast?
1
:
Calvin cycle speeds up
2
:
Cyclic photophosphorylation begins
3
:
Photolysis increases
4
:
Glucose is oxidized
36 : Why is the Calvin cycle also called the dark reaction?
1
:
It occurs at night
2
:
It does not require light directly
3
:
It occurs in dark reactions
4
:
It produces glucose in darkness
37 : What is the primary product of carbon fixation in the Calvin cycle?
1
:
Glucose
2
:
3-Phosphoglycerate
3
:
RuBP
4
:
G3P
38 : What role does Rubisco play in the Calvin cycle?
1
:
It reduces G3P to glucose
2
:
It fixes carbon dioxide to RuBP
3
:
It produces NADPH
4
:
It synthesizes ATP
39 : What is the Calvin Cycle?
1
:
A set of light-dependent reactions in the stroma
2
:
A set of light-independent reactions in the stroma
3
:
A pathway that produces glucose
4
:
A process that requires sunlight for glucose production
40 : The pigment for absorbing light is:
1
:
Rubisco
2
:
NADPH
3
:
Chlorophyll
4
:
ATP
41 : Why is alcoholic fermentation beneficial for yeast?
1
:
Survive without oxygen
2
:
Produce more energy
3
:
Generate lactic acid
4
:
Use CO₂ to make glucose
42 : What happens if glucose is not metabolized in respiration?
1
:
Use lipids for fuel
2
:
Same ATP production
3
:
More oxygen available
4
:
Increase glucose production
43 : Why do muscle cells use lactic acid fermentation during exercise?
1
:
To increase oxygen intake
2
:
To produce ATP
3
:
To release glucose
4
:
To generate heat
44 : How does glycolysis function in both types of respiration?
1
:
Splits glucose
2
:
Generates ATP
3
:
Produces oxygen
4
:
Requires oxygen
45 : Difference between alcoholic and lactic acid fermentation:
1
:
Ethanol vs. Lactic acid
2
:
Muscle vs. yeast
3
:
Requires oxygen vs. Not require
4
:
Both in human
46 : Why is anaerobic respiration less efficient?
1
:
Faster glucose use
2
:
Less ATP produced
3
:
More oxygen needed
4
:
More waste produced
47 : What is produced in alcoholic fermentation?
1
:
Lactic acid
2
:
Ethanol + CO₂
3
:
Oxygen, Glucose
4
:
Water, Energy
48 : How much ATP is produced in anaerobic respiration?
1
:
2 ATP
2
:
4 ATP
3
:
38 ATP
4
:
1 ATP
49 : Which of the following is a product of glycolysis?
1
:
Pyruvic acid
2
:
Lactic acid
3
:
Oxygen
4
:
Water
50 : What is the function of NAD+ in glycolysis?
1
:
Donates a phosphate group
2
:
Breaks down glucose
3
:
Accepts hydrogen ions
4
:
Produces ATP
51 : What is the main purpose of cellular respiration?
1
:
Break down glucose
2
:
Produce glucose
3
:
Store energy
4
:
Release CO₂ and Water
52 : Main product of photosynthesis is:
1
:
Oxygen
2
:
Glucose
3
:
Water
4
:
ATP
53 : Where does glycolysis occur?
1
:
Mitochondria
2
:
Cytosol
3
:
Nucleus
4
:
Chloroplast
54 : What is the importance of NADH in aerobic respiration?
1
:
Supplies electrons to the electron chain
2
:
Directly produces ATP
3
:
Breaks down glucose
4
:
Converts pyruvic acid into lactic acid
55 : Why is glycolysis important in both aerobic and anaerobic respiration?
1
:
Produces ATP without oxygen
2
:
Generates oxygen
3
:
Breaks down glucose into oxygen
4
:
Produces large amount of carbon dioxide
56 : How does pyruvic acid change before entering the Krebs cycle?
