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Biology A level - Jaya > Paper 2 - Gaps in my knowledge > Flashcards

Paper 2 - Gaps in my knowledge Flashcards

1
Q

Explain why the student added glucose solution to the petri dish?

A

The student added glucose solution so that the plant can respire and produce ATP needed for growth

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2
Q

Explain the lids were kept on the petri dish?

A

Prevent evaporation which alters the water potential in the petri dish

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3
Q

Explain how inhibiting adenylate cyclase may help to lower the blood glucose concentration?

A
  • Less ATP is converted to cAMP
  • Prevents the activation of kinase A
  • Less glycogen converted to glucose
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4
Q

What is a DNA probe?

A

A DNA probe is a short single strand of DNA. Bases complementary with DNA

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5
Q

Suggest how someone may have heart irregularities?

A
  1. Slower impulses along the sympathetic and parasympathetic neurones
  2. Impulses from the cardiac centre
  3. To SAN
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6
Q

What are the benefits of gene therapy?

A
  • No donor is needed
  • Less chances of rejection because own stem cells are being used
  • No destruction of bone marroow
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7
Q

What are the negatives of gene therapy?

A
  • Faulty cells still produced
  • Immune system could attack GM cells
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8
Q

Give two reasons why bacteria are able to use human DNA to produce human proteins?

A
  • Human genes are universal
  • The mechanism of transcription is universal
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9
Q

Suggest and explain one reason why bacteria might not be able to produce every human protein?

A

Cannot splice pre-mrna so cannot remove any introns

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10
Q

Where is the starting point for the production of all inorganic compounds?

A

Calvin cycle

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11
Q

What are the 3 limiting factors of photosythesis?

A
  • Light intensity
  • Temperature
  • Carbon dioxide
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12
Q

How could temperature be a limiting factor?

A
  • At too high or too low temps, enzymes may either be inactive or denature
  • At high temperatures, stomata close to prevent the loss of water and so light independent reaction cannot take place
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13
Q

How does anaerobic respiration work in animals and plants?

A

Reduced NAD is used to reduce the pyruvate into ethanol in plants and lactate in animals. This means that the NAD is oxidised which means they can be re-used in glycolysis

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14
Q

How is ATP produced in the krebs cycle?

A
  • Substrate-level phosphorylation
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15
Q

How can mitochondrial diseases impact ATP production?

A

If mitochondria cannot function properly, this could lead to aerobic respiration unable to take place and so anaerobic respiration may take place instead. This could lead to increase build up of lactate which could lead to fatigue and muscle weakness

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16
Q

3 limitations of using a calorimeter

A
  • Can take a long time to full dehydrate a plant sample to find its dry mass
  • Precise equipment which may not be accurate
  • A simple calorimeter may not be as accurate
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17
Q

How is primary and secondary productivity measured?

A

Biomass in a given area in a given time
- Kj ha-1 year-1

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18
Q

How to calculate % yield?

A
  • ( Actual yield / theoretical yield ) x 100
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19
Q

Describe the role of saprobionts in the nitrogen cycle?

A

Saprobionts feed on dead material of waste products and break down nitrogen containing compounds such as DNA and amino acids. This will lead to the production of ammonia

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20
Q

A 3 neuron simple reflex

A

Receptors will detect a stimuli which will cause the sensory neurone to carry the impulse to the relay neurone and then the relay neurone carries the impulse to the motor neurone. The motor neurone sends impulses to the effector

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21
Q

What does a nerve impulse that is short-lived, localised and rapid mean?

A
  • Localised - neurotransmitters are released directly onto the target cells
  • Short-lived - neurotransmitters are quickly removed once they have done their job
  • Rapid - electrical impulses are fast and so they can detect a stimuli quickly
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22
Q

How does the pacinian corpuscle reach a generator potential?

A

When there is a stimulus, the lamella become deformed which presses on the sensory nerve ending which causes the sensory neurones cell membrane to stretch which deforms the stretch-mediated sodium ion channels causing the ion channels to open, sodium ions to diffuse into the cell creating a generator potential

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23
Q

When the heart needs to be slowed, what system are nerve impulses sent down?

A

Parasympathetic system

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24
Q

When the heart needs to increase, what system are nerve impulses sent down?

A

Sympathetic system

25
Q

Why is the refractory period so important?

A

So that action potentials don’t overlap and pass along as discrete impulses, There is a limit to the frequency of impulses, action potentials are unidrectional

26
Q

What is saltatory conduction?

A

This is when nerve impulses jump from node to node in across the neurone

27
Q

Why are electrical impulses quicker along axons with a greater diameter?

A

An axon with a greater diameter means that there is less resistance of the flow of ions so they can move across the axon quicker and easier

28
Q

maximum frequency of impulses within a certain period of time

A

Time ÷ duration of the refractory period

29
Q

maximum frequency of impulses within one second

A

1 ÷ duration of the refractory period

30
Q

Pigments in rods and cone cells?

