🔬 Biology · Class 11 · NEET
Photosynthesis in Higher Plants - Practice Questions with Answers 75 free MCQs on Photosynthesis in Higher Plants, each with its own worked answer and explanation. Light reactions, the Calvin cycle, C 3 /C 4 /CAM pathways, photorespiration, and factors affecting the rate of photosynthesis. One of the highest-yield NEET chapters.
Take the timed Photosynthesis in Higher Plants chapterwise test → 75 practice questions on Photosynthesis in Higher Plants , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Photosynthesis in Higher Plants notes .
Photosynthesis: Inputs and Outputs chloroplast Leaf cell Sunlight CO2 H2O O2 Glucose Simplified photosynthesis diagram: light energy, CO2 , and H2 O enter the leaf and are converted in the chloroplast into glucose and O2 .
Easy - 25 questions Q1.
The yellow-orange accessory pigments that also protect chlorophyll from damage are the:
A CarotenoidsB Chlorophyll aC Chlorophyll bD PhycocyaninsShow answer & explanation →
Q2.
The reaction-centre pigment of both photosystems is a form of:
A Chlorophyll bB Chlorophyll aC Beta caroteneD XanthophyllShow answer & explanation →
Q3.
Accessory pigments are useful in photosynthesis because they:
A Store starch grainsB Split water moleculesC Absorb extra wavelengths of lightD Fix carbon dioxide directlyShow answer & explanation →
Q4.
The release of oxygen by green plants was first shown (candle and mouse experiment) by:
A Jan IngenhouszB Julius von SachsC Cornelius van NielD Joseph PriestleyShow answer & explanation →
Q5.
The fluid-filled space of the chloroplast that surrounds the grana is the:
A StromaB MatrixC CytosolD LumenShow answer & explanation →
Q7.
The overall equation for photosynthesis is:
A C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> + 6O<sub>2</sub> → 6CO<sub>2</sub> + 6H<sub>2</sub>OB 6CO<sub>2</sub> + 6H<sub>2</sub>O → C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> + 6O<sub>2</sub>C CO<sub>2</sub> + H<sub>2</sub>O → glucoseD 6H<sub>2</sub>O + 6CO<sub>2</sub> → 6CH<sub>2</sub>O + 6O<sub>2</sub>Show answer & explanation →
Q8.
Chlorophyll absorbs which colors of light most strongly?
A Green and yellowB Red and blue-violetC White light mainlyD UV mainlyShow answer & explanation →
Q9.
The dark reaction (Calvin cycle) occurs in the:
A Thylakoid membraneB CytoplasmC Stroma of chloroplastD MitochondriaShow answer & explanation →
Q11.
The Calvin cycle is also called:
A Light-dependent reactionB C<sub>3</sub> cycle or dark reactionC Krebs cycle for plantsD C<sub>4</sub> pathwayShow answer & explanation →
Q12.
Photorespiration is the process in which:
A Plants carry out ordinary mitochondrial respiration mainly during daylight hoursB Rubisco fixes O<sub>2</sub> instead of CO<sub>2</sub>, reducing efficiencyC Captured light energy is redirected to drive mitochondrial ATP synthesisD CO<sub>2</sub> is released mainly during the dark hours of the nightShow answer & explanation →
Q13.
In C<sub>4</sub> plants, CO<sub>2</sub> is initially fixed in mesophyll cells to form:
A PGA, a 3-carbon compound formed via the Calvin cycleB Oxaloacetate (4-carbon compound)C Sucrose, synthesized directly within mesophyll cellsD RuBP, regenerated during the Calvin cycleShow answer & explanation →
Q14.
The first product of the Calvin cycle (C<sub>3</sub> pathway) is:
A Glucose, formed directly in a single stepB Sucrose, exported immediately to the phloemC PGA (3-phosphoglycerate)D Oxaloacetate, formed in C<sub>4</sub> mesophyll cellsShow answer & explanation →
Q15.
The green pigment chlorophyll, essential for photosynthesis, is located within which cell organelle?
A NucleusB MitochondrionC Golgi apparatusD ChloroplastShow answer & explanation →
Q19.
The gas absorbed by plants during photosynthesis is:
A carbon dioxideB pure oxygenC pure nitrogenD pure hydrogenShow answer & explanation →
Q21.
The cell organelle in which photosynthesis occurs is the:
A chloroplastB mitochondrionC nucleusD ribosomeShow answer & explanation →
Q23.
