1
Q
What is the structure of DNA?
A
DNA is a polymer.
It’s made up of two strands coiled into the shape of a double helix.
2
Q
What is a gene?
What does it do?
A
- A gene is a small section of DNA found on a chromosome.
- Each gene codes for a particular characteristic.
- There are only 20 amino acids used in genes.
3
Q
Why do we need to understand the human genome?
A
- It allows us to identify genes that are linked to disease.
- Knowing genes are linked to inherited diseases can help us develop effective treatments.
- Scientists can trace migration around the world.
4
Q
What is a Nucleotide made up of?
A
A sugar, a phosphate group and a base.
5
Q
How many different bases are there?
How do they match up?
A
4
A&T
C&G
6
Q
How many bases code for a gene?
A
Three.
7
Q
What is mRNA?
A
As the DNA is too big to leave the nucleus, mRNA is made by copying the code from the DNA. This mRNA acts as a messenger between the DNA and the ribosome.
Then, correct amino acids are brought to the ribosome in the correct order by carrier molecules.
8
Q
What are the 3 different types of proteins?
A
- ENZYMES - biological catalyst, speeds up chemical reactions.
- HORMONES - used to carry messages around the body.
- STRUCTURAL PROTEINS - are physically strong.
9
Q
What is a mutation?
A
A mutation is a random change in an organisms DNA
10
Q
What does a mutation do?
A
It changes the sequence of amino acids that code for proteins. This often leads to the wrong protein being formed.
Most have very little effect on the protein.
Some mutations can seriously affect the protein that can affect its ability to carry out its function.
11
Q
What are the 3 different types of mutation?
A
- Insertions.
- Deletions.
- Substitutions.
12
Q
Differences between Sexual and Asexual reproduction?
A
SEXUAL
- 2 parents
- genetically different
- meiosis
ASEXUAL
- 1 parent
- exactly the same, clone
- mitosis
13
Q
What is meiosis?
A
Meiosis produces cells with half the number of chromosomes (23 chromosomes)
14
Q
Advantages of sexual reproduction?
Advantages of asexual reproduction?
A
- SEXUAL
- Variation
- This increases the chance of a species survival
- Ability to breed - ASEXUAL
- There only needs to be one parent
- Uses less energy
- It’s faster
- Many identical offspring can be produced
15
Q
What were the 3 conclusions Mendel reached after his Pea Plant Experiment?
A
- Characteristics are determined by hereditary units.
- Hereditary units are passed on to offspring unchanged from both parents.
- Hereditary units can be dominant or recessive.
16
Q
What are the two types of variation?
A
Genetic and environmental variation.
17
Q
What is speciation?
A
It is the development of the phenotype of a species that has gone so far that a completely new species is formed
18
Q
What is selective breeding?
What are its issues?
A
Selective breeding is where you breed the best animals from your stock together.
It reduces the gene pool.
19
Q
How do we use genetic modification?
A
- Bacteria modified to produce insulin
- GM crops
- Sheep GM to produce drugs in their milk.
- Gene therapy
20
Q
KPCOFGS?
A
Kingdom
Phylum
Class
Order
Family
Genus
Species
21
Q
What is the carbon cycle?
A
- The CO2 is removed from the atmosphere by green plants and algae during photosynthesis
- The plants & algae respire, some carbon is returned
- When plants & algae are eaten, the carbon moves through the food chain.
- Respire
- When plants and animals sie, microorganisms eat their remains. these microorganisms respire.
- The combustion of wood and fossil fuels releases CO2
- Constant cycle
22
Q
What is the decay Practical?
A
- Measure out 5cm cubed of lipase and add it to a labelled test tube
- Measure out 5cm cubed of milk into a different test tube
- Add 5 drops of phenolphthalein to the milk
- Then measure out 7cm cubed of sodium carbonate and add to the milk.
The solution should turn pink. - Put both tubes in a water bath at 30°
- Once they’ve reached 30° use a pipette to put 1cm cubed of lipase into the milk solution and start a stopwatch.
- Stir the test tube. The enzyme will start to decompose the milk.
