unit 3 Flashcards
1
Q
explain why ATP is sometimes called the universal energy currency [2]
A
- ATP is used by ALL ORGANISMS to PROVIDE ENERGY for many of their BIOCHEMICAL REACTIONS e.g active transport
2
Q
explain the importance of ATP in cells [3]
A
- ATP is used in cells for a number of FUNCTIONS including active transport, muscular contraction and protein synthesis
- ATP is the one molecule used to TRANSFER ENERGY TO CHEMICAL REACTIONS and the energy is supplied in small packages when a SINGLE BOND IS BROKEN
3
Q
explain how nitrate fertiliser leads to eutrophication and how this can lead to the death of fish [3]
A
- plants GROW MORE because of the extra nitrate fertiliser
- this means there is more competition for LIGHT and more of the plants DIE
- the extra dead plants are DECOMPOSED by BACTERIA whose population increases as they have a greater supply of organic material
- the decomposition process in bacteria requires OXYGEN for RESPIRATION which leads to a lowering of oxygen levels in the water and therefore the death of the fish
4
Q
questions related to ‘reabsorption of water in kidney’
A
- SOLUTES are REABSORBED from the FILTRATE in the proximal convoluted tubule
- this leads to OSMOSIS OF WATER from the proximal convoluted tubule into the CORTEX and then into the blood
- as the filtrate moves into the ASCENDING LIMB of the loop of Henle, SODIUM IONS are actively transported out of the ascending limb and into the MEDULLA
- this means that there is a high concentration of solutes and therefore a low water potential in this area of the medulla, the highest concentration of solutes and therefore the lowest water potential being found at the APEX of the loop of Henle
- the structure of the loop of Henle allows a COUNTERCURRENT MULTIPLIER SYSTEM to operate
- this leads to water being reabsorbed from the filtrate along the entire length of the descending limb of the loop of Henle into the medulla because of the water potential gradient that has been produced along its entire length
- water is also reabsorbed from the urine in the collecting duct into this area of the medulla again because of the water potential gradient that has been produced
5
Q
questions related to ‘how an action potential forms/refractory period/speeding up action potential conduction’
A
- an axon’s resting potential is maintained at -70mV by a sodium/potassium pump which moves sodium ions out of the axon and potassium ions into the axon
- this movement of ions requires energy in the form of ATP
- when the axon is depolarised to about -40mV (the threshold potential), voltage gated sodium channels open which allows sodium ions to flood into the axon down an electrochemical gradient, which leads to the axon becoming more depolarised
- when the potential difference gets to +40mV the voltage gated sodium channels close and the voltage gated potassium channels open
- this lead to the potassium ions flooding out of the axon down the electrochemical gradient which causes the axon to be repolarised
- when the potential difference gets to about -80mV, the sodium/potassium pump takes a little time to move the sodium ions out of the axon and the potassium ions back into the axon
- until this is achieved, and the resting potential is restored to -70mV no further action potential can form, this time period is called the refactory period
- action potentials conduction/transmission along a neurone can be sped up if the neurone is myelinated
- myelin electrically insulates the axon and prevents the movement of ions across the axon membrane
- action potentials can only form in the gaps between the myelin which are called Nodes of Ranvier
- this causes saltatory conduction to occur when action potentials form between the sections of myelin in the Nodes of Ranvier
- the action potentials ‘jump’ between Nodes of Ranvier which reduces the conduction time
6
Q
questions related to ‘the proton gradient can be maintained as long as reduced NAD is available in the mitochondrion. explain the reasons for reduced NAD being required to maintain a proton gradient’
A
- the reduced NAD in the mitochondrial matrix supplies both hydrogen ions (protons) and high energy electrons
- the high energy electrons are passed to electron carriers (proton pumps) in the inner mitochondrial matrix which use the energy provided to actively transport the hydrogen ions (protons) against their concentration gradient into the inter-membrane space from the mitochondrial matrix
- this means that a hydrogen ion (proton) gradient is maintained between the inter-membrane space and the mitochondria matrix
7
Q
questions related to ‘outline the pathway for the production of triose phosphate in glycolysis’
A
- glucose is phosphorylated twice using ATP to produce hexose bisphosphate (6C), then this splits to form 2 triose phosphate molecules (3C)
8
Q
questions related to ‘anaerobic respiration/regenerating oxidised NAD for aerobic respiration’
A
- as there is no oxygen available to act as the final electron acceptor, oxidative phosphorylation stops and no ATP can be produced in this way
- the link reaction and the Krebs cycle also stops because there are no oxidised BAD molecules available to act as hydrogen carriers
- some ATP (2 per glucose molecules) can be generated without oxygen (anaerobic respiration) during glycolysis because oxidised NAD can be regenerated to act as a hydrogen carrier for these reactions which allows them to continue
- the regeneration of oxidised NAD happens as a reduced NAD molecule is oxidised as it donates a hydrogen ion (proton) and high energy electrons to the reaction that converts pyruvate to lactate
9
Q
questions related to ‘the organic cycle to the Nitrogen cycle’
