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Level: JHS, Basic 7  |  Subject: Integrated Science  |  Strand: Diversity of Matter  |  Sub-strand: Living Cells

Curriculum reference: B7.1.2.1 Understand the structure of organisms and the functions of cells.

1. What is a Cell?

• A cell is the smallest unit of life. All living things are made of cells.
• Cells are too small to see with the naked eye. We use a microscope to see them.
• Some organisms have only one cell (unicellular), for example amoeba. Others have many cells (multicellular), for example humans, goats and mango trees.
• Organelles are the small parts inside a cell, each doing a special job.

2. The Animal Cell

Part	Function
Cell membrane	A thin covering that controls what enters and leaves the cell
Cytoplasm	A jelly-like fluid where most cell activities take place
Nucleus	The control centre. It controls all the activities of the cell and carries the hereditary information
Mitochondria	Release energy from food (respiration). Called the powerhouse of the cell
Vacuoles (small)	Store water and food temporarily

3. The Plant Cell

A plant cell has all the parts of an animal cell, plus the following:

Part	Function
Cell wall	A strong outer layer made of cellulose. It gives the cell its fixed shape and protects it
Chloroplasts	Contain chlorophyll (green colour). They trap sunlight to make food by photosynthesis
Large central vacuole	Stores water and cell sap, and keeps the cell firm

4. Differences between Plant and Animal Cells

Feature	Plant cell	Animal cell
Cell wall	Present	Absent
Chloroplasts	Present	Absent
Vacuole	One large vacuole	Small or none
Shape	Fixed, regular	Round or irregular

5. Using a Microscope

• A microscope makes very small objects look bigger so that we can see their parts.
• Put the slide on the stage, look through the eyepiece and turn the focus knob until the image is clear.
• An onion skin placed on a slide is often used to observe plant cells in school.

Remember: The nucleus controls the cell, the mitochondria give energy, the cell wall and chloroplasts are found only in plant cells.

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