- Stop the stopwatch when the solution turns white and record the time.
- Repeat at different temperatures.
- Calculate the rate of decay
23
Q
How do we pollute
Water
Land
Air?
A
WATER
1. sewage
2. toxic chemicals
3. agriculture
LAND
1. pesticides & herbicides
2. nuclear waste
3. landfill
AIR
1. Smoke
2. Gases, Acid rain
24
Q
What are trophic levels?
A
Seperations in the food chain such as primary consumer, producer etc.
25
What happens to energy and biomass as we move up the trophic levels?
It shrinks.
100 dandelion feed
10 rabbits which feed
1 fox
26
Give an example for hormonal and structural proteins.
Hormonal - insulin.
Structural - cellulose.
27
How does an insertion mutation work?
- Insertions are where a new base is inserted into the DNA base sequence where it shouldn’t be.
- An insertion changed the way the base groups read as it moves it along by 1.
28
How does a deletion mutation work?
- Deletions are where a random base is deleted from the DNA base sequence.
- Like insertions, they change the way the base sequence reads and move it back by 1.
29
How does a substitution mutation work?
- Substitutions are when a random base in the DNA base sequence is changed to a different base.
30
What is stage 1 of meiosis?
Before the cell divided, it duplicates its genetic information. This forms 2 identical armed chromosomes.
31
What is stage 2 of meiosis?
In the first division the chromosome pairs line up in the centre of the cell.
32
What is stage 3 of meiosis?
The pairs are pulled apart so each new cell has only one copy of each chromosome.
33
What is stage 4 of meiosis?
In the second division, the chromosomes line up again in the centre of the cell. The arms of the chromosomes are then pulled apart.
34
What is the final stage of meiosis?
At the end you get four gametes, each with only a single set of chromosomes in it. Each of the gamete is genetically different because the chromosomes get shuffled up during meiosis
35
Why is variation good?
It increases a species chance of surviving a change in the environment.
36
What is natural selection?
The idea that individuals with better adapted features will live longer and therefore be able to breed more, making said features more common.
37
What is selective breeding?
Where we speed up natural selection by breeding animals with desirable characteristics together.
38
How does the parasite malaria reproduce?
It reproduces via both sexual and asexual reproduction.
The parasite reproduces sexually when it’s on the mosquito host and asexually when in the human host.
39
How are spores produced?
They are produced by fungi through asexual and sexual reproduction. The sexually produced spores have variation which is good for the fungi population.
40
What is something controlled by a single gene?
Red-green colour blindness in humans.
The colour of mouse fur.
41
What are most characteristics controlled by?
Several genes interacting.
42
What does homozygous mean?
An organism has two identical alleles for a particular gene.
43
What does heterozygous mean?
An organism has two different alleles for a particular gene.
44
What is a disorder caused by a recessive allele?
Cystic fibrosis.
45
What are the symptoms of cystic fibrosis?
It causes the body to produce mucus in the air passages and pancreas.
46
What is a disorder caused by a dominant allele?
Polydactyly.
47
How common is the cystic fibrosis allele?
1 in 25 people have the gene.
48
What are the advantages of embryonic screening?
- Helps to avoid suffering.
- Treating disorders will be expensive if the baby is born.
- There are laws to stop it going too far.
49
What are the disadvantages of embryonic screening?
- It implies babies with genetic problems are undesirable.
- It could lead to people being too choosy about their babies. ‘Designer babies’.
- Screening is expensive.
50
Who did the Pea Plant experiment?
Gregor Mendel
51
What was the problem with Mendel’s work?
People didn’t understand how significant it was at the time.
52
What are common examples of genetic variation?
Eye colour, blood group and inherited disorders.
53
Give an example of how characteristics may be influenced by the environment.
In a garden, some plants may get more sunlight than others based on their position in the garden, causing them to be luscious and green.
54
What are some reasons for extinction?
- The environment changes too quick.
- A new predator.
- A new disease.
- Another species out competes them for food.
55
Why was Darwin’s Theory of Evolution controversial?
- It went against common religious beliefs.
