Cell – The Structure and Functions
ICSE Class 6 · Biology · Chapter 3
What this chapter covers
- Cells: the building blocks of life
- Parts of a cell and their functions
- The plant cell
- The animal cell
- Differences between plant and animal cells
Key definitions
Plastids are small, coloured or colourless bodies found in the cytoplasm of plant cells.
Key points
- The cell is the basic unit of life. All living things are made of one or more cells.
- Most cells can be seen only with a microscope. Robert Hooke first named cells in 1665.
- Unicellular organisms, such as Amoeba and Chlamydomonas, have one cell. Multicellular organisms, such as humans and plants, have many.
- The cell wall gives a plant cell shape, strength and protection.
- The cell membrane surrounds every cell and controls what enters and leaves.
- The cytoplasm is the jelly-like part where the organelles lie and many activities take place.
- The nucleus controls the cell and carries information passed from parents to young.
- The vacuole stores water, food and wastes. Plant cells have one large vacuole that keeps them firm.
- Plastids are found only in plant cells. Chloroplasts are green and help make food.
- A plant cell has a cell wall, plastids and a large vacuole. An animal cell has none of these.
Questions answered
What is a cell?
A cell is the smallest unit of a living thing that can carry out all the activities of life.
Name one unicellular organism and one multicellular organism.
Amoeba is unicellular. A mango tree (or a human) is multicellular.
Which instrument do you need to see most cells?
A microscope.
Which part of the cell controls all its activities?
The nucleus.
Name the green plastids in a leaf cell and give their job.
Chloroplasts. They use sunlight to make food for the plant.
Name two parts found in a plant cell but not in an animal cell.
Any two of: cell wall, plastids, a large central vacuole.
Why does a plant droop when it is not watered?
Its vacuoles lose water and shrink, so the cells become soft and cannot keep the plant firm.
A microscope makes things look 200 times bigger. A cell is 0.02 mm across. How big will it look?
0.02 mm × 200 = 4 mm.