1
:
Converted to glucose
2
:
Forms acetyl-CoA after losing CO₂
3
:
Convert to lactic acid
4
:
Remains unchanged
57 : Why is oxygen necessary for the stages after glycolysis in aerobic respiration?
1
:
ATP production
2
:
Convert pyruvic acid to lactic acid
3
:
Final electron acceptor
4
:
Provides energy for glycolysis
58 : How does the Krebs cycle contribute to energy production?
1
:
It produces glucose from pyruvate
2
:
It stores oxygen for cellular use
3
:
It produces ATP and electron carriers like NADH and FADH₂
4
:
It directly produces oxygen for the cell
59 : Why is the Krebs cycle also called the citric acid cycle?
1
:
Because citric acid is the final product
2
:
Because citric acid is the most abundant molecule
3
:
Because citric acid is the first product formed
4
:
Because citric acid is oxidized in the cycle
60 : What is the initial molecule that combines with acetyl-CoA in the Krebs cycle?
1
:
Fumaric acid
2
:
Oxaloacetic acid
3
:
Malic acid
4
:
Succinic acid
61 : Where does the Krebs cycle occur in the cell?
1
:
Cytoplasm
2
:
Nucleus
3
:
Mitochondria
4
:
Golgi apparatus
62 : How does the energy released from glucose during aerobic respiration benefit cells?
1
:
Stored as glucose
2
:
Forms ATP, powers functions
3
:
Released as heat
4
:
Stored as fat
63 : What is the first molecule formed in the Krebs cycle?
1
:
Citric acid
2
:
Alpha-ketoglutaric acid
3
:
Succinic acid
4
:
Malic acid
64 : What is the importance of NADH in aerobic respiration?
1
:
Supplies electrons to the electron transport chain
2
:
Breaks down glucose
3
:
Converts pyruvic acid to lactic acid
4
:
Directly produces ATP
65 : How does the energy release from glucose during aerobic respiration benefit cells?
1
:
Stored as glycogen
2
:
Forms ATP, powers functions
3
:
Released as heat
4
:
Stored as fat
66 : What would happen if the electron transport chain were blocked?
1
:
ATP production would increase
2
:
Oxygen consumption would increase
3
:
The cell would rely on anaerobic respiration
4
:
The Krebs cycle would stop
67 : Where does the electron transport chain occur in the cell?
1
:
Cytoplasm
2
:
Mitochondrial inner membrane
3
:
Nucleus
4
:
Plasma membrane
68 : What is produced when NADH is oxidized in the electron transport chain?
1
:
Two ATP
2
:
One ATP
3
:
Three ATP
4
:
Four ATP
69 : What is the final electron acceptor in the electron transport chain?
1
:
Oxygen
2
:
Carbon dioxide
3
:
Water
4
:
NAD+
70 : How does chemiosmosis contribute to ATP production?
1
:
By adding phosphate groups to glucose
2
:
By using energy from electrons to pump protons across the membrane
3
:
By reducing NADH to NAD+
4
:
By splitting glucose into pyruvic acid
71 : Why is oxygen important for cellular respiration?
1
:
It forms ATP
2
:
It combines with electrons to form water
3
:
It acts as a proton pump
4
:
It increases the energy yield of glycolysis
72 : How do lipids contribute to ATP production in cellular respiration?
1
:
Lipids are converted to glucose for glycolysis
2
:
Fatty acids are converted to acetyl CoA, which enters the Krebs cycle
3
:
Lipids are used to produce NADH and FADH₂ directly
4
:
Lipids are converted to lactic acid for ATP production
73 : Why do C-4 plants have specialized cells?
1
:
To isolate CO₂ and O₂, reducing photorespiration
2
:
To reduce water loss
3
:
To increase oxygen production
4
:
To enhance nitrogen uptake
74 : How does C-4 photosynthesis help in hot climates?
