Variation And Evolution Flashcards
1
Q
What is variation?
A
The differences in the characteristics of individuals in a population.
2
Q
What are the 3 main causes of variation? Give an example of each.
A
- Genetic causes e.g hair colour, eye colour.
- Environmental causes e.g language
- A combination of environmental and genetic causes e.g height, weight.
3
Q
What causes genetic variation?
A
Mutations in our DNA
4
Q
State the definition of a mutation.
How often do mutations take place? Do they usually have an effect on our phenotype?
A
- A mutation is a random change in our DNA.
- Mutations take place all the time, but they don’t usually have any effect on our phenotype.
5
Q
What can a mutation cause that can lead to huge changes in a species?
A
A mutation can cause a new phenotype.
6
Q
What is the definition of natural selection?
A
The process through which populations of living organisms adapt and change.
7
Q
What is the definition of evolution?
A
The change in the inherited characteristics of a population over a long time through a process of natural selection.
8
Q
“Question about evolution” (4/5 marker)
A
9
Q
State 4 examples of selective breeding.
A
- Dogs - they have been selectively bred for their gentle nature.
- Food crops - they have been selectively bred for disease resistance.
- Cows - they have been selectively bred to produce more meat and milk.
- Plants - they have been selectively bred to produce large or unusual flowers.
10
Q
Imagine we want to breed large cows for more meat. Explain the process of selectively breeding those cows.
A
- In a mixed population of cows, choose the largest male and female cow.
- Breed these cows together. The offspring should receive the desirable gene from the parents.
- Then select the largest male and female offspring, and breed these together.
- Continue this process over generations, until all of the cows are large.
11
Q
State 2 problems with selective breeding.
A
- We can cause ‘inbreeding’ which can create physical problems in the organisms e.g mobility problems in certain inbred dogs.
- It can cause a reduction in variation in a species, leading to increased vulnerability to diseases and environmental changes.
12
Q
What is genetic engineering? Provide an example.
A
- Genetic engineering is when genes from one organism are cut out and transferred to the cells of a different organism.
- We can transfer genes into plants to produce genetically modified crops.
13
Q
State 3 reasons why we genetically modify crops.
A
- We can make GM crops extreme weather resistant, so they can survive in conditions like snow.
- We can make GM crops herbicide resistant. This means farmers can spray & kill weeds without harming the crops.
- We can make GM crops produce a bigger yield or have increased size.
14
Q
State 2 disadvantages to GM crops.
A
- There may be health effects to eating GM crops.
- They may be dangerous to insects or wild flowers.
15
Q
What is gene therapy? What could be a consequence?
A
- A way to treat inherited disorders in humans.
- The long term effects aren’t known. If we modify a gene, it could have an effect on other genes.
16
Q
Explain the process of genetic engineering.
A
- Identify the gene you want to transfer.
- Use enzymes to isolate the gene.
- Transfer the gene into a plasmid or a virus.
- The plasmid / virus transfers the gene from one organism to another. We call them vectors.
- The gene is transferred into the cells of the target organism.
17
Q
When do we transfer the gene? Why?
A
- We transfer the gene at an early stage in the organisms development.
- This is to make sure that all of the cells receive the transferred gene, and the organism develops with the characteristic we want.
18
Q
What is the definition of a fossil?
A
Fossil: The remains of organisms from millions of years ago that are formed in rocks.
19
Q
State the 3 ways fossils can form.
A
- Fossils can form when parts of organisms haven’t decayed.
- Fossils can be produced even if an organism has decayed, if parts of the organisms are slowly replaced with minerals during the decay process.
- Fossils can be preserved traces. For example in animals they can be footprints or burrows.
In plants they can be preserved spaces where roots were.
20
Q
What prevents an organism from decaying?
A
- Certain conditions can prevent an organism from decaying. For example if the temperature was too cold, of there was a lack of oxygen, or a lack of water.
21
Q
Why can fossils not help scientists determine how life on earth began?
A
- There were few fossils of the earth forms of life.
- This is b/c many of the earths earliest life forms were soft bodied organisms which very rarely formed fossils.
- Many of the fossils that did form were destroyed by changes to rocks in the earths crust.
