CBSE Questions for Class 11 Medical Biology Cell The Unit Of Life Quiz 4 - MCQExams.com

• Prokaryotes lack a true nucleus with a well-defined nuclear membrane and other membrane-bound organelles.
•  They have a simple structural organization. They are unicellular and division of labour is absent.

Cell membrane or plasma membrane is the outer covering of all the cell but in plant cells, it is present below the cell wall. It is mainly composed of phospholipid bilayer structure with embedded proteins which gives the mosaic-like appearance. The membrane proteins help in transportation of water, ions and solute molecules and the plasma membrane is semi-permeable. In plant cells, plasma membrane contains chitin. The transportation of water and molecule soluble in organic solvent occurs through the membrane. These statements explained about the movement of molecule and not the structure of cell membrane.

Therefore, the correct answer is option E.

$$\textbf{Correct option: D}$$

$$\textbf{Solution:}$$

Option A:

$$\bullet$$ Nucleus has genetic material enclosed in the nuclear membrane and it cannot exist without cytoplasm.

Option B:

$$\bullet$$ Cytoplasm is the semi-liquid part of the cell that holds the nucleus and the cellular organelles like mitochondria, endoplasmic reticulum, ribosomes, etc.

$$\bullet$$ Cytoplasm can exist without a nucleus. For example, Erythrocytes (Red Blood Cells) and Thrombocytes (Platelets).

Option C:

$$\bullet$$ The synthesis of organellar proteins by translation of nuclear messages on cytoplasmic ribosomes are referred to as nucleocytoplasmic interaction.

$$\bullet$$ Nucleocytoplasmic interactions are very essential for the functioning of a cell.

Option D:

$$\bullet$$ Both statements B and C are correct statements.

Hence the correct option is option D.

Solution

Correct answer is option B.

Explanation for correct option:

• A nucleus is a membrane-bound organelle that contains the cell's chromosomes.
• The nucleus controls and regulates the activities of the cell (e.g., growth and metabolism) and carries the genes, structures that contain the hereditary information.
• Robert Brown, Scottish botanist, discovered the nucleus of a cell in 1831.

• Lysosomes are small vesicles containing hydrolyzing enzymes and surrounded by a single membrane of up to 100 nm thickness. 
• Nucleus and mitochondria are double membranes bound to cell organelles.
• The endoplasmic reticulum is a system of membrane-lined channels found in all eukaryotic cells except mature erythrocytes. It constitutes more than 30 to 60 percent of the total cell membrane. The membrane system of the endoplasmic reticulum is double-membraned and is often connected with the outer membrane of the nuclear envelope.