Summary and Exam Tips for Cloning
Cloning is a subtopic of Use of Biological Resources, which falls under the subject Biology in the Edexcel IGCSE curriculum. Cloning involves creating genetically identical copies of organisms. In plants, micropropagation is a common method where small pieces of plant tissue are cultured in vitro using nutrient media. This process involves several steps, including sterilization, growth in nutrient agar, and the use of plant growth regulators to develop plantlets. The advantages of micropropagation include producing clones cheaply, quickly, and at any time of the year, with identical and disease-free characteristics. However, it requires trained personnel and sterile conditions, and the lack of genetic variation makes clones vulnerable to diseases.
In mammals, cloning can be achieved through embryo cloning and adult cell cloning. Embryo cloning involves artificially fertilizing egg cells and splitting the embryo to create identical copies. Adult cell cloning, famously used to create Dolly the sheep, involves transferring the nucleus from an adult cell into an unfertilized egg cell. This technique, known as pharming, has been used to produce transgenic animals that generate useful compounds in their milk, such as antibodies and blood clotting factors. Despite its potential, cloning in mammals is complex and requires numerous attempts for success.
Exam Tips
- Use precise Biology terms: Always use specific biological terminology when answering questions to demonstrate your understanding.
- Understand the question: Carefully read what the question is asking. Differentiate between 'what' and 'why' questions to provide appropriate answers.
- Be concise but thorough: The number of marks allocated to a question can guide you on how much detail to include in your answer.
- Avoid vague terms: Do not use ambiguous words like "it" or "they" without clear references.
- Practice clarity: Ensure your answers are clear and well-structured, making it easy for examiners to follow your logic.
