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
