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Taking the pollen from one rose flower and using it to pollinate a flower on a different rose plant is an example of selective breeding.

Biology - Genetic Engineering (AQA Syllabus A)

Genetic variation and its control is one of the subjects looked at in GCSE Science. This is the last of four quizzes on the subject and it looks specifically at genetic engineering.

Humans have sought to control genes and to exploit genetic variation for thousands of years. Selective breeding has been used to modify the characteristics of plants and animals to better suit our needs. Examples are disease resistant plants, or cattle that give high yields of milk. But there are problems with this, since future generations of selectively bred organisms will share increasingly similar genes.

During the twentieth century, scientists began to understand genes and genetics more deeply than before. Knowledge has reached the point where it is now possible to identify a gene for a particular characteristic and transfer it artificially into an organism. This is called genetic engineering and it allows genes to be transferred from the same species or from different species.

Some examples of genetic engineering are:

Adding the carotene gene from carrots into rice so that people lacking vitamin A in their normal diet can make it if they eat genetically modified (GM) rice.
Adding a gene from weedkiller resistant plants into soya beans. This means the farmer can spray their crop with weedkiller and only the weeds will die, meaning there is less competition and the yield of soya will be increased.
Adding the insulin gene from humans into bacteria, meaning that insulin can be produced rapidly and cheaply to treat diabetics.

There are many ethical issues surrounding human control of genes by genetic engineering, and plenty of health worries too. Since the science is new, no-one knows what the long trem effects on the health of people eating genetically modified (GM) crops or animals will be. There are also religious objections because it seems like scientists are 'playing God'. You need to make up your own mind after considering the facts from both sides carefully.

Mutations are changes to an organism's what?

Cells

Appearance

DNA

Behaviour

Whilst mutations can lead to changes in all three of the others, a mutation is a change to a gene which is part of the DNA

Taking the pollen from one rose flower and using it to pollinate a flower on a different rose plant is an example of what?

Selective breeding

Mutation

Genetic engineering

None of the above

Cross-pollination of plants is a common form of selective breeding

Which of the following is not a disadvantage of selective breeding?

The long term health issues are unknown

The gene pool is diliuted

Disease could spread quickly through a population

There could be an increase in genetic diseases

This is a disadvantage of genetic engineering rather than selective breeding

How do scientists cut out a specific gene ready to place into another organism?

They use a scalpel and a microscope

They use a small pice of thin glass

They use an enzyme

They use a hot wire to cut the DNA in the right place

The enzymes used to cut genes from DNA are called restriction enzymes

What is the correct order of these steps which describe genetic modification?

1. Isolation of the gene responsible for the characteristic.
2. Replication of the transgenic organism.
3. Selection of the desired characteristic.
4. Insertion of the gene into another organism.

1,2,3,4

4,3,2,1

2,3,1,4

3,1,4,2

A transgenic organism is one which has at least one gene from a different species added to its DNA. With questions like this, even when you don't know the answer you can often work it out using common sense

Where in a cell are the genes found?

They make up the chromosomes

They make up the cell wall

They are floating around in the cytoplasm

They are contained in the cell membrane

The chromosomes are strings of genes and are found in the nucleus of cells

These statements are about the role of enzymes in genetic modification. Which is correct?

Ligase enzymes are used to cut DNA in specific places

Restriction enymes are used to cut DNA in specific places

Restriction enzymes join DNA together

None of the statements are correct

Were you paying attention to Q4? Ligase enzymes are used to join pieces of DNA together

Which of the following can be used as vectors?

Bacteria, plasmids and viruses

Bacteria and plasmids

Plasmids and viruses

Plasmids only

Plasmids are small circular pieces of genetic material found in bacteria. Vectors are used to carry the new gene into a cell where it is to be added. It is unlikely, but possible, that this could be asked in the higher tier exam

Nowadays, most insulin is made using genetically modified bacteria that have had the human gene for insulin inserted into them. Which of the following could be regarded as an advantage of GM insulin over natural insulin?

It can be made in very large amounts from gentically modified bacteria

It is less likely to cause an adverse reaction

It overcomes ethical concerns from vegetarians, vegans and some religious groups

All of the above

Natural insulin is taken from the pancreases of pigs or cattle. Its supply is limited and it can cause adverse reactions in some people

10.

Which of the following is a moral objection to genetic engineering of a crop?

GM food could contain substances that create allergic reactions in some people

Moving genes from one organism to another is unnatural

It could cross breed with the same crops in nearby fields, contaminating it in unpredictable ways

It could reduce biodiversity

The other three objctions are scientific. There are many more issues that need discussing and investigating before going ahead with GM cops or banning them altogether

Author: Kev Woodward