Animal cells and plant cells under the microscope: WASSCE Biology

Every living thing — from the rice plant in your father's farm to your own body — is built from cells. A WASSCE question on this topic usually shows you a labelled diagram of an animal or plant cell and asks you to identify the parts, or to compare the two. This lesson covers what each part looks like under a light microscope, what it does, and how plant and animal cells differ.

Definition

Cell — the basic structural and functional unit of all living organisms.

Organelle — a small structure inside a cell that performs a specific job, like the nucleus, mitochondria, or chloroplasts.

Cell membrane — the thin outer layer that surrounds every cell and controls what enters and leaves it.

Cell wall — a rigid outer layer found only in plant cells, made of cellulose, that gives the cell shape and support.

The animal cell

Under a light microscope, an animal cell appears as an irregular, often rounded shape with no clear outer boundary apart from a thin membrane. The cell membrane forms its outer edge, the cytoplasm fills most of it, and the nucleus sits as a large dark body usually near the centre.

The parts you need to know:

Cell membrane — a thin layer forming the outer boundary. Selectively permeable, meaning it lets some substances pass through and blocks others.
Cytoplasm — fills most of the cell. Looks granular and slightly transparent under the microscope.
Nucleus — a large, darker rounded body, usually near the centre. It controls all the activities of the cell.
Nucleolus — a smaller dark spot inside the nucleus. It is where ribosomes are made.
Mitochondria — small rod-shaped or oval bodies scattered in the cytoplasm. They release energy through respiration.
Ribosomes — tiny dots, often attached to a network of membranes called the endoplasmic reticulum. They build proteins.
Vacuoles — small fluid-filled sacs, usually small and scattered.

A cheek cell is the classic example because students can prepare a slide of their own cheek cells in the school laboratory.

The plant cell

A plant cell looks very different. It is usually rectangular or box-shaped because of the rigid cell wall holding it in place. Inside, a large central vacuole takes up most of the space, pushing the cytoplasm and nucleus to the edges.

The parts you need to know:

Cell wall — a thick outer layer made of cellulose. It is fully permeable, meaning water and dissolved substances pass through freely.
Cell membrane — sits just inside the cell wall. It is selectively permeable, just like in an animal cell.
Cytoplasm — pushed to the edges of the cell because of the large central vacuole.
Nucleus — usually pushed to one side rather than in the middle, but still controls the cell.
Chloroplasts — green, oval-shaped organelles found only in plant cells. They contain chlorophyll and carry out photosynthesis.
Large central vacuole — a single, large fluid-filled sac. The fluid inside is called cell sap, and it gives the cell its turgor pressure (firmness).
Mitochondria and ribosomes — also present, just as in animal cells.

A typical plant cell used in WASSCE diagrams is the cell from a leaf, or the cell from the onion epidermis (which has no chloroplasts because onions grow underground).

Comparing plant and animal cells

The differences are exactly what WAEC tests most often. Learn this table.

Feature	Animal cell	Plant cell
Cell wall	Absent	Present, made of cellulose
Shape	Irregular, often rounded	Regular, usually rectangular
Chloroplasts	Absent	Present in cells exposed to light
Vacuole	Small or absent	One large central vacuole
Position of nucleus	Usually central	Pushed to one side
Storage carbohydrate	Glycogen	Starch

Both types share: cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, and endoplasmic reticulum.

Common mistake

Students often say plant cells do not have a cell membrane because they have a cell wall. They have both. The cell membrane sits just inside the cell wall.

Worked example

Question: A student examined a cell under the microscope and observed the following features — a rigid outer layer, a large vacuole occupying most of the cell, and green structures in the cytoplasm. Identify the type of cell and give one reason for your answer.

Solution: The cell is a plant cell.

Any one of these reasons scores the mark:

The rigid outer layer is the cell wall, which is only found in plant cells.
The large central vacuole is a feature of plant cells, not animal cells.
The green structures are chloroplasts, which contain chlorophyll and are only present in plant cells.

WAEC tests this

Labelling a diagram — given an unlabelled cell diagram, identify the parts. The diagrams above are exactly what you'll see.
Stating the function of a named part — for example, "state the function of the cell membrane". Answer: it controls the movement of substances into and out of the cell.
Differences between plant and animal cells — a near-guaranteed question. The table above is the answer in compact form.
Why a particular cell looks the way it does — for example, "why is the nucleus of a plant cell pushed to one side?" Answer: because the large central vacuole takes up most of the space.

Summary

All cells share: cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes.
Plant cells additionally have: a cell wall, chloroplasts (in cells exposed to light), and one large central vacuole.
Animal cells lack all three plant-specific structures.
The cell wall is rigid and gives plant cells their box-like shape.
The nucleus controls the cell. The cell membrane controls what goes in and out. The mitochondria release energy. The chloroplasts make food in plants.

Animal cells and plant cells under the microscope

The animal cell

The plant cell

Comparing plant and animal cells

Summary

Keep going with cell structure

More lessons in Cell Structure