Cloning Edexcel International GCSE Biology revision
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In plain words
A clone is a genetic copy. Gardeners have made clones for centuries by taking cuttings. In 1996 scientists did the same with a mammal: Dolly the sheep was grown from a single cell of an adult ewe, and was genetically identical to her.
Three things to know
- Micropropagation: tiny pieces of a plant (explants) are grown in sterile nutrient jelly until they become whole plants. Thousands of identical plants can be made quickly from one good parent.
- Cloning a mammal: the nucleus is removed from an egg cell. A nucleus from a body cell of the animal to be cloned is put in. The cell is made to divide into an embryo, which is placed in the uterus of a surrogate mother.
- Cloned animals that have been genetically modified can produce human proteins, such as medicines, in their milk.
Tips and tricks
- The clone is identical to the animal that gave the nucleus, not the one that gave the egg or the one that gave birth.
- Sterile conditions in micropropagation stop bacteria and fungi growing on the nutrient jelly.
It lands in your notebook with its questions as flashcards.
Cloning: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is a clone?
It has exactly the same DNA as its parent.
In micropropagation, what are the small pieces of plant called?
They are grown on nutrient jelly.
In cloning a mammal, what is removed from the egg cell?
It is replaced with the nucleus of a body cell.
A clone is genetically identical to which animal?
The nucleus holds the genetic information.
Why is micropropagation carried out in sterile conditions?
Microbes would grow on the nutrient medium.
Quiz
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Worksheet
3 questions, 9 marks. Write your answers on paper, then check them.
Cloning
Edexcel International GCSE Biology 4BI1 · 9 marks · papermunch.org
Name ______________________________ Date ______________
Describe how plants are produced by micropropagation.[3]
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Small pieces of tissue (explants) are cut from a plant. They are grown in sterile conditions on a nutrient medium (agar) containing plant hormones. They develop roots and shoots and grow into small plants, which are then planted out.
Describe how a mammal such as Dolly the sheep is cloned.[4]
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The nucleus is removed from an egg cell. A diploid nucleus is taken from a body cell of the animal to be cloned and inserted into the empty egg. The cell is stimulated to divide and forms an embryo. The embryo is implanted into the uterus of a surrogate mother.
Give two advantages of producing plants by micropropagation.[2]
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Any two: large numbers are produced quickly; all have the same desirable features; it can be done at any time of year; little space is needed; plants are disease-free.
Answers: Cloning
- 1. Small pieces of tissue (explants) are cut from a plant. They are grown in sterile conditions on a nutrient medium (agar) containing plant hormones. They develop roots and shoots and grow into small plants, which are then planted out.
- 2. The nucleus is removed from an egg cell. A diploid nucleus is taken from a body cell of the animal to be cloned and inserted into the empty egg. The cell is stimulated to divide and forms an embryo. The embryo is implanted into the uterus of a surrogate mother.
- 3. Any two: large numbers are produced quickly; all have the same desirable features; it can be done at any time of year; little space is needed; plants are disease-free.