Section 4- Natural Selection And Genetic Modification

Question 1

Examples of social pressures

Answer 1

Predation
Competition
Disease

Question 2

Steps for evidence of evolution

Answer 2

G = there is genetic variation between organisms. Those who have desirable traits and are better adapted and those who don’t
E= there is environmental pressure/competition, meaning that it will affect an organisms chance of surviving and reproducing. Organisms who are well adapted and have beneficial characteristics have an advantage of surviving, and therefore are more likely to be successfully.
N= this means they undergo natural selection meaning the organism who have the traits to survive against the competition/environmental pressure and that means they survive the survival of the fittest
I= the organisms with the beneficial traits and are well adapted that have survived The survival of the fittest have alleles that are responsible for the useful characteristics and will be passed on to the next generation, making the population increase of those organisms having beneficial characteristics and alleles.
E- this is evolution

Question 3

How does bacteria provide evidence for evolution?

Answer 3

G - bacteria has a genetic variation between bacteria who are affected of a particular antibiotic and those who become less affected
E- there is environmental pressure (the antibiotic) and the bacteria who is less affected by the antibiotic will survive as they have alleles that contain specific characteristics against that particular antibiotic.
N- the ability to resist the antibiotic is a big advantage. Resistant bacterium is better able to survive than a non-resistant bacteria, so it lives longer and reproduces many more times meaning it won the survival of the fittest
I- the resistance bacterium then lives longer and reproduces many more times passing on that beneficial trait to their offspring making it more common
E- this is known as evolution

Question 4

What does natural selection cause bacteria

Answer 4

It makes the bacteria better adapted to the environment in which antibiotics which is known as selection pressure are present. As a result, antibiotic resistance becomes more common in the population over time. Emergence of other resisted organisms, such as rats resistant to the poison of warfarin Also provides evidence for evolution.

Question 5

How does fossil provide more evidence for evolution?

Answer 5

Fossils are any trace of animal or a plant that lived a long time ago
Most commonly found in rocks and the deeper the rock the older the fossil
1. By arranging fossils in chronological order, Gradual changes in organisms can be observed. This provides evidence for evolution because it shows how species have changed and developed over billions of years

Question 6

Ardi

Answer 6

• 4. 4 million years old.
• Found in Ethiopia
• The structure of her feet suggests she climb trees She had an ape like a big toe to grasp branches
• long arms and short legs
• Her brain size was about the same size as a chimpanzees
• However, the structure of her legs suggest that she walked up right like human
• The structure of a hand bones also suggests she didn’t use her hands to help her walk like apes

Question 7

Lucy

Answer 7

• 3. 2 million years old.
• Lucy had arched feet and legs more adapted to walking and climbing however, no ape like big toe
• The size of arms and legs was between what you would expect to find in apes and humans
• her brain was slightly larger than ardis , but still similar in size of a chimps brain
• The structure of Lucy’s leg bones and feet suggest she walked upright but more efficiently than ardis

Question 8

Turkana boy

Answer 8

• Leakey discovered Turkana boy
• 1.6 million years old
• He was a mixture of human and ape like features, but is more human like than Lucy
• Short arms and longlegs a much more like a human than an ape.
• His brain size was much more larger than Lucy is similar to a human
• The structure of his legs and feet suggest he was even better adapted to walking up right than Lucy

Question 9

How to find out the brain size

Answer 9

Working out the cranial capacity, which is the space taken up by the brain in a skull

Question 10

What tools did Homo habilis use?

Answer 10

• Made simple stone tools called pebble tools by hitting rocks together to make sharp flakes
• these could be used to scrape meat from bones or crack bones open

Question 11

What tools did homo erectus use?

Answer 11

• Sculpted rocks into shapes to produce more complex tools like simple hand axes
• these could be used to hunt, dig, chopped and scrape meat from bones

Question 12

What did homo neanderthalensis use

Answer 12

• more complex tools
• Evidence for Flint tools, pointed tools and wooden spears

Question 13

What did Homo sapiens use?

Answer 13

• flint tools were widely used
• pointed tools including arrowheads, fish hooks, and needles

Question 14

Ways to work out how old a stone or a hominid fossils

Answer 14

• Looking at structural features
• stratigraphy
• carbon-14 dating

Question 15

Looking at structural features

Answer 15

The simply the tools, the more likely it is older than more complex tools

Question 16

Stratigraphy

Answer 16

The study of rock layers. Older rock layers are normally found below younger layers so tools or fossils in deeper layers are usually older.

Question 17

Carbon-14 dating

Answer 17

Stone tools are often found with carbon containing material carbon 14 dating can be used to date this material

Question 18

What are the five kingdom classification system?

Answer 18

1. Animals : fish, mammals, reptiles.
2. Plants: grasses, trees.
3. Fungi: mushrooms and toadstools, yeast
4. Prokaryotes.: organisms without a nucleus.
5. Protists: eukaryotic celled organisms.

Question 19

How has a classification system change over time?

Answer 19

Overtime technology has developed further and our understanding of things like biochemical processes in genetics has increased. We can now unable to determine the sequences of DNA bases in different organisms, genes and compare them
the more similar to sequence of a gene, the more closely related the organisms.

