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Biology AQA A Level > Mistakes/ Exam Tips > Flashcards

Mistakes/ Exam Tips Flashcards

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1
Q

Phylogenetic relationship

A

Shows evolutionary relationship

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2
Q

Why is it important when making a sample of hybrid DNA that they use the same gene

A

Base sequence will be similar. These bases will bind together as they are complementary pairs and will form hydrogen bonds.

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3
Q

In hybrid DNA why does a closer relationship between the two species cause the DNA to separate at higher temperature then if the DNA was made of two species less closely related?

A
  1. Relationship is closer so there will be more complementary
    bases.
  2. More hydrogen bonds;
  3. More heat energy needed (to separate bonds);
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4
Q

Why does diversity decrease when a tropical forest is cleared for growing crops

A
  1. few species of plants
  2. Fewer types of food
  3. Few habitats
  4. Fewer species
  5. Aspect of agriculture (killing animals);
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5
Q

Why are graphs joined with a straight line

A

Cannot predict/ do not know intermediate values

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6
Q

How is antibiotic resistance genes passed to other bacteria?

A

Horizontal (gene) transmission;

Conjugation through pilus;

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7
Q

Suggest how adding antibiotics to food of cattle increased profit for the farmers?

A
  • Kills pathogenic/harmful bacteria/pathogens;
  • reduces spread of infection;
  • more food converted to meat due to greater survival
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8
Q

Why does rate of transpiration increase when windy

A

-Removes water vapour in the air;
-Increasing the water potential gradient so more
diffusion/ evaporation

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9
Q

Why does increase temperature increase rate of transpiration

A
  1. Increases kinetic energy;
  2. Water molecules move faster;
  3. Increases diffusion/evaporation;
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10
Q

Explain the increased change of rate of water through xylem when the light intensity increases as well.

A
  1. Stomata open;
  2. Photosynthesis increases/transpiration increases;
  3. More water pulled up;
  4. Due to Cohesion between water molecules
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11
Q

Why is there a smaller diameter in the trunk when transpiration is greater

A
  1. Water pulled up trunk/moves up at fast rate;
  2. Water column under tension;
  3. Adhesion between water andxylem
  4. Pulls xylem in
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12
Q

Explain how the structure of the walls of arteries and arterioles are related to their functions

A

Elastic tissue- stretches under pressure and then recoils evening out pressure
Muscle- Muscle contracts reducing the diameter of the
lumen and changes the flow/pressure
Epithelium- is smooth and reduces friction

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13
Q

How does standard deviation help interpret date

A
  1. Standard deviation gives a measure of
    spread/variation
  2. More standard deviations overlap, the less likely it is
    that differences are real/the more likely
    they are caused by chance;
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14
Q

How does the founder effect cause one species in a habitat to have the same allele

A
  1. A small number of the one species were /went into the habitat;
  2. All shrimps had the allele
  3. The population in the habitat descended from these as they reproduced
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15
Q

What happen when milk and lactase mix

A

Lactase HYDROLYSES lactose into glucose and galactose

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16
Q

Galactose has a similar structure to part of the lactose molecule. Explain how galactose inhibits lactoase

A

Galactose would act as a competitive inhibitor.

Therefore, fewer enzyme-substrate complex can be formed. Prevent lactose binding

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17
Q

Does Bacteria have; cell surface-membrane, nucleus, cytoplasm or capsid?

A

Has cell surface-membrane and cytoplasm.

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18
Q

Does Virus have; cell surface-membrane, nucleus, cytoplasm or capsid?

A 
Virus has Cytoplasm 
NOT capsid (has protein coat but thats different)
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19
Q

Give two ways nucleotides in DNA are different from the nucleides in RNA

A
  1. Nucelotides in DNA have Thymine whereas in RNA they have Uracil.
  2. DNA has deoxyribose whereas RNA has ribose.
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20
Q

In an experiment that measures the change in concentration of enzymes, what would be the control?

