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Biology Help: Compare Respiration And Photosynthesis Models

Review real example questions for Compare Respiration And Photosynthesis Models in Biology.

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Photosynthesis and cellular respiration can be compared using their overall equations:

Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Which statement best describes how these two processes are related in terms of matter and energy?

All questions

Question 1

Photosynthesis and cellular respiration can be compared using their overall equations:

Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Which statement best describes how these two processes are related in terms of matter and energy?

Both processes store energy by building glucose, and both require light energy to occur.
Photosynthesis releases energy as ATP, while cellular respiration stores energy by making glucose.
The products of photosynthesis (glucose and $O_2$ ) are reactants for cellular respiration, and the products of respiration ( $CO_2$ and $H_2O$ ) are reactants for photosynthesis; photosynthesis stores energy while respiration releases it. (correct answer)
The two processes are independent: photosynthesis uses only oxygen, and respiration uses only carbon dioxide.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially reverse chemical processes with opposite energy transformations: photosynthesis takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), storing solar energy in glucose bonds (equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2), while cellular respiration takes glucose and oxygen and breaks them down to carbon dioxide and water, releasing the stored energy as ATP (equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy). Notice how the reactants of photosynthesis (CO2, H2O) are the products of respiration, and the products of photosynthesis (glucose, O2) are the reactants of respiration—they're chemical opposites that create matter cycling at the ecosystem level, with photosynthesis producing O2 that respiration consumes and respiration producing CO2 that photosynthesis uses. Choice C correctly compares them by recognizing their opposite equations, opposite energy directions (storing vs. releasing), and complementary relationship in cycling matter. Choices like A and B fail because they confuse the energy roles—photosynthesis stores energy in glucose using light, not both storing and requiring light for the same purpose, and respiration releases ATP, not stores glucose. Remember the photosynthesis-respiration comparison table: photosynthesis (equation: CO2 + H2O + light → glucose + O2, energy: light input stored in glucose, location: chloroplasts, organisms: autotrophs, function: builds glucose) versus cellular respiration (equation: glucose + O2 → CO2 + H2O + ATP, energy: chemical output as ATP, location: mitochondria, organisms: all, function: breaks down glucose)—every feature is opposite except the cycling molecules! This interdependence means protecting plants is key, as they supply O2 and glucose for all life—great job exploring these vital processes!

Question 2

Consider the overall equations:

Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Which choice best describes how the reactants and products of these two processes are related?

The reactants of photosynthesis are the same as the reactants of cellular respiration.
The products of photosynthesis (glucose and $O_2$ ) are used as reactants in cellular respiration, and the products of respiration ( $CO_2$ and $H_2O$ ) are used as reactants in photosynthesis. (correct answer)
Both processes produce glucose as their main product, but only respiration produces oxygen.
Only energy cycles between the two processes; matter (atoms) does not cycle.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially REVERSE chemical processes with opposite energy transformations: PHOTOSYNTHESIS takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), STORING solar energy in glucose bonds (equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2). CELLULAR RESPIRATION takes glucose and oxygen and breaks them down to carbon dioxide and water, RELEASING the stored energy as ATP (equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy). Notice: the reactants of photosynthesis (CO2, H2O) are the products of respiration, and the products of photosynthesis (glucose, O2) are the reactants of respiration—they're chemical opposites! Examining the equations carefully shows that the products of photosynthesis (glucose and O2) become the reactants of cellular respiration, while the products of respiration (CO2 and H2O) become the reactants of photosynthesis—creating a perfect cycle of matter between the two processes. Choice B correctly identifies this complementary relationship where the products of one process serve as reactants for the other, enabling matter to cycle continuously between organisms. The incorrect choices miss this key relationship: A wrongly claims both have the same reactants; C incorrectly states both produce glucose; D wrongly suggests only energy cycles when actually matter (atoms) cycles perfectly between the processes. This complementary cycling is ecologically crucial: plants photosynthesize using CO2 and H2O to produce O2 and glucose → animals (and plants) respire using O2 and glucose to produce CO2 and H2O → plants reuse that CO2 and H2O for photosynthesis → the cycle continues, sustaining all life on Earth!

Question 3

Which choice correctly compares the reactants of one process to the products of the other?

