What is inside a cell, and is a plant cell the same as an animal cell?
Your guess
Pick one before you read on. It is fine to be wrong.
By the end you can
Draw and label the nucleus, cytoplasm, membrane, cell wall and chloroplast
Compare plant and animal cells in a table
In the last chapter you saw cells as boxes and ovals, each with a dark spot. Now look inside one. A cell has parts, like a house has rooms.
We start with an animal cell. People, dogs and birds are made of animal cells. We draw one in three steps.
Draw it first
Draw an animal cell
1 Draw a soft oval. This outline is the cell membrane. It is a thin skin around the cell.
2 Fill the inside with dots. The dots are the cytoplasm. It is a watery jelly where the cell does its work.
3 Draw a round nucleus inside, with a dark spot. The nucleus is the part that controls the cell.
Almost every plant and animal cell has a membrane, cytoplasm and a nucleus. A plant cell has more.
A plant cell has a stiff cell wall outside the membrane. It has small green parts inside, and each one is a chloroplast. It has a large vacuole, which is a bag of watery liquid.
A plant cell. The wall is the hatched band, drawn outside the membrane.
Look at the order from the outside. First comes the cell wall. Next comes the membrane. Then the cytoplasm fills the inside, with the vacuole, the nucleus and the chloroplasts in it.
The two kinds of cell, side by side.
See it three ways
With things
Imagine an animal cell. Now add a stiff box round it, add a large bag of water, and add little green parts. You have a plant cell.
As a picture
In words
Both kinds of cell have a nucleus, cytoplasm and a membrane. Of these two kinds, only the plant cell has a cell wall and chloroplasts. An animal cell never has them. A plant cell has a much larger vacuole.
The table says "some" for chloroplasts. Not every plant cell has them. Look at a leaf cell and a root cell.
A leaf cell has chloroplasts. A root cell does not.
Try it
Build a model cell
You need: a small cardboard box, a clear plastic bag, water, a dry bean or a pebble.
Be safe: Plastic bags can stop a small child from breathing. Keep them away from young children and from your face. Do not eat the bean.
Put the bean in the plastic bag. Add a little water, enough to cover it. Tie the bag shut.
Hold the bag in your hands. It is floppy, like an animal cell.
Now put the bag in the box and shut the lid. The bag keeps its shape, like a plant cell.
Match each part of the model with a part of a cell.
What you will see: The bag alone is floppy. The bag in the box keeps its shape. The stiff box does the job of a cell wall.
If you cannot try it, this is what happens.
A wrong idea many people have
Every plant cell has chloroplasts.
Why it feels right: Plants are green, so it seems that all their cells are green.
The test that breaks it: Look at a root pulled from the soil. It is pale, not green. Root cells have no chloroplasts, and the root is still part of a plant.
What is true: Only cells in green parts of a plant, such as leaves, have chloroplasts.
Key words
cell membrane
the thin skin around a cell.
cytoplasm
the watery jelly inside a cell, where it does its work.
nucleus
the round part that controls the cell.
cell wall
a stiff layer outside the membrane of a plant cell.
chloroplast
a small part in green plant cells.
vacuole
a bag of watery liquid in a cell.
Back to your guess
The answer is A: A cell has parts inside, and a plant cell has some parts that an animal cell does not.
A cell has parts, each with a job. A plant cell has three extra things: a cell wall, a large vacuole and, in green parts, chloroplasts.
Check yourself
Try each one before you look. A wrong answer tells you where to go next.
Which part is in a plant cell but not in an animal cell?
See the answer
The cell wall
An animal cell has only a thin membrane round it. A plant cell has a stiff cell wall outside its membrane.
If you chose B: Plant cells and animal cells both have a nucleus. So it is not the part that only plants have. Go to S3.1.3.
If you chose C: Both kinds of cell are filled with cytoplasm. Look for the part that is only in plants. Go to S3.1.3.
What is the thin skin round every cell called?
See the answer
The cell membrane
Every cell, plant or animal, has a cell membrane round it.
If you chose A: An animal cell has no wall. Every cell has a membrane, and it is the thin skin round the cell. Go to S3.1.3.
If you chose C: The nucleus is the round part inside the cell, not the skin around it. Go to S3.1.3.
Which list goes from the outside of a plant cell inward?
See the answer
Cell wall, cell membrane, cytoplasm
The stiff wall is outermost. The thin membrane is just inside it, and the cytoplasm fills the inside.
If you chose B: You have the wall and membrane the wrong way round. The wall is the outer layer. Go to S3.1.3.
If you chose C: That list goes from the inside to the outside. Start at the edge of the cell. Go to S3.1.3.
Which plant cell has no chloroplasts?
See the answer
A cell from a root
A root grows in the dark soil. Its cells have no chloroplasts.
If you chose B: Leaf cells have many chloroplasts. They are in the green part of the plant. Go to S3.1.3.
If you chose C: That is a common mistake. Plants are green, so it feels right, but roots are not green and have none. Go to S3.1.3.
In the model cell, the bean stands for which part?
See the answer
The nucleus
The bean is a round thing inside the water, like the nucleus inside the cytoplasm.
If you chose A: The water, not the bean, is the cytoplasm. The bean is the round part inside it. Go to S3.1.3.
If you chose B: The stiff box is the wall. The bean sits deep inside. Go to S3.1.3.
From an earlier chapter
Which part of a microscope do you look through?
See the answer
The eyepiece
You put your eye to the eyepiece. The objective lens is near the slide.
If you chose A: The objective lens is near the slide. Your eye is at the other end of the tube. Go to S3.1.2.
If you chose C: The stage is the flat shelf that holds the slide. It is not a lens. Go to S3.1.2.
Keep it
Copy this into your exercise book.
Plant and animal cells have a membrane, cytoplasm and, nearly always, a nucleus. A plant cell also has a cell wall, a large vacuole and, in green parts, chloroplasts.
Draw: Draw an animal cell and a plant cell next to each other. Label every part.