A
- nitrogen must be recycled as it is a component part of proteins which all organisms need
- nitrogen gas cannot be used to produce proteins by either plants or animals
- however, plants can use nitrates (which are chemicals that contain nitrogen) to produce proteins
- the nitrates are obtained by the plants from the soil
- for nitrates to be produced a number of steps are required
- decomposition of dead plants, dead animals and animal waste by decomposing bacteria which leads to the digestion of protein into amino acids and the deamination of amino acids to produce ammonia
- the ammonia is then converted into nitrates in a process called nitrification, this involves two different bacteria, Nitrosomonas converts ammonia to nitrite and Nitrobacter converts nitrite to nitrate
- the nitrogen in the nitrate is then available to the plant so that it can use it to make proteins
- animals obtain nitrogen to make their proteins by feeding on either plants or animals which contain protein
10
Q
questions related to ‘explain how carbon dioxide is used in the production of glycerate-3-phosphate during photosynthesis’
A
- RuBP (5 carbon compound) and carbon dioxide are linked together to produce a 6C compound in a chemical reaction catalysed by the enzyme RUBISCO
- the 6C compound is unstable and splits into two glycerate-3-phosphate (3C) molecules
11
Q
questions related to ‘osmoregulation/ADH’
A
- when there is a low blood volume this is detected by osmoreceptors in the hypothalamus which causes the release of more antidiuretic hormone (ADH) from the posterior lobe of the pituitary gland
- the ADH is carried in the blood and affects target cells in the distal convoluted tubule and the collecting duct by causing them to become more permeable to water
- this results in water leaving the distal convoluted tubule and the collecting duct by osmosis as the water potential of the medulla is lower than that of the distal convoluted tubule and the collecting duct
- the water that enters the medulla is rapidly removed by the capillary network and water is therefore conserved
- the urine released from the collecting ducts would be concentrated and would have a small volume
- the reason for the low water potential in the medulla is because of the countercurrent multiplier system occurring in the Loop of Henle
- as the filtrate moves into the ascending limb of the loop of Henle sodium ions are actively transported out of the ascending limb and into the medulla
- this means that there is a high concentration of solutes and therefore a low water potential in this area of the medulla, the highest concentration of solutes and therefore the lowest water potential being found at the apex of the loop of Henle
- this leads to water being reabsorbed from the filtrate along the entire length of the descending limb of the loop of Henle into the medulla because of the water potential gradient that has been produced along its entire length
- water is also reabsorbed from the urine in the collecting duct into this area of the medulla again because of the water potential gradient that has been produced
- some animals are adapted to a dry environment by having a long loop of Henle which leads to more water being reabsorbed
12
Q
questions related to ‘describe how energy is released from ATP’ [3]
A
- ATP is hydrolysed into ADP and phosphate in a reaction catalysed by ATPase releasing 30.6kJ of energy
13
Q
questions related to ‘explain how impulses are transmitted across a synapse’ [3]
A
- when an impulse reaches the synaptic knob this depolarises the membrane which leads to an influx of calcium ions into the synaptic knob
- the presence of calcium ions causes the secretory vesicles containing the neurotransmitters to migrate towards the presynaptic membrane
- at the presynaptic membrane the secretory vesicles fuse with the membrane and the neurotransmitter is released into the synaptic cleft by exocytosis
- the neurotransmitter diffuses across the synaptic cleft and binds to receptors on the post synaptic membrane causing the depolarisation of the post synaptic membrane
14
Q
questions related to ‘describe what is meant by the term facultative anaerobes’ [2]
A
- facultative anaerobes GROW best when they use the available OXYGEN to carry out aerobic respiration but can also carry out anaerobic respiration if oxygen is not available
15
Q
questions related to ‘how would you use the dilutions produced to carry out a viable count’ [4]
A
- each dilution would require its own sterile nutrient agar plate
- 1cm^3 of the dilution would be transferred onto the nutrient agar plate and then spread with a sterile spreader
- the nutrient agar plate would then be re-covered and it would then be incubated at 30°C for 3 days
- colonies would then be counted on the assumption that one colony is equal to one original viable cell
16
Q
questions related to ‘explain the term carrying capacity’ [2]
A
- the MAXIMUM size of the population that can be SUPPORTED INDEFINITELY by a particular environment
17
Q
questions related to ‘describe how the principles of a batch culture fermenter are applied in the industrial production of penicillin’ [10]
A
- in batch culture fermenters, all of the materials are present at the start
- the fermenter must be kept sterile so when the Penicillium culture is added it will only be this microorganism that grows
- as well as the Penicillium culture, the fermenter will also contain a sterile nutrient medium the microorganisms can use and a pH buffer to maintain the optimum pH for the Penicillium
- optimum temperatures also need to be maintained using a water jacket to maximise the growth in the population of Penicillium and therefore the production of penicillin
