Correct option is B
Explanation:
Let's go over each statement about axonal transport:
A. Orthograde transport occurs from the axonal terminal to the cell body.
This statement is incorrect.
Orthograde transport actually refers to the movement of materials from the cell body to the axonal terminal. The retrograde transport occurs from the axon terminal to the cell body. So, this statement is false.
B. Orthograde transport has two components – fast axonal transport and slow axonal transport.
This statement is correct.
Orthograde transport indeed has two components:
Fast axonal transport (moves membrane-bound organelles and vesicles).
Slow axonal transport (moves proteins, enzymes, and other components).Therefore, B is true.
C. The rate of orthograde fast axonal transport is higher than that of retrograde transport.
This statement is correct.
Orthograde fast axonal transport is generally faster than retrograde transport. Fast axonal transport moves materials from the cell body to the axon terminal at a higher rate than retrograde transport, which brings materials from the axon terminal back to the cell body. Hence, C is true.
D. The molecular motor dynein is required for orthograde transport while kinesin is molecular motor for retrograde transport.
This statement is incorrect.
The molecular motor dynein is responsible for retrograde transport, while kinesin is the motor protein responsible for orthograde transport. This statement is incorrectly swapped, so D is false.
Conclusion:
Option B is correct because orthograde transport involves both fast and slow axonal transport.
Option C is correct because the rate of orthograde fast axonal transport is faster than retrograde transport.
Option A and D are incorrect.
