Topic 5 - Energy transfers in and between organisms Flashcards
.Organisms in an ecosystem rely on a source of ____ to carry out all their activities
energy
.The ultimate source of energy is the ___ , which plants conserve as ______ energy
sun
chemical
.Most plants use sunlight in making ______________
organic compounds
.An example of an organic compound made by plants using sunlight is _____, which is used by plants as ____________
Sugar
respiratory substrates
When plants use sunlight to form organic compounds, other biological molecules formed (apart from sugar) make up what?
the biomass of plants, that is the means by which energy is passed between other organisms
.Organisms can be divided into ___ groups according to how they obtain their energy and nutrients, these are: what?
3
producers, consumers and saprobionts
What are producers?
photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions
What are consumers?
organisms that obtain their energy by feeding on (consuming) other organisms rather than using the energy of sunlight directly
Are animals consumers?
yes
Those that directly eat producers are called _____, because?
Primary consumers
they are the first in the chain of consumers
Those animals easting primary consumers are called ______ consumers and those eating secondary consumers are called _____ consumers.
Secondary
Tertiary
Secondary and tertiary consumers are usually predators but they may also be …
scavengers or parasites
What are saprobionts
(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.
What is the majority of saprobionts work carried out by?
The majority of this work is carried out by fungi and bacteria.
What is a food chain?
.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
What can be seen in long food chains?
In a long food chain the tertiary consumers may in turn be eaten by further consumers called quaternary consumers
What is each stage in a food chain referred to as?
A trophic level
.The arrows on food chain diagrams represent what?
The direction of energy flow
.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 a
what?
Food web
.It is likely that all organisms within a ____, even within an ________, will be liked to others in the food web
habitat
ecosystem
Define herbivore
An animal which eats plants (producers) and is therefore a primary consumer
Define carnivore
An animal that eats animals and may therefore be a secondary or a tertiary consumer
Define omnivore
An animal that eats both plants and animals and is therefore a primary consumer and also a secondary or a tertiary consumer
What is biomass?
.Biomass is the total mass of living material in a specific area at a given time
.The fresh mass is quite easy to assess, but the presence ______________ makes it unreliable
of varying amounts of water
How do you get over the problems that arise with measuring fresh biomass?
.Measuring the mass of carbon, or dry mass
What are the drawbacks of measuring dry biomass?
because the organism must be killed it is usually only made on a small sample, and this sample may not be representative
How is biomass measured?
.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
The chemical energy store in dry mass can be estimated using what?
Calorimetry
What happens in bomb calorimetry?
.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
Suggest how you could determine the dry mass of a sample of plant material
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
Give one reason why not all the light energy falling on the producers is used in photosynthesis.
Some will be reflected
What percentage of the Sun’s energy is captured by plants or algae?
1-3%
Most of the Sun’s energy is not converted to organic matter by photosynthesis. Explain why.
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, e.g. low temperature, may reduce the rate of photosynthesis
Gross is?
the total amount before anything is deducted.
Net is?
the amount remaining after certain adjustments have been made for debts, deductions or expenses
What is gross primary production (GPP)?
The total quantity of energy that plants in an area/volume convert into organic matter (biomass) in a given time
Respiration uses how much of GPP?
20-50%
What is net primary productivity?
the energy left over from GPP after some has been sed by respiration, it is to be stored
Net primary productivity =
gross primary products – respiratory losses
Why is mean GPP different between different environments?
Temperature variations Constant/ no / little seasonal change Higher plant density Higher water availability / rainfall Evergreen / deciduous More light (energy) / intensity
What is NPP used for? How much is used by who?
- 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.
Why is their energy loss in food chains?
- Not all of the organism is eaten.
- Not all is digested, and is lost as faeces.
- Some lost in excretory materials, such as urine.
- Heat loss to the environment.
N = I – (F+R), in this equation what does each letter represent?
N = Net production I = Chemical energy store of ingested food F = Energy lost in faeces and urine R = Energy lost in respiration
Finish the equation, N=
I – (F+R)
Why can food chains only support up to 5 trophic levels?
Food chains are extremely inefficient
Insufficient energy available to support a large population at higher trophic levels
The totally biomass is less at each trophic level
Therefore the amount of energy available is less
How could we improve the efficiency of a food chain?
Shorten it
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?
That the same piece of land can make different amounts of food, depending on what is being grown
Intensive farming can be hugely ….
… profitable
Intensive farmers aim to …
… produce the maximum yield with the minimum input
.The focus of intensive rearing is to …
… convert the smallest amount of food energy into the greatest quantity of animal mass
How can intensive farmers increase the efficiency of mass of food to mass of animal?
.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)
What measures may farmers take to improve the energy-conversion rate in the livestock (animals) they rear?
- Limit movement – less movement = less energy lost during exercise
- Heat the environment around the animals (in barns) – they don’t have to waste energy keeping themselves warm
- Control diet – food is high in protein and low in fibre as this builds muscle which means more meat to eat
- Remove predators and pests – sick animals use energy fighting infections
What are the features of intensive rearing?
- Efficient energy conservation
- Low cost food production
- Inferior food quality
- Less space required
- Safety – easier to control as it’s a small area
- High spread of disease
- Over use of drugs
- Poor animal welfare
- High pollution
- Reduced genetic diversity
- High use of fossil fuels
- Chickens have their beaks cut so they are unable to peck and injure each other
Points for intensive farming
Efficient energy conversion – restricting wasteful energy loss means more energy is passed on to humans along the food chain
Low 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 helpful
Use 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 habitats
Safety – 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 happens
Food is essential for life – with an ever expanding human population, there is pressure to produce more and more food intensively
Points against intensive farming
Quality of food – the taste of foods produced by intensive rearing is inferior to food produced less intensively
Disease – large numbers of animals living in close proximity means that infections can spread easily amongst them. To control this, the animals are regularly given antibiotics
Use 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 health
Animal 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 gain
Pollution – 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.
Draw a labelled diagram for the nitrogen cycle
Check your notes
Nitrogen molecules are made up of a triple bond, is this hard or easy to break up?
