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AQA A Level Biology > Paper 2A part 1 > Flashcards

Paper 2A part 1 Flashcards

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1
Q

.Organisms in an ecosystem rely on a source of ____ to carry out all their activities

A

energy

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2
Q

.The ultimate source of energy is the ___ , which plants conserve as ______ energy

A

sunchemical

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3
Q

.Most plants use sunlight in making ______________

A

organic compounds

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4
Q

.An example of an organic compound made by plants using sunlight is _____, which is used by plants as ____________

A

Sugarrespiratory substrates

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5
Q

When plants use sunlight to form organic compounds, other biological molecules formed (apart from sugar) make up what?

A

the biomass of plants, that is the means by which energy is passed between other organisms

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6
Q

.Organisms can be divided into ___ groups according to how they obtain their energy and nutrients, these are: what?

A

3producers, consumers and saprobionts

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7
Q

What are producers?

A

photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions

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8
Q

What are consumers?

A

organisms that obtain their energy by feeding on (consuming) other organisms rather than using the energy of sunlight directly

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9
Q

Are animals consumers?

A

yes

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10
Q

Those that directly eat producers are called _____, because?

A

Primary consumersthey are the first in the chain of consumers

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11
Q

Those animals easting primary consumers are called ______ consumers and those eating secondary consumers are called _____ consumers.

A

SecondaryTertiary

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12
Q

Secondary and tertiary consumers are usually predators but they may also be …

A

scavengers or parasites

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13
Q

What are saprobionts

A

(decomposers) are a group of organisms that break down the complex materials in dead organisms into simple ones. In doing so, they release valuable materials and elements in a form that can be absorbed by plants and so contribute to recycling.

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14
Q

What is the majority of saprobionts work carried out by?

A

The majority of this work is carried out by fungi and bacteria.

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15
Q

What is a food chain?

A

.A food chain described a feeding relationship in which the producers are eaten by primary consumers, these in turn are eaten by secondary consumers, which are then eaten by tertiary consumers

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16
Q

What can be seen in long food chains?

A

In a long food chain the tertiary consumers may in turn be eaten by further consumers called quaternary consumers

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17
Q

What is each stage in a food chain referred to as?

A

A trophic level

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18
Q

.The arrows on food chain diagrams represent what?

A

The direction of energy flow

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19
Q

.In reality, most animals do not rely on a single food source.Within a single habitat many food chains will be linked together to form awhat?

A

Food web

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20
Q

.It is likely that all organisms within a ____, even within an ________, will be liked to others in the food web

A

habitatecosystem

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21
Q

Define herbivore

A

An animal which eats plants (producers) and is therefore a primary consumer

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22
Q

Define carnivore

A

An animal that eats animals and may therefore be a secondary or a tertiary consumer

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23
Q

Define omnivore

A

An animal that eats both plants and animals and is therefore a primary consumer and also a secondary or a tertiary consumer

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24
Q

What is biomass?

A

.Biomass is the total mass of living material in a specific area at a given time

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25
Q

.The fresh mass is quite easy to assess, but the presence ______________ makes it unreliable

A

of varying amounts of water

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26
Q

How do you get over the problems that arise with measuring fresh biomass?

A

.Measuring the mass of carbon, or dry mass

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27
Q

What are the drawbacks of measuring dry biomass?

A

because the organism must be killed it is usually only made on a small sample, and this sample may not be representative

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28
Q

How is biomass measured?

A

.Biomass is measured using dry mass per given area, in a given time.It is measured in grams per square metre (g m-2) when an area is being sampled, for example on grassland or a sea shore.It is measured in grams per cubic metre (g m-3) when a volume is being sampled, for example in a pond or ocean

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29
Q

The chemical energy store in dry mass can be estimated using what?

A

Calorimetry

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30
Q

What happens in bomb calorimetry?

A

.In bomb calorimetry, a sample of dry material is weighed and is then burnt in pure oxygen within a sealed container called a bomb, the bomb is surrounded by a water bath and the heat of combustion causes a small temperature rise in this water. We know how much energy is required to raise the temperature of 1g of water by 1’C, so if we know the volume of the water we can calculate the energy released from the mass of burnt biomass in units such as kJkg-1

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31
Q

Suggest how you could determine the dry mass of a sample of plant material

A

Heat till all the water evaporates then weigh it, heat it again and weigh, repeat this till there is no change in mass and that is the mass of the dry mass

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32
Q

Give one reason why not all the light energy falling on the producers is used in photosynthesis.

A

Some will be reflected

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33
Q

What percentage of the Sun’s energy is captured by plants or algae?

A

1-3%

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34
Q

Most of the Sun’s energy is not converted to organic matter by photosynthesis. Explain why.

A

Not all light will hit a chlorophyll moleculeNot all wavelengths of light can be absorbed and used for photosynthesisOver 90% of the Sun’s energy is reflected back into space by clouds/dust or absorbed by the atmosphereLimiting factors, e.g. low temperature, may reduce the rate of photosynthesis

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35
Q

Gross is?

A

the total amount before anything is deducted.

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36
Q

Net is?

A

the amount remaining after certain adjustments have been made for debts, deductions or expenses

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37
Q

What is gross primary production (GPP)?

A

The total quantity of energy that plants in an area/volume convert into organic matter (biomass) in a given time

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38
Q

Respiration uses how much of GPP?

A

20-50%

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39
Q

What is net primary productivity?

A

the energy left over from GPP after some has been sed by respiration, it is to be stored

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40
Q

Net primary productivity =

A

gross primary products – respiratory losses

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41
Q

Why is mean GPP different between different environments?

A

Temperature variationsConstant/ no / little seasonal change Higher plant densityHigher water availability / rainfall Evergreen / deciduous More light (energy) / intensity

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42
Q

What is NPP used for? How much is used by who?

A

• The NPP is available for plant growth and reproduction.• It can also be passed along the food chain to other trophic levels.• However, <10% is used by primary consumers for growth.• Secondary/tertiary consumers transfer about 20% of the energy from their prey to their own biomass.

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43
Q

Why is their energy loss in food chains?

A
  1. Not all of the organism is eaten.2. Not all is digested, and is lost as faeces.3. Some lost in excretory materials, such as urine.4. Heat loss to the environment.
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44
Q

N = I – (F+R), in this equation what does each letter represent?

A

N = Net productionI = Chemical energy store of ingested foodF = Energy lost in faeces and urineR = Energy lost in respiration

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45
Q

Finish the equation, N=

A

I – (F+R)

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46
Q

Why can food chains only support up to 5 trophic levels?

A

Food chains are extremely inefficientInsufficient energy available to support a large population at higher trophic levelsThe totally biomass is less at each trophic levelTherefore the amount of energy available is less

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47
Q

How could we improve the efficiency of a food chain?

A

Shorten it

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48
Q

From the information, ‘1 hectare of land can produce 0.3 tonnes of beef (1,200 steaks) or 7.5 tonnes of wheat grain (11,500 loaves of bread)’, what can you infer?

A

That the same piece of land can make different amounts of food, depending on what is being grown

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49
Q

Intensive farming can be hugely ….

A

… profitable

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50
Q

Intensive farmers aim to …

A

… produce the maximum yield with the minimum input

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51
Q

.The focus of intensive rearing is to …

A

… convert the smallest amount of food energy into the greatest quantity of animal mass

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52
Q

How can intensive farmers increase the efficiency of mass of food to mass of animal?

