Biology

Photosynthesis in Plants

1,508 Questions

Photosynthesis is the biological process by which plants convert light energy into chemical energy. This page contains practice questions covering essential topics like chlorophyll, light reactions, and the pathways specific to plants. This material is crucial for medical entrance exams and academic assessments.

Chlorophyll and pigmentsLight reactionsCalvin cycleCAM plantsElectron transportPhotosynthesis factors

Photosynthesis in Plants Questions

Multiple choice bio-chemistry structure and function of cell organelles microbodies living organisms and energy production single membrane bound organelles

Peroxisomes, in plant cells, are involved in

  1. Photooxidation

  2. Photorespiration

  3. Photophosphorylation

  4. Photolysis of water
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Peroxisomes are microbodies which have enzymes for peroxide metabolism. They include :
(a) Peroxide producing oxidative enzymes like peroxidase, urate oxidase or uricase, amino acid oxidase and (b) Peroxide destroying enzymes like catalase.
Peroxisomes occur widely in animals cells, protists, fungi, higher plants but quite common in photosynthetic cells. In mesophyll cells, peroxisomes interact with chloroplasts, and mitochondria to take part in photorespiration.
Multiple choice bio-chemistry structure and function of cell organelles microbodies living organisms and energy production single membrane bound organelles

Which is not true about sphaerosomes?

  1. Involved in photorespiration

  2. Arise from E.R.

  3. Related to fat metbolism

  4. Single membane bound
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sphaerosomes are single membrane bound organelles which takes part in storage and synthesis of fats. They were discovered by Perner (1953). Sphaerosomes are spherical bodies with a diameter of about 0.5-1 mm. They contain granular contents, rich in lipids but also have some proteins. Some proteins are probably enzymatic and take part in the synthesis of fat. But they are not involved in photorespiration.

Multiple choice bio-chemistry structure and function of cell organelles microbodies living organisms and energy production single membrane bound organelles

In which type of reactions related to plant photosynthesis peroxisomes are involved?

  1. Glycolate cycle

  2. Calvin cycle

  3. Bacterial photosynthesis

  4. Glyoxylate cycle
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Glycolate cycle, also known as C$ _2$ cycle, is a complex metabolic pathway, that takes place in chloroplasts, mitochondria and peroxisomes of plant cells and is responsible for the formation of the amino acids, serine and glycine from non-phosphorylated intermediates of the carbon reduction cycle of photosynthesis.

Multiple choice

What are Primary Producers?

  1. Chemically infused kiwi abstract through strawberries

  2. Chemically infused strawberries

  3. Sunshine and rainbows

  4. They receive their energy from the sun in a process called photosynthesis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Primary producers are organisms that produce their own food using energy from sunlight, water, and carbon dioxide. This process is known as photosynthesis, and it forms the base of the food chain.

Multiple choice

During photosynthesis plants take in and release what?

  1. Carbon Dioxide and oxygen

  2. Carbon monoxide and oxygen

  3. Hydrogen and argon

  4. Chlorine and ammonia
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

During photosynthesis, plants take in carbon dioxide and water, and release oxygen as a byproduct. This is the reverse of cellular respiration in many ways.

Multiple choice

The primary site of photosynthesis

  1. Paint

  2. Flower

  3. Potassium Nitrate

  4. Leaves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Leaves are the primary site of photosynthesis in most plants because they contain chlorophyll, the pigment that captures light energy.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, $CO _2$ required for photosynthesis enters the plant body during

  1. Daytime when the stomata are open.

  2. Night when the hydathodes are open.

  3. Daytime through the lenticels.

  4. Nights through the stomata which are kept open.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CAM plants are those plants whose stomata open at night so that they can fix carbon-dioxide in the form of organic acids because these plants are adapted to grow in arid conditions. They accumulate carbon dioxide at night in vacuoles whereas in day time malic acid in transported to chloroplasts where it is again converted into carbon dioxide for photosynthesis. 

Thus, the correct answer is option D. 