Photosynthesis: $6CO_2 + 6H_2O +$ light $\rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O +$ ATP

The reactants of photosynthesis are the same as the reactants of respiration.
The products of photosynthesis ( $C_6H_{12}O_6$ and $O_2$ ) are reactants in respiration, and the products of respiration ( $CO_2$ and $H_2O$ ) are reactants in photosynthesis. (correct answer)
The products of both processes are glucose and oxygen, but they occur in different organelles.
The products of respiration are light energy and glucose, which are then used in photosynthesis.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially REVERSE chemical processes with opposite energy transformations: PHOTOSYNTHESIS takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), STORING solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂). CELLULAR RESPIRATION takes glucose and oxygen and breaks them down to carbon dioxide and water, RELEASING the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy). Notice: the reactants of photosynthesis (CO₂, H₂O) are the products of respiration, and the products of photosynthesis (glucose, O₂) are the reactants of respiration—they're chemical opposites! Examining the equations shows that photosynthesis produces C₆H₁₂O₆ (glucose) and O₂ as products, which are exactly the reactants needed for respiration; conversely, respiration produces CO₂ and H₂O as products, which are exactly the reactants needed for photosynthesis. Choice B correctly identifies this relationship: the products of photosynthesis (C₆H₁₂O₆ and O₂) are reactants in respiration, and the products of respiration (CO₂ and H₂O) are reactants in photosynthesis. Choice A incorrectly states that both processes have the same reactants, when actually they have opposite reactants and products. Why this complementarity matters ecologically: imagine Earth with only animals (no plants): animals do respiration (use O₂, produce CO₂), atmospheric O₂ would deplete, CO₂ would accumulate, glucose would run out—animals couldn't survive! Now imagine Earth with only plants: plants do photosynthesis (use CO₂, produce O₂), CO₂ would deplete (limiting photosynthesis), O₂ would accumulate. Plants would struggle without CO₂ recycling from respiration. TOGETHER: plants photosynthesize (produce O₂ and glucose) → animals respire (consume O₂ and glucose, produce CO₂ and H₂O) → plants photosynthesize (use CO₂ and H₂O) → cycle continues!

Question 4

A student says: "Because plants photosynthesize, they do not need cellular respiration." Using the overall equations below, which statement best corrects the student?

Photosynthesis: $6CO_2 + 6H_2O +$ light $\rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O +$ ATP

Plants do both: photosynthesis makes glucose and $O_2$ , and respiration breaks down glucose with $O_2$ to make ATP for cellular work. (correct answer)
Plants do not perform respiration; only animals can make ATP.
Plants perform respiration only at night because respiration requires darkness.
Plants perform photosynthesis in mitochondria and respiration in chloroplasts, so respiration is optional.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially REVERSE chemical processes with opposite energy transformations: PHOTOSYNTHESIS takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), STORING solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂). CELLULAR RESPIRATION takes glucose and oxygen and breaks them down to carbon dioxide and water, RELEASING the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy). Notice: the reactants of photosynthesis (CO₂, H₂O) are the products of respiration, and the products of photosynthesis (glucose, O₂) are the reactants of respiration—they're chemical opposites! The student's misconception is thinking that because plants can make their own glucose through photosynthesis, they don't need to break it down for energy, but plants absolutely need cellular respiration to convert glucose into usable ATP for all cellular work (growth, reproduction, transport, etc.). Choice A correctly explains that plants do both: photosynthesis makes glucose and O₂, and respiration breaks down glucose with O₂ to make ATP for cellular work. Choice B incorrectly claims plants do not perform respiration and only animals can make ATP, which would mean plants couldn't power any cellular processes! The photosynthesis-respiration comparison table: PHOTOSYNTHESIS: Equation: CO₂ + H₂O + light → glucose + O₂. Energy: light energy INPUT (endergonic), stored in glucose. Location: chloroplasts (plants only). Organisms: autotrophs (plants, algae). Time: daytime (requires light). Function: BUILDS glucose (anabolic). CELLULAR RESPIRATION: Equation: glucose + O₂ → CO₂ + H₂O + ATP. Energy: chemical energy OUTPUT (exergonic), released from glucose. Location: mitochondria (all organisms). Organisms: all living things. Time: continuously (no light needed). Function: BREAKS DOWN glucose (catabolic). The pattern: every feature is opposite except both involve same molecules cycling!