22
Q
What do fossils show?
A
Fossils do show us that many species have become extinct.
23
Q
Name 4 causes of extinction
A
- Species can become extinct due to a catastrophic event - like an asteroid.
- Species can become extinct due to environmental changes - like an extreme change in weather.
- Species can become extinct due to a new disease or predator - it could kill all of the individuals in a species.
- Species can become extinct if a more evolved species competed with it - for scarce water or food.
24
Q
Why can bacteria evolve rapidly?
A
- Bacteria evolve rapidly because they reproduce at a very fast rate..
25
How often do bacteria reproduce? How are bacteria killed?
- Bacteria reproduce every 30 minutes.
- Bacteria are killed by antibiotics.
26
Name an example of an antibiotic. Apart from medicine, where are antibiotics used?
- An example of an antibiotic is penicillin.
- Antibiotics are used in intensive farming, to prevent closely packed animals from getting + spreading bacterial diseases.
27
What is antibiotic resistance? Give an example of a strain of antibiotic resistant bacteria.
- Antibiotic resistance is when strains of bacteria are no longer killed by antibiotics.
- MRSA
28
Explain the process of how antibiotic resistance happens.
1. Bacteria cause a disease in humans.
2. A mutation in a bacterium makes it resistant to antibiotics.
3. The human takes an antibiotic. The anti kills all bacteria apart from the resistant one.
4. The resistant bacteria survives and reproduces with no competition form other bacteria.
5. Over time, the population of resistant bacteria increases and spreads as there’s no effective treatment.
29
Name 3 ways to reduce antibiotic resistance.
1. Doctors should not prescribe antibiotics inappropriately.
2. People taking antibiotics must finish their course. This means that all of the bacteria can be killed, and none survive and mutate + evolve to become resistant.
3. We should restrict the number of antibiotics used in farming.
30
Who developed the binomial classification system?
Carl Linnaeus
31
State the order of the classification system.
What is the acronym we can use to remember this?
Kingdom, Phylum, Class, Order, Family, Genus, Species.
King Phillip Comes Over For Good Soup
32
What is every organism named from?
Their genus and their species.
33
What was the binomial classification system based upon?
The characteristics we could see in each organism
34
Name 2 other ways we can classify organisms.
- We can analyse organisms biochemistry
- we can look at internal structures in a microscope.
35
Who developed the 3 domain system?
Carl Woese
36
What are the 3 different ‘domains’ found in the three domain system?
1. Archae - these are primitive bacteria. They are found in extreme conditions e.g hot springs.
2. True bacteria - these live in the human digestive system
3. Eukaryota - these include animals, fungi, plants and some protists eg amoeba.
37
What do evolutionary trees show?
Evolutionary trees show how organisms are related to one another.
38
How do we make evolutionary trees for:
1. living organisms
2. Extinct ones.
1. We use their DNA
2. We use fossils
39
What is the problem with using fossils to create evolutionary trees for extinct organisms?
Many fossil records in species are incomplete.
40
Draw an evolutionary tree that shows:
1. Species 1 & 2 are closely related to each other. Species 3 is more distantly related.
2. That species 1,2 and 3 all share a common ancestor.
3. That species 1 & 2 share two common ancestors.
Draw correct tree.
41
Describe the process of how fossils are formed.
1. The animals dies.
2. The soft parts of the animals body rot away.
3. The rest of the body is buried by sediment. Lots of layers of sediment build up on top.
4. This puts lots of weight and pressure onto the layers below, and eventually they turn into sedimentary rock.
5. Water seeps into the bones and teeth, turning them into stone. This process happens over millions of years.
42
Name the two different domains in the binomial system.
Animalia and Eukaryota
43
‘What is the problem with selectively breeding ———‘
All —- are genetically similar therefore they are more susceptible to disease.
44
Describe how an orchid with bright purple flowers may have evolved from an ancestral species which had pale yellow flowers.
- Mutation in ancestral species caused a flower to have purple leaves.
- Purple orchid more suited to new environment.
- plants with purple flowers survive and breed.
- plants with purple flowers pass on DNA
- until they were so different they could no longer interbreed with ancestral species.