A

.Minimise energy loss.This allows more food energy taken in by the animals to be converted to body mass.This is then passed along the food chain to human (this means more profit)

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53
Q

What measures may farmers take to improve the energy-conversion rate in the livestock (animals) they rear?

A
  1. Limit movement – less movement = less energy lost during exercise2. Heat the environment around the animals (in barns) – they don’t have to waste energy keeping themselves warm3. Control diet – food is high in protein and low in fibre as this builds muscle which means more meat to eat4. Remove predators and pests – sick animals use energy fighting infections
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54
Q

What are the features of intensive rearing?

A
  1. Efficient energy conservation2. Low cost food production3. Inferior food quality4. Less space required5. Safety – easier to control as it’s a small area6. High spread of disease7. Over use of drugs8. Poor animal welfare9. High pollution10. Reduced genetic diversity11. High use of fossil fuels12. Chickens have their beaks cut so they are unable to peck and injure each other
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55
Q

Points for intensive farming

A

Efficient energy conversion – restricting wasteful energy loss means more energy is passed on to humans along the food chainLow cost – foods such as meat, eggs and milk can be produced more cheaply than by other methods, with more and more families now reliant on foodbanks tis could be helpfulUse of space – intensive rearing uses less land which efficient production meaning that less of the country side is required for agriculture, leaving more as natural habitatsSafety – small, concentrated units are easier to control and regulate, it is easier to prevent infections being introduced from the outside and to isolate the animals if this happensFood is essential for life – with an ever expanding human population, there is pressure to produce more and more food intensively

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56
Q

Points against intensive farming

A

Quality of food – the taste of foods produced by intensive rearing is inferior to food produced less intensivelyDisease – large numbers of animals living in close proximity means that infections can spread easily amongst them. To control this, the animals are regularly given antibioticsUse of drugs – over-use of antibiotics to prevent disease in animals has led to the evolution of antibiotic resistance. This resistance can be transferred to bacteria that cause human diseases, making their treatment with certain antibiotics ineffective. Other drugs may be given to animals to improve their growth or reduce aggressive behaviour. These may alter the flavour of the food or pass into the foods and then into humans, affecting their healthAnimal welfare – the larger intensive farms have the resources to maintain a high level of animal welfare and are most easily regulated. However, animals are kept unnaturally and this may cause stress, resulting in aggressive behaviour. This may cause them to harm each other or themselves, which is why battery chickens are de-beaked. Restricted movement can lead to osteoporosis and joint pain. The wellbeing of animals may be sacrificed for financial gainPollution – intensively reared animals produced large concentrations of waste in a small area. Rivers and ground water may become polluted. Pollutant gases may be dangerous and smell. Large intensive farms may have their own disposal facilities that enable them to treat waste more effectively than smaller non-intensive farms.Reducing genetic diversity – selective breeding is used to develop animals with high energy conversion rates and a tolerance of confined conditions. This reduces the genetic diversity of domestic animals, resulting in the loss of genes that might later prove to have been beneficial.Use of fossil fuels – high energy conversion rates are possible because fossil fuels are used to heat the buildings that house the animals, in the production of the materials in the buildings (especially cement) and in the production and transportation of animal feeds. The carbon dioxide emitted increases global warming.

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57
Q

What can farmers do to increase productivity?

A

 Reduce energy loss Shorten food chains Use fertilisers

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58
Q

List the things that plants need to grow:

A

.Water.Light.Carbon dioxide.Mineral ions

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59
Q

• Most farming is an intensive process.• Farmland is used repeatedly, sometimes several times a year, to rear animals or grow crops.• Plants take up the nutrients and are then harvested.Referring to the nitrogen cycle, explain the effect this would have on the ecosystem.

A
  1. Ammonification is reduced as less plants and dying and decaying• In natural ecosystems, dead matter remains and it is allowed to decompose.• On farmland mineral ions are continually removed from the soil, leaving it deficient.
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60
Q

How do farmers counteract reduced ammonification?

A

farmers apply fertiliser to their crops

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61
Q

What are the two types of fertilisers?

A

Organic and inorganic (natural and artificial)

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62
Q

Describe organic fertiliser

A

• Dead and decaying plant and animal matter• Animal excreta such as manure and slurry• Bone meal

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63
Q

Describe inorganic fertiliser

A

• Mined from rock• Converted to suitable form• Blended to suit a particular crop• Includes:- Nitrogen- Phosphorous- Potassium

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64
Q

The best yields are achieved when a combination of …

A

… the 2 types of fertilisers are applied

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65
Q

describe and explain the shape of the graph for fertiliser use (incerasing volumes of fetilser)

A

The yield increases until an optimum mass is reach and then it decreases, this is because increasing the nitrogen content of the soil increases the productivity of the crop. After an optimum amount of nitrogen is supplied the yield decreases, this is due to the water potential. Increased nitrates in the soil reduce the water potential which will eventually draw water out of the plant by osmosis.

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66
Q

What do plants need nitrogen for?

A

Plants need nitrogen for amino acids, DNA nucleotides and ATP which are all essential for plant growth

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67
Q

• Outline a method that would scientifically test the effect of nitrogen on plant growth.• Include independent, dependent and control variables.

A
  1. Gather 11 plant seeds of the same species2. Place them in equal volumes of soil in separate pots3. Make up 11 batches of fertiliser, one with 0% nitrogen, one with 10% nitrogen, etc. all the way up to one with 100% nitrogen4. Fertilise each plant with different fertilizers but of the same volume (labelling each pot with the fertiliser used)5. Water the plants throughout the week6. Measure how much each plant grew at the end7. Draw a conclusion from your resultsIV = the concentration of nitrogen in the fertiliserDV = the growth of the plantsCV = temperature, light intensity, water for watering, volume of soil, volume of fertiliser, type of plant, humidity, concentration of other things in the fertiliser (keep the ratio of other aspects of the fertiliser the same)
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68
Q

What is leaching?

A

.Rainwater dissolves soluble nutrients and washes them deep into the soil.The plant roots are unable to reach and absorb them.The leached nutrients then find their way into watercourses and drinking water

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69
Q

What a can excessive nitrates lead to?

A

.Excessive nitrates can prevent efficient O2 transport in babies and has links to stomach cancer.It can also lead to eutrophication

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70
Q

What is eutrophication? Include a description and explanation of the process in detail

A

.Watercourses tend to contain low levels of nitrates.This limits the growth of algae and bacteria.Farmers apply fertilisers to their fields.Rainfall dissolves the nutrient ions.These dissolved nutrient ions are leached into watercourses.Nutrient content is no longer a limiting factor for algae and bacteria.Both populations grow.Algae grow on the water surface, forming an algal bloom.The algae absorb light and prevent it from reaching the bottom of the water body.Light is now a limiting factor for plants below the surface.The algae and plants below the surface die.The lack of dead organic matter is no longer a limiting factor for saprobionts.Their population increases.Their growing population requires more oxygen.Oxygen concentration reduces.More nitrates are released from the decaying organisms.Oxygen is now the limiting factor for organisms that aerobically respire.They die.Now less competition for anaerobically respiring organisms.Their population increases.They continue to decompose dead material releasing further nitrates and toxins (hydrogen sulphide).They water becomes putrid

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71
Q

Equations for photosynthesis

A

Carbon dioxide + water  light  glucose + oxygen6CO2 + 6H2O  C6H12O6 + 6O2

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72
Q

What is the importance of photosynthesis?

