Cloning

Question 1

How was dolly the sheep made?

Answer 1

Dolly the sheep was produced by a process called nuclear transfer. This involves removing the nucleus from a body cell and placing it into an egg cell that had its nucleus removed.

Question 2

Animals could be cloned to:

Answer 2

• Mass-produce animals with desirable characteristics
• Produce animals that have been genetically engineered to provide human products
• Produce human embyros to supply stem cells.

Question 3

What are the ethical issues concerning human cloning?

Answer 3

Some people think that it is wrong to clone people as they will not be ‘true individuals’.

Question 4

When Dolly was produced by nuclear transfer, it involved a number of steps:

Answer 4

1. The donor egg cell had its nucleus removed.
2. The egg cell nucleus was replaced with the nucleus from an udder cell.
3. The egg cell was then given an electric shock to make it divide.
4. The embyro was implanted into a surrogate mother sheep.
5. The embryo then grew into a clone of the sheep from which the udder cell came.

Question 5

Cloning technology could be useful in a number of ways. Some of these may carry risks.

Answer 5

For example, genetically modified animals could be cloned to supply replacement organs for humans. Some people are worried that this could lead to diseases being spread from animals to humans.

Question 6

Advantages and disadvantages of producing cloned plants.

Answer 6

• Advantages: growers can be sure of the characteristics of each plant since all the plants will be genetically identical. It is also possible to mass-produce plants that may be difficult to grow from seed.
• Disadvantages: if the plants become susceptible to disease or to change in the environmental conditions, then all the plants will be affected. There is a lack of genetic variation in the plants.

Question 7

Plants can be cloned by a process called tissue culture, as follows:

Answer 7

1. A plant is selected that has certain characteristics.
2. A large number of small pieces of tissues are then cut from the plant.
3. The small pieces of tissue are grown in test tubes or dishes containing a growth medium.
4. Aseptic technique is used at all stages to stop any microbes infecting the plants.

Question 8

Which type of cloning is easier plant or animal?

Answer 8

• Cloning plants is easier than cloning animals because many plant cells retain the ability to differentiate.
• Animal cells, however, usually lose this ability at an early stage.