1. How long ago did simple life forms first develop ?
Answer
More than three billion years ago.
2. What is "tissue culture" ?
Answer
Tissue culture uses small groups of cells from part of a plant to grow identical new plants.
3. Describe how likely it is that a mutation will impact the phenotype of an organism.
Answer
Most mutations have no effect on the phenotype, some influence phenotype, but very few determine phenotype.
4. Evolution can result in the formation of a new species. Describe what it means when organisms are the same species.
Answer
The organisms can breed together to produce fertile offspring.
5. Selective breeding can be used to breed cattle that produce more meat or milk. Describe how a farmer could selectively breed cattle that produce a large volume of milk.
Answer
The farmer should choose a female that produces a large volume of milk and a male whose daughters produce a large volume of milk then breed the two animals together. Choose the offspring that have the desired characteristic. Continue over many generations until all the (female) offspring show the desired characteristic.
6. Bacterial cells have been genetically engineered to produce useful substances. Name some useful substances produced by genetically modified bacteria.
Answer
Human insulin, blood clotting factors, human growth hormone, etc.
7. Banana crops can be destroyed by a fungal disease called TR4. A gene from a nematode worm can cause resistance to the fungus that causes TR4. The nematode gene can be used to produce GM banana crops resistant to TR4. Describe the main steps in the process of genetic engineering to produce banana crops resistant to TR4.
Answer
Enzymes are used to isolate or 'cut out' the resistance gene from the nematode. This gene is then inserted into a vector, such as a bacterial plasmid or virus. The vector is used to transfer the gene into banana plant cells. The genes are introduced at an early stage of development so that the plants grow with resistance to TR4.
8. Give one advantage of cloning plants by taking cuttings rather than using tissue culture.
Answer
The cuttings method is simpler, as it does not require sterile conditions or a sterile growth medium.
9. Evaluate the use of adult cell cloning to preserve endangered species like the mouflon.
Answer
Pros: It prevents the extinction of a species, and there may not be enough individuals to breed naturally.
Cons: The success rate for adult cell cloning is very low. Clones are genetically identical, so there is less genetic variation. Cloned animals can develop health problems or may die earlier than normal. Some people also believe it is ethically wrong to clone animals.
Conclusion: The low success rate and developmental problems are major drawbacks of cloning, but it may be worth the risk to ensure the survival of a species that would otherwise become extinct.