Photosynthesis MCQ Quiz - Objective Question with Answer for Photosynthesis - Download Free PDF

Key Points

Photosynthesis:

• Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy.
• During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

• There are two types of photosynthetic processes: oxygenic photosynthesis and anoxygenic photosynthesis. 
• Oxygenic photosynthesis functions as a counterbalance to respiration by taking in the carbon dioxide produced by all breathing organisms and reintroducing oxygen to the atmosphere.
• Oxygenic photosynthesis is written as follows: 
• 6CO₂ + 12H₂O + Light Energy → C₆H₁₂O₆ + 6O₂ + 6H₂O
• During oxygenic photosynthesis, light energy transfers electrons from water (H2O) to carbon dioxide (CO2), to produce carbohydrates.
• In this transfer, the CO2 is "reduced," or receives electrons, and the water becomes "oxidized," or loses electrons.
• Ultimately, oxygen is produced along with carbohydrates.

Therefore it is clear that Nitrogen does NOT form an essential part of the process of photosynthesis.

The correct answer is Carbon dioxide, oxygen.

Key Points

• During photosynthesis, plants take in carbon dioxide (CO₂) from the atmosphere and use it to produce glucose.
• Plants release oxygen (O₂) as a byproduct of photosynthesis, which is essential for the respiration of most living organisms.
• Chlorophyll in plant cells captures sunlight, which drives the photosynthetic process.
• The overall chemical reaction of photosynthesis can be summarized as 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.

Additional Information

• Photosynthesis Stages
  • Light-dependent reactions: These occur in the thylakoid membranes of chloroplasts where sunlight is converted into chemical energy (ATP and NADPH).
  • Calvin Cycle (Light-independent reactions): These occur in the stroma of chloroplasts where ATP and NADPH are used to convert CO₂ into glucose.
• Importance of Photosynthesis
  • It is the primary source of organic matter for almost all organisms.
  • It is crucial for the oxygen cycle, maintaining atmospheric oxygen levels.
• Factors Affecting Photosynthesis
  • Light Intensity: Higher light intensity increases the rate of photosynthesis to a certain point.Carbon Dioxide Concentration: Increased CO₂ levels can enhance photosynthetic rates.
  • Temperature: Optimal temperatures facilitate enzyme activities involved in photosynthesis.
• Chloroplast Structure
  • Thylakoids: Membrane-bound compartments where light-dependent reactions occur.
  • Stroma: Fluid-filled space where the Calvin cycle takes place.

Concept:

Photosynthesis:

• Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy.
• During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

• There are two types of photosynthetic processes: oxygenic photosynthesis and anoxygenic photosynthesis. 
• Oxygenic photosynthesis functions as a counterbalance to respiration by taking in the carbon dioxide produced by all breathing organisms and reintroducing oxygen to the atmosphere.
• Oxygenic photosynthesis is written as follows: 

6CO₂ + 12H₂O + Light Energy → C₆H₁₂O₆ + 6O₂ + 6H₂

Explanation:

• Roots, the underground part of the plants, absorbs air from the air gaps/spaces found between the soil particles.
• Hence, absorbed oxygen through roots is utilized to liberate the energy that in the future, is used to transport salts and minerals from the soil.
• Photosynthesis takes place in only those parts of the plants which have chlorophyll, the green plant parts. Photosynthesis is so evident that at times it seems to mask the respiratory process in plants.
• Respiration must not be mistaken for photosynthesis. Respiration occurs all through the day, but the photosynthesis process occurs in the daytime, in the presence of sunlight only.
• Consequently, respiration becomes evident at night time in plants.

Important Points Respiration:

• Respiration is a chemical reaction, which occurs inside cells to release energy from the food.
• Transport of gases takes place.
• The food that is ingested through the process of digestion is broken down to release energy.
• This energy is utilized by the body to produce water and carbon dioxide as by-products.
• Respiration takes by all living organisms and is vital for survival.
• However, it is not an important process that maintains the balance of oxygen and carbon dioxide in the atmosphere.

The correct answer is autotrophic nutrition.Key Points

• Autotrophic nutrition is the mode of nutrition in which organisms make their food themselves from simple substances.
• The process of autotrophic nutrition involves the use of light energy (in photosynthesis) or chemical energy (in chemosynthesis) to produce organic compounds.
• Autotrophs are organisms that carry out autotrophic nutrition, such as plants, algae, and some bacteria.

Additional Information

• Heterotrophic nutrition is the mode of nutrition in which organisms obtain their food by consuming other organisms or organic matter.
• Saprotrophic nutrition is a type of heterotrophic nutrition in which organisms obtain their food by decomposing dead organic matter.
• Phototrophic nutrition is a subcategory of autotrophic nutrition, in which organisms use light energy to produce their own food.

The correct answer is Photosynthesis.