- Darwin couldn’t explain why these new characteristics appeared in the gene pool.
- There was a lack of evidence, many scientists were unconvinced.
56
What was Lamarck’s theory for evolution?
He argued that an organism acquired changes throughout its life that it passes on to its offspring.
E.g. A giraffe may need to grow its neck. Then it would pass on a longer neck to its offspring.
57
Why was Lamarck’s hypothesis rejected?
It was proved wrong by experiments.
58
What is a recent discovery that backs up Darwin’s theory?
Bacteria becoming resistant to antibiotics.
59
What are the advantages of GM crops?
- GM crops can be engineered to contain nutrients that a population is missing.
- They can have very high yields.
- Can survive extreme conditions.
60
What are the disadvantages of GM crops?
- Reduces biodiversity.
- Not everyone is convinced they are safe.
- There are worries about transplanted genes getting into the natural environment.
61
What are the two methods of plant cloning?
- Using tissue culture.
- Using cuttings.
62
Why do we use plant cloning?
- Can be used to preserve rare plants.
- Used to produce lots of stock for plant nurseries.
- Takes up little space.
- Cheap.
63
How do we clone animals using embryo transplants?
Sperm cells are taken from an animal and egg cells are taken from another animal.
They artificially fertilise the egg.
The embryo that develops is split many times to form clones.
These clones can be planted into other cows.
This creates many ideal offspring.
64
How do we clone animals using adult cell cloning?
We take an unfertilised egg cell and remove the nucleus. The nucleus is then also removed from an adult body cell and inserted into the ‘empty’ egg cell.
The egg cell is stimulated using electric shock.
This embryo is implanted into the womb of an adult female. It creates a clone of the adult body cell.
65
What are the issues with cloning?
- A reduced gene pool.
- It’s possible the animal may not be as healthy as normal.
- There is a worry around attempts at human cloning.
66
What are the three types of fossilisation?
- Gradual replacement by minerals.
- Casts and impressions.
- Preservation in places with no decay.
67
How does gradual replacement happen?
- Things like teeth, shells and bones last a long time when buried.
- They’re replaced by minerals as they decay, forming a rock like substance shaped like the original part.
- Rhe fossil stays distinct inside the rock.
68
How do casts and impressions form?
- Fossips are sometimes buried in soft materials like clay.
- The clay later hardens as the organism decays, leaving a cast of itself.
- Things like footprints can also create these impressions.
69
How does complete preservation happen?
- In amber and tar pits, there is no oxygen or moisture so decay microbes can’t survive.
- In glaciers it’s too cold for decay microbes to work.
- Peat bogs are too acidic for decay microbes.
70
Why can’t we prove exactly where life began?
- Many early forms of life were soft bodied so they largely decayed away completely.
- Fossils that did form may have been destroyed by geological activity such as the movement of tectonic plates.
71
What are two reasons for speciation?
- Isolation.
- Natural selection.
72
What is the definition for a species?
Two similar organisms that can reproduce to create fertile offspring.
73
What did Alfred Wallace observe?
- Wallace independently came up with the idea of natural selection.
- Wallace realised warning colours are used by some species to deter predators.
74
What are the problems with antibacterial resistance?
- It means we can’t treat infections easily, if at all.
- If it enters hospitals, it can be fatal for the already ill people. MRSA is an example.
75
Why is the problem of antibiotic resistance getting worse?
- Overuse of antibiotics.
- Inappropriate use of antibiotics, such as treating somebody for the wrong thing.
76
How can we limit antibiotic resistance?
- Only prescribe antibiotics when it’s necessary.
- Patients must take the full course in order to destroy all bacteria so none are left to mutate.
77
Who came up with the first classification system?
Carl Linnaeus.
78
Who invented the three domain system?
Carl Woese.
79
What were the categories for the three domain system?
- Archaea.
- Bacteria.
- Eukaryota.
80
What do the first and second parts of an organisms name refer to?
FIRST - Genus.
SECOND - Species.
81
Why are evolutionary trees used?
They show common ancestors. The
more recent a common ancestor, the more closely related the two species.
Biology
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