B4- Natural Selection and Genetic Modification

Question 1

Selection pressures that could affect an individual’s chance of survival

Answer 1

• predation
• competition for resources (e.g. food, water, mates, etc.)
• disease

Question 2

MRSA is a bacterium that is resistant to antibiotics, what does this mean?

Answer 2

The bacteria cannot be killed by antibiotics

Question 3

Why can bacteria evolve so rapidly?

Answer 3

-they reproduce at a fast rate

Question 4

What is meant by ‘natural selection’?

Answer 4

Individuals with characteristics that make them better adapted to the selection pressures in their environment have a better chance of surviving and reproducing successfully. This means that the alleles that are responsible for the useful characteristics are more likely to be passed on to the next generation.

Question 5

How can a population of bacteria become resistant to a particular antibiotic

Answer 5

Bacteria can develop random mutations in their DNA that make them resistant to a particular antibiotic. Antibiotic-resistant bacteria are more likely to survive and reproduce, passing on the gene for resistance. The gene for resistance becomes more common in the population due to natural selection.

Question 6

What was Darwin’s book called?

Answer 6

On the origin of the species

Question 7

When was Darwin’s book published?

Answer 7

1859

Question 8

How have Darwin and Wallace’s ideas about evolution influenced how living organisms are classified by biologists today?

Answer 8

• led to the understanding that all living things have descended from a common ancestor and must therefore be related in some way
• based on this, biologists now classify organisms based on how closely related they are

Question 9

Other than changing how organisms are classified, how have Darwin and Wallace’s ideas had an impact modern biology?

Answer 9

• now understand the importance of finishing a course of antibiotics to prevent resistant bacteria spreading and the need to constantly develop new antibiotics to fight newly evolved bacteria
• now understand the importance of genetic diversity and how it helps populations adapt to changing environments which has lead to conservation projects to protect species

Question 10

Wallace observed that some butterfly species have warning colours that are used to deter predators from eating them. How does this observation provide evidence to support the theory of evolution by natural selection?

Answer 10

-warning colours are an example of a characteristic that can make an individual more likely to survive and breed successfully

Question 11

How many digits does a pentadactyl limb have?

Answer 11

-five

Question 12

What does a complexity of a stone tool say about its age?

Answer 12

The simpler the tool the older it’s likely to be

Question 13

How can stratigraphy (the study of rock layers) be used to date stone tools?

Answer 13

The deeper the layer of rock that a stone tool is found in, the older the tool is likely to be. This is because older rock layers are normally found below younger layers.

Question 14

Why do differences between stone tools used by each Homo species provide evidence for evolution?

Answer 14

-the stone tools become gradually more complex over time, suggesting that their brains were getting larger, providing evidence for evolution.

Question 15

The pentadactyl limb of a whale and a bird have very different functions, but have similarities in their structures. Explain why this provides evidence that a whale and a bird share a common ancestor.

Answer 15

It is very unlikely that a whale and a bird would have limbs with similar structures unless they both evolved from a common ancestor that also had a pentadactyl limb.

Question 16

What does classification mean?

Answer 16

Organisation of living organisms into groups

Question 17

Name the five kingdoms traditionally used in classification

Answer 17

animals, plants, fungi, prokaryotes, and protists

Question 18

Name the three domains proposed for use in classification instead of the five kingdoms

Answer 18

archaea, bacteria, and eukarya

Question 19

How can the genes of an organism be used to determine how closely related it is to other organisms?

Answer 19

The sequence of DNA bases in the genes can be determined and then compared with other other organisms. Those with more similar DNA sequences are more closely relaete

Question 20

What is ‘inbreeding’?

Answer 20

When closely related organisms are bred together

Question 21

Two characteristics a cattle farmer might want to develop in her cows over time using selective breeding.

Answer 21

• increase the size of the cattle so they produce more meat

- increase the amount of milk produced by the cows

Question 22

When carrying out a tissue culture of animal cells how are the cells in a sample separated from each other before they are placed in the culture vessel?

Answer 22

Using enzymes

Question 23

How can tissue culture be used in medicine?

Answer 23

-to carry out experiments on tissues in isolation, so the effects of a particular substance or environmental change on the cells of a single tissue can be tested

Question 24

How could a farmer clone an apple tree?

Answer 24

The farmer could put small pieces of tissue from the apple tree in a growth medium containing nutrients and growth hormones. This should be done under aseptic conditions. Once the tissues have started growing shoots and roots, the farmer can move them to potting compost to carry on growing.

Question 25

Why might a farmer want to clone an apple tree with unusually colourful and attractive fruit?

Answer 25

So he can produce genetically identical copies of the apple tree that all produce unusually colourful and attractive fruit.

Question 26

What is ‘genetic engineering’?

Answer 26

-involves modifying an organism’s genome to introduce desirable characteristics

Question 27

Give one useful substance that bacteria have been genetically modified to produce?

Answer 27

Insulin- used to treat diabetes

Question 28

How can genetically engineered animals be used in medicine?

Answer 28

• human genes that produce useful proteins can be transferred into animals such as sheep or cows
• these proteins can then be extracted from the animal’s mild and used to treat patients
• animals that have organs suitable for organ transplantation into humans might also be produced in the future

Question 29

One ethical concern with genetically modified animals being used in medicine.

Answer 29

-many genetically modified embryos don’t survive and some genetically modified animals suffer from health problems later in life

Question 30

Many GM crops contain transplanted genes that make them resistant to weed killer. Why could this be a problem if these genes got out into the environment?

Answer 30

Transplanted genes could be picked up by a weed. This would make the weed resistant to weed killer, which would be a big problem for farmers if the weed spreads.

Question 31

How can the use of fertilisers improve crop yield?

Answer 31

-can increase crop yield when growing crops on poor soil by providing the minerals the crops need for growth.

Question 32

Two ways in which GM crops can improve people’s health?

Answer 32

• increase food production, so more people would have enough food to eat
• can also be engineered to contain more nutrients so people are less likely to suffer from deficiency diseases

Question 33

An advantage of using biological control instead of chemical pesticides

Answer 33

Biological control can have longer-lasting effects on the pest population than chemical pesticides and can be less harmful to wildlife

Question 34

Explain how transplanting genes form ‘Bacillus thuringiensis’ inti crops has increase crop yield

Answer 34

• crops containing genes from Bacillus thuringiensis produce toxins that make them resistant to insect pests
• this means less of the crop is eaten by pests, increasing crop yield

Question 35

Why are people concerned that the genes from Bacillus thuringiensis will be less beneficial in the future?

Answer 35

The insects that feed on the crops are constantly exposed to the toxin, so it’s possible that the insects will develop resistance to the toxin and be able to eat the crop.