Engineering Questions with Answers - Multiple Choice Questions

MCQs on Chloroplast Function – CO2 Fixation and Carbohydrate Synthesis in C4 Plants

1 - Question

Who discovered C4 cycle?
a) Hatch and Slack
b) Kolliker
c) Robert Brown
d) Rudolph Markus

View Answer

Answer: a
Explanation: Hatch and Slack discovered the C4 pathway in the year 1966. It is also called a Hatch – Slack pathway. The pathway produces four carbon sugar molecules.




2 - Question

What is the enzyme used in the conversion of pyruvate to phosphoenolpyruvate?
a) Pyruvate monophosphate dikinase
b) Pyruvate orthophosphate dikinase
c) Pyruvate monophosphate reductase
d) Pyruvate orthophosphate reductase

View Answer

Answer: b
Explanation: This reaction is the first step in the Hatch – Slack pathway. The enzyme pyruvate orthophosphate dikinase is used to convert pyruvate to phosphoenolpyruvate along with ATP.




3 - Question

Which of the following leaf anatomy is a characterization of C4 plants?
a) Piezo anatomy
b) Norman anatomy
c) Kranz anatomy
d) Richard anatomy

View Answer

Answer: c
Explanation: Kranz has the meaning “wreath” in German anatomy. There are two rings surrounding the vascular bundle. The inner ring is made of bundle sheath while the outer ring is made up of mesophyll cells.




4 - Question

Which of the following is an example of C4 plants?
a) Sugarcane
b) Wheat
c) Rice
d) Cactus

View Answer

Answer: a
Explanation: The plants that produce four carbon sugar molecules by taking atmospheric CO2 is known as C4 plants. These plants undergo Hatch – Slack pathway.




5 - Question

What is the final product of the C4 cycle?
a) Aspartate
b) Malate
c) Oxalate
d) Acetate

View Answer

Answer: b
Explanation: Malate is formed as a final product of the C4 pathway. Malate in the final step regenerates the pyruvate and fixes CO2.




6 - Question

Where does the C4 pathway take place?
a) Bundle sheath
b) Xylem
c) Mesophylls
d) Phloem

View Answer

Answer: c
Explanation: The C4 pathway takes place in the mesophyll cells of the plant system. They are dark reaction and does not require light to take place. The Calvin cycle on the other hand takes place on the bundle sheath.




7 - Question

The C4 plants grow in the cold climate places.
a) True
b) False

View Answer

Answer: b
Explanation: C4 plants suppress photorespiration and thus require high light, high temperature and low carbon-dioxide conditions. Thus only a handful of C4 plants are found in cold climates. Most of them are found in temperate regions.




8 - Question

The total carbon dioxide fixation done by the C4 plants is _________
a) 3%
b) 13%
c) 23%
d) 33%

View Answer

Answer: c
Explanation: They are more efficient than C3 plants in the carbon dioxide fixation in the atmosphere. They usually grow in higher temperature regions where the activity of the enzyme RuBisCO is high.




9 - Question

Which enzyme plays the role of a catalyst in CO2 fixation in C4 plants?
a) Carbonic mutase
b) Carbonic reductase
c) Carbonic anhydrase
d) Carbonic dehydrogenase

View Answer

Answer: c
Explanation: Carbonic anhydrase is an enzyme, which plays the role of catalyst in the first CO2 fixation step of C4 pathway. It helps the CO2 molecule to bind to the active site of RuBisCO.




10 - Question

What is the chemical formula for oxaloacetic acid?
a) C4H3O5
b) C4H4O5
c) C4H4O6
d) C3H4O5

View Answer

Answer: b
Explanation: The oxaloacetic acid is formed when phosphoenolpyruvate reacts with CO2. This is the first product of the pathway which is a four carbon compound.




11 - Question

. C4 pathway uses 5 ATP molecules and 4 NADPH molecules as the energy source.
a) True
b) False

View Answer

Answer: b
Explanation: The C4 pathway uses 5 ATP and 2 NADPH molecules as its energy source. This is higher than the energy requirement in Calvin cycle but C4 can be effective under hot and less water content.

Get weekly updates about new MCQs and other posts by joining 18000+ community of active learners