Asexual reproduction — one parent, identical offspring
The Core definition has two elements and both score: a process resulting in the production of genetically identical offspring from one parent. The mechanism is mitosis, which copies the parent's DNA exactly, so no new combination of alleles is created and no gametes or nuclei fuse. "Reproduction without a mate" describes what is missing rather than defining the process, and earns little.
Binary fission, budding, vegetative propagation, spores
Binary fission — one bacterial cell divides into two identical daughter cells. Budding — an outgrowth on yeast or Hydra grows and separates. Vegetative propagation — a new plant grows from a part of the parent (runner, tuber, bulb), never from a seed. Spore formation — a fungus releases many spores, each a clone. Core statement 2 only asks you to identify these from diagrams, images or written information.
Supplement: the trade-off in a wild population
Advantages — numbers rise fast with no mate to find, every individual can reproduce so one survivor can found a population, and in a stable habitat offspring are automatically well-suited because the parent already survived there. Disadvantages — no genetic variation, so a new disease, predator or climate shift threatens every individual at once, and identical offspring compete for identical resources. Speed and reliability are traded for adaptability.
Drawn from real examiner reports.
Defining it by what is absent
Answers describe what is absent — "it doesn't need a mate", "no fertilisation" — instead of the two positive elements the mark scheme rewards: one parent, and offspring genetically identical to it. A related slip is writing "cell division" without naming mitosis or stating the identical-offspring outcome. Build every answer around those two ideas.
Grounding (digest B16, the same "genetically identical by mitosis" idea): mitosis and meiosis statements are frequently swapped, or one point restated three ways instead of stating the distinguishing point · Jun 2022 P41 Q4b, P42 Q1c · Jun 2023 P43 Q7iii
Double at each division, never add
Binary fission turns one cell into two, so from a single cell the population after n divisions is 2 raised to the power n — the total doubles, it never grows by a fixed amount. Candidates who add reach 8 x 2 = 16 for eight divisions instead of 256. If unsure, step it out: 1, 2, 4, 8, 16, 32, 64, 128, 256. That compounding is why asexual reproduction is fast.
Jun 2023 P32 Q1d — bacterial binary fission, where the required route was 2 to the power 8 = 256
One-sided "discuss" answers
"Discuss" demands both sides. A 6-mark question needs roughly balanced coverage, so a detailed list of advantages alone cannot reach the tariff. The second half of the error is leaving points generic: "genetic variation is good" earns little unless it is tied to the survival of a population in the wild — name the consequence for that population.
Grounding (digest cross-cutting exam technique, all sittings and all sciences): "not matching the number of points to the mark tariff"
Sexual reproduction mislabelled asexual
Seeing only one organism in a diagram does not make the process asexual. One flower that is pollinated and fertilised makes a seed sexually, because two gamete nuclei fuse; examiners also report ordinary animal reproduction being called asexual. The test is always whether gametes fused, not how many individuals appear in the image.
Jun 2022 P43 Q10b · Jun 2023 P32 Q7ciii — chicken reproduction described as asexual when it is sexual
A seed is not a tuber or a bulb
Vegetative propagation uses a part of the parent plant — a runner, tuber or bulb — and is asexual. A seed forms only after pollination and fertilisation, so germination is the growth of a sexually produced embryo, not vegetative propagation. Tubers and bulbs are swollen parent tissue; a seed never is.
Looking similar is not proof
"Genetically identical" is a claim about DNA copied exactly by mitosis, not about appearance. Offspring produced sexually often resemble a parent closely, for instance by inheriting a dominant characteristic. Resemblance is therefore never evidence of asexual reproduction — look instead for one parent and no fusion of gametes.
Point, then mechanism, then effect
Build every "discuss" point as a three-link chain: the point ("rapid population increase"), the mechanism ("one parent only, so no time spent finding a mate"), then the effect on the wild population ("a new habitat is colonised quickly"). Three links, every point.
Plan two columns, then match the tariff
Sketch advantages and disadvantages as two lists before writing a sentence, then match the number of points to the marks — roughly three each for a 6-mark "discuss", or fewer points developed more fully. Never spend a whole answer on one side.
Name the threat, not just "no variation"
For disadvantages, state a specific risk: no variation means no individual is likely to be resistant or tolerant when a named disease, pest, predator or climate change arrives, so the whole population is affected together. Close with one weighing sentence if space allows.
Cambridge 0654 spec reference: Section B15 "Reproduction", sub-topic B15.1 (Core statements 1-2; Supplement statement 3). This leaf covers the definition of asexual reproduction, recognising examples of it, and (Extended) discussing its advantages and disadvantages to a wild population.
Out of scope for B15.1 (do not use here): sexual reproduction/fertilisation detail (B15.2), flower structure and pollination (B15.3), human reproductive anatomy and hormones (B15.4/B15.5), the mechanism of mitosis vs meiosis and chromosome numbers (B16), and the detailed mechanism of natural selection (B17).
| Term | Mark-scheme-precise definition |
|---|---|
| Asexual reproduction | A process resulting in the production of genetically identical offspring from one parent |
| Binary fission | A single (bacterial) cell divides to form two genetically identical daughter cells |
| Budding | A new individual develops as a small outgrowth on the parent's body and then separates, genetically identical to the parent |
| Vegetative propagation | A new plant develops from a part of the parent plant (e.g. a runner, tuber or bulb), not from a fertilised seed |
| Spore formation | The parent produces many small spores, each capable of growing into a new, genetically identical individual |
The one idea that unlocks the topic: every example — binary fission, budding, vegetative propagation, spore formation — shares the same two features: only one parent, and offspring that are genetically identical to that parent (a "clone"). This happens because the parent's cells divide by mitosis, which copies the deoxyribonucleic acid (DNA) exactly, rather than by the fusion of two gametes.
Define asexual reproduction.
(a) Define asexual reproduction. (2 marks)
(b) Name the type of cell division that produces genetically identical offspring during asexual reproduction. (1 mark)