1
:
Concentrates CO₂, reduces photorespiration
2
:
Slows Calvin cycle
3
:
Increases oxygen supply
4
:
Improves water use efficiency
75 : Why is photorespiration problematic for crops in hot climates?
1
:
Increases rate, reduces yield
2
:
Reduces oxygen production
3
:
Inefficient light absorption
4
:
Low photosynthesis efficiency
76 : How does temperature affect photorespiration rate?
1
:
Increases oxygen fixation by Rubisco
2
:
No effect
3
:
Lowers competition for Rubisco
4
:
Decreases photorespiration
77 : Why does photorespiration decrease photosynthesis efficiency?
1
:
Loss of fixed carbon
2
:
Produces more ATP
3
:
Accelerates Calvin cycle
4
:
Prevents oxygen buildup
78 : Which molecule is formed from phosphoglycolate?
1
:
Glyoxylate
2
:
Glycine
3
:
Serine
4
:
Malate
79 : What does Rubisco do in photorespiration?
1
:
Breaks down RuBP to phosphoglycolate
2
:
Synthesizes glucose
3
:
Fixes CO₂ in Calvin cycle
4
:
Converts glycerate to phosphoglycerate
80 : Which plants use CAM metabolism?
1
:
Cacti, pineapples
2
:
All tropical trees
3
:
Only C-3 plants
4
:
All aquatic plants
81 : What is photorespiration?
1
:
Oxygen used, CO₂ released in light
2
:
ATP produced in green cells
3
:
Occurs in mitochondria
4
:
Only in dark
82 : How does CAM contribute to plant survival in arid regions?
1
:
Fixes CO₂ during the day
2
:
Minimizes water loss
3
:
Increases transpiration
4
:
Fixes CO₂ in soil
83 : How does CAM help Cacti survive?
1
:
Stomata open during the day
2
:
Prevents glucose formation
3
:
Stores CO₂ at night
4
:
Reduces oxygen intake at night
84 : What is the function of CAM metabolism in hot climates?
1
:
Fix CO₂ in the morning
2
:
Fix CO₂ at night
3
:
Increase photorespiration
4
:
Open stomata all day
85 : How does CAM reduce photorespiration?
1
:
By absorbing CO₂ during the day
2
:
By storing CO₂ at night
3
:
By storing oxygen for later use
4
:
By reducing water intake
86 : Why is CAM metabolism beneficial for desert plants?
1
:
CO₂ is fixed only at night
2
:
Stomata open during the day
3
:
Increases photosynthesis during the day
4
:
Limits oxygen intake
87 : Why do CAM plants close their stomata during the day?
1
:
To prevent oxygen intake
2
:
To conserve water
3
:
To absorb CO₂ at midday
4
:
To absorb more oxygen
88 : Which is an advantage of CAM in agriculture?
1
:
Increases water usage
2
:
Makes plants drought-resistant
3
:
Increases plant growth rate
4
:
Limits CO₂ absorption
89 : Where do light dependent reactions take place?
1
:
Stroma
2
:
Cytoplasm
3
:
Thylakoid membrane
4
:
Outer membrane
90 : What is the main purpose of light dependent reactions?
1
:
Produce glucose
2
:
Absorb carbon dioxide
3
:
Form ATP and NADPH
4
:
Split sugars
91 : What is CAM metabolism?
1
:
Stomata open during the day
2
:
Stomata open at night
3
:
Only occurs in aquatic plants
4
:
Only occurs in C-3 plants
92 : Which wavelengths are least absorbed by Chlorophylls?
1
:
Blue
2
:
Green
3
:
Red
4
:
Violet
93 : What is the energy transfer path in plants?
1
:
Carotenoids → Chlorophyll a
2
:
Chlorophyll a → Xanthophylls
3
:
Chlorophyll b → CO₂
4
:
Chlorophyll a → Carotenes
Biology 11th MCQs || Ilam Ghar
Chapter 6 : Bioenergetics
Biology 11th