Question 5

A leaf cell contains both chloroplasts and mitochondria. Which statement best describes what processes this plant cell can perform and where?

Photosynthesis: $6CO_2 + 6H_2O +$ light $\rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O +$ ATP

It can perform photosynthesis in chloroplasts and cellular respiration in mitochondria. (correct answer)
It can perform photosynthesis in mitochondria and cellular respiration in chloroplasts.
It can perform photosynthesis only; plants do not perform cellular respiration.
It can perform cellular respiration only; photosynthesis happens only in animal cells.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially REVERSE chemical processes with opposite energy transformations: PHOTOSYNTHESIS takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), STORING solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂). CELLULAR RESPIRATION takes glucose and oxygen and breaks them down to carbon dioxide and water, RELEASING the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy). Notice: the reactants of photosynthesis (CO₂, H₂O) are the products of respiration, and the products of photosynthesis (glucose, O₂) are the reactants of respiration—they're chemical opposites! Plant cells are unique because they contain both chloroplasts (for photosynthesis) and mitochondria (for cellular respiration), allowing them to both produce glucose from sunlight and break down glucose for ATP—they're energy self-sufficient! Choice A correctly states that the plant cell can perform photosynthesis in chloroplasts and cellular respiration in mitochondria. Choice C incorrectly claims plants do not perform cellular respiration, but plants absolutely need respiration to break down glucose and produce ATP for cellular work, especially at night when photosynthesis cannot occur. The photosynthesis-respiration comparison table: PHOTOSYNTHESIS: Equation: CO₂ + H₂O + light → glucose + O₂. Energy: light energy INPUT (endergonic), stored in glucose. Location: chloroplasts (plants only). Organisms: autotrophs (plants, algae). Time: daytime (requires light). Function: BUILDS glucose (anabolic). CELLULAR RESPIRATION: Equation: glucose + O₂ → CO₂ + H₂O + ATP. Energy: chemical energy OUTPUT (exergonic), released from glucose. Location: mitochondria (all organisms). Organisms: all living things. Time: continuously (no light needed). Function: BREAKS DOWN glucose (catabolic). The pattern: every feature is opposite except both involve same molecules cycling!

Question 6

A student writes the overall equations below to compare two processes:

Photosynthesis: $6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP energy}$

Which statement correctly describes how these two processes are related (including matter and energy)?

Both processes require light energy and both store energy by building glucose from $CO_2$ and $H_2O$ .
Photosynthesis releases energy by breaking down glucose, while cellular respiration stores energy by building glucose.
Photosynthesis stores energy in glucose and produces $O_2$ , while cellular respiration releases energy as ATP by using glucose and $O_2$ ; the products of one are the reactants of the other. (correct answer)
Photosynthesis and cellular respiration are unrelated because they occur in different organelles and do not share reactants or products.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially reverse chemical processes with opposite energy transformations: photosynthesis takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), storing solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂), while cellular respiration takes glucose and oxygen and breaks them down to carbon dioxide and water, releasing the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy)—notice how the reactants of one are the products of the other, creating matter cycling! In this comparison, the equations highlight their opposite nature, with photosynthesis being endergonic (energy-requiring) and anabolic (building up), versus respiration being exergonic (energy-releasing) and catabolic (breaking down), together sustaining life by recycling molecules like CO₂, H₂O, O₂, and glucose across organisms. Choice C correctly compares photosynthesis and respiration by recognizing their opposite equations, opposite energy directions, and complementary relationship in cycling matter, accurately capturing that photosynthesis stores energy while producing O₂, and respiration releases it using those products. Choice B fails by reversing the roles—photosynthesis actually stores energy by building glucose, not releasing it, so remember to check which process is anabolic versus catabolic. The photosynthesis-respiration comparison table: Photosynthesis: Equation: CO₂ + H₂O + light → glucose + O₂, Energy: light input (endergonic), stored in glucose, Location: chloroplasts (plants), Organisms: autotrophs, Function: builds glucose; Cellular Respiration: Equation: glucose + O₂ → CO₂ + H₂O + ATP, Energy: chemical output (exergonic), released from glucose, Location: mitochondria (all), Organisms: all, Function: breaks down glucose—every feature is opposite except the shared molecules! Why this complementarity matters ecologically: plants photosynthesize to produce O₂ and glucose that animals respire to produce CO₂, creating a balanced cycle—keep exploring these connections, you're building a strong foundation in biology!

