250+ TOP MCQs on Photosynthesis Basics and Answers

Biology Multiple Choice Questions on “Photosynthesis Basics – 1”.

1. The process in which green plants synthesize organic food by utilizing carbon dioxide and water as raw materials, in the presence of sunlight is called as ______
a) Respiration
b) Food synthesis
c) Photosynthesis
d) Light synthesis
Answer: c
Clarification: The process in which green plants synthesize organic food by utilizing carbon dioxide and water as raw materials, in the presence of sunlight is called Photosynthesis. This is the pure definition. Oxygen is a byproduct which is advantageous for all living organisms.

2. Which is correct regarding photosynthesis?
a) Carbon dioxide is obtained from the atmosphere
b) Water is absorbed from the soil through the stem system
c) Sunlight is trapped by pigments called xanthophyll
d) Chlorophyll absorbs green light
Answer: a
Clarification: The carbon dioxide is obtained from the atmosphere whereas water is absorbed from the soil through the root system. Sunlight is trapped by pigments present in the leaf called chlorophyll and it absorbs violet, blue, and red lights and reflects green light.

3. The half leaf experiment showed that _____ is important for photosynthesis.
a) O2
b) CO2
c) Sunlight
d) Chlorophyll
Answer: b
Clarification: This experiment showed that CO2 is important for photosynthesis. It was experimented by a scientist named Molls. It was named half leaf experiment because half of the leaf was enclosed in a test tube.

4. A compound was used in the half leaf experiment to absorb CO2. This compound is ______
a) KMNO4
b) HCl
c) NaOH
d) KOH
Answer: d
Clarification: KOH was the compound used in half leaf experiment to absorb CO2. The part of the leaf enclosed in test tube contained some KOH soaked cotton while the other half was exposed to air. KOH has got the capability to absorb CO2.

5. Chlorophyll b is the major pigment associated with photosynthesis.
a) True
b) False
Answer: b
Clarification: It is a wrong statement as chlorophyll a is the chief or main pigment associated with photosynthesis. Whereas chlorophyll b, carotenoids, and xanthophyll all are accessory pigments.

6. Which scientist showed that only the green part of the plants will release oxygen?
a) Jan Ingenhousz
b) Joseph Priestly
c) C. Van Neil
d) T. W. Engelmann
Answer: a
Clarification: Jan Ingenhousz showed that sunlight is essential for the plant process as it purifies the fouled air due to pollution or breathing animals. He found out the presence of bubbles in the green part of the plant whereas it was absent during dark. These bubbles were later termed as oxygen.

7. Who found the presence and properties of glucose in green plants?
a) T. W. Engelmann
b) C. Van Neil
c) Julius Von Sachs
d) Jan Ingenhousz
Answer: c
Clarification: Julius Von Sachs found out the production of glucose in plants growth. He also found out that green parts of the plant store glucose and it is usually in the form of starch. Glucose was not stored in plants as it increases the osmotic pressure.

8. The first action spectrum based on photosynthesis was given by ______
a) Jan Ingenhousz
b) Joseph Mathew
c) Cornelius Van Neil
d) T. W. Engelmann
Answer: d
Clarification: T. W. Engelmann discovered the first action spectrum based on photosynthesis. He split light into its spectral components VIBGYOR by using a prism. A green alga i.e. Cladophora was used to detect the sites of O2 evolution.

9. Joseph Priestley did his experiments with which organism?
a) Chlorella
b) Mint plant
c) Green sulfur bacteria
d) Cladophora
Answer: b
Clarification: Joseph Priestly did his experiments with a mint plant. He placed a mint plant in a bell jar containing a mouse and candle. Presence of just a candle or animal in the jar removed the air in it. But due to the presence of the mint plant, the air was restored.

10. Which of the following is the correct equation of photosynthesis?
a) 6CO2 + 12H2O → C6H12O6 + 6H2O + 6O2
b) 12H2O → C6H12O6 + 6H2O + 6O2
c) 6CO2 + 6O2 → C6H12O6 + 12H2O
d) 6CO2 → C6H12O6 + 6H2O + 6O2
Answer: a
Clarification: The correct equation is 6CO2 + 12H2O → C6H12O6 + 6H2O + 6O2. This occurs in the presence of sunlight. Six molecules of CO2 react with twelve molecules of H2O to produce one molecule glucose. The byproducts are six molecules of H2O and O2.

11. The method by which leaf pigments of any green plants can be separated is called as _____
a) condensation
b) centrifugation
c) paper chromatography
d) distillation
Answer: c
Clarification: Paper chromatography is used to remove or separate leaf pigments of any green plants. With the proper mobile and stationary phase, the pigments such as chlorophyll, xanthophyll, etc. can be converged. The remaining methods cannot separate the leaf pigment from the plants as it will only destroy its pigments.

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