A

.The energy all living things rely on came from photosynthesis.This includes the food we need for respiration and the fuel we use (wood, oil, gas, coal).It also produces oxygen.During photosynthesis chlorophyll absorbs and converts light energy into chemical energy.The plant then uses these molecules to produce ATP during respiration.Non-photosynthetic organisms feed on the molecules produced by plants and use them to make ATP during respiration.Plant cells are perfectly adapted to carry out photosynthesis

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73
Q

Label a plant cell

A

IDK google it

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74
Q

Label a leaf cross section

A

IDK google it

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75
Q

What makes leaves good at photosynthesis?

A

.Large surface area – absorb maximum light.Leaf arrangement – minimises leaves overlapping.Thin – most light absorbed by the first few micrometres, efficient gas exchange.Transparent cuticle and epidermis – allows light into upper mesophyll.Palisade cells are long and thin and tightly packed – max light absorption.Many stomata – efficient gas exchange, short diffusion distance.Stomata open and close in response to light intensity – reduces transpiration.Many air spaces in lower mesophyll – allows rapid gas exchange.Xylem and phloem – allow transport around the plant

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76
Q

Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants. (5 marks)

A
  1. Protein / amino acids / DNA into ammonium compounds / ammonia / urea2. By saprobionts;3. Ammonium / ammonia into nitrite;4. Nitrite into nitrate;5. By nitrifying bacteria / microorganisms;6. Nitrogen to ammonia / ammonium;7. By nitrogen-fixing bacteria / microorganisms in soil;
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77
Q

Mutualism is …

A

… the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other.

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78
Q

Example of mutualistic relationship

A

mycorrhizae and plants, birds and flowers

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79
Q

Describe the role of mycorrhizae

A

.Mycorrhizas are beneficial fungi growing in association with plant roots.They exist by taking sugars and amino acids from plants ‘in exchange’ for moisture and nutrients gathered from the soil by the fungal strands.The mycorrhizas greatly increase the absorptive area of a plant, acting as extensions to the root system.They hold water close to the roots making the plant more drought tolerant.Phosphorus is often in very short supply in natural soils.It would require a vast root system for a plant to meet its phosphorus requirements unaided.Mycorrhizas are crucial in gathering this element in uncultivated soils.Neither fungi nor plants could survive in many uncultivated situations without this mutually beneficial arrangement.Mycorrhizas also seem to confer protection against root diseases

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80
Q

Describe how the relationship between mycorrhizae and plants can be described as a mutualistic one. (4 marks)

A

 Mycorrhizae gain glucose Amino acids Plants gain increased drought resistance Larger root surface area So increase absorption of water and minerals

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81
Q

What is the law of limiting factors –

A

When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply

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82
Q

The rate of photosynthesis in a plant can be limited by:

A

.Light intensity.Availability of water.Availability of carbon dioxide.Availability of chlorophyll.Temperature

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83
Q

Draw and annotate graphs showing how the following affect rate of photosynthesis:.Light intensity.Availability of water.Availability of carbon dioxide.Availability of chlorophyll.Temperature

A

IDK google it or something

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84
Q

what are the 3 main stages in photosynthesis?

A

.Capturing of light energy.The light-dependent reaction.The light-independent reaction

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85
Q

What is oilrig?

A

Oxidation is loss, reduction is gain

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86
Q

Where does the light-dependent reaction occur?

A

In the thykaloid membrane

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87
Q

What does the light-dependent reaction provide?

A

.Provides: Energy, hydrogen, and oxygen

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88
Q

What is the type of chlorophyll common to all plants?

A

Chlorophyll a

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89
Q

Ionised meaning

A

the addition or removal of electrons to create an ion

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90
Q

In the light-dependent reaction, does the chlorophyll get oxidised or ionised?

A

oxidised

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91
Q

What are the two photosystems?

A

P680 and P700Or photosystem 2 and 1

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92
Q

In the light dependent reaction, a ____ of electrons get excited, always _____

A

pairpairs

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93
Q

First molecule to accept the molecule is the ________ in the light-dependent reaction

A

primary acceptor molecule

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94
Q

What is photophosphorylation?

A

the addition of phosphate because of light

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95
Q

Going through two photosystems allows the electrons to be at the same energy level as ____

A

NADP+

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96
Q

NADP+ is …

A

… a coenzyme that accepts electrons and protons

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97
Q

Reduced NADP+ is …

A

… NADPH

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98
Q

What happens in the photolysis of water?

A

H2O turns into H+, e-, and O22H2O  O2 + 4H+ + 4e-NADP gains the H+ also

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99
Q

Photosynthesis equation

A

6CO2 + 6H2O  C6H12O6 + 6O2

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100
Q

.There are three main stages involved in photosynthesis, what are they?

A
  1. Capturing of Light Energy2. The Light-Dependent Reaction3. The Light-Independent Reaction
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101
Q

.In the light-dependent stage of photosynthesis, the majority of reactions involve molecules being _____ and _______

A

oxidisedreduced

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102
Q

What is oxidation?

A

.Loss of HYDROGEN.Loss of ELECTRONS.Gain of OXYGEN.Energy given out

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103
Q

What is reduction?

A

.Gain of HYDROGEN.Gain of ELECTRONS.Loss of OXYGEN.Energy taken in

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104
Q

Oxidation and reduction always happen together, what is this called?

A

REDOX reactions

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105
Q

Where does the LDR occur?

A

.Occurs on the thylakoid membranes

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106
Q

What does the LDR provide?

A

Provides energy, hydrogen, and oxygen

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107
Q

LDR catches light, which is used for what?

A
  1. To combine ADP + Pi (inorganic phosphate) to form ATP2. To split water into H+ (protons) and OH- ions – photolysis
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108
Q

What is chlorophyll a?

A

.Type of chlorophyll common to all plants.Absorbs light mainly in the red-orange and blue-violet part of the visible spectrum.Accessory pigments absorb energy that chlorophyll a does not absorb, e.g. chlorophyll b

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109
Q

.When a photon of light is absorbed by chlorophyll a, it boosts the energy levels of what?

A

a pair of chlorophyll electrons

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110
Q

What is photoionisation?

A

.When a photon of light is absorbed by chlorophyll a, it boosts the energy levels of a pair of chlorophyll electrons.These excited electrons leave the chlorophyll molecule.As a result the chlorophyll molecule becomes ionised (addition or removal of electrons to create an ion).This process is called photoionisation

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111
Q

In photoionization, what has been oxidised, and what has been reduced?

A

.As the chlorophyll has lost electrons it has been oxidised.As the electron carrier has gained electrons it has been reduced

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112
Q

T or F, Oxidation is the loss of electrons

A

T

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113
Q

T or F, LDR takes place in the stroma

A

F (thylakoid membranes)

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114
Q

T or F, Chlorophyll a absorbs green wavelengths of light

A

F (reflects it)

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115
Q

T or F, Photons of light cause electrons to leave chlorophyll molecules

A

T

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116
Q

T or F, Photoionisation is the loss of electrons due to light

A

T

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117
Q

What are photosystems?

A

.Functional and structural protein complexes involved in photosynthesis

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118
Q

What do photosystems do?

A

.Together they:- absorb light- transfer energy and electrons

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119
Q

Where are photosystems found?

