Ch 1 · Asexual Reproduction · IGCSE Biology 0610
Topic 1 of 5 in Reproduction — IGCSE Biology 0610 — 38 lessons.
Introduction
A single bacterium in warm food can become millions within hours; a strawberry plant surrounds itself with copies by the end of summer. Neither needs a partner. This is asexual reproduction, found in every kingdom. The examiner wants the exact definition, recognition of named examples in pictures, and (Extended) a balanced discussion of when copying yourself is a good strategy and when it is a dangerous one.
Key ideas — The definition
Asexual reproduction is a process resulting in the production of genetically identical offspring from one parent.
🧑🏫 Teacher's explanation
Think of asexual reproduction as biological photocopying. When a bacterium divides, it is not mixing two sets of instructions; it is simply duplicating its single set of DNA and splitting it evenly. This is fundamentally different from sexual reproduction, which is like shuffling two decks of cards. Because no shuffling occurs, the offspring are exact genetic copies of the parent, known as clones.
📖 Definitions
🔍 Worked example — Easy
A single bacterium undergoes binary fission. After 3 hours, the population has increased to 8 bacteria. Calculate the time it takes for one division to occur.
🔍 Worked example — Standard
A strawberry plant produces runners that root and grow into new plants. Explain why these new plants are considered clones of the parent, even if they grow in different soil conditions.
🔍 Worked example — Exam-style
A farmer grows potatoes from tubers. One tuber is infected with a virus. Explain why the entire crop produced from this tuber will be infected, and discuss one advantage and one disadvantage of this method of reproduction for the farmer.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(a) Calculate the number of bacteria after 2 hours if the initial population was 100. [2 marks] (b) Explain why a population of bacteria produced by asexual reproduction is more vulnerable to a new antibiotic than a population produced by sexual reproduction. [3 marks] [5 marks]
Key ideas — Examples you must recognise
Bacteria: binary fission. The single circular chromosome is copied, the cell grows, and it divides into two equal daughter cells. In ideal conditions this happens every 20 minutes, which is why bacterial numbers grow so fast.
🧑🏫 Teacher's explanation
Asexual reproduction is like photocopying a document. You start with one original page (the parent) and produce exact duplicates (offspring). Because there is no mixing of genetic material from two parents, every copy is genetically identical to the original. This is the key distinction from sexual reproduction, where two parents contribute half the genes each, creating variation.
📖 Definitions
🔍 Worked example — Easy
Describe the process of binary fission in bacteria.
🔍 Worked example — Standard
Identify the structure in a diagram of a mushroom that produces spores and explain how the spores are dispersed.
🔍 Worked example — Exam-style
Explain why a strawberry plant produces runners and how this benefits the plant in the wild.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
(b) Explain one advantage and one disadvantage of asexual reproduction for a population of bacteria in the wild. (2 marks) [5 marks]
Key ideas — Advantages and disadvantages
A good answer weighs both sides and links each point to genetic identity or the absence of a second parent.
🧑🏫 Teacher's explanation
Think of asexual reproduction as a biological photocopier. When you press the copy button, the machine takes one original document and produces many identical copies. In biology, the 'document' is the DNA. Because there is only one parent, the offspring are genetically identical clones. This is efficient and fast, but it creates a population where everyone looks the same and has the same weaknesses.
📖 Definitions
🔍 Worked example — Easy
A single bacterium undergoes binary fission every 20 minutes. How many bacteria will be present after 2 hours if no bacteria die?
🔍 Worked example — Standard
Explain why a population of dandelions reproducing asexually via runners might be more successful in a stable, sunny meadow than in a forest that is gradually becoming shadier.
🔍 Worked example — Exam-style
A farmer grows potatoes asexually using tubers. Explain one advantage and one disadvantage of this method for the farmer, relating your answer to genetic identity.
⚠️ Common errors
🧠 Quick check 1
🧠 Quick check 2
🎯 Exam question
Worked example
(a) A horizontal stem grows along the soil surface from the parent plant [B1]; at a node a bud develops roots and shoots, forming a new plant that eventually separates from the parent [B1].
🔍 Worked example — Easy
Identify the type of reproduction shown in a diagram of a strawberry plant with a horizontal stem touching the ground and a new plant growing from it. State one structural feature that distinguishes this from a root.
🔍 Worked example — Standard
Explain why a population of strawberries reproducing only by runners is more vulnerable to a new fungal disease than a population reproducing by seeds.
🔍 Worked example — Exam-style
A farmer wants to produce 1000 strawberry plants with the exact same high-yield trait in the shortest time possible. Compare the use of runners versus seeds for this goal, referencing the advantages and disadvantages of asexual reproduction.
⚠️ Common errors
Common mistakes
Practice
Questions