Unit 4 Revision

Question 1

State the pros for Gm crops

Answer 1

Farmers have a higher yield
Less deforestation
Less costs on pesticides

Question 2

State the cons of Gm crops

Answer 2

Less pollination
Reduction in biodiversity
Potential health issues
Not natural (ethical reasons)

Question 3

What is tissue culture ?

Answer 3

Used for cloning plants and reproducing cells in a sterile environment

Question 4

Why is tissue culture a preferred way of cloning plants over cuttings?

Answer 4

It is quicker, more efficient, ,produces more at once (bigger yield)

Question 5

What is a eukaryotic cell

Answer 5

A cell that has a nucleus

Question 6

Wha is a prokaryotic cell

Answer 6

A cell that doesn’t have a nucleus

Question 7

What is selective breeding

Answer 7

A farmer picks organisms with desirable features to breed

Question 8

Explain how natural selection works

Answer 8

There is variation within population, within the population the strongest survive. The strongest breed more often and pass on genes more frequently.
(Give example)

Question 9

Describe how the skull size of humans ancestors has changed over time,
State the names of each ancestor in your answer as well as how long ago it was….

Answer 9

The size of the human skull has increased. The smallest starting with the ardi (4.4m) lucy (3.2m) homo habilis(2-1.5m) homo erectus (500,000) and then lastly the homo sapien- the biggest and present state.

Question 10

Define evolution

Answer 10

Evolution is how species of living organisms have changed over geological time

Question 11

How are stone tools dated from their environment

Answer 11

Stone tools are dated by the age of the rock they are found in, NOT the age of the actual stone they are made from.

Question 12

Name the human like species skulls that e rI found along side their dates

Answer 12

Ardi- 4-4.5m 
Lucy-2.5-3m
Homo habilis-1.8-2m
Homo erectus-1.5m
Homo sapiens-present skull & 100,000 years ago

Question 13

Cause of genetic variation

Answer 13

Mutations

Environmental factors

Question 14

How can natural selection lead to the evolution of a new species

Answer 14

If an organism in a species had a mutation that benefited it in it’s environment it will successfully pass on these genes and the offspring will have the benefit as well

Question 15

How does the development of resistance in organisms support darwins theory

Answer 15

Microorganisms such as bacteria and viruses reproduce rapidly and can evolve In a relatively short time.
Consequently if a bacteria let’s say had a mutation when being produced, this mutation could protect them against certain antibiotics. This would then be passed down therefore causing resistance.

Question 16

Names of scientists who first developed the idea of evolution by natural selection

Answer 16

Charles Darwin

Alfred Russel Wallace

Question 17

What is the pentadactyl limb and where is it found and how does it provide evidence for evolution

Answer 17

Many vertebrates have a similar bone structure despite their limbs looking different on the outside. It is A limb with 5 digits (fingers) such as a human hand or foot, it suggests that many vertebrates descended from the same common ancestor.

Question 18

How are organisms classified into smaller groups based on their characteristics

Answer 18

Classification of living things ;

Kingdom 
Phylum 
Classes 
Order
Families 
Genus 
Specials

Question 19

What are the 5 kingdoms

Answer 19

Monera
Protist
Fungi 
Plant
Animal

Question 20

What are the three domains

Answer 20

Archaea
Bacteria
Eukarya

Question 21

Why are new breeds and varieties being created

Answer 21

By natural selection

Selective breeding

Question 22

What is meant by a genetically modified organism

Answer 22

A gmo is an organism whose genome has been altered by the techniques of genetic engineering so that it’s DNA contains one or more genes not normally found there.

Question 23

How Is selective breeding carried out

Answer 23

A human takes organisms with favourable traits and breeds them so those traits can be produced and made again

Question 24

Effects of selective breeding

Answer 24

Less variation within population

Disease is more likely to affect more of the organisms if they all share a similar genome

Question 25

How is genetic engineering done

- bacteria example -

Answer 25

The human cell contains the gene for insulin, this gene is isolated. A bacterium cell contains a plasmid. The gene for insulin is removed from the Human cell by restriction enzymes, the plasmids is removed from the bacterium by restriction enzymes.
These enzymes cut the plasmids and create sticky ends; bases that don’t match. The insulin gene is then inserted into the plasmid by ligase enzymes which creates a vector. The bacteria then multiply and the insulin protein is created

Question 26

Uses of genetically engineered organisms

Answer 26

In medicine genetic engineering has been used to mass produced insulin, human growth hormones and vaccines. In agriculture it has been used to produce desired traits e.g. - drought tolerance and pest resistance

Question 27

Benefits and risks of using selective breeding and genetic engineering

Answer 27

Higher yield of goods
Healthier animals 
More desirable traits 
But 
Reduces variation 
Playing god 
Disease risk

Question 28

How can crop plants become modified to make them resistant to insect pests

Answer 28

Genetically modified to be toxic to certain pests

Question 29

Advantages and disadvantages of GM

Answer 29

Higher yield
Resistant crops

Could harm people if chemicals have been used
Expensive

Question 30

What is biological control

Answer 30

The control of a pest by the introduction of a natural enemy or predator

Question 31

How can biological control cause problems

Answer 31

Can have unknown ecological effects- the opposing natural enemy could cause more problems.
Research and development costs can be high
Decreases biodiversity

Question 32

How can fertilises damage the environment

Answer 32

Causing pollution by the mass of fumes being given off by the crops.
Pollute water supplies

Question 33

What is genetic engineering

Answer 33

Modifying the genome of an organism to introduce desirable characteristics

Question 34

Describe the work of Darwin and Wallace in the development of the theory of evolution by natural selection and the impact of these ideas on modern biology.

Answer 34

Charles Darwin and Alfred Russel Wallace went to the Galapagos islands in 1835, it helped Darwin formulate his ideas on natural selection, he saw animals of the same species but of different adaptions eg- different size beaks on finches and how this could effect their food source.

Question 35

Explain Darwin’s theory of evolution by natural selection

Answer 35

More individuals are being produced each generation that can survive. Phenotypic variation exists among individuals and they are heritable. Those individuals with heritable and desirable traits will be more suited to the environment and will survive

Question 36

What is Bacillus Thuringiensis and uses of it in crop plants

Answer 36

This bacteria naturally produces a toxin which is poisonous to many insects, the gene for producing this poison has been inserted into crop plants which are now resistant to these insect pests.

Question 37

Advantages and Disadvantages of using Bacillus Thuringiensis

Answer 37

Advantages- less insecticide (chemicals to kill insects) has to be used and crop yield is higher.
Disadvantages- Toxin could kill other, harmless insects, the gene could be transferred into other wild plants and some insect species have already evolved resistance to the toxin