A

.Photosystems are found in the thylakoid membranes of plants

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120
Q

What are the two photosystems and how can you tell them apart?

A

.P700 (PSI) – red light.P680 (PSII) – orangey light

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121
Q

After photoionisation, what happens to the electrons?

A

.The excited electrons are taken up by an electron carrier.The excited electrons move along the ETC from PS2

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122
Q

What are carrier molecules?

A

.The carrier molecules are a series of proteins found in the thylakoid membrane

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123
Q

What makes the electrons move down the ETC?

A

.Each carrier has a slightly higher affinity for the electrons than the last.This draws the electrons along the chain to PS1

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124
Q

Why do electrons lose energy down the ETC?

A

.A series of redox reactions happen between the chlorophyll and then the carrier’s.One carrier donates – oxidised.The next accepts – reduced.Each carrier is at a slightly lower energy level than the previous one in the chain.Therefore the electrons lose energy at each stage

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125
Q

What happens to the energy lost by electrons in the ETC?

A

.The energy that is released by the electrons is used to synthesise ATP

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126
Q

What is the formation of ATP called during photosynthesis?

A

photophosphorylation

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127
Q

As the electrons move along the chain they pass through 2 photosystems, why?

A

.Further absorbed light energy increases the energy of the electrons.This makes the energy sufficient for the reduction of NADP+ to NADPH

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128
Q

What is NADP+?

A

nicotinamide adenine dinucleotide phosphate is a coenzyme that accepts electrons and protons

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129
Q

What do coenzymes do?

A

help enzymes to function

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130
Q

.NADP+ is the final acceptor in the chain and therefore what happens to it?

A

It becomes reduced NADP+ (NADPH)

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131
Q

What reduces NADP+ to NADPH?

A

The electrons and protons

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132
Q

.The NADPH stores the electrons and protons until when?

A

they are transferred into the light-independent reaction

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133
Q

.Every molecule of NADPH formed in the LDR needs what?

A

2 electrons from PSI

134
Q

.Every molecule of NADPH formed in the LDR needs 2 electrons from PSI, what replaces those lost electrons? and those ones?

A

.These electrons are replaced by those from PSII.These are replaced by the electrons from photolysis

135
Q

T or F, Photosystems are protein complexes that absorb light found in thylakoid membranes

A

T

136
Q

T or F, Excited electrons move from PS1 to PS2

A

F - from PS2 to PS1

137
Q

T or F, Excited electrons move along the electron transport chain due to gravity

A

F - Each carrier has a higher affinity for e- compared to the last

138
Q

T or F, As electrons move along the electron transport chain they gain energy

A

F - Loose energy, it is used to phosphorylate ADP, forms ATP

139
Q

.When the light struck the chlorophyll, ___ electrons were lost

A

two

140
Q

When electrons are lost from the chlorophyll, how are they replaced?

A

.They are replaced by the other set of reactions in the light dependent stage

141
Q

If electrons are not replaced in the chlorophyll what happens?

A

.These need to be replaced or the chlorophyll can no longer absorb light energy

142
Q

.Water molecules are split using light energy absorbed by __________

A

chlorophyll a

143
Q

.When chlorophyll a absorbs light it loses electrons and becomes _____ ______ (electrons carry a negative charge), chlorophyll is now _______

A

positively chargedoxidised

144
Q

Is photolysis fully understood?

A

no

145
Q

Photolysis equation?

A

2H2O  O2 + 4H+ + 4e-

146
Q

What is photolysis?

A

break down of water using light

147
Q

.Proton + electron =

A

hydrogen atom

148
Q

.A hydrogen ion is formed when a hydrogen atom loses its what?

A

electron

149
Q

hydrogen ion/proton symbol

A

H+

150
Q

The electrons produced in photolysis, what are they used for?

A

to reduce the chlorophyll molecule – restoring the electrons it had lost

151
Q

Is oxygen produced in photolysis? Wheat is is produced as and used for?

A

.The oxygen produced is a by-product which is either used in respiration, or leaves the cell

152
Q

Why are the hydrogen ions from photolysis so important?

A

.The hydrogen ions are taken up by the electron carrier – NADP (nicotinamide adenine dinucleotide phosphate).NADP is also the final acceptor of the pair of electrons released at the beginning of the light-dependent stage.Along with the ATP formed earlier, reduced NADP is vital for the next stage of photosynthesis – the light-independent stage

153
Q

T or F, NADP is the final acceptor on the electron transport chain

A

T

154
Q

T or F, NADPH is reduced NADP

A

T

155
Q

T or F, When chlorophyll loses electrons it becomes more negatively charged

A

F - e- carry a negative charge so their loss results in chlorophyll becoming more positively charged

156
Q

T or F, Hydrogen ions have a proton and an electron

A

F - proton (H+) only

157
Q

T or F, 5. Electrons released during photolysis are used to reduce chlorophyll

A

T

158
Q

In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5 marks)

A
  1. Light (energy) excites / raises energy level of electrons in chlorophyll;2. Electrons pass down electron transfer chain;3. (Electrons) reduce carriers / passage involves redox reactions;4. ETC / role of chain associated with chloroplast membranes / in thylakoids / grana;5. Energy released / carriers at decreasing energy levels;6. ATP generated from ADP and phosphate / Pi / phosphorylation of ATP;
159
Q

Label a chloroplast

A

google it idk

160
Q

What is a chloroplast?

A

.Photosynthesis organelles.2-10µm in length and 1µm in diameter.The chloroplast envelope is a double plasma membrane that surrounds the organelle.It is highly selective

161
Q

What are thykaloids?

A

.Thylakoids are discs that contain chlorophyll

162
Q

What are grana?

A

.The grana are stacks of thylakoids

163
Q

.Some thylakoids have tube shape extensions that join with the thylakoids in another grana, what are they called?

A

intergranal lamellae

164
Q

What are intergranal lamellae?

A

tube shape extensions that join with the thylakoids in another grana

165
Q

Were does the LDR take place?

A

Thykaloids

166
Q

What is the stroma?

A

.The stroma is a fluid-filled matrix around the grana where the light-independent stage takes place

167
Q

What other functions are found in the stroma

A

starch grains

168
Q

Function of Granal membranes

A

Provide a large surface area for chlorophyll, electron carriers and enzymes to attach

169
Q

Function of A network of proteins in the grana hold the chlorophyll in a specific way

A

Allow maximum light absorption

170
Q

Function of The fluid in the stroma contains the enzymes

A

Needed for the light-independent stage of photosynthesis, as the chloroplast is membrane bound it allows it to maintain the optimum enzyme concentration

171
Q

Function of Chloroplasts contains DNA and ribosomes

A

Can quickly and easily manufacture proteins needed for photosynthesis

172
Q

Function of The granal membranes have ATP synthase channels

A

Catalyse the production of ATP, also selectively permeable

173
Q

Function of Stroma surrounds the grana

A

So products from the LDR easily diffuse into the stroma for the LIDR

174
Q

How Chloroplasts are Adapted to their Function

A
  1. Granal membranes provide a large surface area for chlorophyll, electron carriers and enzymes to attach2. A network of proteins in the grana hold the chlorophyll in a specific way to allow maximum light absorption3. The fluid in the stroma contains the enzymes needed for the light-independent stage of photosynthesis, as the chloroplast is membrane bound it allows it to maintain the optimum enzyme concentration4. Chloroplasts contain DNA and ribosomes so they can quickly and easily manufacture proteins needed for photosynthesis5. The granal membranes have ATPase channels which catalyse the production of ATP, also selectively permeable6. Stroma surrounds the grana so products from the LDR easily diffuse into the stroma for the LIDR
175
Q

.Photosynthetic organisms have _____ (light-absorbing molecules) that only absorb specific wavelengths of visible light, and they reflect others

A

pigments

176
Q

define absorption spectrum

A

The set of wavelengths absorbed by a pigment

177
Q

.The three key pigments involved in photosynthesis are, what?

