Topic 4 - Natural selection and Genetic Modification

Question 1

Define ‘Evolution’

Answer 1

An organism developing over generations to adapt to its environment in order to survive (natural selection)

Question 2

Describe how binomial species names work

Answer 2

It goes the genus then the species second

Question 3

How does evidence from fossils and stone tools support ideas about human evolution?

Answer 3

When we lay them out in chronological order we can see the gradual changes as they advance through their structure features becoming more complex over time. Or how their bond features change.

Question 4

How can we date stone tools?

Answer 4

Carbon-14 dating

Stratigraphy - study of rock layers- deeper = older

Question 5

Describe how stone tools have developed over time

Answer 5

2.5 million - simple stone tools called people? tools by hitting rocks together - scrape meat
2 million - sculpted more complex tools to hit with eg azes
300,000 - more complex tools spears and flint
200,000 - Flint tools, pointed arrowheads

Question 6

Name the fossil hominids in chronological order

Answer 6

Ardi - 4.4 million - climb trees, more ape like, chimp brain size
Lucy - 3.2 million - Arched feet for walking, slightly larger brain, more upright
Leakey’s turkone boy - 1.6 million, more human than ape, larger brain, more upright than Lucy

Question 7

What is the cause of genetic variation?

Answer 7

Change in an organisms alleles which arise due to mutations

Question 8

Why do adaptations allow organisms to survive?

and what is natural selection

Answer 8

They become more adapted to the conditions in their environment meaning that they can survive. This is called ‘Natural Selection’.

Question 9

How does natural selection allow some members of species to survive better than others?

Answer 9

Ones that have better characteristics for their conditions survive longer than others do (survival of the fittest)

Question 10

How does natural selection lead to the evolution of new species?

Answer 10

Over many generations as one species evolves it becomes a new species adapted for its environment.

Question 11

How does development of resistance in organisms support Darwin’s theory?

Answer 11

An organism can become for example resistant to pesticides if it’s a bug which supports evolution as it has adapted to survive the impact.

Question 12

What are the names of scientists who developed first ideas of evolution?

Answer 12

Charles Darwin and Alfred Russel Wallace

Question 13

What evidence supports their theories and what are their theories?

Answer 13

Wallace - Animals have warning colours to deter predators as an example of beneficial characteristics showing evolution
Darwin - Variation noticed in some species meaning they are more suited to survive in their environment

Question 14

What was the impact of the Theory of Evolution on modern Biology?

Answer 14

• Classification - we can now classify organisms into groups based on how closely related they are
• Antibiotic resistance - we understand importance of finishing a course of drugs to prevent bacteria spreading and new antibiotics to fight newly evolved bacteria.
• Conservation - Importance of genetic diversity and how populations adapt to changing environments and has led to conservation projects.

Question 15

What is a pentadactyl limb and how does it provide evidence for evolution by natural selection?

Answer 15

Limb with 5 digits shows evidence for common ancestor but we have evolved for different adaptations eg bat wing or human hand

Question 16

How are organisms classified into smaller groups?

Answer 16

Based on their common features, organisms are separated into 5 kingdoms then the phylum, class, order, family, genus, species

Question 17

What are the five kingdoms?

Answer 17

Animal, Plant, Fungi, Prokaryotes, Protists

Question 18

What is genetic analysis?

Answer 18

Being able to read someone’s genome (all genes and base sequence)

Question 19

What are the 3 domains we now classify organisms into?

Answer 19

Archaea, Bacteria, Eukarya

• Archaea = found in extreme places eg hot springs and salt lakes, look like bacteria
• Bacteria = true bacteria, prokaryotic
• Eukarya = broad range eukaryotic : fungi, plants, animals and protists

Question 20

How are new breeds and varieties created? And why?

Answer 20

Through selective breeding, selectively breed to develop features making it more useful and attractive 
eg animals more meat  and milk, 
dogs with good temperament, 
crops with disease resistance, 
plants bigger fruit

Question 21

What is a genetically modified organism?

Answer 21

An organism you change the base sequence of the DNA to become for example, resistant to insects or increase food production.

Question 22

How is selective breeding carried out?

Answer 22

Select best characteristics you want and two organisms with this phenotype and breed them. Then select best offspring and breed them together. Continue over several generations so all offspring have characteristics eg edible crops from wild plants over thousands of years

Question 23

What are the impacts? (Positive and negatives)

Answer 23

\+ better characteristics
\+ can help investigate alcoholism
- reduces gene pool
- leads to inbreeding health problems
- new disease appears populations can be wiped out

Question 24

How is tissue culture carried out?

Answer 24

1) Take plant you want to clone based on characteristics
2) Remove tissues from parent plant from short tips of fast? root
3) Grow tissue in growth medium containing nutrients and growth hormones under aseptic conditions to prevent microbes getting in
4) Remove to potting compost to carry on growth

Question 25

Why does it produce many identical cells?

Answer 25

Because they are genetically identical clones of the parent cell

Question 26

What are the advantages of tissue culture in medical research?

Answer 26

• You can carry out experiment on the tissue culture in isolation so you don’t need to test drugs on animals
• Look at effects of particular substance or environment change on a single culture without processes in whole organism

Question 27

What are the advantages of tissue culture in plant breeding programmes?

Answer 27

You can get lots of clones of a larger fruit so whole population is larger

Question 28

What are the main stages of genetic engineering?

Answer 28

1) DNA you want to insert is cut with restriction enzyme
2) Vector DNA cut open using same restriction enzyme
3) These two DNA’s (Vector’s DNA and DNA) are left with sticky ends and are mixed together with ligase enzymes
4) Ligase sticks ends together to make recombiant DNA
5) The recombiant DNA is reinserted into other cells
6) These cells now use the gene you inserted to make the protein you want

Question 29

Name some selectively bred organisms in agriculture and medicine

Answer 29

• Crops resistant to herbicides - this means then resistant to weedkillers
• bacteria to produce insulin

Question 30

What are the benefits of using selective breeding and genetic engineering to produce new varieties and breeds and risks?

Answer 30

\+ higher yields
\+ chosen characteristics
- decreases biodiversity
- decreases gene pool
- can leak into wildlife

Question 31

What are some useful GMO’s?

Answer 31

Resistant to insecticides Bt toxin inserted to make resistant to insecticides however soon insects could become resistant so farmers should use multiple ones

Question 32

How can GMO’s increase crop yield?

Answer 32

Pests can be controlled with pesticides
Crops can be genetically engineered to be grown better in drought conditions
Golden rice has been GE’ed to convert to Vitamin A

Question 33

How can GMO’s cause problems in environment?

Answer 33

Pesticides/pest resistant plants can get into environments and could kill natural pests in their habitats therefore decreasing biodiversity

Question 34

What is biological control? (Advantages)

Answer 34

Using methods to reduce pest numbers

Has longer lasting effects and less harmful

Question 35

Why do we need to produce more food?

Answer 35

Because we have a growing population

Question 36

How can Biological control increase crop yield?

Answer 36

Biological control can introduce an animal to act as a predator to get rid of pests that damage crops increasing crop yield.
For example, cane toads were introduced to Australia to get rid of beetles.

Question 37

What are the negatives of introduction of cane toads?

Answer 37

Cane toads are now a pest themselves as they poison native toad species that eat them.
Decrease biodiversity

Question 38

Why do fertilisers increase crop yield?

Answer 38

They contain minerals essential for plant growth so we have access to enough food. They replace nutrients that are lost from the soil from the last crops.

Question 39

Why are fertilisers bad for the environment?

Answer 39

They can leak into nearby streams and rivers and cause eutrophication, killing fish species.