Hard
____ which is the only biological enzyme which can break the nitrogen triple bond
nitrogenase
Nitrogen oxides turns back into nitrogen gas though the enzyme of _____________
nitrate reductase
.Limited availability of nutrient ions in a usable form and so the flow of nutrients within an ecosystem is not linear, but mostly …
… cyclical
All nutrient cycles have one simple sequence at heart, which is:
- The nutrient is taken up by producers as simple, inorganic molecules
- The producer incorporates the nutrient into complex organic molecules
- When the producer is eaten, the nutrient passes into consumers (animals)
- The complex molecules containing the nutrient are passed along the food chain as each consumer is eaten by the next
- When the producers and consumers die, their complex molecules are broken down by saprobiontic microorganisms (decomposers) that release the nutrient in its original simple form, the cycle is then complete
________ are the driving force in the nutrient cycles which ensure the nutrients are released for reuse
.Without them, nutrients would remain locked up as part of complex molecules that cannot be taken up and used again by plants
Saprobionts
.Living organisms use nitrogen to …
… manufacture proteins, nucleic acids and other nitrogen-containing compounds
__% of the atmosphere is nitrogen
78
.Few organisms can absorb nitrogen gas _____
directly
How does nitrogen enter the living component of the ecosystem?
.Plants take up most of the nitrogen they require in the form of nitrate ions (NO3 -) from the soil
.These ions are absorbed, using active transport, by the roots
.Animals obtain nitrogen-containing compounds by …
… eating and digesting plants
.Nitrate ions are very soluble and easily leach (wash) through the soil, beyond the reach of plant roots
.In natural ecosystems, the nitrate concentrations are restored largely by …
… the recycling of nitrogen containing compounds
.In agricultural ecosystems, the concentration of soil nitrate can be further increased by …
… the addition of fertilisers
.When plants and animals die, the process of __________ begins
decomposition
The release of nitrate ions by decomposition is most important as, in natural ecosystems, there are
very few nitrate ions available from other sources
.There are 4 main stages in the nitrogen cycle: _______, _______, ______ ______ __ _______, each of which involces __________________ __________________
ammonification, nitrification, nitrogen fixation and denitrification, each of which involves saprobiontic microorganisms
What is the process of ammonification?
.Ammonification is the production of ammonia from organic nitrogen-containing compounds
.In nature, these compounds include urea (from the breakdown of excess amino acids) and proteins, nucleic acids and vitamins (found in faeces and dead organisms)
.Saprobiontic microorganisms, mainly fungi and bacteria, feed on faeces and dead organisms materials, releasing ammonia, which then forms ammonium ions in the soil
.This is where nitrogen returns to the non-living component of the ecosystem
What is the process of nitrification?
.Some bacteria obtain their energy from chemical reactions involving inorganic ions
.One such reaction is the conversion of ammonium ions to nitrate ions
.This is an oxidation reaction and so releases energy
.It is carried out by free-living soil microorganisms called nitrifying bacteria
.This conversion occurs in two stages:
1. Oxidation of ammonium ions to nitrite ions (NO2-)
2. Oxidation of nitrite ions to nitrate ions (NO3-)
.Nitrifying bacteria require oxygen to carry out these conversions and so they require a soil that has many air spaces
.To raise productivity, it is important for farmers to keep soil structure light and well aerated by ploughing
.Good drainage also prevents the air spaces from being filled with water and so prevents air being forced out of the soil
What is the process of nitrogen fixation?
.The process by which nitrogen gas is converted into nitrogen containing compounds
.It can be carried out industrially and also occurs naturally when lightning passes through the atmosphere
.By far, the most important form of nitrogen fixation is carried out by microorganisms, of which there are two main types:
• Free-living nitrogen-fixing bacteria. These bacteria reduce gaseous nitrogen to ammonia, which they then use to manufacture amino acids, nitrogen rich compounds are released from them when they die and decay
• Mutualistic nitrogen-fixing bacteria. These bacteria live in nodules on the roots of plants such as peas and beans, they obtain carbohydrates from the plant and the plant acquires amino acids from the bacteria
What is the process of denitrification?
.When soils become waterlogged, and have a low oxygen concentration, the type of microorganism present changes
.Fewer aerobic nitrifying and nitrogen-fixing bacteria are found, and there is an increase in anaerobic denitrifying bacteria
.These convert soil nitrates into gaseous nitrogen
.This reduces the availability of nitrogen-containing compounds for plants
.For land to be productive, the soils on which plants grow must be kept well aerated to prevent the build-up of denitrifying bacteria
.The delicate balance can be easily upset by human activities
Describe and explain the nitrogen cycle
The basic outline of the nitrogen cycle is that plants use nitrogen to form complex nitrogen-containing organic molecules, these are either passed along to consumers up the food chain where they die or the producer dies itself. Saprobiontic microorganisms, mainly fungi and bacteria, feed on faeces and dead organism’s materials, this releases ammonia in the process of ammonification, which then forms ammonium ions in the soil. Free-living soil microorganisms called nitrifying bacteria convert ammonium ions into nitrate ions in the process of nitrification. Which occurs in two stages (oxidation of ammonium ions to nitrite ions (NO2-) and oxidation of nitrite ions to nitrate ions (NO3-)) which required oxygen. These nitrate ions can then be absorbed back into the plant or go through the process of denitrification (anaerobic denitrifying bacteria converting soil nitrates into gaseous nitrogen) which turns them into nitrogen in the atmosphere. Here they can go through the process of nitrogen fixation by free-living bacteria (where they are reduced form gaseous nitrogen to ammonia) or mutualistic bacteria (where bacteria on the nodules on the roots of plants obtain carbohydrates from the plant while the plant acquires amino acids from the bacteria, thereby putting nitrogen back into the producer). And so the cycle starts again.
Basics of phosphate cycle
.Phosphorus is found in the lithosphere and does not have a gaseous phase
.Phosphorus is usually found as phosphate ions PO4-3
.These are found in rocks
.Phosphorous must be recycled as it is required by all living things, give some examples of when phosphorous is required
.It is used in phospholipids, nucleic acids and ATP
Draw a diagram of the phosphate cycle
Check notes
What is the lithosphere?
earths crust
Where are sedimentary rock deposits, where phosphate ions are, found?
.These have their origins in the sea but are brought to the surface by the geological uplifting of rocks
How does phosphate get from the rocks to the soil/water then to plants?
