Mix Examples- Photosynthesis in Higher Plants Questions in English

(B) Organisms that prepare their own organic food using sunlight are called $Photoautotrophs$.
Green plants,some protists like $Euglena$,and certain bacteria like green sulphur bacteria fall under this category.
They possess pigments like chlorophyll that capture solar energy and convert it into chemical energy stored in simple carbohydrates (glucose).
This synthesis occurs using simple inorganic compounds,specifically $CO_2$ and $H_2O$,through the process of photosynthesis.

(B) The major process by which carbon is fixed from the atmosphere is $Photosynthesis$. During this process,green plants and other autotrophs absorb $CO_2$ from the atmosphere and convert it into organic compounds (glucose),which forms the basis of the food chain.

(D) In non-cyclic photophosphorylation,both $PS-II$ and $PS-I$ work in series,resulting in the production of both $ATP$ and $NADPH + H^+$.
Stroma lamellae lack $PS-II$ and $NADP$ reductase enzyme,so they only perform cyclic photophosphorylation involving $PS-I$.
Grana lamellae contain both $PS-I$ and $PS-II$,allowing for non-cyclic electron flow.
Cyclic photophosphorylation involves only $PS-I$,not $PS-II$. Therefore,the statement that cyclic photophosphorylation involves both $PS-I$ and $PS-II$ is incorrect.

(B) The primary product of photosynthesis is glucose,which is converted into starch for storage.
Food is stored in roots,stems,or specific types of parenchyma cells.
These parenchyma cells act as storage tissues,where carbohydrates are stored in the form of starch,which is a polysaccharide.

(A) Photosynthesis is an anabolic process because it involves the synthesis of complex organic molecules (glucose) from simpler inorganic substances ($CO_2$ and $H_2O$).
It is an endergonic process because it requires the input of energy in the form of light to drive the chemical reactions.

(D) Photosynthesis is a biological process where green plants,algae,and some bacteria convert light energy into chemical energy.
$1$. Organisms capable of performing photosynthesis are known as autotrophs because they synthesize their own food.
$2$. During photosynthesis,$O_2$ is released as a byproduct,which increases the atmospheric oxygen concentration.
$3$. It serves as the fundamental basis for the food chain,acting as the primary source of organic food for all heterotrophic organisms on Earth.
Therefore,all the given statements are correct.

(D) Photosynthesis is a complex physiological process by which green plants synthesize organic food using inorganic raw materials.
Essential factors for photosynthesis include:
$1$. Light: Provides the energy required to excite electrons.
$2$. $CO_2$: Acts as the carbon source for the synthesis of carbohydrates.
$3$. Chlorophyll: The pigment responsible for trapping light energy.
$4$. Water: Acts as a source of electrons and protons.
Since light,$CO_2$,and chlorophyll are all critical components,the correct answer is all of the above.

(D) Photosynthesis is a redox reaction.
In this process,water $(H_2O)$ is oxidized to release oxygen $(O_2)$.
Carbon dioxide $(CO_2)$ is reduced to form glucose $(C_6H_{12}O_6)$.
Therefore,$H_2O$ undergoes oxidation and $CO_2$ undergoes reduction.

(A) In photosynthesis,the light-dependent reaction (light reaction) occurs in the thylakoid membranes of the grana within the chloroplasts,where light energy is captured to produce $ATP$ and $NADPH$.
The dark reaction (light-independent reaction or Calvin cycle) occurs in the stroma of the chloroplast,where $CO_2$ is fixed into sugars using the $ATP$ and $NADPH$ produced during the light reaction.

(A) The light-dependent reaction (light reaction) occurs in the thylakoid membranes and involves:
$II-$ Absorption of light energy.
$III-$ Photolysis of water leading to the release of $O_2$.
$V-$ Synthesis of energy carriers $ATP$ and $NADPH_2$.
The light-independent reaction (dark reaction or Calvin cycle) occurs in the stroma and involves:
$I-$ Fixation of $CO_2$ (carboxylation).
$IV-$ Utilization of $ATP$ and $NADPH_2$ produced in the light reaction.
$VI-$ Synthesis of glucose (sugar).
Therefore,the light reaction includes $II, III, V$ and the dark reaction includes $I, IV, VI$.

(D) photosystem is the functional unit for photosynthesis where light energy is converted into chemical energy.
It is referred to as a 'Pigment system' because it consists of chlorophyll and accessory pigments.
It contains a 'Light-harvesting complex' $(LHC)$ that absorbs light and transfers it to the reaction center.
This entire structural and functional assembly is also known as a 'Photosynthetic unit'.
Therefore,all the given options are correct.

