Question

Which of the following is an incorrect statement ?

• A. Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles.
• B. Microbodies are present both in plant and animal cells.
• C. The perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm.
• D. Nuclear pores act as passages for proteins and RNA molecules in both directions between nucleus and cytoplasm.

Answer 1

The Correct Option is A

The question asks which of the given statements is incorrect regarding cellular structures. Let's analyze each statement:

1. Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles.

   This statement is incorrect. Mature sieve tube elements, which are part of phloem tissue in plants, lose their nucleus and most organelles to facilitate efficient transport of nutrients. The absence of these structures reduces cellular resistance, allowing for smooth flow of sap through the tube elements.

2. Microbodies are present both in plant and animal cells.

   This statement is correct. Microbodies such as peroxisomes are found in both plant and animal cells. They play a role in various metabolic processes, including the breakdown of fatty acids and detoxification of hydrogen peroxide.

3. The perinuclear space forms a barrier between the materials present inside the nucleus and that of the cytoplasm.

   This statement is partially misleading but not outright incorrect. The perinuclear space is the space between the inner and outer nuclear membranes, which are continuous with the endoplasmic reticulum. While it doesn't directly form the primary barrier, it is part of the structural barrier consisting of the nuclear envelope that separates nuclear content from the cytoplasm.

4. Nuclear pores act as passages for proteins and RNA molecules in both directions between nucleus and cytoplasm.

   This statement is correct. Nuclear pores play a crucial role in the regulation of the passage of macromolecules such as RNA and proteins between the nucleus and the cytoplasm, allowing for controlled communication and transport essential for cellular function.

Thus, the incorrect statement is: "Mature sieve tube elements possess a conspicuous nucleus and usual cytoplasmic organelles."