.The weathering and erosion of phosphate rich rocks helps phosphate ions to become dissolved and so available for absorption by plants which incorporate them into their biomass
How do phosphate ions pass from plants back to the water or soil?
.The phosphate ions pass into animals which feed on plants
.Excess phosphate ions are excreted by animals and may accumulate in waste material such as guano formed from the excretory products of some sea birds
.On the death of plants and animals, decomposers such as certain bacteria and fungi break them down releasing phosphate ions into the water or soil
How are sedimentary rocks formed in the phosphate cycle?
.Some phosphate ions remain in parts of animals, such as bones or shells, that are very slow to breakdown
.Phosphate ions in excreta, released by decomposition and dissolved out of rocks, are transported by streams and rivers into lakes and oceans where they form sedimentary rocks thus completing the cycle
Describe and explain the phosphorous cycle
The phosphorous cycle starts with phosphorus, in the form of PO43-, in the lithosphere (earth’s crust) specifically in rocks. This rock can be eroded and so the phosphate dissolves into a body of water or soil, where they are absorbed by plants. These plants can die and decompose or be eaten by animals, which then die and decompose. This decomposed organic material is either eroded, which sends the phosphate ions back into the body of water or soil, or deposited which forms rocks and thus the cycle starts again.
Describe and explain the carbon cycle
Carbon dioxide in the atmosphere is absorbed by plants for photosynthesis. The carbon compounds found in plants either get turned into fossil fuels and burnt, which releases CO2 back into the atmosphere, or the plants respire, which releases CO2 back into the atmosphere, or the plant feeds animals which then respire and so CO2 is released back into the atmosphere. Thus the cycle continues.
Draw the carbon cycle diagram
check notes
What is mutualism?
the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other
Give an example of mutualism
For example, a bird and a flower, or an insect and a flower
Mycorrhizae is pronounced …
… my-corr-eye-ziy
What are mycorrhizas and how is their relationship with plants mutualistic?
.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
Describe how the relationship between mycorrhizae and plants can be described as a mutualistic one.
(4 marks)
Mycorrhizae gain glucose
Amino acids
Plants gain increased drought resistance
Larger root surface area
So increase absorption of water and minerals
What can farmers do to increase productivity?
Reduce energy loss
Shorten food chains
Use fertilisers
List the things that plants need to grow:
.Water
.Light
.Carbon dioxide
.Mineral ions
• 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.
- 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.
How do farmers counteract reduced ammonification?
farmers apply fertiliser to their crops
What are the two types of fertilisers?
Organic and inorganic (natural and artificial)
Describe organic fertiliser
- Dead and decaying plant and animal matter
- Animal excreta such as manure and slurry
- Bone meal
Describe inorganic fertiliser
• Mined from rock • Converted to suitable form • Blended to suit a particular crop • Includes: - Nitrogen - Phosphorous - Potassium
The best yields are achieved when a combination of …
… the 2 types of fertilisers are applied
describe and explain the shape of the graph for fertiliser use (incerasing volumes of fetilser)
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.
What do plants need nitrogen for?
Plants need nitrogen for amino acids, DNA nucleotides and ATP which are all essential for plant growth
- Outline a method that would scientifically test the effect of nitrogen on plant growth.
- Include independent, dependent and control variables.
- Gather 11 plant seeds of the same species
- Place them in equal volumes of soil in separate pots
- Make up 11 batches of fertiliser, one with 0% nitrogen, one with 10% nitrogen, etc. all the way up to one with 100% nitrogen
- Fertilise each plant with different fertilizers but of the same volume (labelling each pot with the fertiliser used)
- Water the plants throughout the week
- Measure how much each plant grew at the end
- Draw a conclusion from your results
IV = the concentration of nitrogen in the fertiliser
DV = the growth of the plants
CV = 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)
What is leaching?
.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
What a can excessive nitrates lead to?
.Excessive nitrates can prevent efficient O2 transport in babies and has links to stomach cancer
.It can also lead to eutrophication
What is eutrophication? Include a description and explanation of the process in detail
.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
Equations for photosynthesis
Carbon dioxide + water light glucose + oxygen
6CO2 + 6H2O C6H12O6 + 6O2
What is the importance of photosynthesis?
.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
Label a plant cell
IDK google it
Label a leaf cross section
IDK google it
What makes leaves good at photosynthesis?
.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
Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants. (5 marks)
- Protein / amino acids / DNA into ammonium compounds / ammonia / urea
- By saprobionts;
- Ammonium / ammonia into nitrite;
- Nitrite into nitrate;
- By nitrifying bacteria / microorganisms;
- Nitrogen to ammonia / ammonium;
- By nitrogen-fixing bacteria / microorganisms in soil;
Mutualism is …
… the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other.
Example of mutualistic relationship
mycorrhizae and plants, birds and flowers
Describe the role of mycorrhizae
.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
Describe how the relationship between mycorrhizae and plants can be described as a mutualistic one.
(4 marks)
Mycorrhizae gain glucose
Amino acids
Plants gain increased drought resistance
Larger root surface area
So increase absorption of water and minerals
What is the law of limiting factors –
When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply
The rate of photosynthesis in a plant can be limited by:
.Light intensity .Availability of water .Availability of carbon dioxide .Availability of chlorophyll .Temperature
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
IDK google it or something
what are the 3 main stages in photosynthesis?
.Capturing of light energy
.The light-dependent reaction
.The light-independent reaction
What is oilrig?
Oxidation is loss, reduction is gain
Where does the light-dependent reaction occur?
In the thykaloid membrane
What does the light-dependent reaction provide?
.Provides: Energy, hydrogen, and oxygen
What is the type of chlorophyll common to all plants?
Chlorophyll a
Ionised meaning
the addition or removal of electrons to create an ion
In the light-dependent reaction, does the chlorophyll get oxidised or ionised?
oxidised
What are the two photosystems?
P680 and P700
Or photosystem 2 and 1
In the light dependent reaction, a ____ of electrons get excited, always _____
pair
pairs
First molecule to accept the molecule is the ________ in the light-dependent reaction
primary acceptor molecule
What is photophosphorylation?
the addition of phosphate because of light
Going through two photosystems allows the electrons to be at the same energy level as ____
NADP+
NADP+ is …
… a coenzyme that accepts electrons and protons
Reduced NADP+ is …
… NADPH
What happens in the photolysis of water?