Question 20

What did woese find

Answer 20

3 domain system

Question 21

What are the three domain systems

Answer 21

• archaea
• bacteria
• eukarya

Question 22

Archaea

Answer 22

Organisms in this domain look similar as bacteria.
The genetic sequences show a difference.
They were first found in extreme places, such as hot springs, and salt lakes

Question 23

Bacteria

Answer 23

This domain contains true bacteria

Question 24

Eukarya

Answer 24

Includes a broad range of organisms, including fungus, plants, animals and protists

Question 25

What is selective breeding?

Answer 25

• When humans artificially select the plants or animals that are going to breed so that the genes for a particular characteristic remain in the population.
• Organisms are selectively bred to develop features that are useful or attractive

Question 26

Organisms that are selectively bred

Answer 26

• Animals that produce more meat or milk
• crops with disease resistance
• Dogs with good, gentle temperament
• Plants that reproduce, bigger fruit

Question 27

Process to selective breeding

Answer 27

1. From your existing stock select the ones which have the characteristics youre after
2. Breed them with each other.
3. Select the best of The Offspring and breed them together.
4. Continue this process over several generations and desirable traits Get stronger and stronger. Eventually all the offsprings will have the characteristics.

Question 28

How is selective breeding useful in agriculture

Answer 28

Genetic variation means that some cattle will have better characteristics for producing meat than others. To improve meat yields, farmers select cows and bulls with these characteristics and breed them together. After doing this and selecting the best of The Offspring for several generations the farmer would get cows with a high meat yield

Question 29

How is selective breeding useful for medical research?

Answer 29

Studies investigating the reason behind alcoholism, rats, have been bred with either a strong preference for alcohol or a weak preference for alcohol. This has allowed research is to compare the difference between the two different types of rats including difference in their behaviour in the way that their brains work.

Question 30

Disadvantages for selective breeding

Answer 30

1. Reduces the gene pool- the number of different alleles in a population. This is because the best animals or plants are always used for breeding and they are all closely related. This is known as inbreeding. 
2. Inbreeding cause health problems.- there’s more chance of the organism inheriting harmful genetic defects on the gene pool is limited. Some dog breeds are susceptible to certain defects because of inbreeding such as heart disease in boxer dogs. This leads to ethical considerations, specifically if animals are deliberately bred to have negative characteristics for medical research.
3. They can be a problem if a new disease appears, there’s not much variation in a population, so there’s less chance of resistance alleles being present. All the stocks are closely related to each other so if one is going to be killed by new disease, the other are also likely to be killed.

Question 31

What does genetic engineering involve?

Answer 31

Modifying an organisms genome to introduce desirable characteristics

Question 32

How are enzymes used in genetic engineering?

Answer 32

Enzymes can be used to cut up DNA or join DNA pieces together

Question 33

Restriction enzymes

Answer 33

Recognise specific sequences of DNA and cut the DNA at these points,. The pieces of DNA are left with sticky ends where they have been cut.

Question 34

Ligase enzymes

Answer 34

Used to join two pieces of DNA together at the sticky ends

Question 35

Recombinant DNA

Answer 35

two different bits of DNA stuck together are known as recombinant DNA

Question 36

What are vectors used for

Answer 36

Used to transfer DNA into a cell

Question 37

Two different types of vectors

Answer 37

• plasmids
• Viruses

Question 38

Plasmids

Answer 38

Small circular molecules of DNA that can be transferred between bacteria

Question 39

Viruses

Answer 39

Insert DNA into the organisms they infect

Question 40

How does genetic engineering work?

Answer 40

1. The DNA you want to insert, (for example, the chain for human insulin) is cut out with a restriction enzyme. The vector DNA is then cut open using the same restriction enzyme.
2. The vector DNA and DNA youre inserting, are left with sticky ends. they are mixed together with ligase enzymes.
3. The ligases join the pieces of DNA together to make recombinant DNA.
4. The recombinant DNA is inserted into other cells such as bacteria.
5. The cells can now use the gene you inserted to make the protein you want. For example, bacteria containing the gene for human insulin can be grown in huge numbers in a fermenter to produce insulin for people with diabetes.

Question 41

How is genetic engineering useful for agriculture ?

Answer 41

1. In agriculture, crops can be genetically modified to be resistant to herbicides, which are chemicals that kill plants. Making crops herbicide resistant means farmers can spread across to kill weeds without affecting the crop its self. This can also increase crop yield.

Question 42

How is genetic engineering useful for medicine?

Answer 42

As well as genetically engineering bacteria to produce human insulin researchers, have managed to transfer human genes that produce useful proteins into sheep and cows. For example, human antibodies used in therapy for illnesses like arthritis, some types of cancer in multiple scelerosis. These proteins can be extracted from the animal. Animals that have organs suitable for organ transplantation into humans might also be produced in the future.

Question 43

Concerns about genetic engineering of animals

Answer 43

1. It can be hard to predict what affect modifying genome will have on the organism
   - many genetically modified embryos don’t survive
   some genetically modified animals suffer from health problems later in life

Question 44

Concerns about genetic engineering in crops

Answer 44

• Transplanted genes may get out into the environment
• Genetically modified crops could adversely affect food chains, or even human health