Difference Between Photosynthesis and Cellular Respiration: Types, Transformation, Comparison, Chart

What Are Photosynthesis And Cellular Respiration?

Photosynthesis and cellular respiration are the biological activities that keep life going on Earth. In photosynthesis, light energy is converted into chemical energy in which glucose and oxygen become the byproducts of carbon dioxide and water. This occurs in the chloroplasts. On the other hand, cellular respiration is when cells convert glucose and oxygen into energy, carbon dioxide, and water. It happens in the mitochondria of eukaryotic cells.

In both processes, there is the flow of energy in biological systems: photosynthesis captures it and stores it from sunlight, while cellular respiration releases this stored energy for use by the organism. Together they are the cycle that feeds the activities of living organisms and at the same time balances the gases in the atmosphere.

Photosynthesis

Photosynthesis is a process in which green plants, algae, and some bacteria transform light energy into chemical energy. It produces glucose and oxygen from carbon dioxide and water. This key process takes place in plant cells and other photosynthetic organisms in organelles called chloroplasts. Photosynthesis can be split into two major steps: light-dependent reactions and the Calvin cycle.

• In light-dependent reactions, sunlight is absorbed by pigments like chlorophyll and others, which starts the production of ATP and NADPH through the splitting of water molecules into oxygen gas.

• The Calvin cycle involves using this ATP and NADPH to turn carbon dioxide into glucose, an energy-rich molecule needed by living organisms to sustain life.

Cellular Respiration

Cellular respiration refers to the process which involves converting glucose and oxygen into energy in the form of ATP, carbon dioxide, and water. The process mainly takes place within the mitochondria of eukaryotic cells. Cellular respiration is important for the survival of aerobic organisms because it is an effective way of extracting energy from organic molecules to power cellular functions. This process is summarized in three stages or steps: glycolysis, citric acid cycle, and oxidative phosphorylation.

• In glycolysis, glucose is broken down into pyruvate within the cytoplasm, producing a small amount of ATP.

• The pyruvate formed enters the mitochondria, where, via the citric acid cycle, electron carriers are produced.

• These carriers transport electrons to the electron transport chain, where most ATPs are produced during the process of oxidative phosphorylation.

Comparison Of Photosynthesis And Cellular Respiration

The difference between photosynthesis and cellular respiration is:

Importance of Both Processes

The importance of photosynthesis and cellular respiration includes:

• Sustain global energy and carbon cycle: Photosynthesis captures solar energy and stores it as glucose, while respiration releases that energy for physiological work, keeping balance between Earth’s energy and carbon cycle.

• Maintain oxygen carbon dioxide balance: Plants release oxygen and take in carbon dioxide, whereas animals release carbon dioxide and consume oxygen. This maintains atmospheric gas concentrations.

• Provide ATP for metabolism: Photosynthesis produces glucose that serves as raw material and respiration breaks it down to generate ATP.

• Essential for life: This interdependence between the two processes enables survival of plants, animals and microorganisms.

Photosynthesis vs Cellular Respiration NEET MCQs (With Answers & Explanations)

Important topics for NEET are:

• Stages of photosynthesis

• Stages of cellular respiration

• Photosynthesis vs cellular respiration

Practice Questions for NEET

Q1. Which among the following has the greatest energy in its quantum?

1. Red light

2. Blue light

3. Green light

4. Yellow light

Correct answer: 2) Blue light

Explanation:

According to the equation E = hc/λ, energy is inversely proportional to wavelength. Blue light has the greatest energy in its quantum compared to longer wavelengths because it has a shorter wavelength (450–495 nm). According to the wave-particle duality of light, energy is inversely proportional to wavelength. This means that shorter wavelengths like blue light carry more energy per photon than longer wavelengths, such as red or infrared light.

Hence, the correct answer is Option (2) Blue light.

Q2. Oxygen is not produced during photosynthesis by

1. Cycas

2. Nostoc

3. Green sulphur bacteria

4. Chara

Correct answer: 3) Green sulphur bacteria

Explanation:

Photosynthesis -

Enzyme-regulated anabolic process of manufacture of organic compounds inside the chlorophyll-containing cells.

Since Charan Cycas come under the plant kingdom, they perform oxygenic photosynthesis. Green sulfur bacteria utilize H2S instead of H2O and perform anoxygenic photosynthesis or do not evolve oxygen.

Hence, the correct answer is Option (3) Green sulfur bacteria.

Q3. Cluster of light-harvesting antenna pigments in a photosystem

1. Absorbs electron

2. Do not absorb photons

3. Pass energy to the reaction centre

4. Breakdown H2O

Correct answer: 3) Pass energy to the reaction centre

Explanation:

Serve as an antenna of several hundred light-harvesting chlorophyll molecules and a pair of photochemically reactive chlorophyll a (P700 and P680) molecules called the reaction centre. These two chlorophyll molecules form the reaction centre, a vital component where the energy captured from light is converted into chemical energy. This transformation is essential for the process of photosynthesis, allowing plants to convert light energy into a usable form to fuel their growth and metabolism. The reaction centre plays a pivotal role in initiating this energy conversion, facilitating the transfer of electrons and setting off a series of biochemical reactions to sustain life.

Hence, the correct answer is Option (3) Pass energy to the reaction centre.

Also Read:

• MCQs on Photosynthesis

• C4 Pathway

• Difference between Photosystem 1 and 2

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