Lesson T1.1.5

T1.1.5 Unicellular organisms and their adaptations Quiz: KS3 Biology, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T1.1.5, Unicellular organisms and their adaptations: 20 multiple choice questions for the KS3 Biology (National Curriculum), Unit 1: Structure and function of living organisms, written with Revision Ninja.

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The 20 questions

  1. What does unicellular mean?

    • Made of organs only
    • Made of a single cell
    • Made of many cells in layers
    • Made of tissues only

  2. How does an amoeba take in its food?

    • It sucks food in through a long tube that connects to its interior
    • It surrounds the food with extensions of its cytoplasm
    • It absorbs food through a rigid cell wall around its outside surface
    • It uses cilia to sweep food into a fixed mouth on its outer surface

  3. Which structures does a paramecium use to move through water?

    • A long whip-like flagellum
    • Hair-like cilia
    • Pseudopodia that flow outward
    • A cell wall that contracts

  4. Euglena has a flagellum and chloroplasts. Which is the best description of it?

    • It has no nucleus and cannot move
    • It can only absorb food and cannot move
    • It can move and make food by photosynthesis
    • It has a cell wall and cannot photosynthesise

  5. Yeast is used to make bread rise. Which gas causes the dough to rise?

    • Carbon dioxide
    • Oxygen, which is released as the yeast cells photosynthesise in the dough
    • Nitrogen, which is released when the yeast cells break down the flour
    • Hydrogen, which is released as the yeast cells break down the sugar

  6. What is produced when yeast respires anaerobically in dough?

    • Lactic acid and oxygen, which are released as the yeast cells break down sugar
    • Starch and glucose, which are stored in the yeast cells for later use
    • Alcohol and carbon dioxide
    • Oxygen and water, which are released as the yeast cells break down glucose

  7. Why does a large surface area compared with volume help a single-celled organism?

    • It makes it heavier so it stays in place on the bottom of the pond
    • It lets it grow many tissues that work together to support the body
    • It lets food and gases pass in and out quickly
    • It stops it losing any water to the surrounding pond water by evaporation

  8. Why can unicellular organisms survive without organs?

    • They have no need for energy because they live in still and calm water
    • They rely on the organs of other organisms that live close by in the pond
    • They use tissues outside the cell to carry out their life processes
    • All their life processes happen within one cell

  9. A single-celled organism with a cell wall and chloroplasts is most likely to be

    • A plant-like single-celled alga
    • An animal-like protozoan that has no cell wall and no chloroplasts at all
    • A paramecium with cilia that beat to swim through the water in the pond
    • An amoeba with no cell wall that moves by flowing its cytoplasm outwards

  10. Why does a paramecium need cilia?

    • To make the cell wall stronger so the paramecium does not burst
    • To make food by photosynthesis using light energy from the sun
    • To move towards food and away from danger
    • To store water in a large vacuole when the pond dries up

  11. A unicellular alga floats near the surface of a pond. Why does it have chloroplasts?

    • To digest food outside the cell by releasing enzymes into the water
    • To release energy without oxygen, so it can survive in the dark water
    • To store water for dry days when the pond level drops in the summer
    • To make food from sunlight by photosynthesis

  12. Why are unicellular organisms usually very small?

    • Large cells cannot be made from water, so cells must always stay small
    • Small cells are needed to fit inside organs of larger organisms in the body
    • A small size gives a large surface area compared with volume for exchange
    • Small cells produce more energy than large cells of the same type

  13. Which of these is a unicellular fungus used in baking?

    • Lichen
    • Yeast
    • Mushroom
    • Mould on bread

  14. Compared with aerobic respiration, anaerobic respiration in yeast produces

    • energy without any glucose
    • less energy per glucose molecule
    • the same amount of energy with oxygen
    • more energy per glucose molecule

  15. Which feature distinguishes a bacterial cell from an animal cell?

    • No genetic material at all, so bacteria cannot pass on any information
    • No cell membrane at all, which means bacteria cannot control what enters
    • No nucleus enclosed by a membrane
    • No cytoplasm at all, so bacteria have no space for chemical reactions

  16. An amoeba is about 0.5 mm across. Why can it survive without a heart or lungs?

    • Oxygen and waste can diffuse directly across its cell membrane
    • It uses a cell wall to absorb oxygen from the pond water around it
    • It has lungs inside its cytoplasm that take in oxygen from the water
    • It has a heart pumping blood through tiny tubes that run around its cytoplasm

  17. Which statement correctly compares a single-celled organism with a multicellular animal?

    • Multicellular animals do not need cells because they are made of tissue
    • A multicellular animal has only one cell that carries out all of its life processes
    • A single cell cannot carry out any life processes, so it must rely on others
    • A single cell carries out all life processes, while an animal's cells are specialised

  18. A unicellular protist and a bacterium are both found in pond water. What is a true similarity?

    • Both are multicellular, made of many cells that work together as one body
    • Both are made of tissues that work together to keep the organism alive
    • Both have organs that carry out separate jobs inside the body of the organism
    • Both are single-celled organisms

  19. What is a pseudopodium?

    • A permanent layer of cellulose around the cell that supports the cell wall
    • A temporary extension of the cytoplasm used for movement and feeding
    • A pigment that absorbs light energy and turns it into chemical energy
    • A small pump in the cell membrane that moves particles into the cell

  20. Which term describes an organism that carries out all its life processes inside one cell?

    • A tissue
    • An organ system
    • A multicellular organism
    • A unicellular organism

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