A

Boil enzyme solution, so denature enzymes so they don’t work

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21
Q

Give two differences between the structure of mRNA and the structure of tRNA

A
  1. mRNA is longer
  2. mRNA is a straight molecule but tRNA is folded
  3. mRNA contains no paired bases but tRNA has paired bases
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22
Q

How can you ensure a solution contains no oxygen

A

Put oil on top of the solution

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23
Q

Name they type of chemical bond that joins the two monomers to form maltose

A

glycosidic bond

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24
Q

5cm3 of maltose solution with 0.6moldm-3 is mixed with 10cm3 of distilled water. How would you calculate the concentration

A

5/15= 1/3

Times answer by 0.6

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25
Q

When is index of diversity higher

A

Greater variety of plant species, more food sources, more habitat

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26
Q

Name the process by which bacterial cells divide

A

Binary fission

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27
Q

Describe two aseptic techniques used when transferring a sample of broth culture onto an agar place

A
  1. Open lid of the Petri dish as little as possible to prevent unwanted bacteria contaminating the dish
  2. Wear gloves/mask/wash hands to prevent contamination from bacteria on hand/mouth to the dish
  3. Flame the loop/ use sterile pipette to maintain a pure culture of bacteria
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28
Q

Describe and explain the process that occur during meiosis that increases the genetic variation

A
  1. Independent Segregation
  2. Homologous chromosomes pair up
  3. Maternal and paternal chromosomes are re-shuffled in any combination
  4. Crossing over leads to exchange alleles between homologous chromosomes.
  5. Both create new combinations of alleles.
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29
Q

Name the process in which cells become adapted for different functions

A

Differentiation

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30
Q

Explain one way a palisade cell is adapted for photosynthesis

A
  1. Chloroplasts absorb light;
  2. Large vacuole pushes chloroplasts to edge (of cell);
  3. Thin/permeable (cell) wall to absorb carbon dioxide;
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31
Q

What’s the definition of Hierarchy

A 
Groups within (larger) groups;
No overlap;
32
Q

Explain how a change in sequence of DNA bases could result in a non-functional enzyme

A

Change in sequence of amino acids
Change in hydrogen/ionic/disulfide BONDS;
Alters tertiary structure/active site (of enzyme);
Substrate cannot bind / no enzyme-substrate complexes form;

33
Q

What is Primary Structure

A

The linear sequence of amino acids

34
Q

An increase in respiration in the tissue of a mammal affects the oxygen dissociation curve of haemoglobin. Describe and explain how.

A

Increase in carbon dioxide so the curve moves to the right.

This means there is a lower affinity for oxygen so that oxygen is released more readily and picked up less readily.

35
Q

Explain why a specimen needs to be thin in order to use a microscope

A

So there is only a`single layer of cells

So that light that can pass through

36
Q

Explain how having stomata in pits below the leaf surface helps reduce water loss

A

Water vapour accumulates due to reduced air
movement around stomata.
Water potential/diffusion gradient is therefore reduced;

37
Q

Explain how the left ventricle causes the blood to be at high pressure

A

Ventricle CONTRACTS

38
Q

Why is it useful to calculate index of diversity

A

Measures number of individuals of each species and number of species;
Some species only present in small numbers, so the index diversity will take this into account

39
Q

Explain how two features of the gills all efficient gas exchange

A

Large Surface area

Counter Current System

40
Q

Why is a logarithmic scale sometimes used to plot a graph

A

For when you have big values and a wide range, you can fit all of it on a graph

41
Q

Why does having a bigger body mass mean that the uptake of oxygen is lower

A

small sa:volume
less heat loss
Less aerobic respiration
less oxygen

42
Q

Explain the advantage of using volume rather then length to measure the growth of tumours

A

Tumours vary in shape

43
Q

What information does standard deviation give

A

The spread/ variation from the mean

44
Q

Describe how comparison of biological molecules in two species can be used to find out if they are closely related

A
  1. Compare DNA and sequence of bases
  2. DNA hybridisation- separate DNA strands by breaking hydrogen bonds, mix DNA strands of different species.
    The amount of heat required to separate (hybrid) strands indicates how closely related;
  3. Compare same protein and the sequence of amino acids in it
45
Q

How do you use Biuret Test

A

Add Buiret reagent, if turns lilac protein is positive

46
Q

Describe the path by which oxygen goes from the alveolus to the blood

A

Through alveolar epithelium;

Through capillary endothelium;

47
Q

A drug is a competitive inhibitor. Explain how the drug lowers lowers the rate of reaction

A
  • Drug is similar shape
  • Bind to the complementary active site
  • The other substrate can’t bind and less enzyme-substrate complexes formed;
48
Q

If the microvilli is damaged why would concentration of amino acids in the blood decrease even though protein is digested

A
  • Reduced surface area so less absorption;
  • Membrane-bound enzymes less effective so proteins are not digested;
  • Cell membranes damaged so fewer channel proteins OR Channel proteins damaged so less absorption
49
Q

Explain why take additional readings makes the graph better

A

Line of best fit is more accurate so point of interception is better

50
Q

Give two ways a pathogen may cause disease when it has entered the body

A
  • Produces toxins;

- Damages cells / tissues

51
Q

Monoclonal antibodies are specific. Use knowledge of protein structure to suggest why

A
  • Specific primary structure / order of amino acids;
  • Specific tertiary / 3D structure;
  • So only binds to complementary antigen
52
Q

Name two structures present in an epithelial cell from the small intestine that are not present in chlorea bacterium.

