Lesson T4.1.2

T4.1.2 Chromosomes, genes and DNA Quiz: KS3 Biology, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson T4.1.2, Chromosomes, genes and DNA: 20 multiple choice questions for the KS3 Biology (National Curriculum), Unit 4: Genetics and evolution, written with Revision Ninja.

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The 20 questions

  1. What is a chromosome made of?

    • Cellulose and lignin found in plant cell walls
    • DNA wound around proteins
    • Fats and oils only, found in the cell membrane
    • Glucose and starch stored in the cell

  2. Which structure in a cell contains the chromosomes?

    • The cytoplasm
    • The nucleus
    • The vacuole
    • The cell membrane

  3. How are genes arranged in a chromosome?

    • Genes are scattered randomly in the cytoplasm around the nucleus
    • Genes are in the cell membrane that surrounds the whole cell
    • Genes are stored in the cell wall of plant and fungal cells
    • Genes sit at particular positions along the chromosome

  4. A model of DNA shows two strands twisted together. What is this shape called?

    • A single sphere
    • A double helix
    • A straight rod
    • A flat square

  5. Which two chemical units make up the rungs of the DNA double helix?

    • Sugar molecules only
    • Protein chains only
    • Base pairs
    • Fatty acid chains

  6. Which statement about a gene and a chromosome is correct?

    • A gene carries many chromosomes
    • A chromosome is the same as a gene
    • Genes and chromosomes never meet
    • A chromosome carries many genes

  7. A student models DNA with two strands of beads. What does this model show?

    • The shape of a plant root system underground
    • The structure of a leaf and its many cells
    • The shape of a red blood cell in the circulation
    • The double helix structure of DNA

  8. In humans, what does a pair of chromosomes contain?

    • Two copies of the same gene from the mother only
    • Two copies of each gene, one from each parent
    • Two different organisms
    • Two copies of protein from the father

  9. What is the difference between a gene and an allele?

    • Genes are found only in red blood cells of the body
    • Alleles are found in the cytoplasm only of animal cells
    • Genes are different versions of the same allele in cells
    • Alleles are different versions of the same gene

  10. Which organisms have chromosomes made of DNA?

    • Only animals that move around and hunt for food
    • All organisms with a nucleus
    • Only bacteria that live in soil and water
    • Only plants that make their own food in leaves

  11. Why do cells in one person's body contain the same genes?

    • Each cell receives a different set of genes from its neighbour
    • Each cell makes its own DNA from glucose
    • Each cell is copied from the zygote by cell division
    • Each cell absorbs genes from food

  12. Which feature of DNA allows it to be copied before cell division?

    • Starch stored in the vacuole of plant cells
    • Chlorophyll in the cytoplasm of green plant cells
    • Base pairs that link the two strands
    • Cellulose in the cell wall of plants and fungi

  13. What is a genome?

    • All of an organism's DNA
    • The part of the cell that makes starch
    • The gas exchange surface in a leaf
    • The chemicals that make up a cell membrane

  14. Why is a DNA strand often described as a sequence?

    • The strand is always exactly the same length in every cell type
    • The strand makes oxygen during photosynthesis in the leaves
    • The strand changes colour as it grows inside the cell nucleus
    • The order of bases along the strand carries information

  15. Which structure controls the activities of a cell by carrying genetic information?

    • The nucleus
    • The cell wall
    • The vacuole
    • The cell membrane

  16. What might happen to a gene that is changed in its DNA sequence?

    • The nucleus will be destroyed, so the cell can no longer make proteins
    • The cell will need more water to survive, but the gene itself is unchanged
    • The gene will always be repaired so the characteristic never changes
    • The protein it codes for may change, altering a characteristic

  17. Why did the discovery of DNA's structure matter for biology?

    • It explained how genetic information is copied and inherited
    • It explained why cells need oxygen to release energy from their food
    • It proved that plants make their own cell walls from cellulose fibres
    • It showed that cells do not need a nucleus to store their genetic information

  18. What is a DNA molecule made of?

    • Lipid bilayers with no nucleotides or base pairs
    • Amino acids only, folded into a three-dimensional shape
    • Two strands of nucleotides joined by base pairs
    • Glucose molecules joined in long chains with branches

  19. Why is the nucleus important for the control of cell activity?

    • It contains the DNA that directs the making of proteins
    • It produces the energy needed for photosynthesis
    • It stores water for the cell
    • It digests food taken into the cell

  20. What type of molecule do genes code for when they are expressed?

    • Starch
    • Proteins
    • Cellulose
    • Glucose

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