Question 7

A student says: "Because photosynthesis makes oxygen, plants do not need to do cellular respiration." Which option best corrects this statement while comparing the two processes?

Plants do not respire; only animals use mitochondria to make ATP.
Plants do cellular respiration to make ATP from glucose in mitochondria, even though they can also produce glucose and $O_2$ by photosynthesis in chloroplasts. (correct answer)
Plants only respire at night because mitochondria work only in the dark.
Plants use cellular respiration to convert $CO_2$ and $H_2O$ into glucose using light energy.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially reverse chemical processes with opposite energy transformations: photosynthesis takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), storing solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂), while cellular respiration takes glucose and oxygen and breaks them down to carbon dioxide and water, releasing the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy)—notice how the reactants of one are the products of the other, creating matter cycling! Correcting the misconception, plants do both photosynthesis (in chloroplasts) to make glucose and O₂, and respiration (in mitochondria) to break down glucose for ATP, as they need energy constantly, not just from light. Choice B best corrects by explaining plants respire to make ATP from glucose in mitochondria, despite also photosynthesizing. Choice A fails by saying plants don't respire—they do, continuously—so remember plants are autotrophs but still need respiration. The photosynthesis-respiration comparison table: Photosynthesis: Equation: CO₂ + H₂O + light → glucose + O₂, Energy: light input (endergonic), stored in glucose, Location: chloroplasts (plants), Organisms: autotrophs, Function: builds glucose; Cellular Respiration: Equation: glucose + O₂ → CO₂ + H₂O + ATP, Energy: chemical output (exergonic), released from glucose, Location: mitochondria (all), Organisms: all, Function: breaks down glucose—every feature is opposite except the shared molecules! Why this complementarity matters ecologically: even plants recycle their own products, balancing the system—keep questioning misconceptions, you're doing amazingly!

Question 8

In an ecosystem, plants and animals exchange gases. Using the overall equations:

Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Which pair correctly identifies a substance produced by animals (through respiration) that plants can use for photosynthesis, and a substance produced by plants (through photosynthesis) that animals can use for respiration?

$O_2$ produced by animals; $CO_2$ produced by plants
$CO_2$ produced by animals; $O_2$ produced by plants (correct answer)
Glucose produced by animals; ATP produced by plants
Light energy produced by animals; water produced by plants

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially reverse chemical processes with opposite energy transformations: photosynthesis takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), storing solar energy in glucose bonds (equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂), while cellular respiration takes glucose and oxygen and breaks them down to carbon dioxide and water, releasing the stored energy as ATP (equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP energy)—notice how the reactants of one are the products of the other, creating matter cycling! In an ecosystem context, this shows how animals produce CO₂ through respiration that plants use for photosynthesis, while plants produce O₂ through photosynthesis that animals use for respiration, illustrating gas exchange and interdependence. Choice B correctly identifies CO₂ produced by animals (respiration product) for plant photosynthesis, and O₂ produced by plants (photosynthesis product) for animal respiration, capturing the cycling of these gases. Choice A fails by reversing the gases—animals produce CO₂, not O₂, so double-check which process outputs which gas in each organism. The photosynthesis-respiration comparison table: Photosynthesis: Equation: CO₂ + H₂O + light → glucose + O₂, Energy: light input (endergonic), stored in glucose, Location: chloroplasts (plants), Organisms: autotrophs, Function: builds glucose; Cellular Respiration: Equation: glucose + O₂ → CO₂ + H₂O + ATP, Energy: chemical output (exergonic), released from glucose, Location: mitochondria (all), Organisms: all, Function: breaks down glucose—every feature is opposite except the shared molecules! Why this complementarity matters ecologically: this gas exchange keeps atmospheric levels balanced, supporting life—keep up the great work, you're connecting biology to the real world!