The small pores on a leaf through which gases are exchanged are the:
A stomataB leaf veinsC root hairsD flower petalsShow answer & explanation →
Medium - 25 questions Q26.
Jan Ingenhousz showed that the release of oxygen by plants needs:
A Warm soilB SunlightC Rich nitrogenD Still airShow answer & explanation →
Q28.
In C<sub>4</sub> plants, the four-carbon acid releases its CO<sub>2</sub> in the:
A Guard cellsB Epidermal cellsC Root cortex cellsD Bundle-sheath cellsShow answer & explanation →
Q29.
The photolysis (splitting) of water in photosynthesis releases protons, electrons and:
A OxygenB GlucoseC NitrogenD AmmoniaShow answer & explanation →
Q30.
The principle that photosynthesis is limited by the factor in shortest supply is:
A The Van't Hoff temperature ruleB Blackman's law of limiting factorsC Mendel's law of segregationD The Hardy-Weinberg equilibriumShow answer & explanation →
Q31.
C<sub>4</sub> plants like maize have an advantage over C<sub>3</sub> plants because:
A They fix the majority of their CO<sub>2</sub> during the night using stored malateB PEP carboxylase does not fix O<sub>2</sub>, reducing photorespiration in hot climatesC They universally require less water regardless of ambient temperature or humidityD They show a consistent growth advantage specifically in cold climatesShow answer & explanation →
Q32.
The compensation point in photosynthesis is where:
A Mitochondrial respiration reaches its absolute maximum measured rateB Photosynthesis rate equals respiration rate (net gas exchange = 0)C Guard cells fully close the stomatal pore, halting all gas exchangeD Ambient temperature reaches the optimum for Rubisco carboxylase activityShow answer & explanation →
Q33.
The ratio of cyclic to non-cyclic photophosphorylation differs in:
A Amount of ATP and NADPH produced (cyclic makes only ATP; non-cyclic makes ATP + NADPH + O<sub>2</sub>)B The specific wavelength of light absorbed by the reaction center pigments specificallyC The total amount of carbon dioxide that becomes fixed directly during each separate pathwayD The type of chlorophyll molecule, a or b, used specifically within each photosystem complexShow answer & explanation →
Q34.
In the dark, CAM plants open their stomata to:
A Maximize transpirational water loss while ambient humidity is highestB Fix CO<sub>2</sub> at night as malate (stored in vacuole) to reduce water loss during dayC Carry out the full light-dependent reactions of photosynthesis under starlightD Release oxygen generated by water-splitting at the oxygen-evolving complexShow answer & explanation →
Q35.
ATP and NADPH from light reactions are used in the Calvin cycle to:
A Split water molecules at the oxygen-evolving complex of Photosystem IIB Synthesize new chlorophyll pigment molecules within the thylakoid membraneC Reduce CO<sub>2</sub> to produce G3P (glyceraldehyde-3-phosphate)D Produce molecular oxygen released as a byproduct of water oxidationShow answer & explanation →
Q36.
Rubisco catalyzes in the Calvin cycle:
A ATP synthesisB CO<sub>2</sub> fixation: CO<sub>2</sub> + RuBP → 2 PGAC Sugar to starch conversionD Electron transferShow answer & explanation →
Q37.
The site of the light-dependent reactions of photosynthesis within the chloroplast is the:
A Stroma, the fluid-filled matrixB Matrix found inside mitochondriaC Thylakoid membrane, within the granaD Outer membrane of the chloroplastShow answer & explanation →
Q38.
Photorespiration in C<sub>3</sub> plants occurs mainly because rubisco:
A Can bind O<sub>2</sub> as well as CO<sub>2</sub> when CO<sub>2</sub> is low and O<sub>2</sub> is highB Functions mainly at night, away from light reactionsC Binds only CO<sub>2</sub>, regardless of ambient O<sub>2</sub> levelsD Is largely absent from mesophyll cells in C<sub>3</sub> leavesShow answer & explanation →
Q39.
Splitting of the water molecule during photosynthesis (photolysis) takes place in association with:
A The outer membrane of the chloroplast envelope as widely reportedB Photosystem I, near the stromal face according to most studiesC Photosystem II, replacing electrons lost by chlorophyllD The Calvin cycle, occurring in the stroma in the majority of documented casesShow answer & explanation →
Q40.
