Coaching Centre
Cells review
A summary of the whole Cells chapter, key words, and a mixed test covering microscopes, cell structure, cell size, specialised cells, respiration, mitosis, levels of organisation and the skin.
Use this page to check the whole chapter. Read the summary, make sure you can explain every key word, then do the test without looking back.
Chapter summary
| Topic | What you need to know |
|---|---|
| 3A Discovering cells | Hooke named cells (cork, 1665); van Leeuwenhoek saw living single cells. Cell theory: all living things are made of cells, the cell is the basic unit of life, all cells come from existing cells. Electron microscopes show far finer detail. |
| 3B Using a microscope | Total magnification = eyepiece × objective. Start at low power; coarse focus only at low power, fine focus only at high power. Wet mounts, iodine and methylene blue. Specimen drawing rules. |
| 3C Inside the cell | Both: membrane, cytoplasm, nucleus, mitochondria. Plants also: cellulose wall, large vacuole, chloroplasts. Bacteria are prokaryotes with no nucleus. |
| 3D Cell size and specialised cells | 1 mm = 1000 µm. Cell size ≈ field of view ÷ number of cells across. Specialised cells' structures suit their jobs. Stem cells are unspecialised. |
| 3E Cellular respiration | Glucose + oxygen → carbon dioxide + water + energy, in mitochondria, in all living cells. Not the same as breathing. Limewater turns milky with carbon dioxide. |
| 3F Cell division and cancer | Mitosis: DNA copied, then shared to make two identical cells, for growth, repair and replacement. Apoptosis removes damaged cells. Cancer is uncontrolled division; tumours are benign or malignant. |
| 3G From cells to systems | Cell → tissue → organ → organ system → organism. Body systems depend on each other. |
| 3H Skin | An organ with three layers: epidermis, dermis, fat. Protects, controls temperature, senses, makes vitamin D. UV damages DNA and causes skin cancer. |
Key words
apoptosis · binary fission · cell membrane · cell theory · cell wall · cellulose · chlorophyll · chloroplast · chromosome · cytoplasm · dermis · DNA · epidermis · eukaryote · field of view · magnification · malignant · melanin · micrometre · mitochondrion · mitosis · multicellular · nucleus · organ · organelle · prokaryote · respiration · specialised cell · stain · stem cell · system · tissue · tumour · unicellular · vacuole
Test yourself
A student uses a ×10 eyepiece and a ×10 objective. The total magnification is
10 × 10 = 100.
Which part would you find in a cheek cell?
Animal cells have mitochondria but no wall, chloroplasts or large vacuole.
Which of these is a prokaryote?
Only bacteria (and their relatives) lack a nucleus.
A cell is 0.04 mm long. In micrometres this is
0.04 × 1000 = 40.
Which cell has no nucleus, leaving more room to carry oxygen?
Mature red blood cells lose their nucleus.
Which equation describes cellular respiration?
The first option is photosynthesis, the reverse.
Mitosis is used for
Mitosis makes new identical cells.
The heart is an example of
It is made of several tissues working together.
A malignant tumour differs from a benign tumour because it
Malignant tumours invade tissues and spread.
Which layer of the skin contains cells that make melanin?
Melanin-making cells sit at the base of the epidermis.
Sort each word into its group.
Label the plant cell.
All living things are made of . The structures inside cells are called . Energy is released from glucose by in the mitochondria. Body cells divide by to make identical cells. A group of similar cells doing the same job is a . One thousandth of a millimetre is a .
A student looks at a cell under a microscope at ×400 and sees a cell wall, a nucleus, a large vacuole and no chloroplasts. Twelve of these cells fit across a field of view of 450 µm.
(a) Identify what type of cell this could be, and justify your answer. (b) Calculate the approximate length of one cell.
(a) It is a plant cell from a part that gets no light, such as a root or onion skin. The cell wall and large vacuole show it is a plant cell, and the lack of chloroplasts means it doesn't photosynthesise. (b) 450 ÷ 12 = 37.5 µm.
Trace the journey of oxygen from the air to a muscle cell in your leg, and explain what the muscle cell does with it. Name the body systems and the organelle involved.
Oxygen is breathed in through the nose and trachea into the lungs (respiratory system). In the lungs it passes into the blood, where red blood cells carry it. The heart pumps the blood through blood vessels to the leg (circulatory system). The oxygen passes through the muscle cell's membrane and into the mitochondria, where it reacts with glucose in cellular respiration. This releases the energy the muscle cell needs to contract, and produces carbon dioxide and water. The carbon dioxide is carried back in the blood to the lungs and breathed out.