- the penicillium also requires oxygen and this is obtained from the air outside the fermenter, the air passes through filters to ensure it is sterile
- finally, some form of mixing is required to ensure that all the penicillium has access to oxygen and nutrients
- during the growth phase the glucose in the sterile nutrient medium will be depleted
- as penicillin is a secondary metabolite it is produced during the stationary phase
- once the penicillin is produced it is isolated from the Penicillium by filtering
- the penicillin is then extracted from the solution
18
Q
questions related to ‘how do you accoubt for the low rate of population growth in the first three hours of the experiment’ [2]
A
- initially, the microorganism is switching on the genes required for the new nutrient source which will take time
- the synthesis of the proteins coded for by these genes will also take time
- the cells will then need to digest then absorb the nutrients; grow in size and their DNA will need to be replicated before mitosis can begin
- all of these steps require time
19
Q
questions related to ‘differences betwen primary and secondary succession’
A
- primary succession involves the colonisation of an area where no living organism has lived before
- while secondary succession involves the colonisation of an area where living organisms previously lived
20
Q
questions related to ‘problems of fish farming’
A
- eutrophication caused by the fishes waste products and the waste food
- as the fish are kept so closely together diseases are more likely to spread throughout the population and they may also infect wild fish
- to prevent diseases and parasites spreading through the population, the fish farmer can apply pesticides and treat the fish with antibiotics which cause their own problems
- as well as the high costs these treatments place on the fish farmers, they also cause other problems
- the introduction of pesticides can harm other marine organisms directly as well as entering food chains which can lead to bioaccumulation causing harm particularly to top predators
- the overuse of antibiotics can lead to the development of populations of antibiotic resistant bacteria
- finally some alleles from the farmed fish may find their way into the wild fish population leading to the genetic contamination of the wild fishes genome
21
Q
questions related to ‘crops to increase nitrate levels’
A
- leguminous plants could be planted as they contain the nitrogen fixing bacterium Rhizobium in their root nodules
- the Rhizobium converts nitrogen gas into ammonium
- the ammonium can be converted into amino acids and used for the growth of the plant
- these crops are then allowed to decay in the soil or ploughed into the soil
22
Q
questions related to ‘eutrophication’
A
- plants GROWING MORE because of the extra nitrate fertiliser
- this means there is more competition for LIGHT and more of the plants DIE
- the extra dead plants are decomposed by bacteria whose population increases as they have a greater supply of organic material
- the decomposition process in bacteria requires oxygen for respiration which leads to a lowering of oxygen levels in the water and therefore the death of the fish
23
Q
technical terms need to be used and spelt correctly
A
24
Q
many lost marks due to carelessness with ‘simple’ maths
A
25
important to give detailed answers
26
diagrams only get marks if they have been annotated in detail
27
primary succession:
- colonisation of an area where nothing has been before (no mark)
- colonisation of an area where NO LIVING ORGANISM HAS LIVED BEFORE (mark)
28
gross primary production:
- the amount of energy produced by the plant (no mark)
- the rate of conversion of light energy into chemical energy by photosynthesis (mark)
- the rate at which the products of photosynthesis are formed (mark)
29
understand the difference between egestion and excretion
30
careful with language:
- cellulose cannot be digested by herbivores (no mark)
- herbivores are less efficient at digesting cellulose
31
- conservation is the preservation of wildlife (no mark)
- conservation is the PLANNED preservation if wildlife (mark)
32
conservation can maintain the GENE POOL of a species
33
conservation, if you are describing laws e.g conservation areas, fishing quotas etc then you must use the word LEGISLATION
34
gram +ve purple (mark)
gram -ve red (mark)
35
facultative / obligate anaerobes must mention oxygen for the mark
36
- anaerobic conditions encourage pathogenic bacteria (mark)
- anaerobic condition encourages bacteria / bad bacteria (no mark)
37
- body temperature encourages pathogenic bacteria (mark)
- body temperature encourages bacteria / bad bacteria (no mark)
38
ATP:
- nitrogenous base (mark)
- base (no mark)
- ribose/pentose sugar (mark)
- sugar (no mark)
39
- ATP is used for ALL reactions/organisms (mark)
- ATP is used for most reactions/organisms (no mark)
40
- ATP supplies or releases energy (mark)
- ATP produces energy (no mark)
41
- ATP can be used for muscle contraction (mark)
- ATP can be used for movement (no mark)
42
- NADP in photosynthesis
- NAD in respiration
43
- photosynthesis produces organic material or organic compounds (mark)
- produces nutrients (no mark)
- produces food (no mark)
44
- impulses move along neurones (mark)
- signal moves along neurones (no mark)
- prefer neurones rather than nerves
45
- if asked to compare, compare in same sentence
- remember comparison is similarities AND differences
46
Loop of Henle, use correct terms i.e counter current mechanism, water potential, renal filtrate, medulla etc
47
why does the urea concentration increase at bottom of loop of Henle?