In C<sub>3</sub> plants, the first stable product formed after CO<sub>2</sub> fixation by rubisco is:
A Glucose, a 6-carbon compound under most conditions studiedB Malic acid, a 4-carbon compound in most observed casesC Oxaloacetate, a 4-carbon compound in standard reference materialD 3-phosphoglycerate (PGA), a 3-carbon compoundShow answer & explanation →
Q41.
The light-dependent reactions of photosynthesis take place in the:
A thylakoid membranesB the fluid stromaC the cell cytoplasmD the cell nucleusShow answer & explanation →
Q42.
The light-independent (Calvin cycle) reactions take place in the:
A stromaB thylakoidsC cytoplasmD nucleusShow answer & explanation →
Q43.
The splitting of water molecules during photosynthesis is called:
A photolysisB glycolysisC hydrolysisD electrolysisShow answer & explanation →
Q44.
The two products of the light reaction that power the Calvin cycle are ATP and:
A NADPHB oxygenC glucoseD plain waterShow answer & explanation →
Q47.
Plants that first fix carbon dioxide into a 4-carbon compound are called:
A C<sub>4</sub> plantsB C<sub>3</sub> plantsC only CAM plantsD green algaeShow answer & explanation →
Q50.
Chlorophyll molecules are located within the ___ of the chloroplast:
A thylakoidsB stromaC outer envelopeD nucleusShow answer & explanation →
Hard - 25 questions Q51.
Cyclic photophosphorylation involves only Photosystem I and produces:
A Only NADPHB Oxygen and sugarC Only ATPD Both water and CO2Show answer & explanation →
Q52.
The number of ATP and NADPH molecules used to fix one CO<sub>2</sub> in the Calvin cycle is:
A 1 ATP and 1 NADPHB 2 ATP and 3 NADPHC 6 ATP and 6 NADPHD 3 ATP and 2 NADPHShow answer & explanation →
Q53.
To build one molecule of glucose, the Calvin cycle must fix:
A Six molecules of CO2B One molecule of CO2C Two molecules of CO2D Three molecules of CO2Show answer & explanation →
Q54.
In CAM plants, the CO<sub>2</sub> taken in at night is stored in vacuoles as:
A Starch grainsB Malic acidC Pyruvic acidD Glucose sugarShow answer & explanation →
Q55.
The first CO<sub>2</sub> acceptor in the mesophyll of C<sub>4</sub> plants is the compound:
A Ribulose bisphosphateB Oxaloacetic acidC PhosphoenolpyruvateD Glyceraldehyde phosphateShow answer & explanation →
Q56.
In the Q cycle of photosynthesis, the function is to:
A Fix atmospheric CO<sub>2</sub> directly onto ribulose bisphosphate molecules within the chloroplast stroma matrix region in the majority of cases studiedB Pump protons across thylakoid membrane via plastoquinone (PQ) oxidation/reduction, increasing H+ gradient for ATP synthesisC Directly reduce NADP+ to NADPH using electrons donated by reduced ferredoxin specifically at PSI as widely reported in standard practiceD Transport electrons backward from Photosystem I to Photosystem II against the normal directional flow under most conditions encounteredShow answer & explanation →
Q57.
Ferredoxin-NADP+ reductase (FNR) in the light reactions:
A Splits water molecules at the manganese cluster of Photosystem IIB Reduces NADP+ to NADPH using electrons from ferredoxinC Actively pumps protons across the thylakoid membrane into the lumenD Catalyzes phosphorylation of ADP to ATP at the F<sub>1</sub> head of ATP synthaseShow answer & explanation →
Q58.
The oxygen-evolving complex (OEC) in PS II contains:
A An iron-sulfur cluster that shuttles electrons toward plastoquinoneB A manganese cluster (Mn4CaO5) that oxidizes water to release O<sub>2</sub>C A copper-containing center analogous to that found in plastocyaninD A zinc-finger motif that stabilizes the reaction center protein scaffoldShow answer & explanation →
Q59.
In the Calvin cycle, 3 turns are needed to produce one net G3P because:
A Mainly a single CO<sub>2</sub> molecule is ever fixed across the entire three-turn cycle process as frequently observed in practiceB Each turn fixes one CO<sub>2</sub> and regenerates RuBP; 3 CO<sub>2</sub> are needed to produce 1 net G3P (a 3-carbon molecule)C The cycle consumes exactly three ATP molecules during each individual turn taken in many documented casesD Ribulose bisphosphate itself is built from a three-carbon precursor skeleton structure according to conventional understandingShow answer & explanation →
Q60.
