121. The function of sieve tube in plants includes transmission of
A. Chemical signals
B. mRNAs
C. electrical signals
D. spheroplasts
1. b. c and d only
2. a, b and c only
3. a and b only
4. a and c only

Correct Answer:

2. a, b, and c only

Explanation:

Sieve tubes are essential components of the phloem tissue in plants, primarily responsible for the transport of nutrients, signaling molecules, and other substances within the plant.

Functions of sieve tubes:

• A. Chemical signals: Sieve tubes are involved in the transmission of various chemical signals that regulate plant growth and responses to environmental stimuli.

• B. mRNAs: Sieve tubes are also responsible for the transport of mRNAs. This allows for communication between different parts of the plant, enabling the regulation of gene expression in distant tissues.

• C. Electrical signals: Sieve tubes transmit electrical signals, which are important for coordinating responses to environmental changes, such as light, gravity, and mechanical stress.

D. Spheroplasts are not transmitted by sieve tubes. Spheroplasts are a form of plant cells with the cell wall partially removed, which are not typically involved in the function of sieve tubes.

Conclusion:

Sieve tubes are crucial for transmitting chemical signals, mRNAs, and electrical signals, but not spheroplasts. Therefore, the correct answer is 2. a, b, and c only.