A

Rod cells - rhodopsin
Cone cells - Opsins

31
Q

What is the role of phosphocreatine in muscle contraction?

A

Phosphocreatine provides phosphate groups which can bind to ADP to regenerate ATP

32
Q

Why is having multiple negative feedback systems important?

A

It will provide your body with more control to deal with multiple changes to your internal body environment at the same time

33
Q

Describe how ADH works?

A

When someone is dehydrated, osmoreceptors in the hypothalamus will detect a lower water potential and so it will create more ADH. This will be released by the posterior pituitary gland and bind to the collecting duct which will active phosphorylase which will cause aquaporins to fuse with the collecting duct causing the collecting duct to become more permeable to water and so water will diffuse in by osmosis

34
Q

2 reasons why maintaining a constant body temperature is so important?

A
  • prevents damage to cell membranes
  • Prevents the denaturing of enzymes
35
Q

What are podocytes?

A

They line the bowman’s capsule which create a large surface area for molecules to go thru

36
Q

What is a genotype and a phenotype?

A

Genotype = Genetic constitution of an organism
Phenotype = The expression of this genetic constitution and its interaction with the environment

37
Q

Why may a species may be considered to be 2 populations?

A
  • They may not interbreed
  • They may not live in the same geographical location
38
Q

What are the ratios for recessive epistasis and dominant epistasis?

A

9:3:4 - recessive
12:3:1 - dominant

39
Q

What is the mark-release-recapture calculation?

A

(Number of organisms initially caught x number of organisms in second sample) / Number marked in the second sample

40
Q

2 ways to accurately sample a population

A

Random sampling
Large samples over 30+

41
Q

Examples of biotic factors

A

Disease, competition, predation, humans, insects

42
Q

What is epigenetics?

A

Heritable changes in gene function, without changes to the base sequence of DNA

43
Q

Why may genome sequencing be harder in complex organisms?

A

The DNA will contain introns and regulatory genes which means that the knowledge of the genome cannot be easily translated into the proteome

44
Q

Explain the process of DNA hybridisation

A

A gene is determined and a complementary DNA probe is produced. The DNA is multiplied in a PCR so that the chances of DNA probe binding is higher. A label is added so it can be detected. The sample is heated so hydrogen bonds between the double stranded DNA can break and then the sample is cooled again and the DNA probes will be added. Then the sample will be washed and the label will be detected

45
Q

The benefits of using stem cell therapy?

A
  • Relatively non-invasive
  • Cure any diseases if they are replaced with healthy cells
  • Stem cells can be used in research and development for other disease cures
  • New procedures ensure greater safety of embryos
46
Q

The drawbacks of using stem cell therapy

A
  • Conflicting legal and ethical standards
  • Possibility for cells to be rejected
  • A great cost
  • Obtaining cell culture can be challenging
47
Q

How does oestrogen initiate transcription of a gene?

A

moves from cytoplasm to the nucleus and then binds to the oestrogen receptor. this will allow the transcriptional factor to change shape and so it will be able to bind to the promoter region on the gene so, it allows RNA polymerase to attach more easily

48
Q

What are the benefits of using a gene machine?

A
  • DNA template isn’t needed
  • Any sequence can be produced
  • Quick process
  • High accuracy
49
Q

Why are phenotypic ratios obtained in offspring sometimes not the same as the expected ratios?

A

Crossing over takes place, random fertilisation, linked genes, epistasis, small sample size

50
Q

Suggest 2 features of the structure of different proteins that enable them to be separated by gel electrophoresis

A
  • Different sized proteins
  • Different charges on the proteins
  • Different R - groups
51
Q

Feature of a climax community?

A
  • Stable community over a longer period of time
  • Abiotic factors more constant
  • Population stable around carrying capacity
52
Q

Two reasons why observed ratios are often not the same as expected

A
  • Fertilisation is random
  • Small sample
  • Lethal alleles
53
Q

Why could a green pigment be produced after staring at a red image for too long?

A

Staring at a red image would cause red sensitive pigment to be stimulated. However, the when pigment will eventually become exhausted which means green-sensitive will start working

54
Q

What is a phenotype?

A

This is the expression of a genotype due to a change in the environment

55
Q

Why does PCR stop after a while?

A

Limited number of primers

56
Q

How to calculate the mass of carbon in a wood of a plantation of trees or a particular species which could be estimated

A
  • Calculate the mean diameter of the organism
  • Use this to determine the mean biomass
  • Use this % water content to find the dried mass
  • Use the dried density to calculate the mass of the organism
  • Estimate the number of organisms in the given area and multiply by the mean carbon content to find the total carbon.
57
Q

What are some agricultural practises which could reduce biodiversity?

A
  • Woodland clearance
  • Hedgerow removal
  • Pesticides
  • Herbicides
  • Monoculture
58
Q

How to calculate energy transfer?

A

Net productivity/total energy available

Biology A level - Jaya (48 decks)

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