Rubisco is a poor catalyst because:
A It is sometimes thought to function mainly at unusually high temperatures well above the normal physiological leaf range found in natureB It has low catalytic rate (kcat ~3/sec) and reacts with O<sub>2</sub> as well as CO<sub>2</sub> (oxygenase activity), causing photorespirationC It is sometimes thought to require rare transition metal cofactors that are absent from typical photosynthetic leaf tissue altogetherD It is sometimes thought to become catalytically active mainly when CO<sub>2</sub> concentration far exceeds normal atmospheric levels found outdoorsShow answer & explanation →
Q61.
The 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway in plastids produces:
A Fatty acid chains assembled by the plastid-localized fatty acid synthase complexB Terpenoids (isoprene, carotenoids, diterpenes) for photosynthesis and plant defenseC Free amino acids synthesized via nitrogen assimilation in the chloroplast stromaD Starch granules deposited and stored within the chloroplast stromaShow answer & explanation →
Q62.
Crassulacean acid metabolism (CAM) evolved as:
A An adaptation enabling survival specifically in persistently cold, frost-prone alpine and arctic mountain climates in routine practiceB Adaptation to arid conditions -- temporally separating CO<sub>2</sub> fixation (night) from Calvin cycle (day) to minimize water lossC An adaptation for capturing limited light filtering down through deeply shaded forest understory regions overall in most casesD An adaptation allowing root respiration to continue normally within waterlogged, oxygen-poor soil environments under typical conditionsShow answer & explanation →
Q63.
State transition (dark-to-light adaptation) in chloroplasts involves:
A De novo synthesis of additional chlorophyll molecules occurring within minutes of bright illuminationB Reversible phosphorylation of LHCII, which migrates between PS II and PS I to balance excitationC Light-driven activation of Rubisco carboxylase by specialized Rubisco activase enzymes nearbyD Rapid stomatal pore opening triggered directly by specific blue light photoreceptors presentShow answer & explanation →
Q64.
The photorespiratory salvage pathway (C2 cycle) recycles:
A Excess sucrose into stored starch granules within the chloroplast stroma region in general practiceB Glycolate (toxic product of Rubisco oxygenase) back to PGA via chloroplast, peroxisome, and mitochondriaC Degraded storage proteins back into their constituent free amino acid molecules as frequently describedD CO<sub>2</sub> released mainly from mitochondrial respiration occurring during the dark period in most textbook accountsShow answer & explanation →
Q65.
The Hill reaction, a classic experiment demonstrating the light reaction of photosynthesis, established that:
A Oxygen evolved in photosynthesis is derived from carbon dioxide rather than from water as generally observed in typical laboratory settingsB Isolated chloroplasts can evolve oxygen from water in the presence of a suitable electron acceptor, even without CO<sub>2</sub> fixationC Carbon dioxide fixation can occur in complete darkness if sufficient ATP is supplied externally under normal conditionsD Chlorophyll molecules can directly fix CO<sub>2</sub> into a 3-carbon compound without any enzyme involvement under usual circumstancesShow answer & explanation →
Q66.
In the Calvin cycle, carbon dioxide is first attached to the 5-carbon molecule:
A RuBPB glucoseC pyruvateD plain ATPShow answer & explanation →
Q67.
The two photosystems that take part in the light reactions are Photosystem I and:
A Photosystem IIB Photosystem IIIC Photosystem IVD Photosystem VShow answer & explanation →
Q68.
C<sub>4</sub> plants are efficient in hot, dry climates chiefly because they minimise:
A photorespirationB transpirationC normal respirationD seed germinationShow answer & explanation →
Q70.
The ATP and NADPH generated in the light reactions are used mainly to synthesise:
A glucoseB waterC oxygenD chlorophyllShow answer & explanation →
Q72.
Specialised bundle-sheath cells around the veins are a distinctive feature of ___ plants:
A C<sub>4</sub>B C<sub>3</sub>C aquaticD fungalShow answer & explanation →
Q73.
On a cloudy day, the factor most likely to limit photosynthesis is:
A light intensityB carbon dioxideC soil waterD chlorophyllShow answer & explanation →
Q74.
Photorespiration begins when the enzyme RuBisCO binds ___ instead of carbon dioxide:
A oxygenB nitrogenC waterD glucoseShow answer & explanation →