H2O turns into H+, e-, and O2
2H2O O2 + 4H+ + 4e-
NADP gains the H+ also
Photosynthesis equation
6CO2 + 6H2O C6H12O6 + 6O2
.There are three main stages involved in photosynthesis, what are they?
- Capturing of Light Energy
- The Light-Dependent Reaction
- The Light-Independent Reaction
.In the light-dependent stage of photosynthesis, the majority of reactions involve molecules being _____ and _______
oxidised
reduced
What is oxidation?
.Loss of HYDROGEN
.Loss of ELECTRONS
.Gain of OXYGEN
.Energy given out
What is reduction?
.Gain of HYDROGEN
.Gain of ELECTRONS
.Loss of OXYGEN
.Energy taken in
Oxidation and reduction always happen together, what is this called?
REDOX reactions
Where does the LDR occur?
.Occurs on the thylakoid membranes
What does the LDR provide?
Provides energy, hydrogen, and oxygen
LDR catches light, which is used for what?
- To combine ADP + Pi (inorganic phosphate) to form ATP
2. To split water into H+ (protons) and OH- ions – photolysis
What is chlorophyll 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
.When a photon of light is absorbed by chlorophyll a, it boosts the energy levels of what?
a pair of chlorophyll electrons
What is photoionisation?
.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
In photoionization, what has been oxidised, and what has been reduced?
.As the chlorophyll has lost electrons it has been oxidised
.As the electron carrier has gained electrons it has been reduced
T or F, Oxidation is the loss of electrons
T
T or F, LDR takes place in the stroma
F (thylakoid membranes)
T or F, Chlorophyll a absorbs green wavelengths of light
F (reflects it)
T or F, Photons of light cause electrons to leave chlorophyll molecules
T
T or F, Photoionisation is the loss of electrons due to light
T
What are photosystems?
.Functional and structural protein complexes involved in photosynthesis
What do photosystems do?
.Together they:
- absorb light
- transfer energy and electrons
Where are photosystems found?
.Photosystems are found in the thylakoid membranes of plants
What are the two photosystems and how can you tell them apart?
.P700 (PSI) – red light
.P680 (PSII) – orangey light
After photoionisation, what happens to the electrons?
.The excited electrons are taken up by an electron carrier
.The excited electrons move along the ETC from PS2
What are carrier molecules?
.The carrier molecules are a series of proteins found in the thylakoid membrane
What makes the electrons move down the ETC?
.Each carrier has a slightly higher affinity for the electrons than the last
.This draws the electrons along the chain to PS1
Why do electrons lose energy down the ETC?
.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
What happens to the energy lost by electrons in the ETC?
.The energy that is released by the electrons is used to synthesise ATP
What is the formation of ATP called during photosynthesis?
photophosphorylation
As the electrons move along the chain they pass through 2 photosystems, why?
.Further absorbed light energy increases the energy of the electrons
.This makes the energy sufficient for the reduction of NADP+ to NADPH
What is NADP+?
nicotinamide adenine dinucleotide phosphate is a coenzyme that accepts electrons and protons
What do coenzymes do?
help enzymes to function
.NADP+ is the final acceptor in the chain and therefore what happens to it?
It becomes reduced NADP+ (NADPH)
What reduces NADP+ to NADPH?
The electrons and protons
.The NADPH stores the electrons and protons until when?
they are transferred into the light-independent reaction
.Every molecule of NADPH formed in the LDR needs what?
2 electrons from PSI
.Every molecule of NADPH formed in the LDR needs 2 electrons from PSI, what replaces those lost electrons? and those ones?
.These electrons are replaced by those from PSII
.These are replaced by the electrons from photolysis
T or F, Photosystems are protein complexes that absorb light found in thylakoid membranes
T
T or F, Excited electrons move from PS1 to PS2
F - from PS2 to PS1
T or F, Excited electrons move along the electron transport chain due to gravity
F - Each carrier has a higher affinity for e- compared to the last
T or F, As electrons move along the electron transport chain they gain energy
F - Loose energy, it is used to phosphorylate ADP, forms ATP
.When the light struck the chlorophyll, ___ electrons were lost
two
When electrons are lost from the chlorophyll, how are they replaced?
.They are replaced by the other set of reactions in the light dependent stage
If electrons are not replaced in the chlorophyll what happens?
.These need to be replaced or the chlorophyll can no longer absorb light energy
.Water molecules are split using light energy absorbed by __________
chlorophyll a
.When chlorophyll a absorbs light it loses electrons and becomes _____ ______ (electrons carry a negative charge), chlorophyll is now _______
positively charged
oxidised
Is photolysis fully understood?
no
Photolysis equation?
2H2O O2 + 4H+ + 4e-
What is photolysis?
break down of water using light
.Proton + electron =
hydrogen atom
.A hydrogen ion is formed when a hydrogen atom loses its what?
electron
hydrogen ion/proton symbol
H+
The electrons produced in photolysis, what are they used for?
to reduce the chlorophyll molecule – restoring the electrons it had lost
Is oxygen produced in photolysis? Wheat is is produced as and used for?
.The oxygen produced is a by-product which is either used in respiration, or leaves the cell
Why are the hydrogen ions from photolysis so important?
.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
T or F, NADP is the final acceptor on the electron transport chain
T
T or F, NADPH is reduced NADP
T
T or F, When chlorophyll loses electrons it becomes more negatively charged
F - e- carry a negative charge so their loss results in chlorophyll becoming more positively charged
T or F, Hydrogen ions have a proton and an electron
F - proton (H+) only
T or F, 5. Electrons released during photolysis are used to reduce chlorophyll
T
In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5 marks)
- Light (energy) excites / raises energy level of electrons in chlorophyll;
- Electrons pass down electron transfer chain;
- (Electrons) reduce carriers / passage involves redox reactions;
- ETC / role of chain associated with chloroplast membranes / in thylakoids / grana;
- Energy released / carriers at decreasing energy levels;
- ATP generated from ADP and phosphate / Pi / phosphorylation of ATP;
Label a chloroplast
google it idk
What is a chloroplast?
.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
What are thykaloids?
.Thylakoids are discs that contain chlorophyll
What are grana?
