Edexcel IGCSE Biology · Section 3
Reproduction & Inheritance
Reproduction in plants and humans, then DNA, cell division, genetic inheritance, variation and natural selection.
What this section covers
This section links reproduction, inheritance and variation. Students need to understand how organisms reproduce, how genetic information is passed on, and how variation can lead to natural selection.
- Describe sexual and asexual reproduction in plants and humans.
- Explain DNA, genes, chromosomes, mitosis, meiosis and inheritance.
- Use genetic diagrams and key terms accurately.
- Explain variation, mutation, natural selection and antibiotic resistance.
-
1
Watch ▶
Sexual and Asexual Reproduction
Spec 3.1
The differences between sexual and asexual reproduction, and the advantages and disadvantages of each.
-
2
Watch ▶
Fertilisation
Spec 3.2
What fertilisation is and how the male and female gametes join to form a zygote.
-
3
Watch ▶
Pollination
Spec 3.3
Pollination in flowering plants, and the differences between insect-pollinated and wind-pollinated flowers.
-
4
Watch ▶
Seeds and Fruits
Spec 3.4
How seeds and fruits form after fertilisation, and the structure of a seed.
-
5
Watch ▶
Germination - Required Practical
Spec 3.5
Required practical: investigating the conditions that seeds need in order to germinate.
-
6
Watch ▶
Germination
Spec 3.6
The conditions needed for germination — water, oxygen and a suitable temperature.
-
7
Watch ▶
Asexual Reproduction in Plants
Spec 3.7
Natural and artificial asexual reproduction in plants, including growing new plants from cuttings.
-
8
Watch ▶
Reproductive Structures and Their Functions
Spec 3.8
Covers state the functions of male reproductive structures, State the functions of female reproductive structures and Relate structure location to reproductive function.
-
9
Watch ▶
Reproductive Systems
Spec 3.8
The human male and female reproductive systems and the function of each part.
-
10
Watch ▶
The Menstrual Cycle
Spec 3.9
The stages of the menstrual cycle and the changes in the ovaries and the lining of the uterus.
-
11
Watch ▶
The Menstrual Cycle (Triple)
Spec 3.9-3.10B
The hormones that control the menstrual cycle — FSH, LH, oestrogen and progesterone.
-
12
Watch ▶
Pregnancy and the Placenta
Spec 3.11-3.12
How the placenta and amniotic fluid support and protect the developing fetus during pregnancy.
-
13
Watch ▶
Puberty
Spec 3.13
The physical changes that happen at puberty and the secondary sexual characteristics.
-
14
Watch ▶
DNA, Genes and Chromosomes
Spec 3.14-3.15
The relationship between DNA, genes and chromosomes, and the structure of a DNA molecule.
-
15
Watch ▶
Protein Synthesis (Triple)
Spec 3.16B-3.18B
How genes code for proteins through transcription and translation (protein synthesis).
-
16
Watch ▶
Translation: tRNA, Codons and Anticodons
Spec 3.18B
Covers define codons and anticodons, Explain how tRNA delivers specific amino acids and Describe translation at a ribosome.
-
17
Watch ▶
Genetics: Key Words
Spec 3.19-3.20
Key genetics terms you must know — gene, allele, dominant, recessive, genotype and phenotype.
-
18
Watch ▶
Codominance (Triple)
Spec 3.21B
Codominance and how to work out genetic crosses, using human blood groups as an example.
-
19
Watch ▶
Variation
Spec 3.22, 3.33
Genetic and environmental variation, and the difference between continuous and discontinuous variation.
-
20
Watch ▶
Monohybrid Crosses
Spec 3.23-3.25
How to complete monohybrid genetic crosses using Punnett squares and predict the offspring ratios.
-
21
Watch ▶
Family Pedigrees
Spec 3.24
How to read and interpret family pedigree diagrams to follow inherited characteristics.
-
22
Watch ▶
Sex Determination
Spec 3.26-3.27
How the X and Y sex chromosomes determine whether offspring are male or female.
-
23
Watch ▶
Mitosis and Meiosis
Spec 3.28-3.32
The two types of cell division — mitosis and meiosis — and where each is used in the body.
-
24
Watch ▶
Mutation
Spec 3.34
What a mutation is and how mutations create new alleles and increase variation.
-
25
Watch ▶
From Mutation to Protein and Phenotype
Spec 3.34-3.35B
Covers explain when a mutation can be inherited, Trace the effect of a mutation from DNA to phenotype and Recognise why some mutations have no observable effect.
-
26
Watch ▶
Mutation (Triple)
Spec 3.34-3.37B
Mutations and mutagens, and how they can lead to variation and to cancer.
-
27
Watch ▶
Natural Selection
Spec 3.38
How natural selection works and how it drives evolution over many generations.
-
28
Watch ▶
Antibiotic Resistance
Spec 3.39
How antibiotic resistance develops in bacteria through natural selection, and how to reduce it.
Frequently asked questions
What is the difference between sexual and asexual reproduction?
Sexual reproduction involves two parents and gametes and produces variation; asexual reproduction involves one parent and produces genetically identical offspring.
What is the difference between mitosis and meiosis?
Mitosis produces two genetically identical cells for growth and repair; meiosis produces four genetically different gametes for sexual reproduction.
What is the difference between a gene and an allele?
A gene is a section of DNA that codes for a protein; an allele is a different version of the same gene.
How do you complete a monohybrid cross?
Use a Punnett square to combine the parents' alleles, then read off the genotype and phenotype ratios of the possible offspring.
Biology revision app
Practise Biology and get it marked
275 guided topics across Biology, Chemistry and Physics, with questions marked as you answer them, section checkpoints and timed practice papers. Fifteen topics are free to try, with no card needed.