Question 9

A student writes the overall equations below.

Photosynthesis: $6CO_2 + 6H_2O +$ light energy $\rightarrow C_6H_{12}O_6 + 6O_2$

Cellular respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O +$ ATP energy

Which statement best explains how these two processes are related in living systems?

Both processes store light energy by building glucose, but respiration happens in chloroplasts while photosynthesis happens in mitochondria.
They are complementary: photosynthesis stores energy in glucose and produces $O_2$ , while respiration uses glucose and $O_2$ to release energy as ATP and produces $CO_2$ and $H_2O$ . (correct answer)
They are unrelated because photosynthesis occurs only in plants and respiration occurs only in animals.
They have the same reactants and products, but respiration requires light and photosynthesis does not.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially reverse chemical processes with opposite energy transformations: photosynthesis takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), storing solar energy in glucose bonds (equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2), while cellular respiration takes glucose and oxygen and breaks them down to carbon dioxide and water, releasing the stored energy as ATP (equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy)—notice how the reactants of one are the products of the other, making them chemical opposites! In this question, the equations provided highlight their reversed roles, with photosynthesis building up molecules using energy input and respiration breaking them down with energy output, together enabling the cycling of carbon, oxygen, and water in living systems. Choice B correctly compares photosynthesis and respiration by recognizing their opposite equations, opposite energy directions, and complementary relationship in cycling matter. Choice A fails because it incorrectly swaps the organelles and misstates that both store light energy in glucose—respiration actually releases energy and occurs in mitochondria. Remember the photosynthesis-respiration comparison table: photosynthesis in chloroplasts stores light energy in glucose for autotrophs during daytime, while respiration in mitochondria releases chemical energy as ATP for all organisms continuously—their opposition ensures matter cycles! Why this matters ecologically: plants photosynthesize to produce O2 and glucose that animals respire, recycling CO2 back to plants, creating a balanced cycle that sustains life—keep exploring these connections, you're doing great!

Question 10

A plant leaf cell contains both chloroplasts and mitochondria. Which statement correctly describes what the plant can do compared with an animal cell?

(Use the overall equations as a guide.)

Photosynthesis: $6CO_2 + 6H_2O + \text{light} \rightarrow C_6H_{12}O_6 + 6O_2$ Respiration: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$

Plants perform photosynthesis only, while animals perform both photosynthesis and respiration.
Plants perform both photosynthesis (to make glucose and $O_2$ ) and respiration (to make ATP), while animals perform respiration but not photosynthesis. (correct answer)
Animals perform photosynthesis in mitochondria, while plants perform respiration in chloroplasts.
Neither plants nor animals perform cellular respiration; only plants make ATP from sunlight.

Explanation: This question tests your understanding of how photosynthesis and cellular respiration are complementary opposite processes that cycle matter and enable energy flow through ecosystems. Photosynthesis and cellular respiration are essentially REVERSE chemical processes with opposite energy transformations: PHOTOSYNTHESIS takes carbon dioxide and water (low-energy molecules) and uses light energy to build glucose and oxygen (high-energy molecules), STORING solar energy in glucose bonds (equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2). CELLULAR RESPIRATION takes glucose and oxygen and breaks them down to carbon dioxide and water, RELEASING the stored energy as ATP (equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy). The key insight is that plant cells contain BOTH chloroplasts AND mitochondria, enabling them to perform BOTH processes: they photosynthesize in chloroplasts (making glucose and O2 from CO2 and H2O using light) AND respire in mitochondria (breaking down glucose with O2 to make ATP), while animal cells lack chloroplasts and can only perform respiration. Choice B correctly identifies that plants perform both photosynthesis (to make their own glucose and O2) and respiration (to make ATP for cellular activities), while animals can only perform respiration since they lack chloroplasts for photosynthesis. The incorrect choices contain serious misconceptions: A wrongly claims only plants respire; C reverses the organelle functions; D incorrectly states neither organism respires. This dual capability makes plants energy self-sufficient: they manufacture their own glucose fuel through photosynthesis, then burn it through respiration for ATP—like having both a solar panel factory AND a power generator, while animals only have the generator and must obtain glucose by eating plants or other organisms!