.The grana are stacks of thylakoids
.Some thylakoids have tube shape extensions that join with the thylakoids in another grana, what are they called?
intergranal lamellae
What are intergranal lamellae?
tube shape extensions that join with the thylakoids in another grana
Were does the LDR take place?
Thykaloids
What is the stroma?
.The stroma is a fluid-filled matrix around the grana where the light-independent stage takes place
What other functions are found in the stroma
starch grains
Function of Granal membranes
Provide a large surface area for chlorophyll, electron carriers and enzymes to attach
Function of A network of proteins in the grana hold the chlorophyll in a specific way
Allow maximum light absorption
Function of 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 concentration
Function of Chloroplasts contains DNA and ribosomes
Can quickly and easily manufacture proteins needed for photosynthesis
Function of The granal membranes have ATP synthase channels
Catalyse the production of ATP, also selectively permeable
Function of Stroma surrounds the grana
So products from the LDR easily diffuse into the stroma for the LIDR
How Chloroplasts are Adapted to their Function
- Granal membranes provide a large surface area for chlorophyll, electron carriers and enzymes to attach
- A network of proteins in the grana hold the chlorophyll in a specific way to allow maximum light absorption
- 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 concentration
- Chloroplasts contain DNA and ribosomes so they can quickly and easily manufacture proteins needed for photosynthesis
- The granal membranes have ATPase channels which catalyse the production of ATP, also selectively permeable
- Stroma surrounds the grana so products from the LDR easily diffuse into the stroma for the LIDR
.Photosynthetic organisms have _____ (light-absorbing molecules) that only absorb specific wavelengths of visible light, and they reflect others
pigments
define absorption spectrum
The set of wavelengths absorbed by a pigment
.The three key pigments involved in photosynthesis are, what?
chlorophyll a, chlorophyll b, and β-carotene
Why do plants appear green?
.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
.The majority of photosynthetic organisms contain a range of types of pigments, which means they can what?
absorb energy from a variety of wave lengths
.Two important groups of pigments in plants are what ?
chlorophylls and carotenoids
.There are 5 main chlorophylls , what are they?
a, b, c, d, and bacteriochlorophyll (found in prokaryotes)
.For plants, chlorophyll a and b are the what?
key photosynthetic pigments
What do chlorophyll a and b absorb?
.They absorb the red and blue wavelengths
Describe the structure of chlorophyll molecules
.Chlorophyll molecules have a hydrophobic tail, which inserts into the thylakoid membrane
.Chlorophyll molecules have a porphyrin ring head, which absorbs light
What is porphyrin ring head
circular group of atoms surrounding a magnesium ion
.Both chlorophyll a and b absorb what?
light
Chlorophyll a has a critical role in converting what to what?
light energy to chemical energy
Where is chlorphyll a found?
All photosynthetic plants
All photosynthetic algae
All photosynthetic cyanobacteria
Where is chlorophyll b found?
Plants
Green algae
A few types of cyanobacteria
.Since chlorophyll a is crucial to photosynthesis, all pigments which are used in addition to chlorophyll a are called _______
accessory pigments
WHat does the term ‘accessory pigments’ include?
includes other chlorophylls, but also other classes of pigments like carotenoids
Why are accessory pigments useful?
.By using accessory pigments, a broader range of wavelengths can be absorbed – and as a result increased energy can be captured from sunlight
.Carotenoids are a key group of pigments, what do they absorb?
violet and blue-green light
.Bright coloured carotenoids, like in fruit, are used often as adverts to attract animals , what does this help?
disperse the plants seeds
.In photosynthesis, carotenoids not only help with the capture of light, but also what?
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
.When a pigment absorbs a photon of light it then becomes excited, what does this mean?
it is no longer at its ground state and instead has extra energy
What is excittion at a molecular level?
.Excitation at a subatomic level is when n electrons jumps up to a higher energy orbital
Why are photons of different wavelengths needed in order to provide an energy boost which matches that gap?
.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
List the types of photosynthetic pgmets
Chlorphyls, carotenoids, phycobilins
List the types of chlorophylls and where they are found
.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)
List the types of carotenoids and where they are found
.Carotenes (higher plants and algae)
.Xanthophylls (higher plants and algae)
List the types of phycobilins and where they are found
.Phycoerythrobilin (BGA and red algae)
.Phycocyanobilin (BGA and red algae)
The role of chlorophyll photosynthetic pigments in photosynthesis
.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]
Role of carotenoids
.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
Role of phycobilins
.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
Why is it useful for a plant to have several different photosynthetic pigments?
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.
Why do shade tolerant plants have different pigments compared to full sun plants?[5]
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.
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 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.
As the excited electrons move along the chain they pass through 2 photosystems. Why?
.Further absorbed light energy increases the energy of the electrons
.This makes the energy sufficient for the reduction of NADP+ to NADPH
What is non-cyclic photophosphorylation?
.Involves both photosystems
What is cyclic photophosphorylation?
.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
What is Chemiosmotic theory?
.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
- Explain how the pair of electrons move from chlorophyll to the electrons carrier system
Photoexcitation occurs, which results in excited electrons, meaning they are able to leave the chlorophyll molecule and are picked up by molecule A.
- Explain how electrons lost from chlorophyll are replaced
Photolysis of water (2H2O O2 + 4H+ + 4e-)
- Explain how ATP is synthesised when electrons pass between electron carriers B and C
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.
- In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5 marks)
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.
Define detritivore
An organism that feeds on and breaks down dead plant or animal matter
Explain why 1-3% of the suns energy is converted into organic compounds –
- 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
.In any ecosystem, plants synthesise organic compounds from what substance?
This can be _____ or ____?
CO2
atmospheric or aquatic
.Most of the sugars synthesised by the plants are used as _______________, the rest is used to make other biological molecules
respiratory substrates
What is biomass?
the mass of carbon or dry mass for tissue per area per time
What is calorimetry?
.Measuring energy changes from combustion
.Energy can be released in chemical reactions as heat energy
.Measuring heat transfers is called calorimetry
What is GPP?
The chemical energy store in plant biomass, in a given area/volume, in a given time
What is NPP?