(D) The $NADP$ reductase enzyme is located on the outer side of the thylakoid membrane,facing the stroma.
During the light reaction of photosynthesis,this enzyme facilitates the reduction of $NADP^+$ to $NADPH + H^+$ by using electrons from the electron transport system and protons from the stroma.
By consuming protons from the stroma to form $NADPH + H^+$,the enzyme effectively decreases the proton concentration in the stroma,which contributes to the proton gradient across the thylakoid membrane.
Therefore,all the given statements are correct.

(D) $RuBisCO$ (Ribulose$-1,5-$bisphosphate carboxylase-oxygenase) is a bifunctional enzyme.
$1$. In the $C_3$ cycle (Calvin cycle),it acts as a carboxylase,catalyzing the fixation of $CO_2$ to $RuBP$.
$2$. In $C_4$ plants,although $PEP$ carboxylase is the primary carboxylase,$RuBisCO$ still performs the carboxylation step within the bundle sheath cells.
$3$. In the presence of high $O_2$ concentration,$RuBisCO$ acts as an oxygenase,initiating the $C_2$ pathway or photorespiration.
Therefore,it performs all the mentioned functions.

(A) Photosynthesis is the fundamental biological process by which green plants,algae,and some bacteria convert light energy into chemical energy.
This process synthesizes glucose and other organic compounds from carbon dioxide and water,which serve as the primary source of food and energy for all living organisms.
Therefore,all food substances essential for life are ultimately obtained through photosynthesis.

(D) $1$. Green plants and blue-green algae are autotrophs that perform photosynthesis to synthesize their own food.
$2$. Photosynthesis is a process where light energy is captured and converted into stable chemical energy stored in organic molecules.
$3$. The energy produced during photosynthesis is stored in the chemical bonds of carbohydrates such as glucose,sucrose,and starch,which serve as the primary fuel for cellular respiration.
$4$. Since all statements $A$,$B$,and $C$ are scientifically correct,the correct option is $D$.

(B) Plants produce food through the process of $Photosynthesis$.
In $Photosynthesis$,plants utilize inorganic raw materials like $CO_2$ and $H_2O$ in the presence of sunlight and chlorophyll to synthesize organic compounds like glucose $(C_6H_{12}O_6)$.
Therefore,the process involves the conversion of inorganic components into organic components.

(A) According to the $NCERT$ textbook,the total amount of carbon fixed annually in the biosphere through the process of photosynthesis is estimated to be $4 \times 10^{13} \ kg$.
This carbon fixation is a fundamental process that forms the basis of the food chain in all ecosystems.

(D) The absorption spectrum of chlorophyll $a$ shows the wavelengths of light absorbed by the pigment.
The action spectrum of photosynthesis shows the rate of photosynthesis at different wavelengths of light.
While the peaks of the action spectrum and the absorption spectrum of chlorophyll $a$ coincide (showing that chlorophyll $a$ is the main pigment),the overlap is not complete.
This is because other accessory pigments (like chlorophyll $b$,xanthophylls,and carotenoids) also absorb light at other wavelengths and transfer the energy to chlorophyll $a$,thereby contributing to photosynthesis.
Thus,the assertion is true.
The reason correctly explains that while blue and red regions are most effective,photosynthesis occurs at other wavelengths as well due to the involvement of accessory pigments.
Therefore,both are true and the reason is the correct explanation.

(A) In the $C_3$ cycle (Calvin cycle),the first stable product formed after the fixation of $CO_2$ is a $3$-carbon compound called $3$-phosphoglyceric acid $(3PGA)$.
In the $C_4$ cycle (Hatch-Slack pathway),the first stable product formed after the fixation of $CO_2$ is a $4$-carbon compound called oxaloacetic acid $(OAA)$.

(D) The correct matches are as follows:
$1$. $P_{680}$ is the reaction centre of $PS-II$ (Photosystem $II$),which absorbs light at $680 \ nm$. Thus,$(A)-(II)$.
$2$. $P_{700}$ is the reaction centre of $PS-I$ (Photosystem $I$),which absorbs light at $700 \ nm$. Thus,$(B)-(I)$.
$3$. $\text{LHC}$ (Light Harvesting Complex) consists of hundreds of pigment molecules bound to proteins,also known as antennae. Thus,$(C)-(III)$.
$4$. Plastoquinone is a mobile electron carrier that transports electrons from $PS-II$ to the cytochrome $b_6f$ complex. Thus,$(D)-(IV)$.
Therefore,the correct sequence is $A-II, B-I, C-III, D-IV$.

