Topic 4 - Natural Selection And Genetic Modification

Question 1

How do organisms evolve through natural selection?

Answer 1

Competition. If a species has a mutation that aids them, then they will survive, reproduce and pass that mutation on to future generations

Question 2

How do antibiotic-resistant bacteria provide evidence for evolution?

Answer 2

They have a mutation that allows them to survive certain antibiotics. These bacteria will reproduce and will pass the mutation on to their offspring

Question 3

What are hominids?

Answer 3

Human beings and their ancestors

Question 4

Which fossil is older - ‘Ardi” or “Lucy”

Answer 4

Ardi - lived 4.4 million years ago

Question 5

How do pentadactyl limbs provide evidence for evolution?

Answer 5

Many species, including humans, have pentadactyl limbs (a limb with five digits/fingers) that look similar and therefore must have evolved from a common ancestor

Question 6

How were organisms classified using the five kingdom classification system?

Answer 6

1) Animals - fish, mammals etc.
2) Plants - grass, trees etc.
3) Fungi - mushrooms and toadstools
4) Prokaryotes - all single-celled organisms without a nucleus
5) Protists - eukaryotic single-celled organisms e.g. algae

Question 7

What are the three groups in the three domains in the classification system?

Answer 7

1) Archaea
2) Bacteria
3) Eukarya

The three domains are then subdivided into smaller groups used in the five kingdom system.

Question 8

What is artificial selection?

Answer 8

When humans artificially select the plants or animals that are going to breed so that the genes for particular characteristics stay in the population

Question 9

How can selective breeding be used to increase yields in the meat industry?

Answer 9

Animals that carry more meat by chance can be bread with another animal that has lots of meat, so that this will be a constant feature of the animal

Question 10

What is a clone?

Answer 10

A genetic copy of another organism. They will have the same DNA

Question 11

What are the benefits of using animal tissue culture for medical research?

Answer 11

You can look at the effects of a particular substance or environmental change on the cells of a single tissue, without complications from other processes in the whole organism

Question 12

What are restriction enzymes used for in genetic engineering?

Answer 12

They recognise specific sequences and cut the DNA at these points - the pieces of DNA are left with sticky ends where they have been cut

Question 13

What are the concerns over creating genetically modified organisms?

Answer 13

1) It can be difficult to predict what effect modifying its genome will have on the organism. Many genetically modified embryos don’t survive and some suffer from health problems later on
2) Transplanted genes in plants may get out into the environment. E.g. herbicide resistance gene could be picked up by weeds, creating a new “super weed” variety

Question 14

How can poor soils be improved to increase crop yields?

Answer 14

By adding fertilisers. Fertilisers contain minerals that are essential for plant growth.

Question 15

Give an example of a biological pest control method

Answer 15

Cane toads were introduced into Australia to eat beetles that were damaging crops.

Biological pest control is the use of other organisms to reduce pest numbers

Question 16

What is recombinant DNA?

Answer 16

Two different parts of DNA stuck together

Question 17

How can you grow new plants using tissue culture?

Answer 17

1) Choose the plant you want to clone based on its characteristics
2) You remove several small pieces of tissue from the parent plant.
3) You grow the tissue in a growth medium containing nutrients and growth hormones. This is done under aseptic (sterile) conditions to prevent the growth of microbes that could harm the plants
4) As the tissue produce shoots and roots they can be moved to potting compost to carry on growing

Question 18

List the process in which vectors insert DNA into other organisms

Answer 18

1) The DNA you want to insert is cut out with a restriction enzyme. The vector DNA is cut open using the same restriction enzyme
2) The vector DNA and the DNA you are inserting are left with sticky ends. They are mixed together using ligase enzymes
3) The ligases join the pieces of DNA together to make recombinant DNA.
4) The recombinant DNA is inserted into other cells
5) These cells can now use the gene inserted to make the protein you want.

Question 19

What are plasmids?

Answer 19

Small, circular molecules of DNA that can be transferred between bacteria