Topic 4 - Natural selection and genetic modification

Question 1

What is natural selection?

Answer 1

– process where organisms better adapted to their environment survive and produce more offspring.

Question 2

Bacterial resistance in antibodies

Answer 2

-Bacteria reproduce at a fast rate.
- Mutations result in new genes e.g.a gene for antibiotic resistance.
- Exposure to antibiotics– those w/ antibiotic resistant
genes survive and those without die.
- w/ antibiotic resistance can reproduce and pass on gene to offspring.
- population of antibiotic resistant bacteria increases.
- Bacterial diseases spread because people aren’t immune to new resistant bacteria and there’s no treatment for it.
e.g. MRSA

Question 3

Describe Ardi

ardipithecus ramidus

Answer 3

• 4.4 mil. yrs old – found in Ethiopia
• structure of feet – climbed trees w/ ape like big toe
• long arms & short legs
• brain the size of a chimp
• walked upright – didn’t use hands to walk

Question 4

Describe Lucy

Austalopithecus afarensis

Answer 4

• 3.2 mil. yrs old – found in Ethiopia
• more human-like than Ardi
• arched feet- more adapted to walking
• arms and legs between ape and human
• brain slightly larger than Ardi, but similar to chimp
• walked upright more efficiently than Ardi

Question 5

Describe Turkana Boy

Homo erectus

Answer 5

• 1.6 mil. yrs ago – found in Kenya
• more human-like than Lucy
• short arms & long legs– more like human than ape
• brain size larger than Lucy - similar to human
• better adapted to walking upright

Question 6

Describe homo habilis

Answer 6

• 2.5-1.5 mil yrs ago
• simple stone tools (pebble tools) – hit rocks together to make sharp flakes – used to scrape meat from bones or crack bones open

Question 7

Describe homo erectus

Answer 7

• 2-0.3 mil. yrs ago
• sculpted rocks to make more complex tools e.g. hand axes
• • used this to hunt, dig, chop and scrape meat from bones

Question 8

Describe homo neanderthalis

Answer 8

• 300,000- 25,000 yrs ago
• more complex tools
• flint and pointed tools and wooden spears

Question 9

Describe homo sapiens

Answer 9

• 200,000 yrs ago - present
• flit tools used
• pointed tools e.g. arrowheads, fish hooks, buttons and needles appeared circa 50,000 yrs ago

Question 10

What is a pentadactyl limb?

Answer 10

• limb w/ 5 digits

- many organisms have this implying they have a common ancestor, but not always e.g. cats and bats

Question 11

What is carbon dating?

Answer 11

• looking at natural radioactive decay of an

isotope of Carbon (Carbon-14) to estimate how long ago an organism lived

Question 12

How can we date tools by stratifying rock layers?

Answer 12

• Each layer of sediment must have been formed at the same time.
• can date the fossils in this layer and use this to estimate when the tools were formed.

Question 13

Animal kingdom classification and order

Answer 13

• kingdom Kinky
• phloem Police
• class Constables
• order Only
• Family Fancy
• Genus Gay
• Species Sergeants ………lol

Question 14

Animal five kingdoms system (what they’re split into)

Answer 14

• animals
• plant
• fungi
• prokaryotes e.g. bacteria
• protist

Question 15

Differences between archea, bacteria and Eukaryota

Answer 15

Archaea - primitive bacteria that live in extreme environments e.g. hot springs

• Bacteria - true bacteria– but are similar to archaea
• Eukaryota- organisms that have a nucleus enclosed in membranes e.g. protists, fungi, plants and animals

Question 16

What is selective breeding?

Answer 16

• when humans choose which organisms to breed to produce offspring w/ a certain desirable characteristic

Question 17

Describe selective breeding?

Answer 17

• Parents w/ desired characteristics are chosen.
  They’re bred together.
• From offspring those w/ desired characteristics are bred together.
• process repeated many times until all the offspring have the desired characteristic.

Question 18

Dangers of selective breeding

Answer 18

• lead to inbreeding.
• Breeding those w/ similar desirable characteristics means you’re breeding closely related individuals.
• so they mostly have the same alleles
• if environment changes or there’s a new disease, species could become extinct-they all have the same genetic make-up
• • important in selective breeding of plants
• also cause genetic defects

Question 19

What is tissue culture?

Answer 19

• a method of culturing living tissue– making it grow outside the organism, within growth medium

Question 20

Describe culturing tissue

Answer 20

• Take organism you want to clone
• Using tweezers, remove piece of tissue from a fast-growing region of organism
• maintain sterile conditions and place tissue on
  special growth medium– contains hormones and nutrients
• when tissue has developed enough can be
  transferred to compost for further growth

Question 21

What is genetic engineering ?

Answer 21

• Modifying genome of an organism by using gene from another organism to give it a desired characteristic.
  e. g. Plant cells have been engineered for disease resistance or to have larger fruits

Question 22

Describe genetic engineering

Answer 22

• Genes from chromosomes are ‘cut out’ using restriction enzymes.
• same restriction enzymes used to cut vector into where genes will be placed.
• Ligase enzyme used to attach sticky ends of gene and vector together, to produce a recombinant gene product.
• vector is placed in another organism at early stage in development so desired gene moves into its cells and organism can grow w/ desired characteristics.
• in plants vector is put into unspecialised cells– so can produce identical copies of modified plant.

Question 23

Benefit and disadvantage of genetic engineering

Answer 23

benefit
-In agriculture used to improve yields by modifying crops to grow in different conditions, e.g. hotter or drier climates
disadvantage
- People worried we don’t completely understand effects of GM crops on human
health.

Question 24

What are fertilisers?

Answer 24

provide nutrients to plants, makes them more resistant to environmental conditions and able to grow faster and
larger -increase crop yields

Question 25

What is biological control?

Answer 25

• use of certain species to control population of other species.

Question 26

Advantages and disadvantages of genetic engineering

Answer 26

advantage
- useful in medicine produce certain hormones in
microorganisms
disadvantage
- herbicides and pesticides can kill insects and other plants, reduces biodiversity

Question 27

Advantages and disadvantages of selective breeding

Answer 27

advantage
-  plants or animals can be bred to be resistant to a particular disease
disadvantage 
- Lack of genetic variation if one
 susceptible to disease
then all are

Question 28

Stages of genetic engineering

Answer 28

• gene from chromosome is cut by restriction enzyme and creates sticky ends
• same restriction enzyme is used to cut vector (virus or bacterial plasmid)
• ligase enzyme used to attach sticky ends of the gene and vector together to produce recombinant DNA
• vector then placed in another organism etc.