Key Points

• Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy, specifically glucose.
• During photosynthesis, carbon dioxide from the atmosphere is absorbed by plants and used to produce sugars.
• The process occurs in the chloroplasts of plant cells, where the pigment chlorophyll captures light energy.
• Photosynthesis can be summarized by the equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
• This process is essential for the carbon cycle as it helps in the fixation of atmospheric carbon into organic molecules.

Additional Information

• Combustion
  • Combustion is the process of burning organic material in the presence of oxygen, which releases carbon dioxide and water vapor.
  • It is a significant source of carbon dioxide emissions into the atmosphere.
• Respiration
  • Respiration is the process by which organisms convert glucose and oxygen into energy, producing carbon dioxide and water as byproducts.
  • It occurs in the mitochondria of eukaryotic cells.
• Transpiration
  • Transpiration is the process by which water vapor is released from plants into the atmosphere through small openings called stomata.
  • It plays a crucial role in the water cycle but is not directly involved in the carbon cycle.

The correct answer is leaves

Explanation:

Photosynthesis - Food-Making Process in Plants - 

• In plants, leaves are the food factories.
• Hence, all the raw materials, like water and minerals, carbon dioxide must reach leaves.
• Chlorophyll, the green pigment present in leaves helps to capture the energy of the sunlight to synthesize (prepare) food from carbon dioxide and water.
• The process is called photosynthesis because the synthesis of food occurs in the presence of sunlight. 

Additional Information

Sweet Potato stored food in their root.

But make their food at leaves.

The correct answer is Mitochondria.

Explanation:

• Mitochondria is a double membrane organelle.
• It is semi-autonomous and can control some of its functioning.
• Its number varies in plant and animal cells.
• Plants have chloroplast, nucleus, mitochondria, and ribosomes.
• Mitochondria in the energy production unit in the plant cell.
• Here, the ATP synthesis takes place.
• The glucose produced by photosynthesis is broken down to produce energy in the form of ATP in the mitochondria.
• The proton gradient that is generated during the electron transport results in the formation of ATP.
• This process is equivalent to the respiratory system and is called as cellular respiration.

​Hence, mitochondria produce energy in plant cells using the respiratory system.

Confusion Points

• Chloroplast helps in Photosynthesis and the formation of Glucose, with the help of Light Energy.
• Mitochondria on the other hand help in cellular respiration which breaks down sugar into ATP inside plant cells.

Additional Information

The correct answer is chemical.

Photosynthesis in plants converts light energy to chemical energy.

Key Points

• Photosynthesis is the process by which green plants produce carbohydrates by absorbing carbon dioxide, water, and sunlight in the presence of chloroplast and liberate chemical energy.
• Sunlight is the main source of energy for Photosynthesis.​
• Only 1% of total sunlight falls on earth trapped by green plants.

​Important Points

• The gas which is taken in by the plants during photosynthesis - Carbon dioxide
• The gas which is given out  by the plants during photosynthesis - Oxygen
• The rate of photosynthesis is maximum - Red light
• The rate of photosynthesis is minimum - Green light
• The pigment in chloroplasts which gives green colour to the plants - Chlorophyll
• The only metal present in chlorophyll - Magnesium
• The pigment which gives a purple and blue colour to the flower of plants - Anthocyanin
• The pigment  which gives the yellow colour to the leaves, fruits, and flowers - Xanthophyll

The correct answer is Oxygen.

Concept:

Photosynthesis: 

• The leaves have a green pigment called chlorophyll.
• It helps leaves to capture the energy of the sunlight.
• This energy is used to synthesise (prepare) food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis.

In the presence of sunlight Carbon dioxide + water → Glucose + oxygen.

• Some plants, green algae, and cyanobacteria can perform photosynthesis.
• The process of photosynthesis is commonly written as

                   6CO2 + 6H2O + Sun-Light → C6H12O6 + 6O2

Key Points

• Plants prepare their food by the process called photosynthesis. 
• During photosynthesis, plants trap solar energy or light energy with the help of chloroplast present in the green leaves and convert it into chemical energy
• A pigment called chlorophyll is present in the chloroplasts which are required in trapping sunlight
• Plants utilize carbon dioxide and water for the synthesis of carbohydrates during photosynthesis, oxygen is liberated as a side product
• This gaseous exchange occurs through the stomata present on the leaf surface

Important Points

• The following events occur in plant cells during photosynthesis.
  • Absorption of light energy.
  • Conversion of light energy into chemical energy.
  • Storage of chemical energy in sugars. 

• Oxygen is liberated during Photosynthesis.
• Photosynthesis is the process through which green plants manufacture food by converting solar energy into chemical energy.
• In this process, water and carbon dioxide react in the presence of sunlight to give off oxygen and form glucose molecules.

• Photolysis of water is the source of oxygen liberated in photosynthesis.

Explanation:

Photosynthesis is the process through which plants utilize sunlight to make food and it takes place inside the green part (chloroplasts) of the plant.

