Chapter 5: The Fundamental Unit of Life Exercise & In-Text Questions & Answers
1Who discovered cells, and how?
Answer & Reference:
Robert Hooke discovered cells in 1665 by observing cork under a microscope and named the honeycomb-like structures “cells”. (Page 50)
2Why is the cell called the structural and functional unit of life?
Answer & Reference:
All organisms are made of cells (structural), and all life processes occur in cells (functional). (Page 51)
3How do substances like CO₂ and water move in and out of the cell?
Answer & Reference:
CO₂ moves by diffusion; water moves by osmosis through the selectively permeable plasma membrane. (Page 51–52)
4Why is the plasma membrane called a selectively permeable membrane?
Answer & Reference:
It allows only certain substances to pass while blocking others. (Page 51)
5Fill in the gaps: Prokaryotic vs Eukaryotic cells.
Answer & Reference:
Prokaryotic: nucleoid (no nuclear membrane), no membrane-bound organelles.
Eukaryotic: True nucleus, organelles present. (Page 54–55)
6Name two organelles with their own genetic material.
Answer & Reference: Mitochondria and plastids have their own DNA and ribosomes. (Page 57)
7Why are lysosomes known as suicide bags?
Answer & Reference:
When a cell is damaged, lysosomes burst and digest the cell itself. (Page 56)
8Where are proteins synthesised inside the cell?
Answer & Reference:
On ribosomes (attached to RER or free in cytoplasm). (Page 55)
9Compare plant and animal cells.
Answer & Reference:
Plant cells have cell wall, plastids, large vacuole; animal cells do not. (Fig. 5.5 & 5.6, Page 56)
10How is a prokaryotic cell different from a eukaryotic cell?
Answer & Reference:
Prokaryotic: no nucleus, no organelles, smaller.
Eukaryotic: true nucleus, organelles, larger. (Page 54–55)