- water reabsorbed into MEDULLA AND THEN BLOOD so concentration of urea increase
48
- loop of Henle can be longer or shorter (mark)
- smaller or larger (no mark)
49
why do athletes produce more urea in their urine?
- high protein diet (no mark)
- high protein diet = excess amino acids = more deamination = more urea
50
collecting ducts, distal convoluted tubules - use correct terms i.e water potential gradient, osmosis, medulla etc
51
- legumes have root NODULES containing … (mark)
- legumes have roots containing … (no mark)
52
- bacteria divide or reproduce (mark)
- bacteria give birth (no mark)
53
lag phase:
- getting used to the environment (no mark)
- time to switch on the appropriate genes and synthesise the appropriate proteins for the environment (mark)
54
exponential growth:
- population doubles per unit time
55
decline phase:
- if population has gone above the carrying capacity (no mark)
- if population has exceeded the carrying capacity (mark)
56
oxidative phosphorylation:
- use correct terms:
• inter-membrane space
• H ions
• chemiosmosis
• electrochemical gradient
57
- suitable temperature required (mark)
- heat required
58
- cyanide INHIBITS respiration (marks)
- cyanide stops/blocks respiration (no marks)
59
- haemoglobin absorbs or has affinity for oxygen (mark)
- haemoglobin takes up oxygen (no mark)
60
nitrogen cycle:
- ‘nitrogen containing compounds’ is too vague (no marks)
- be specific e.g ammonium ions/ammonia/nitrites/nitrates/urea/uric acid/proteins/amino acids etc
61
- bacteria can be antibiotic resistant (mark)
- bacteria can’t be immune
62
- neurotransmitters are released by EXOCYTOSIS from the presynaptic membrane (mark)
- neurotransmitters are released from the presynaptic membrane (no mark)
63
- neurotransmitters DIFFUSE across the synaptic cleft (mark)
- neurotransmitters move across the synaptic cleft (no mark)
64
decarboxylation is the removal of carbon dioxide
65
dehydrogenation is the removal of hydrogen
66
action potentials:
- sodium ions/potassium ions (mark)
- sodium/potassium (no mark)
- ions diffuse in (mark)
- ions move in (no mark)
- ions move along concentration gradient (mark)
67
saltatory conduction:
- detailed explanation using the following phrases, no myelin at nodes, depolarisation can only happen at nodes, action potential jump from one node to the next, nerve impulse transmission faster
68
resting potential:
- when a nerve impulse is not being conducted or no action potential is being produced
69
- when discussing changes in the axon during action potential, use the term polarised and quote figures i.e -40mV
70
50% increase calculations are common
71
- pituitary (no mark)
- posterior pituitary (mark)
72
free living nitrogen fixing bacteria:
- Azotobacter (spelling correct) (mark)
73
- cell walls of bacteria affected by gram stain not cell membranes
74
- bacillus (mark)
- rod (no mark)
- spirillum (mark)
- spiral (no mark)
- coccus (mark)
- round (no mark)
75
- ribulose bisphosphate is regenerated FROM triose phosphate (mark)
- triose phosphate is regenerated into ribulose bisphosphate (no mark)
76
carbon dioxide is FIXED during photosynthesis