A

chlorophyll a, chlorophyll b, and β-carotene

178
Q

Why do plants appear green?

A

.The reflected colours are the colours we see, this is why plants appear green, as they contain many chlorophyll a and chlorophyll b molecules, both of which reflect green light

179
Q

.The majority of photosynthetic organisms contain a range of types of pigments, which means they can what?

A

absorb energy from a variety of wave lengths

180
Q

.Two important groups of pigments in plants are what ?

A

chlorophylls and carotenoids

181
Q

.There are 5 main chlorophylls , what are they?

A

a, b, c, d, and bacteriochlorophyll (found in prokaryotes)

182
Q

.For plants, chlorophyll a and b are the what?

A

key photosynthetic pigments

183
Q

What do chlorophyll a and b absorb?

A

.They absorb the red and blue wavelengths

184
Q

Describe the structure of chlorophyll molecules

A

.Chlorophyll molecules have a hydrophobic tail, which inserts into the thylakoid membrane.Chlorophyll molecules have a porphyrin ring head, which absorbs light

185
Q

What is porphyrin ring head

A

circular group of atoms surrounding a magnesium ion

186
Q

.Both chlorophyll a and b absorb what?

A

light

187
Q

Chlorophyll a has a critical role in converting what to what?

A

light energy to chemical energy

188
Q

Where is chlorphyll a found?

A

All photosynthetic plantsAll photosynthetic algaeAll photosynthetic cyanobacteria

189
Q

Where is chlorophyll b found?

A

PlantsGreen algaeA few types of cyanobacteria

190
Q

.Since chlorophyll a is crucial to photosynthesis, all pigments which are used in addition to chlorophyll a are called _______

A

accessory pigments

191
Q

WHat does the term ‘accessory pigments’ include?

A

includes other chlorophylls, but also other classes of pigments like carotenoids

192
Q

Why are accessory pigments useful?

A

.By using accessory pigments, a broader range of wavelengths can be absorbed – and as a result increased energy can be captured from sunlight

193
Q

.Carotenoids are a key group of pigments, what do they absorb?

A

violet and blue-green light

194
Q

.Bright coloured carotenoids, like in fruit, are used often as adverts to attract animals , what does this help?

A

disperse the plants seeds

195
Q

.In photosynthesis, carotenoids not only help with the capture of light, but also what?

A

get rid of excess light energy.When a leaf is exposed to the sun, it is getting a large amount of energy, which can cause harm to the photosynthetic machinery.In chloroplasts, carotenoids help absorb excess energy, and then dissipate it as het

196
Q

.When a pigment absorbs a photon of light it then becomes excited, what does this mean?

A

it is no longer at its ground state and instead has extra energy

197
Q

What is excittion at a molecular level?

A

.Excitation at a subatomic level is when n electrons jumps up to a higher energy orbital

198
Q

Why are photons of different wavelengths needed in order to provide an energy boost which matches that gap?

A

.Only photons with the correct level of energy to bump an electron between orbitals can excite a pigment.This explains why pigments absorb differing wavelengths of light, the energy gaps in-between the orbitals differ between each pigment.This results in needing photons of different wavelengths in order to provide an energy boost which matches that gap

199
Q

List the types of photosynthetic pgmets

A

Chlorphyls, carotenoids, phycobilins

200
Q

List the types of chlorophylls and where they are found

A

.Chlorophyll-a (all photosynthetic plants but bacteria).Chlorophyll-b (green algae and higher plants).Chlorophyll-c (diatoms and brown algae).Chlorophyll-d (some red algae).Bacteriochlorophyll-a (green and purple bacteria).Bacteriochlorophyll-b (purple bacteria).Chlorobium chlorophyll-a (green sulphur bacteria).Chlorobium chlorophyll-b (green sulphur bacteria)

201
Q

List the types of carotenoids and where they are found

A

.Carotenes (higher plants and algae).Xanthophylls (higher plants and algae)

202
Q

List the types of phycobilins and where they are found

A

.Phycoerythrobilin (BGA and red algae).Phycocyanobilin (BGA and red algae)

203
Q

The role of chlorophyll photosynthetic pigments in photosynthesis

A

.Absorbs wavelengths below 480nm, and between 550nm and 700nm.In plants, only chlorophyll-a is in the photosynthetic reaction centres and consequently, it can be said to be the central photosynthesis pigment.The light energy which is absorbed by chlorophyll-b can be transferred efficiently to chlorophyll-a.Absorb light for use in photosynthesis[3]

204
Q

Role of carotenoids

A

.Secondary (accessory) light absorbing pigments, found in the thylakoid membrane.Absorb light at wavelengths that chlorophyll does not.They protect chlorophyll from photo-oxidation, then they transfer light energy to chlorophylls.In addition, they help in preventing photodynamic damage

205
Q

Role of phycobilins

A

.They absorb blue and blue-green wavelengths of light, the wavelengths that penetrate deep water.This allows red algae to carry put photosynthesis at deeper depths than other organisms

206
Q

Why is it useful for a plant to have several different photosynthetic pigments?

A

The pigments all absorb differing wavelengths of light, and so to be as efficient as possible with the absorption of light energy, the ability to absorb differing wavelengths is incredibly useful. In addition to this, carotenoids protect chlorophyll from photo-oxidation and prevent photodynamic damage.

207
Q

Why do shade tolerant plants have different pigments compared to full sun plants?[5]

A

Those plants who are exposed to large amounts of sunlight have more chlorophyll a, while those grown in the shade tend to make more chlorophyll b. This is because chlorophyll b is better at capturing low intensity light, and so is better and more efficient for plants growing in the shade.

208
Q

The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours. Use your knowledge of photosynthesis to describe these changes and explain why they occur.

A

A high concentration of carbon dioxide is linked with night. No photosynthesis occurs in the dark as light is required. In dark plants respire. In light plants use more carbon dioxide than they produce. There is a decrease in carbon dioxide concentration with height, as at ground level there are fewer and more animals.

209
Q

As the excited electrons move along the chain they pass through 2 photosystems. Why?

A

.Further absorbed light energy increases the energy of the electrons.This makes the energy sufficient for the reduction of NADP+ to NADPH

210
Q

What is non-cyclic photophosphorylation?

A

.Involves both photosystems

211
Q

What is cyclic photophosphorylation?

A

.Only uses PS1.Electrons are not passed to NADP.Go back to PS1 via electron carriers.Doesn’t produce NADP or oxygen.Produces small amounts of ATP

212
Q

What is Chemiosmotic theory?

