Genetics and Evolution

Question 1

Mendel’s discovery

Answer 1

Looked at breeding different kinds of peas
Some characteristics were dominant
Accepted theory in 19th century

Question 2

Lamarck’s theory

Answer 2

All organisms linked by “fountain of life”
Animals are all adapted and evolved to suit environment
Way organisms behaved affected features of body
Theory influenced Darwin

Question 3

Darwin’s main ideas of evolution

Answer 3

Individual organisms in a particular species show wide range of variation for each characteristics
Reproduction gives more offspring than environment can support = inherited characteristics best suited to environment makes them more likely to survive
Breed, pass characteristics enabled them to revive next generation

Question 4

What experiments did Darwin do?

Answer 4

Breeding experiments with pigeons

Wanted to show how featured could be artificially selected

Question 5

What reasons was Darwin’s theory of evolution by natural selective selected by

Answer 5

Conflict with religion and God, all animals and plants made on Earth
Insufficient evidence
No mechanism for explaining variation and inheritance

Question 6

Russel Wallace theory

Answer 6

If a species existed in various forms, those which were poorly adapted to the change were likely to die out, leaving only the better form to survive and breed

Question 7

Isolation

Answer 7

Where 2 populations of a species become separated

Question 8

Genetic variation

Answer 8

Genetic variation is the difference in DNA among individuals or the differences between populations
E.g. mutation and genetic combination

Question 9

Natural selection

Answer 9

Alleles selected to control characteristics = helping organism survive and breed successfully

Question 10

Why might a part of a population become isolted

Answer 10

Because of new environmental changes

Question 11

Speciation

Answer 11

Populations become so different that successful interbreeding is no longer possible

Question 12

Geographical isolation

Answer 12

Leads to speciation

Species evolved to survive with in isolated environments are vulnerable to climate change or habitat loss

Question 13

Environmental isolated

Answer 13

When climate changes in 1 area

Eventually new species emerge

Question 14

How can fossils be formed?

Answer 14

Animals and plants don’t decay e.g. - no oxygen, poisonous gas kills bacteria needed for decay, temperatures too low
Harder parts of animal or plants replaced by minerals as they decay and become part of the rock
Mould fossils formed when organism is made of mud and becomes fossilised
Preserved traces left behind = footprints, burrows, droppings

Question 15

Why are fossil records incomplete

Answer 15

Earliest forms of life were soft-bodies organisms = little fossil trace, destroyed by geological activity (volcanoes, earthquakes)
Most organisms did not fossilise = right conditions for fossil formation were rare
Many fossils that are still to be found

Question 16

Using fossil records

Answer 16

Helps scientists understand how much organisms have changed since life developed on Earth

Question 17

Extinction

Answer 17

Permanent loss of all members of a species
New species evolve better suited to environment, old species die out = natural selection
Change in temperature, catastrophic events

Question 18

Organisms that cause extinction

Answer 18

New predators = wipe out prey with no adaptations to avoid predators, predators may evolve, existing species might move into new territory, human intervention
New diseases
New mutations = give one organism an advantage

Question 19

Environmental changes

Answer 19

Temperatures fallen = ice age

Lack of food or being too cold to breed

Question 20

Extinction on a large scale

Answer 20

Single catastrophic event = volcanic eruption, giant asteroids

Question 21

What destroyed the dinosaurs?

Answer 21

Asteroid had huge impact = fires, earthquakes, landslides, tsunamis, big amounts of material blasted into atmosphere, dust made it dark
Melting of ice triggered mass extinction, drop in sea level flooded seas with very cold water
Layer of rock formed from crater debris in countries. = iridium found which is only formed when rock hits with force such as an asteroid hit

Question 22

Antibiotic resistant bacteria

Answer 22

Resistant bacteria can survive and reproduce increasing population of resistant bacteria
Spreads rapidly = no one is immune

Question 23

Prevent resistant strains or bacteria appearing

Answer 23

Important not to overuse antibiotics
Important to finish course of medicine every time so all bacteria are killed = none survive to mutate and form resistant strains
Important to restrict agricultural use of antibiotics to prevent spread of antibiotic resistance form animal to humans

Question 24

Measures to stop the spread

Answer 24

Antibiotics only used when needed
Specific bacteria treated with specific antibiotics
Medical staff wash hands with soap and water
Medical staff wear disposable clothing or regularly sterilised
Hospitals have high standards of hygiene
Patients infected with antibiotic resistant bacteria isolated
Visitors wash hands before and after entering

Question 25

Negatives in antibiotics

Answer 25

Isn’t easy to find chemicals that kill bacteria without damaging humans cells
Expensive
Slow to produce

Question 26

3 domain system

Answer 26

Archaea = bacteria able to live in extreme conditions 
Bacteria = bacteria that can photosynthesise
Eukaryote = cells that contain a nucleus enclosing genetical material (Protista, animals, fungi, plants)