• The correct equation to represent the overall process of photosynthesis is given as:

6CO₂ + 12H₂O \(\mathop \to \limits^{Light}\) C₆ H₁₂ O₆ + 6H₂O + 6O₂

Where C₆ H₁₂ O₆ represents glucose. H₂O represents water.O₂ represents Oxygen.

• Photosynthesis takes place in the green leaves of plants, and it is the process through which green leafy plants synthesize their food.

Mistake PointsIn general, the equation wrote as -

6CO2 + 12H2O \(\mathop \to \limits^{Light}\) C6 H12 O6 + 6H2O

But the water produced is vaporized.

The correct answer is Stomata.

Key Points

Concept:

Photosynthesis: 

• It is the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water.
• In this process, plants use chlorophyll, carbon dioxide, water, sunlight, and release oxygen.
• Sunlight Is absorbed by this chlorophyll. 
• Stomata are tiny holes present in the epidermis of leaves. It is responsible for the intake of Carbon dioxide gas in plants.

So, Carbon di Oxide is taken in through Stomata.

Stomata:

• Each stoma remains surrounded by two kidneys or bean-shaped epidermal cells the guard cells.
• The stomata may occur on any part of a plant except the roots.
• The epidermal cells bordering the guard cells are called accessory cells or subsidiary cells.
• The number and types of stomata vary in different plant species based on their Habitat.

Additional Information

 Root hairs: The long tubular-shaped outgrowths from root epidermal cells are termed root hairs. it is responsible for getting nutrients and microbe interactions.

Leaf veins: It is used for the transportation of plants and sugar in leaves. 

Petals: Petals are the reproductive part of the flower of a plant used to attract bees and other insects towards the plant. ​

The correct answer is Carbon dioxide.

Key Points

• Photosynthesis is the physiochemical process, in which carbohydrates (organic compounds) are formed from inorganic substrates like H₂O & CO₂  in the presence of light and pigments.
• O₂ is evolved as a by-product during photosynthesis.
• The oxygen molecule present in glucose is derived from carbon dioxide during Calvin cycle of photosynthesis.
• The CO₂ molecule is first added to 3-phosphoglycerate during the carboxylation reaction of Calvin cycle, and is later used to form glucose.
• While molecular oxygen that is liberated during photosynthesis is produced from photolysis of water during the light reaction.

Additional Information

• Photosynthesis can be simply divided into 4 major processes

1. Absorption of light energy by Chlorophyll pigment.
2. Conversion of light energy into chemical energy.
3. Splitting of water or Photolysis during Non-cyclic photophosphorylation.

 H₂O → 2H⁺ +  2e^-- +  O₂ ↑

The oxygen that evolved during this process comes from water.

4. Reduction of CO₂ to carbohydrates (Glucose) during Dark reaction.

​The CO2 undergoes reduction and its O2 is utilized in the formation of Glucose.

Mistake Points

The O₂ released during photolysis is the evolved O₂, whereas the O₂ released during the reduction of CO₂ is the O₂ in glucose.

The correct answer is a half.

Key Points

• Algae photosynthesis accounts for at least half of all carbon dioxide fixing on the planet.
• They enhance the amount of dissolved oxygen in their immediate environment because they are photosynthetic.
• The conversion of inorganic carbon to organic carbon by living organisms is known as carbon dioxide fixation.

Important Points

• Biological carbon fixation, also known as carbon assimilation, is the process by which living organisms transform inorganic carbon (most commonly in the form of carbon dioxide) into organic compounds.
• After that, the compounds are employed to store energy and provide structure for other biomolecules.
• Carbon is typically fixed through photosynthesis, however, in the absence of sunshine, some organisms use a process called chemosynthesis.
• Photosynthesis is the process through which plants produce oxygen and energy in the form of sugar from sunlight, water, and carbon dioxide.
• Plants, algae, and some bacteria are involved in the process, which gathers energy from the sun to produce oxygen (O2) and chemical energy stored in glucose (a sugar). Herbivores get their energy from plants, while predators get theirs from herbivores.

The correct answer is Carotenoid.

Key Points

• Carotenoids are a class of more than 750 naturally occurring pigments synthesized by plants, algae, and photosynthetic bacteria.
• These richly coloured molecules are the sources of the yellow, orange, and red colours of many plants.
• Fruit and vegetables provide most of the 40 to 50 carotenoids found in the human diet.
• Carotenoids are beneficial antioxidants that can protect you from disease and enhance your immune system.
• Provitamin A carotenoids can be converted into vitamin A, which is essential for growth, immune system function, and eye health.

Additional Information

• The folds in the inner membrane of a mitochondrion are called cristae.
• An amyloplast is an organelle found in plant cells. Amyloplasts are plastids that produce and store starch within internal membrane compartments.
• Vacuoles are membrane-bound organelles that can be appearing in both animals and plants. In a way, they're specialized lysosomes. That is to say that their function is really to handle waste products, and by the handle, they mean take in waste products and also get rid of waste products.