A

.Involves the active transport of protons from the stroma into the thylakoid.The proton pump responsible for the movement of the protons is driven by the energy released from the excited electrons as they pass along the ETC.Protons then accumulate inside the thylakoid.This forms a concentration gradient.The protons then diffuse back across the membrane into the stroma.They can only go through chemiosmotic channels as the membrane is impermeable to protons.These channels are formed by an enzyme complex called ATP synthase (ATPase).The channels form small granules on the membrane surface so are called stalked granules.As the protons pass through the ATPase they cause changes to the structure of the enzyme.This enzyme then catalyses the combination of ADP with phosphate to form ATP

213
Q
  1. Explain how the pair of electrons move from chlorophyll to the electrons carrier system
A

Photoexcitation occurs, which results in excited electrons, meaning they are able to leave the chlorophyll molecule and are picked up by molecule A.

214
Q
  1. Explain how electrons lost from chlorophyll are replaced
A

Photolysis of water (2H2O  O2 + 4H+ + 4e-)

215
Q
  1. Explain how ATP is synthesised when electrons pass between electron carriers B and C
A

As electrons move from carrier to carrier energy is released through oxidation, reduction reactions, this energy is used to synthesise ATP from ADP + Pi. H+ moved into the lumen of the thylakoid using light energy. H+ diffuse out of thylakoid synthesising ATP.

216
Q
  1. In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5 marks)
A

Light energy excites electrons in the chlorophyll, the electrons pass down the electron transfer chain, reducing carriers through the use of redox reactions. The electron transfer chain is associated with chloroplast membranes in thylakoids. Energy is released at decreasing energy levels. ATP is generated from ADP and phosphate.

217
Q

Define detritivore

A

An organism that feeds on and breaks down dead plant or animal matter

218
Q

Explain why 1-3% of the suns energy is converted into organic compounds –

A

• Not all light will hit a chlorophyll molecule• Not all wavelengths of light can be absorbed and used for photosynthesis• Over 90% of the Sun’s energy is reflected back into space by clouds/dust or absorbed by the atmosphere • Limiting factors, for example low temperature, may reduce the rate of photosynthesis

219
Q

.In any ecosystem, plants synthesise organic compounds from what substance?This can be _____ or ____?

A

CO2atmospheric or aquatic

220
Q

.Most of the sugars synthesised by the plants are used as _______________, the rest is used to make other biological molecules

A

respiratory substrates

221
Q

What is biomass?

A

the mass of carbon or dry mass for tissue per area per time

222
Q

What is calorimetry?

A

.Measuring energy changes from combustion.Energy can be released in chemical reactions as heat energy.Measuring heat transfers is called calorimetry

223
Q

What is GPP?

A

The chemical energy store in plant biomass, in a given area/volume, in a given time

224
Q

What is NPP?

A

The chemical energy store in plant biomass after respiratory loses to the environment have been deducted

225
Q

NPP =

A

GPP - R

226
Q

.The NPP is available for what?

A

plant growth and reproductionit can also be passed along the food chain to other trophic levels

227
Q

concerning NPP,

A

10

228
Q

Secondary/tertiary consumers transfer about __% of the energy form their prey to their own biomass

A

20

229
Q

Energy Loss in Food Chains, where does it go?

A
  1. Not all of the organism is eaten2. Not all is digested, and is lost as faeces3. Some lost in excretory materials, such as urine4. Heat loss to the environment
230
Q

The Net Production of Consumers, equation and meaning of parts of equation

A

N= Net productionI= Chemical energy store of ingested foodF= Energy lost in faces and urineR= Energy lost in respirationN = I – (F+R)

231
Q

Why can food chains only support up to 5 trophic levels?

A

.It is not efficient enough, not enough energy to support a large population at higher trophic level, the total biomass is less at each trophic level, and therefore the amount of energy available is less

232
Q

Calculation Efficiency, what is it?

A

.Used to calculate the efficiency of the energy transfer between each trophic level.Measured in kilojoules per square metre per year (kJm-2year-1)

233
Q

Percentage efficiency =

A

(energy available after the transfer / energy available before the transfer) x 100

234
Q

How could we improve the efficiency of a food chain?

A

Shorten it

235
Q

.Energy enters an ecosystem in the form of what energy?

A

light

236
Q

In an ecosystem, how is energy moved throughout?

A

.Energy enters an ecosystem in the form of light energy.This is converted to chemical energy.This is then lost as heat

237
Q

.Nutrients are ____ through ecosystems

A

cycled

238
Q

Give three physical things which are recycled and converted into different forms in an ecosystem

A

.Carbon, nitrogen and phosphorus

239
Q

Nutrient cycles have the same key stages, what are they?

A
  • Nutrients absorbed as simple inorganic molecules by the producer- Producer converts it into complex organic molecules- Nutrient passed on during feeding relationships- After death, consumer broken down by saprobionts- Nutrient released back into the soul in its simplest form
240
Q

Photosynthesis equation

A

6H2O + 6CO2  light  C6H12O6 + 6O2

241
Q

What makes leaves good at photosynthesis?

A

.Large surface area – absorb maximum light.Leaf arrangement – minimises leaves overlapping.Thin – most light absorbed by the first few micrometres, efficient gas exchange.Transparent cuticle and epidermis – allows light into upper mesophyll

242
Q

Palisade cells are long and thin and tightly packed, why?

A

maximum light absorption

243
Q

Why do plants have many stomata?

A

efficient gas exchange, short diffusion distance

244
Q

Why does Stomata open and close in response to light intensity ?

A

reduces transpiration

245
Q

Why are there Many air spaces in lower mesophyll ?

A

Allows rapid gas exchange

246
Q

What is the stroma?

A

The stroma is a fluid filled matrix around the grana where the LIDR takes place.Other structures are found here, like starch grains

247
Q

granal members function

A

Large SA for chlorophyll, electron carriers and enzymes to attach

248
Q

Network of proteins in the grana hold the chlorophyll in a specific way function

A

Allow maximum light absorption

249
Q

Fluid in stroma hold enzymes function

A

Needed for LIDR

250
Q

Chloroplasts contains DNA and ribosomes function

A

Quickly and easily manufacture proteins

251
Q

Granal membranes have ATP synthase channels function

A

Catalyse the production of ATP, also selectively permeable

252
Q

Stroma surrounds grana function

A

Products from LDR easily diffuse into the stroma for LIDR

253
Q

What is the law of limiting factors?

A

When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply.

254
Q

The rate of photosynthesis in a plant can be limited by what?

A
  • Light intensity- Availability of water- Availability of carbon dioxide- Availability of chlorophyll- Temperature
255
Q

Draw and label a plant cell

A

check google or notes

256
Q

Draw and label a plant leaf cross section

A

check google or notes

257
Q

Draw and label a chloroplast

A

check google or notes

258
Q

Draw and annotate a graph displaying how the rate of bubbles produced vary as light intensity is increased

A

x axis: light intensityy axis: rate of bubbles producedCurve with decreasing gradient till a plateauCurve starts part of the way along x axis (compensation point)The initial oxygen produced by photosynthesis is used in respirationIncreasing light intensity increases the rate of bubbling (and photosynthesis)Increasing light intensity has no effect as rate of photosynthesis is limited by availability of carbon dioxide, water or chlorophyll

259
Q

What is the compensation point?