(D) The correct matching is as follows:
$1$. $a.$ $3$-carbon organic acid: In the $C_3$ cycle (Calvin cycle),the first stable product formed after $\text{CO}_2$ fixation is $3$-phosphoglyceric acid ($3$-$PGA$),which is a $3$-carbon organic acid $(a-III)$.
$2$. $b.$ $\text{ATP}$ and $\text{NADPH}$: These are the assimilatory powers produced during the light reaction and are utilized as reactants in the dark reaction (Calvin cycle) $(b-I)$.
$3$. $c.$ $\text{CO}_2$: Carbon dioxide is the primary substrate or reactant required for the dark reaction to proceed $(c-II)$.
$4$. $d.$ Oxaloacetic acid: In the $C_4$ pathway (Hatch-Slack pathway),the first stable product formed after $\text{CO}_2$ fixation is oxaloacetic acid $(OAA)$,which is a $4$-carbon compound $(d-IV)$.
Therefore,the correct sequence is $a-III, b-I, c-II, d-IV$.

(D) Photosynthesis is a redox reaction.
In this process, $CO_2$ is reduced to form glucose $(C_6H_{12}O_6)$ by gaining hydrogen atoms.
Simultaneously, water $(H_2O)$ is oxidised to release oxygen $(O_2)$ by losing hydrogen atoms.
The overall chemical equation is: $6CO_2 + 12H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6H_2O + 6O_2$.

(A) Photosynthesis is a redox reaction where $CO_2$ is reduced to carbohydrates and $H_2O$ is oxidized to release $O_2$.
The overall chemical equation is: $6CO_2 + 12H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6H_2O + 6O_2$.
In this process,$CO_2$ gains hydrogen (reduction) to form glucose,while $H_2O$ loses hydrogen (oxidation) to release oxygen.

(D) Photosynthesis is the process by which green plants synthesize organic food (glucose) using inorganic raw materials.
The overall chemical equation for photosynthesis is: $6CO_2 + 12H_2O \xrightarrow{\text{Light, Chlorophyll}} C_6H_{12}O_6 + 6O_2 + 6H_2O$.
From this equation,it is evident that:
$1$. Light energy is required to drive the reaction.
$2$. Chlorophyll (pigment) is essential to capture light energy.
$3$. $CO_2$ and water $(H_2O)$ serve as the primary inorganic substrates.
Therefore,all the listed components are necessary for the process of photosynthesis.

(A) Statement $(A)$ is correct because $C_4$ plants have a specialized anatomy (Kranz anatomy) and a mechanism to concentrate $CO_2$ around the enzyme $RuBisCO$,which minimizes photorespiration and increases photosynthetic efficiency and productivity.
Statement $(B)$ is incorrect because photorespiration in $C_3$ plants is triggered by high $O_2$ concentration and low $CO_2$ concentration,not high $CO_2$ concentration. High $CO_2$ levels actually suppress photorespiration in $C_3$ plants.

(D) Statement-$I$ is incorrect because when $PS-II$ is functional,it involves non-cyclic photophosphorylation ($Z$-scheme),where electrons are not circulated within the photosystem but are transferred from water to $NADP^+$. Cyclic photophosphorylation occurs only when $PS-I$ is functional and electrons circulate within $PS-I$.
Statement-$II$ is incorrect because stroma lamellae membranes lack $PS-II$ and $NADP$ reductase enzyme,but they do contain $PS-I$.

(B) Option $B$ is incorrect because $C_3$ plants do not possess $PEP$ carboxylase $(PEPC)$ enzyme; instead,they use $RuBisCO$ for carbon fixation. $PEP$ carboxylase is a characteristic enzyme of $C_4$ plants.
Option $A$ is correct as tomato and bell pepper are commonly grown in greenhouses to control environmental factors.
Option $C$ is correct because cyclic photophosphorylation occurs to produce additional $ATP$ when the ratio of $ATP$ to $NADPH$ required for the Calvin cycle is not met by non-cyclic photophosphorylation.
Option $D$ is correct as the electron transport chain uses energy to pump protons into the thylakoid lumen,establishing a proton gradient essential for $ATP$ synthesis.

(B) $(i)$ Calvin cycle was discovered by Melvin Calvin using $^{14}CO_2$ in algae. This is a correct match.
$(ii)$ Hatch and Slack pathway ($C_4$ pathway) is found in plants like Sorghum, which exhibit Kranz anatomy. This is a correct match.
$(iii)$ Photorespiration occurs in $C_3$ plants, but the primary product is phosphoglycolate, not $OAA$ (Oxaloacetic acid). $OAA$ is the first stable product of the $C_4$ pathway. This is an incorrect match.
$(iv)$ $CO_2$ fertilization effect is related to $CO_2$ concentration, not $Cu$. This is an incorrect match.
Therefore, $(i)$ and $(ii)$ are correct.