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

The carbon dioxide acceptor in CAM plants is

  1. Malic acid

  2. Oxalo-acetic acid

  3. Pyruvic acid

  4. Phosphoenol pyruvic acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Certain plants which have Crassulacean Acid metabolism (CAM) are known as CAM plants. They have scotoactive stomata. These plants fix carbon dioxide during the night but form sugars only during the day when RuBisCO is active. sedum, kalanchoe, pineapple, opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during day time. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, $CO _2$ required for photosynthesis enters the plant during

  1. Daytime when stomata are open

  2. Night when stomata are open

  3. Night when hydathodes are open

  4. Daytime through lenticels
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Certain plants which have Crassulacean Acid Metabolism (CAM) are known as CAM plants. They have scotoactive stomata. $CO _{2}$ required for photosynthesis enters the plant during the night when stomata are open. Then, this carbon dioxide is fixed during the night but form sugars only during the day when RuBisCO is active. Sedum, Kalanchoe, Pineapple, Opuntia are the examples of CAM plants. These plants also perform double carbon dioxide fixation. The carbon dioxide acceptor in CAM plants is Phosphoenol pyruvic acid (PEP) during the night and Ribulose bisphosphate is carbon dioxide acceptor during the daytime. The first stable product in case of CAM plants is Oxalo acetic acid (OAA).

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In CAM plants, photophosphorylation occurs in

  1. Bundle sheath cell, during night

  2. Mesophyll cell, during day time

  3. Mesophyll cell, during night

  4. Bundle sheath cell, during day time
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In CAM plants, photophosphorylation occurs in bundle sheath cell during night. Hence, stomata is open during night in order to fix the carbon dioxide. During night, a four carbon acid is produced when stomata are open. RuBisCo enzyme fixes carbon during the day time during the light reactions. Examples of plants that show CAM photosynthesis are cactus and pineapple.

Thus, the correct answer is 'Bundle sheath cell, during night.'

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

C A M photosynthesis occurs in plants with 

  1. Thin green leaves with reticulate venation

  2. Thin green leaves with parallel venation

  3. Fleshy green leaves

  4. Thin coloured leaves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

CAM (Crassulacean Acid Metabolism) photosynthesis is found in most desert plants, particularly the succulents (plants that store water in thick, fleshy leaves). CAM plants keep their stomata closed during the day to conserve water. At night, the stomata open to allow CO$ _{2}$ to enter. CO$ _{2}$ is incorporated into organic acids which are then stored within the mesophyll cells. During the day, CO$ _{2}$ is released from the organic acids to supply the Calvin Cycle. Thus, CAM photosynthesis occurs in fleshy green leaves and not in thin green leaves with reticulated venation or Thin green leaves with parallel or thin colored leaves. Thus, option C is correct and other options are incorrect.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In sugarcane plant, ${^{14}CO _2}$ is fixed in malic acid, the enzyme that fixes ${C O _2}$ in this reaction is

  1. Ribulose biphosphate carboxylasc

  2. Phosphoenol pyruvic acid carboxylase

  3. Ribulose phosphate kinase

  4. Fructose phosphatase
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phosphoenol pyruvate is formed from the decarboxylation of oxloacetate and hydrolysis of one guanosine triphosphate molecule. This reaction is catalyzed by the enzyme phosphoenolpyruvate carboxylase. This reaction is a rate limiting step in gluconeogenesis.

GTP + Oxaloacetate -----> GDP + Phosphoenolpyruvate + $CO _2$.

Multiple choice botany photosynthesis cam cycle cam plants photosynthetic cycle

In the mesophyll cells of CAM plants, $CO _{2}$ fixation during the day occurs through 

  1. RuBP oxygenase

  2. PEP carboxylase

  3. RuBP carboxylase

  4. Both RuBP carboxylase and PEP carboxylase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

CAM photosynthesis is a carbon fixation pathway present in some plants, such as desert plants. These plants fix carbon dioxide during night, storing it as the four carbon acid malate. The malate is then reduced to a three carbon compound oxaloacetate and the carbon dioxide. This carbon dioxide is released during the day, where it is concentrated around the enzyme RuBP carboxylase and increases the efficiency of photosynthesis. The carboxylating enzyme used during day is RuBP carboxylase and during the night its PEP carboxylase.

Answer is option C.