A

The point where the rate of photosynthesis and respiration are equal

260
Q

Draw and annotate a graph displaying how the rate of photosynthesis varies as light intensity is increased

A

x axis: carbon dioxide concentrationy axis: rate of photosynthesisCurve with decreasing gradient till a plateauCurve starts at the originIncreasing carbon dioxide concentration increases the rate of photosynthesis Increasing carbon dioxide has no effect as the rate of photosynthesis is limited by other factors

261
Q

Draw and annotate a graph displaying how the rate of photosynthesis varies as chlorophyll availability is increased

A

x axis: chlorophyll availibilityy axis: rate of photosynthesisCurve with decreasing gradient till a plateauCurve starts at the originIncreasing chlorophyll availability increases the rate of photosynthesis Increasing chlorophyll has no effect as the rate of photosynthesis is limited by other factors

262
Q

Draw and annotate a graph displaying how the rate of photosynthesis varies as temperature is increased

A

x axis: temperaturey axis: rate of photosynthesisAlmost an upside down x^2 curveCurve starts at the originTip of the curve is the optimumIncreasing temperature increases the rate of photosynthesis As the temperature reaches too high, it denatures the structures which photosynthesize – so the rate of photosynthesis drops

263
Q

What happens in chemiosmotic theory?

A

.Proton in the stroma moves into the thylakoid through the proton pump using active transport (ATP needed).Protons move down the concentration gradient through the Chemiosmotic channel, prompting the enzyme complexes at the bottom to change shape which catalyses the production of ATP

264
Q

Basic information about the LIDR

A

.Light is not directly required.The products of LDR (NADPH and ATP) are needed.In this reaction, CO2 is fixed.Occurs in the stroma.Steps were worked out by Melvin Calvin (Calvin Cycle)

265
Q

What stages can the LIDR be broken into? What happens in each?

A

Carbon Fixation – CO2 combined with RuBP to make 2GPs (glycerate 3-phosphate)Reduction – ATP and reduced NADP are used to reduce GP to TP (triose phosphate)Regeneration – RuBP is regenerated

266
Q

What are the steps of the calvin cycle (the LIDR)?

A
  1. CO2 diffuses through the stomata and into the stroma of the chloroplast2. The CO2 reacts with a 5-C compound ribulose biphosphate (RuBP)3. The reaction is catalysed by the enzyme ribulose biphosphate carboxylase (rubisco)4. The reaction between CO2 and RuBP forms a very unstable 6-C compound (3-keto-2-carboxyarabinitol 1, 5-biphosphate)5. The 6-C compound is immediately broken down into two 3-c glycerate 3-phosphates (GP)6. NADPH (from LDR) reduces 3-c GP into two 3-c triose phosphate (TP) using ATP (from the LDR)7. NADP is reformed and returns to the LDR8. TP has 2 uses:a. 5/6 – regenerates RuBP using ATP (from LDR)b. 1/6 - forms organic substances (carbohydrates (glucose), lipids, amino acids)
267
Q

Basic knowledge of rubisco

A
  • Rubisco is a very large molecule- 16 polypeptide chains with 8 active sites- Large amounts found in photosynthetic bacteria and green plants- The most abundant enzyme in the world
268
Q

How many times does the Calvin cycle need to turn to make 1 glucose molecule?

A

6 times

269
Q

How much ATP and rNADP is needed to make 1 glucose molecule in the calvin cycle?

A

This required 18 ATP and 12 rNADP

270
Q

What colour is DCPIP (2,6-dichlorophenolindophenol) ?

A

o Blue when oxidisedo Colourless when reduced

271
Q

What is DCPIP used for?

A
  • Used to measure the rate of photosynthesis- DCPIP acts as a substitute for NADP
272
Q

What is dehydrogenase?

A
  • Dehydrogenase is an enzyme that activates oxidation-reduction reactions- In photosynthesis it catalyses the reduction of NADP+/DCPIP
273
Q
  • Some weed killers contain ammonium hydroxide, what does this do?
A

Ammonium hydroxide stops the action of the dehydrogenase

274
Q

If a weed killer absorbs the electrons from photoionised chlorophyll, what impact will this have?

A

The electrons can no longer move along the electron transport chain (stopping the LDR), so it cannot form NADP or ATP, so it cannot produce glucose (stopping the LIDR).

275
Q

Required Practical 8, tube A, contents, reason for this, result, why?

A

Chloroplasts, water, DCPIP (no light) Control, shows what no photosynthesis would look like if no light present Blue No photosynthesis takes place, so the DCPIP is not reduced, so the starting colours are just mixed in solution with no reaction taking place

276
Q

Required Practical 8, tube B, contents, reason for this, result, why?

A

Isolation medium, water, DCPIP Control, shows what no photosynthesis would like if no chloroplasts present Blue No chloroplasts present so no photosynthesis takes place, the DCPIP is not used up

277
Q

Required Practical 8, tube C, contents, reason for this, result, why?

A

Chloroplasts, water Normal photosynthesis, used as a colour standard – lets you know what point you should stop the timer Green Only chloroplasts present, photosynthesis takes place, so no colour change

278
Q

Required Practical 8, tube X, contents, reason for this, result, why?

A

Chloroplasts, water, DCPIP Normal photosynthesis but quantifiable by using DCPIP Green Photosynthesis takes place which reduces the DCPIP, changing it to colourless, so only the green chloroplasts are there

279
Q

Required Practical 8, tube Y, contents, reason for this, result, why?

A

Chloroplasts, ammonium hydroxide, DCPIP Normal photosynthesis but with ammonium hydroxide added to see the affect – simulates weed killer – quantifiable by using DCPIP Slight colour change Ammonium hydroxide slows the rate of photosynthesis and so the rate of DCPIP reduction,

280
Q

What are coenzymes? with example

A
  • Coenzymes are complex organic molecules that are used by enzymes to accept or donate molecules involved in a reaction- They carry chemical groups or ions about, e.g. NAD removes H+ and carries it to other molecules
281
Q

General info of mitochondria

A
  • ‘powerhouse’ of the cell- Found in all cell types- Found in high numbers in cells that have high energy demands- 1um diameter, 10um long
282
Q

Draw and label mitochondria

A

check notes

283
Q

WHat are the 4 stages of respitation with breif description

A
  1. Glycolysisa. Splitting 6C glucose into 2x 3C pyruvates2. Link Reactiona. Converts 3C pyruvate into CO2 and 2C acetylcoenzyme A3. Krebs Cyclea. Acetylcoenzyme A goes through redox reactions that produces ATP and reduced NAD and reduced FAD4. Oxidative Phosphorylationa. Uses electrons associated with rNAD and rFAD to synthesise ATP (and waste water)
284
Q

Where does glycolysis occur?

A

Ctypolasm of the cell

285
Q

Where does link reaction occur?

A

Matric of the mitochondria

286
Q

Where does krebs cycle occur?

A

Matric of the mitochondria

287
Q

WHere does oxidative phosphorylation occur?

A

utilises proteins found in the membrane of the crista

288
Q

What are the 4 stages of glycolysis?

A

Stage 1: Activation of glucose by phosphorylationStage 2: Splitting of the phosphorylated glucoseStage 3: Oxidation of triose phosphateStage 4: Production of ATP

289
Q

Describe stage 1 of glycolysis

A

Before splitting, glucose is made more reactive by adding 2 phosphate molecules (phosphorylation)Phosphates from the hydrolysis of ATP  ADPThis provides the energy to activate glucose and lowers the activation energy needed for the following enzyme controlled reactions2 ATPs have been ‘spent’

290
Q
  • The phosphorylation of glucose is carried out by enzymes called ___________
A

hexokinases

291
Q

Phosphorylation of glucose forms what?