(A) Photosynthesis is considered vital for two main reasons:
$1$. It is the primary source of all food on Earth,as it produces organic compounds (glucose) that form the base of the food chain.
$2$. It is responsible for the release of oxygen into the atmosphere by green plants,which is essential for the survival of aerobic organisms.
Since both statements are scientifically accurate and the reason directly explains why photosynthesis is important,the correct option is $A$.

(A) The carboxylation of $\text{RuBP}$ is the primary step of the Calvin cycle ($C_3$ cycle),which occurs in all photosynthetic plants.
In this process,$\text{RuBP}$ $(5C)$ reacts with $\text{CO}_2$ to form two molecules of $3$-phosphoglycerate ($3$-$PGA$),which is a $3C$ compound.
Since all plants (both $C_3$ and $C_4$ plants) perform the Calvin cycle to synthesize sugars,all the plants listed will produce a $3C$ compound after the carboxylation of $\text{RuBP}$.
The list includes: Pineapple $(CAM)$,Maize $(C_4)$,Rice $(C_3)$,Mustard $(C_3)$,Sorghum $(C_4)$,Opuntia $(CAM)$,Tomato $(C_3)$,and Wheat $(C_3)$.
Total number of plants = $8$.

(B) Both Statement $I$ and Statement $II$ are false.
In the Calvin cycle ($C_3$ cycle),the primary carboxylation reaction is catalysed by the enzyme $RuBisCO$ (ribulose$-1,5-$bisphosphate carboxylase/oxygenase).
In the Hatch-Slack pathway ($C_4$ cycle),the primary carboxylation reaction is catalysed by the enzyme $PEP$ carboxylase $(PEPCase)$.

(A) The correct answer is $A$.
Statement $A$ is false because the enzymes required for carbon fixation (the $Calvin$ cycle),such as $RuBisCO$,are located in the stroma of the chloroplasts,not in the grana.
The grana are primarily the sites for light-dependent reactions,where the thylakoid membranes contain the photosystems and electron transport chain components.
Statement $B$ is true: Non-cyclic photophosphorylation involves both $PS I$ and $PS II$ to produce $NADPH + H^+$.
Statement $C$ is true: The electron transport chain components are embedded within the thylakoid membranes.
Statement $D$ is true: Photosynthesis is a redox reaction where $H_2O$ is oxidized to $O_2$ and $CO_2$ is reduced to carbohydrates.

(A) The correct option is $A$.
Statement $I$ is correct: RuBisCO has a high affinity for $CO_2$,but it can also bind to $O_2$ when $CO_2$ concentration is low,leading to photorespiration.
Statement $II$ is incorrect: In $C_4$ plants,the Calvin cycle occurs in the chloroplasts of bundle sheath cells,but the statement implies a general rule or is often contrasted with $C_3$ plants where it occurs in mesophyll cells. However,statement $III$ is factually incorrect as per $NCERT$.
Statement $III$ is incorrect: Yeast poisons itself to death when the concentration of alcohol reaches about $13\%$,not $7\%$.
Statement $IV$ is correct: During aerobic respiration,oxygen acts as the final hydrogen acceptor at the end of the electron transport chain to form water.

(A) The correct matching is as follows:
$1$. Phosphoenol pyruvate $(PEP)$ is a $3$-carbon compound $(t)$.
$2$. Ribulose biphosphate $(RuBP)$ is a $5$-carbon compound $(s)$.
$3$. Oxaloacetic acid $(OAA)$ is a $4$-carbon compound $(r)$.
$4$. Acetyl coenzyme $A$ is a $2$-carbon compound $(q)$.
Therefore,the correct sequence is $A-t, B-s, C-r, D-q$.

(D) Statement $A$ is incorrect because the water-splitting complex is associated with $PS-II$,not $PS-I$.
Statement $B$ is incorrect because $C_4$ plants use the $C_4$ pathway (Hatch-Slack pathway) as the primary biosynthetic pathway,although they also contain the $C_3$ cycle.
Statement $D$ is incorrect because $C_4$ plants,not $C_3$ plants,exhibit 'Kranz' anatomy.
Statements $C$ and $E$ are correct.
Thus,the incorrect statements are $A, B,$ and $D$. However,based on the provided options,the most appropriate choice identifying the incorrect statements is $(4)$ $A$ and $D$.