The chemical energy store in plant biomass after respiratory loses to the environment have been deducted
NPP =
GPP - R
.The NPP is available for what?
plant growth and reproduction
it can also be passed along the food chain to other trophic levels
concerning NPP,
10
Secondary/tertiary consumers transfer about __% of the energy form their prey to their own biomass
20
Energy Loss in Food Chains, where does it go?
- Not all of the organism is eaten
- Not all is digested, and is lost as faeces
- Some lost in excretory materials, such as urine
- Heat loss to the environment
The Net Production of Consumers, equation and meaning of parts of equation
N= Net production I= Chemical energy store of ingested food F= Energy lost in faces and urine R= Energy lost in respiration
N = I – (F+R)
Why can food chains only support up to 5 trophic levels?
.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
Calculation Efficiency, what is it?
.Used to calculate the efficiency of the energy transfer between each trophic level
.Measured in kilojoules per square metre per year (kJm-2year-1)
Percentage efficiency =
(energy available after the transfer / energy available before the transfer) x 100
How could we improve the efficiency of a food chain?
Shorten it
.Energy enters an ecosystem in the form of what energy?
light
In an ecosystem, how is energy moved throughout?
.Energy enters an ecosystem in the form of light energy
.This is converted to chemical energy
.This is then lost as heat
.Nutrients are ____ through ecosystems
cycled
Give three physical things which are recycled and converted into different forms in an ecosystem
.Carbon, nitrogen and phosphorus
Nutrient cycles have the same key stages, what are they?
- 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
Why do living things need nitrogen?
.Nitrogenous bases (DNA)
.Amino acids, protein
.Few organisms can use gaseous nitrogen, how do plants get nitrogen?
.Plants use nitrate ions (NO3-) from the soil
.They are taken up via active transport
How do animals get nitrogen?
.Animals get their nitrogen from consuming plants
Why are plants unable to use nitrogen straight from the air?
Nitrogen gas is unreactive and is not easily converted into other compounds
Nitrate ions are extremely soluble, how could this be problematic to plants?
Washed away from plant roots by rain water
.Microorganisms play a huge role in cycling nitrogen, why?
During decomposition, microorganisms replenish the nitrate concentration in the soil
Draw the nitrogen cycle
check notes or google it
what 3 ways can nitrogen fixation occur?
- Nitrogen gas can be ‘fixed’ into ammonia by humans using the Haber process, this is then used in the production of fertilisers
- A small amount of nitrogen is fixed to nitrate by lightning
- Microorganisms that carry out this process, either free living or mutualistic
How does free living nitrogen fixing bacteria work?
Nitrogen fixing bacteria reduce: nitrogen gas ammonia
Then used to manufacture amino acids
Nitrogen rich compounds are released from the bacteria when they die
How does mutualistic nitrgen fixing bacteria work?
.The nitrogen fixing bacteria live in colonies inside the cells of root nodules of leguminous plants such as clovers or peas
.The bacteria get carbohydrates from the plant while giving the plant proteins
.The nitrogen in the plant proteins is passed on to animals through food chains – feeding
What does ammonification do?
Organic N containing compounds ammonia
Give examples of Organic N containing compounds
Urea, nucleic acids, proteins and vitamins
When living organisms excrete waste or die, their nitrogen is returned to the soil in the form of what and how?
ammonium compounds by saprobionts (bacteria and fungi)
What do saprobionts do in the nitrogen cycle?
Saprobionts break down proteins in detritus to form ammonium ions (ammonification or deamination), this is where nitrogen return to the non-living component of the ecosystem
What is nitrification?
.Plants can only take up nitrogen in the form of nitrate
.Ammonium compounds are oxidised into nitrates by nitrifying bacteria in two stages
1. First forming nitrite ions (NO2-)
2. Then forming nitrate ions (NO3-)
Is nitrification oxidation or reduction?
This is an oxidation reaction and so releases energy
Nitrifying bacteria are chemosynthetic bacteria, which means what?
they use the energy released by nitrification to live
Nitrifying bacteria require oxygen to carry out these conversions so the soil needs many air spaces
.Farmers can increase the aeration of soils by:
- Ploughing
- Good drainage
What is denitrifcation?
.The anaerobic denitrifying bacteria convert
.nitrate nitrogen gas
.which is then lost to the air
Where is denitrification found?
waterlogged soil
What does denitrifcation represent?
This represents constant loss of ‘useful’ nitrogen from soil, and explain why fertilisers and nitrogen fixation by the nitrifying bacteria are so important
Why must phosphorus be recycled?
as it is required by all living things
What are the uses of phosphorus?
.ATP and ADP
.Phospholipids
.Nucleic acids
Describe the phosphorus cycle
- Phosphorus is trapped in sedimentary rock
- The rocks are formed in the sea but are raised to the surface by geological activity
- Weathering and erosion release the phosphate ions
- These ions are able to dissolve and are taken up by plants
- They are then passed to animals during feeding
- When organisms excrete or die they are broken down by bacteria and fungus which are able to release the phosphates
- These phosphates end up in the soil or dissolved in water
- Some phosphates are fixed into hard tissues such as bones and shells, these take a very long time to break down
- Some of the phosphates remaining in the water are eventually combined into sedimentary rock
What is a mutualistic relationship?
.Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other
Examples of mutualistic relationships
.Birds in the crocodile mouth
.Clownfish in the coral anemone
.Fish on the shark
What are mycorrhizae?
beneficial fungus grown in association with plant roots
What does mycorrhizae do?
- 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, mycorrhizas also seem to confer protection against root diseases
How is the relationship between a plant and mycorrhizae mutualistic?
- This relationship is mutualistic as the mycorrhizae takes sugars and amino acids from plants in exchange for moisture and nutrients gathered from the soil by the fungal strands
Why are mycorrhizae so important?
- Phosphorus is in 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 agreement
Photosynthesis equation
6H2O + 6CO2 light C6H12O6 + 6O2
What makes leaves good at photosynthesis?
.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, why?
maximum light absorption
Why do plants have many stomata?
efficient gas exchange, short diffusion distance
Why does Stomata open and close in response to light intensity ?
reduces transpiration
Why are there Many air spaces in lower mesophyll ?
Allows rapid gas exchange
What is the stroma?