A

glucose 6-phosphate (G6P)

292
Q

Extra info for stage 1 of glycolysis

A
  • The reaction uses ATP, but it acts to keep the glucose concentration low, allowing continuous transport of glucose into the cell- It also blocks glucose from leaking out – the cell lacks transporters for G6P, and free diffusion out of the cell is prevented due to the charged nature of G6P
293
Q

Describe stage 2 of glycolysis

A

Glucose  2x 3C triose phosphates (TP)

294
Q

Describe stage 3 of glycolysis

A

2 hydrogen removed from each TPHydrogen transferred to NAD= (hydrogen carrier)This forms reduced NAD

295
Q

What is NAD+

A

nicotinamide adenine dinucleotide

296
Q

Describe stage 4 of glycolysis

A

Enzymes convert 3C TP  3C pyruvate2 ATPs generated from ADP (net)

297
Q

Summarise what happens in the link reaction

A

converts 3c pyruvate into CO2 and 2C acetyl coenzyme A

298
Q

Where does the link reaction take place? And what happens there?

A

.Takes place in the mitochondrial matrix.Oxidises the pyruvate made in glycolysis.Pyruvate actively transported into matrix of mitochondria

299
Q

Draw a flow chart of the link reaction

A

check notes

300
Q

4 steps of link reaction

A
  • Pyruvate has a hydrogen removed by NAD (NAD is reduced)- CO2 is removed from pyruvate- Acetate is formed- Coenzyme A is added to acetate to form acetyl coenzyme A (2C)
301
Q

How many times must the link reaction occur for each glucose?

A

twice

302
Q

Krebs cycle, who, when, aka

A
  • Sir Hans Krebs 1937- AKA Citric acid cycle
303
Q

Where does krebs cycle take place?

A

matrix

304
Q

How many kreb cycles for each glucose?

A

2

305
Q

Draw krebs cycle

A

check notes

306
Q

Define Substrate level phosphorylation

A

the direct phosphorylation of ADP with a phosphate group by using the energy obtained from a coupled reaction

307
Q

Define oxidative phosphorylation

A

the production of ATP from oxidised NADH and FADH

308
Q

So each acetyle CoA enterign the krebs cycle results in what?

A
  1. 2CO2 molecules (plus 1 from LR)2. 1 ATP molecule3. Reduced co-enzymes NAD and Fad
309
Q

.Coenzymes NADH and FADH are carrying what?

A

Hydrogen atoms

310
Q

.During oxidative phosphorylation, some of the energy of the electrons is conserved in the formation of what?

A

ATP

311
Q

Where does oxidative phosphorylation occur?

A

The cristae of the mitochondria

312
Q

Enzymes and proteins needed for oxidative phosphorylation are found where?

A

The inner membrane of the mitochondria

313
Q

Draw a labelled diagram of oxidative phosphorylation

A

check notes

314
Q
  1. Oxygen is important in respiration, why?
A

it is the final acceptor in oxidative phosphorylation, joining with protons and electrons to form water.

315
Q

If no oxygen was present in respiration what would happen?

A
  1. If there was no oxygen present, then there would be nothing to takeaway the protons and electrons, they would block the flow along the ETC and so respiration would stop
316
Q

Why is the step by step approach in the movement of electrons along the ETC in respiration important?

A

When a lot of energy is released in one step, a lot is lost as heat (and therefore energy is wasted). If it is released slowly over several steps, more energy is available for the use of the organism. Therefore, NAD and FAD transfer the electrons gradually.

317
Q

Other substances are also able to undergo oxidation to release energy, what are they?

A

lipids and proteins

318
Q

Describe the process of Oxidative Phosphorylation

A
  1. Hydrogen atoms from glycolysis and Krebs join with coenzymes NAD and FAD2. Reduced NAD and FAD donate the electrons of the hydrogen atoms they are carrying to the first electron transport molecule3. The electrons pass along the ETC in a series of redox reactions4. As the electrons pass along the chain they release energy which causes the active transport of protons across the inner mitochondrial membrane into the inter-membranal space5. The protons gather in the area between the mitochondrial membranes6. They then diffuse back into the mitochondrial matrix through ATP synthase channels in the inner mitochondrial membrane7. At the end of the chain the electrons combine with the protons and oxygen making water8. Oxygen is the final acceptor of the electrons in the ETC
319
Q

if there was no oxygen availible for respiration, what problems would occur?

A

Oxygen is the final electron acceptor in aerobic respirationWithout it, NADH no longer releases hydrogen at the ETCThis creates a backlog of NADH, and no NAD being regeneratedWithout NAD, the Kreb’s cycle, link reaction, and glycolysis cannot take placeThe NADH produced during glycolysis must be oxidised back into NAD+ so that it can be reusedIf NAD+ remained as NADH, there would be no carriers to take up the hydrogen atoms released during glycolysisGlycolysis would stopIn anaerobic respiration conditions, neither Krebs nor the ETC can continue as all the coenzymes are reducedThis means there will be no available NAD+ pr FAD to take up the hydrogen atoms producedThis will cause the enzymes to stop workingAs a result the only ATP produced would be the two net produced during glycolysis

320
Q

How does anaerobic respiration get around the problems of lack of oxygen?

A

NAD+ is replenished by pyruvatePyruvate accepts the hydrogen from NADHThe newly oxidised NAD+ can then be reused in glycolysis

321
Q

There are two types of anaerobic respiration carried out by eukaryotic cells, what are they?

A
  1. Plants and microorganisms – pyruvate converted to ethanol and CO22. Animals – pyruvate converted to lactate
322
Q

Describe anaerobic respiration for Bacteria and certain fungus (yeast)

A
  1. Pyruvate is decarboxylated (loses CO2)2. Forms ethanal3. Ethanal is reduced by H atoms supplied by NADH4. This forms ethanolPyruvate + NADH  ethanol + CO2 + NAD+
323
Q

What are the uses of anaerobic respiration in bacteria and certain fungus?

A
  • Yeast and the brewing industry- Yeast grown anaerobically- Ferments natural carbohydrates from plant products:o Grapes (wine)o Barley seeds (beer)
324
Q

Why is anaerobic respiration good for animals?

A

Occurs in animals to overcome a temporary oxygen shortageSurvival advantage (immediately after birth, water with low O2, escape)

325
Q

Where is anaerobic respiration most common in animals?

A

Skletal muscles

326
Q
  • During an oxygen shortage, NADH from glucose can accumulate and must be recovered in animals, how is it gotten rid of?
A

pyruvate takes up 2 hydrogen atoms from NADH- This forms lactate

327
Q

Draw the diagram of pyruvate + NADH –>

A

Lactate + NAD+check notes for diagram

328
Q
  • When oxygen is availible again, the lactate is oxidised back to what?
A

pyruvate

329
Q

When pyruvate is oxidised from lactate, what can be done to it?

A

o Further oxidised to release energyo Converted back to glucose

330
Q

Problems associated with lactate

A
  • Muscles cramp and fatigue- Lactate is an acid so causes pH changes that affect enzyme action- It is removed by the blood and taken to the liver where it is converted into glycogenD#- This regeneration requires lots of ATP (which is produced in aerobic respiration)- This regeneration therefore leads to an oxygen debt, where the athlete is continuing an elevated level of oxygen consumption (post exercise oxygen consumption)

AQA A Level Biology (19 decks)

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