Biology: Cells
1 SPEAKING Work with a partner. Which statements do you think are true?
1 All plants and animals are made of cells.
2 Plant cells and animal cells are the same.
3 It is impossible for a human to see a single cell.
2 Read the text about cells. Match the paragraph headings with the correct paragraphs. Were your answers to Exercise 1 correct?
Paragraph A
You are made of cells. The tomato in your lunch box is made of cells. In fact, all living things are made of cells and only cells. Cells are so small, it is almost impossible to say how many there are in an average person, but scientists think it’s around 30 trillion – that’s 30,000,000,000,000! Cells are different sizes. For instance, red blood cells make up over 80% of the number of cells in our bodies, but only take up around 4% of the space. Fat cells are much bigger. However, you need a microscope to see almost all cells.
Paragraph B
Cells have several different parts:
The cell membrane surrounds the cell. It lets food come in and waste go out.
The nucleus contains DNA, a molecule that carries genetic information. In other words, it controls the way a living thing grows, functions and .
Cytoplasm is a bit like jelly. Chemical reactions happen there.
Mitochondria are the parts that produce energy from food. This important process is called .
Paragraph C
The shape of animal cells is usually irregular, whereas plant cells are normally regular. Plant cells also have some extra parts:
The cell wall is outside the cell membrane and supports the cell.
The vacuole is a space in the cytoplasm for , the liquid in plants and trees.
Chloroplasts are where the process of photosynthesis happens. This is when plants make food with energy from the sun.
Paragraph D
Animal and plant cells of a similar type join together to make . Examples of this are muscle in humans and in plants. An organ is a group of tissues that work together to do a particular job. For example, your heart and lungs are organs, and the leaf of a plant is an organ.
Paragraph E
In the human body, about a million cells die every second. But don’t worry, your body is replacing them all the time! Different types of cell last for different lengths of time. Red blood cells live for around four months, while brain cells usually last for our whole life.
3 Read the text again. Complete the sentences.
4 Drag the names of cell parts onto the picture.
Add Slovenian translations to the names of cell parts.
