Consider statements about cell biology: 1. The cell membrane is selectively permeable. 2. The cell wall is present in animal cells. 3. The nucleus controls cell activities. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 2 and 3 only
D. 1 and 3 only
Answer: Option D
Solution (By JKSSB Mock Tests)
The cell membrane (plasma membrane) is selectively permeable, meaning it allows certain substances to pass through while restricting others, maintaining cellular homeostasis. The nucleus is the control center of the eukaryotic cell, housing the DNA and directing cellular activities like growth, metabolism, and reproduction. The cell wall is a rigid outer layer present in plant cells, fungi, and bacteria, but it is completely absent in animal cells, which only have a flexible cell membrane. Thus, statements 1 and 3 are correct.
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