How people change organisms on purpose: selective breeding, genetic engineering, and cloning plants and animals (Biology only), with benefits and risks.
What you will learn
- Put the steps of selective breeding in order and analyse breeding data
- Describe the steps of genetic engineering (Higher) and its benefits and risks
- Explain how restriction enzymes, sticky ends and ligase are used (Edexcel and OCR, Higher)
- Describe cloning by cuttings, tissue culture, embryo transplants and adult cell cloning (Biology only)
Selective breeding
In selective breeding humans choose parents with a wanted characteristic (high milk yield, disease resistance, gentle nature, large flowers), breed them, then choose the best offspring and breed again, over many generations.
- Mean milk yield before: 20.0 litres per day
- Mean after 8 generations: 24.5 litres per day
- Increase: 24.5 − 20.0 = 4.5
- Percentage increase: 4.5 ÷ 20.0 × 100 = 22.5%
The risk is inbreeding: the gene pool shrinks, so inherited defects appear more often and one new disease can hit every plant or animal.
Divide the increase by the starting value, not the new one.
The rest of this lesson and its 13 practice questions are locked.
In this lesson
- Selective breeding
- Genetic engineering
- Restriction enzymes and ligase (Edexcel and OCR, Higher)
- Cloning (Biology only)
13 practice questions, marked as you go; about 20 minutes in all.
Key terms
Selective breeding, Genetic engineering, Vector, Sticky ends, Cut, Joins, Nucleus
In this unit: Inheritance, variation and evolution
Meiosis and DNA, Punnett squares and family trees, inherited disorders and embryo screening, natural selection, selective breeding, genetic engineering and cloning, and classification.