The stroma is a fluid filled matrix around the grana where the LIDR takes place
.Other structures are found here, like starch grains
granal members function
Large SA for chlorophyll, electron carriers and enzymes to attach
Network of proteins in the grana hold the chlorophyll in a specific way function
Allow maximum light absorption
Fluid in stroma hold enzymes function
Needed for LIDR
Chloroplasts contains DNA and ribosomes function
Quickly and easily manufacture proteins
Granal membranes have ATP synthase channels function
Catalyse the production of ATP, also selectively permeable
Stroma surrounds grana function
Products from LDR easily diffuse into the stroma for LIDR
What is the law of limiting factors?
When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply.
The rate of photosynthesis in a plant can be limited by what?
- Light intensity
- Availability of water
- Availability of carbon dioxide
- Availability of chlorophyll
- Temperature
Draw and label a plant cell
check google or notes
Draw and label a plant leaf cross section
check google or notes
Draw and label a chloroplast
check google or notes
Draw and annotate a graph displaying how the rate of bubbles produced vary as light intensity is increased
x axis: light intensity
y axis: rate of bubbles produced
Curve with decreasing gradient till a plateau
Curve starts part of the way along x axis (compensation point)
The initial oxygen produced by photosynthesis is used in respiration
Increasing 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
What is the compensation point?
The point where the rate of photosynthesis and respiration are equal
Draw and annotate a graph displaying how the rate of photosynthesis varies as light intensity is increased
x axis: carbon dioxide concentration
y axis: rate of photosynthesis
Curve with decreasing gradient till a plateau
Curve starts at the origin
Increasing carbon dioxide concentration increases the rate of photosynthesis
Increasing carbon dioxide has no effect as the rate of photosynthesis is limited by other factors
Draw and annotate a graph displaying how the rate of photosynthesis varies as chlorophyll availability is increased
x axis: chlorophyll availibility
y axis: rate of photosynthesis
Curve with decreasing gradient till a plateau
Curve starts at the origin
Increasing chlorophyll availability increases the rate of photosynthesis
Increasing chlorophyll has no effect as the rate of photosynthesis is limited by other factors
Draw and annotate a graph displaying how the rate of photosynthesis varies as temperature is increased
x axis: temperature y axis: rate of photosynthesis Almost an upside down x^2 curve Curve starts at the origin Tip of the curve is the optimum
Increasing temperature increases the rate of photosynthesis
As the temperature reaches too high, it denatures the structures which photosynthesize – so the rate of photosynthesis drops
What happens in chemiosmotic theory?
.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
Basic information about the LIDR
.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)
What stages can the LIDR be broken into? What happens in each?
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
What are the steps of the calvin cycle (the LIDR)?
- CO2 diffuses through the stomata and into the stroma of the chloroplast
- The CO2 reacts with a 5-C compound ribulose biphosphate (RuBP)
- The reaction is catalysed by the enzyme ribulose biphosphate carboxylase (rubisco)
- The reaction between CO2 and RuBP forms a very unstable 6-C compound (3-keto-2-carboxyarabinitol 1, 5-biphosphate)
- The 6-C compound is immediately broken down into two 3-c glycerate 3-phosphates (GP)
- NADPH (from LDR) reduces 3-c GP into two 3-c triose phosphate (TP) using ATP (from the LDR)
- NADP is reformed and returns to the LDR
- TP has 2 uses:
a. 5/6 – regenerates RuBP using ATP (from LDR)
b. 1/6 - forms organic substances (carbohydrates (glucose), lipids, amino acids)
Basic knowledge of rubisco
- 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
How many times does the Calvin cycle need to turn to make 1 glucose molecule?
6 times
How much ATP and rNADP is needed to make 1 glucose molecule in the calvin cycle?
This required 18 ATP and 12 rNADP
What colour is DCPIP (2,6-dichlorophenolindophenol) ?
o Blue when oxidised
o Colourless when reduced
What is DCPIP used for?
- Used to measure the rate of photosynthesis
- DCPIP acts as a substitute for NADP
What is dehydrogenase?
- Dehydrogenase is an enzyme that activates oxidation-reduction reactions
- In photosynthesis it catalyses the reduction of NADP+/DCPIP
- Some weed killers contain ammonium hydroxide, what does this do?
Ammonium hydroxide stops the action of the dehydrogenase
If a weed killer absorbs the electrons from photoionised chlorophyll, what impact will this have?
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).
Required Practical 8, tube A, contents, reason for this, result, why?
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
Required Practical 8, tube B, contents, reason for this, result, why?
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
Required Practical 8, tube C, contents, reason for this, result, why?
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
Required Practical 8, tube X, contents, reason for this, result, why?
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
Required Practical 8, tube Y, contents, reason for this, result, why?
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,
What are coenzymes? with example
- 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
General info of mitochondria
- ‘powerhouse’ of the cell
- Found in all cell types
- Found in high numbers in cells that have high energy demands
- 1um diameter, 10um long
Draw and label mitochondria
check notes
WHat are the 4 stages of respitation with breif description
- Glycolysis
a. Splitting 6C glucose into 2x 3C pyruvates - Link Reaction
a. Converts 3C pyruvate into CO2 and 2C acetylcoenzyme A - Krebs Cycle
a. Acetylcoenzyme A goes through redox reactions that produces ATP and reduced NAD and reduced FAD - Oxidative Phosphorylation
a. Uses electrons associated with rNAD and rFAD to synthesise ATP (and waste water)
Where does glycolysis occur?
Ctypolasm of the cell
Where does link reaction occur?
Matric of the mitochondria
Where does krebs cycle occur?
Matric of the mitochondria
WHere does oxidative phosphorylation occur?
utilises proteins found in the membrane of the crista
What are the 4 stages of glycolysis?
Stage 1: Activation of glucose by phosphorylation
Stage 2: Splitting of the phosphorylated glucose
Stage 3: Oxidation of triose phosphate
Stage 4: Production of ATP
Describe stage 1 of glycolysis
Before splitting, glucose is made more reactive by adding 2 phosphate molecules (phosphorylation)
Phosphates from the hydrolysis of ATP ADP
This provides the energy to activate glucose and lowers the activation energy needed for the following enzyme controlled reactions
2 ATPs have been ‘spent’
- The phosphorylation of glucose is carried out by enzymes called ___________
hexokinases
Phosphorylation of glucose forms what?
glucose 6-phosphate (G6P)
Extra info for stage 1 of glycolysis
- 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
Describe stage 2 of glycolysis
Glucose 2x 3C triose phosphates (TP)
Describe stage 3 of glycolysis
2 hydrogen removed from each TP
Hydrogen transferred to NAD= (hydrogen carrier)
This forms reduced NAD
What is NAD+
nicotinamide adenine dinucleotide
Describe stage 4 of glycolysis
Enzymes convert 3C TP 3C pyruvate
2 ATPs generated from ADP (net)
Summarise what happens in the link reaction
converts 3c pyruvate into CO2 and 2C acetyl coenzyme A
Where does the link reaction take place? And what happens there?