A

Nucleus, Mitochondrion, (Smooth / rough) ER , Lysosome, Microvillus,Golgi, Linear DNA, 80s ribosomes;

53
Q

Describe the induced fit model of enzyme model

A

Active site / enzyme not complementary;

Active site changes (shape) to allow substrate to fit

54
Q

People with emphysema may feel weak and tired. Explain why

A
  1. Alveoli break down. Less surface area + increases diffusion distance = less diffusion
    2.Loss of elastin alveoli cannot recoil and is more difficult to expel air;
  2. Less oxygen enters blood/tissues;
    4.Less respiration less ATP
    produced;
55
Q

Cells lining ileum of mammals absorb the monosaccharide glucose by co-transport. Explain how

A

1) Sodium ions are actively transported form ileum cell to blood.
2) Forms diffusion gradient for sodium to enter cells from gut
3) Glucose enters by facilitated diffusion with sodium ions

56
Q

What is a monoclonal antibody?

A

Antibodies produced from the same B cells

57
Q

Why does additional readings make the experiment more reliable?

A

You can spot an anomaly easier and can calculate a mean excluding anomaly.

58
Q

What key words to use with competitive inhibitor?

A

Similar shape, less enzyme-substrate complexes, less substrates can bind.

59
Q

What to use with a question about behaviour of movements

A

Name the stimulus and give the direction.

60
Q

What to mention with a question about membrane permeability of ions.

A

State which channels, whether they open or close. The direction of movement of ions and how they move.

61
Q

What does the Na+/K+ pump do?

A

3Na + out for every K+ in. Uses ATP

62
Q

What’s the general gist of negative feedback?

A

As x rises, y rises but inhibits x so it falls and as a result y falls too.

63
Q

Explain how an activated oestrogen receptor affects the target call.

A

Receptor= transcription factor so binds to promoter gene. Stimulates RNA polymerase to bind so transcription increases.

64
Q

Give two characteristic features of stem cells?

A

1) not specialised and 2) will keep dividing and replacing themselves.

65
Q

How might an insertion of DNA have caused cancer?

A

Affects tumour suppressor gene and inactivates the genes. The rate of call division increases.

66
Q

How can you measure a species on a slide with an optical microscope.

A

Measure with the eye piece scale and calibrate against a known size.

67
Q

Explain how the glucagon would affect the person’s blood glucose concentration

A

Glucagon converts glycogen to glucose by activating enzymes. The process of Gluconeogenisis.

68
Q

What key words to use when talking about alleles in populations.

A

Name the cause: Bottleneck, founders effect.

69
Q

Points for how CO2 affects organisms

A
  • Global warming
  • Yield of crop plants
  • Rate of photosynthesis
  • Increases heart rate
  • Increases ventilation
  • Changes affinity
  • Changes pH and enzymes start to denature
70
Q

All the Taxis groups

A 
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
71
Q

Stomata are found in pits, how does this reduce water loss

A

Decreased water potential, reduced air movement

72
Q

Describe how mark, release and recapture method can be used to determine the population.

A
  • Catch, mark and RELEASE
  • Leave a long enough time for dispersion
  • (catch1 x catch2) / how many marked in catch2
73
Q

Explain why an increase in shoot biomass can be taken as a measurement of net primary productivity.

A

NPP= GPP - R

Biomass of shoot is the same as dry mass which is GPP - R

74
Q

Why is mitochondria needed when nerve impulses arrive at the synapse?

A

ATP used to reassemble neurotransmitters and bring back the products of the neurotransmitters.

75
Q

What is wild type?

A

The normal and commonly found phenotype/ gene

76
Q

Explain why it is important to check the repeatability of measurements

A
  • Increases the reliability of the measurements;

- If measurements are repeatable, differences less likely to be due to errors in measuring.

77
Q

How could use a scatter diagram to check the repeatability of measurements made by two observers.

A
  • Plot graph/scatter diagram of one set of results against the other
  • Expect to see points lying close to line

Biology AQA A Level (15 decks)

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