5.2 Selective Breeding — Studia

REVISION NOTES

IGCSE Edexcel Biology

5.2 Selective Breeding

5.2.1 Understand how selective breeding can develop plants with desired characteristics

Selective breeding:

The process of breeding individuals with desirable traits together
In the first generation not all offspring express the desired trait
Offsprings expressing the desirable trait are selected and bred together
This pattern is repeated over multiple generations
- Until all offsprings start reliably expressing the desired trait
Same process is used for animals and plants

Selective breeding of plants:

Plants are selectively bred for characteristics such as:
Disease resistance in agricultural crops to increase crop yield
Resistance or tolerance to harsh weather conditions for increased crop yield
Better tasting fruits
Large or better looking flowers

5.2.2 Understand how selective breeding can develop animals with desired characteristics

Selective breeding of animals:

Animals are selectively bred for characteristics such as:
- Cows, goats and sheep producing more milk or meat
- Sheep that produce better quality wool
- Horses that have better features and are faster

Disadvantages of selective breeding:

Can lead to inbreeding
- Occurs when plants or animals closely related to each other are bred together
Decreases the variation of genes within the population
- Number of different alleles decreases
Decreases the size of the gene pool
- Increases chances of inheriting genetic diseases
- Population is more vulnerable to unforeseen pathogens

1. The Nature & Variety of Living Organisms

1.1 Characteristics of Living Organisms

1.2 Variety of Living Organisms

2. Structure & Function in Living Organisms

2.1 Level of Organisation

2.2 Cell Structure

2.3 Biological Molecules

2.4 Movement of Substances Into and Out of Cells

2.5 Nutrition (in Plants)

2.6 Nutrition (in Human)

2.7 Respiration

2.8 Gas Exchange (in Plants)

2.9 Gas Exchange (in Human)

2.10 Transport (in Plants)

2.11 Transport (in Human)

2.12 Excretion (in Plants)

2.13 Excretion (in Human)

2.14 Coordination and Response (in Plants)

2.15 Coordination and Response (in Human)

3. Reporduction & Inheritance

3.1 Reproduction (in Plants)

3.2 Reproduction (in Human)

3.3 Inheritance

4. Ecology & The Environment

4.1 The Organism in the Environment

4.2 Feeding Relationships

4.3 Cycles within Ecosystems

4.4 Human Influences on the Environment

5. Use of Biological Resources

5.1 Food Production

5.2 Selective Breeding

5.3 Genetic Modification (Genetic Engineering)