.Takes place in the mitochondrial matrix
.Oxidises the pyruvate made in glycolysis
.Pyruvate actively transported into matrix of mitochondria
Draw a flow chart of the link reaction
check notes
4 steps of link reaction
- 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)
How many times must the link reaction occur for each glucose?
twice
Krebs cycle, who, when, aka
- Sir Hans Krebs 1937
- AKA Citric acid cycle
Where does krebs cycle take place?
matrix
How many kreb cycles for each glucose?
2
Draw krebs cycle
check notes
Define Substrate level phosphorylation
the direct phosphorylation of ADP with a phosphate group by using the energy obtained from a coupled reaction
Define oxidative phosphorylation
the production of ATP from oxidised NADH and FADH
So each acetyle CoA enterign the krebs cycle results in what?
- 2CO2 molecules (plus 1 from LR)
- 1 ATP molecule
- Reduced co-enzymes NAD and Fad
.Coenzymes NADH and FADH are carrying what?
Hydrogen atoms
.During oxidative phosphorylation, some of the energy of the electrons is conserved in the formation of what?
ATP
Where does oxidative phosphorylation occur?
The cristae of the mitochondria
Enzymes and proteins needed for oxidative phosphorylation are found where?
The inner membrane of the mitochondria
Draw a labelled diagram of oxidative phosphorylation
check notes
- Oxygen is important in respiration, why?
it is the final acceptor in oxidative phosphorylation, joining with protons and electrons to form water.
If no oxygen was present in respiration what would happen?
- 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
Why is the step by step approach in the movement of electrons along the ETC in respiration important?
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.
Other substances are also able to undergo oxidation to release energy, what are they?
lipids and proteins
Describe the process of Oxidative Phosphorylation
- Hydrogen atoms from glycolysis and Krebs join with coenzymes NAD and FAD
- Reduced NAD and FAD donate the electrons of the hydrogen atoms they are carrying to the first electron transport molecule
- The electrons pass along the ETC in a series of redox reactions
- 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 space
- The protons gather in the area between the mitochondrial membranes
- They then diffuse back into the mitochondrial matrix through ATP synthase channels in the inner mitochondrial membrane
- At the end of the chain the electrons combine with the protons and oxygen making water
- Oxygen is the final acceptor of the electrons in the ETC
if there was no oxygen availible for respiration, what problems would occur?
Oxygen is the final electron acceptor in aerobic respiration
Without it, NADH no longer releases hydrogen at the ETC
This creates a backlog of NADH, and no NAD being regenerated
Without NAD, the Kreb’s cycle, link reaction, and glycolysis cannot take place
The NADH produced during glycolysis must be oxidised back into NAD+ so that it can be reused
If NAD+ remained as NADH, there would be no carriers to take up the hydrogen atoms released during glycolysis
Glycolysis would stop
In anaerobic respiration conditions, neither Krebs nor the ETC can continue as all the coenzymes are reduced
This means there will be no available NAD+ pr FAD to take up the hydrogen atoms produced
This will cause the enzymes to stop working
As a result the only ATP produced would be the two net produced during glycolysis
How does anaerobic respiration get around the problems of lack of oxygen?
NAD+ is replenished by pyruvate
Pyruvate accepts the hydrogen from NADH
The newly oxidised NAD+ can then be reused in glycolysis
There are two types of anaerobic respiration carried out by eukaryotic cells, what are they?
- Plants and microorganisms – pyruvate converted to ethanol and CO2
- Animals – pyruvate converted to lactate
Describe anaerobic respiration for Bacteria and certain fungus (yeast)
- Pyruvate is decarboxylated (loses CO2)
- Forms ethanal
- Ethanal is reduced by H atoms supplied by NADH
- This forms ethanol
Pyruvate + NADH ethanol + CO2 + NAD+
What are the uses of anaerobic respiration in bacteria and certain fungus?
- Yeast and the brewing industry
- Yeast grown anaerobically
- Ferments natural carbohydrates from plant products:
o Grapes (wine)
o Barley seeds (beer)
Why is anaerobic respiration good for animals?
Occurs in animals to overcome a temporary oxygen shortage Survival advantage (immediately after birth, water with low O2, escape)
Where is anaerobic respiration most common in animals?
Skletal muscles
- During an oxygen shortage, NADH from glucose can accumulate and must be recovered in animals, how is it gotten rid of?
pyruvate takes up 2 hydrogen atoms from NADH
- This forms lactate
Draw the diagram of pyruvate + NADH –>
Lactate + NAD+
check notes for diagram
- When oxygen is availible again, the lactate is oxidised back to what?
pyruvate
When pyruvate is oxidised from lactate, what can be done to it?
o Further oxidised to release energy
o Converted back to glucose
Problems associated with lactate
- 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 glycogen
D# - 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)
When the nervous stimulation stops on a muscle, what will happen?
- Calcium ions are actively transported back into the sarcoplasmic reticulum (uses energy from ATP hydrolysis)
- Troponin no longer changes the shape of the tropomyosin
- Tropomyosin blocks the actin filament
- Myosin heads are unable to bind
- Muscle relaxes
Why is energy important in muscle contraction?
Muscle contraction relies on energy to:
- Move myosin heads
- Reabsorb calcium ions into the ER
Where does the energy for muscle contraction come from?
Where does this energy come from?
- Oxidation phosphorylation in the mitochondria
- Anaerobically: phosphorylation using phosphocreatine (PCr)
What is phosphocreatine?
A buffer supply of energy stored in the muscle used to restore ATP
How does phosphocreatine restore ATP?
- A reserve supply of phosphate
- Broken down when energy is released
- Combines with ADP to reform ATP
- Is immediately available
