UNIT 5 - Photosynthesis, Respiration and Nutrient Cycles Flashcards
how is chloroplast adapted for the light dependent reaction
- thylakoids provide a large surface area for electron carriers and enzymes
- the network of proteins in the chloroplast hold chlorophyll in the optimal postiton for photoionisation
- grana membranes have ATP synthase channels which catalyse the production of ATP
- chloroplast contain DNA and ribosomes so can quickly make proteins that are involved in the light dependent reaction
how are chloroplast adapted for the light independent reaction
- The stroma contains all of the enzymes needed for the light independent reaction
- high concentration of enzymes can be held within in the membrane bound stroma
- the products of the light dependent reaction can easily diffuse into the stroma
4.It contains DNA and ribosomes so can quickly manufacture proteins involved in the light independent stage
where does the light dependent reaction take place
the chlorophyll
what is photolysis
the breakdown of water to produce protons, electrons and oxygen
what happens in photoionisation
- chlorophyll absorbs light and electrons raise to a higher energy level and are in the excited state
- electrons leave the chlorophyll and are replaced by the electrons produced by the photolysis of water
what happens in the electron transfer chain
- electrons are taken up by an electron carrier and are passed from one electron carrier to another in a series of redox reactions in the thylakoid
- electrons lose energy when passed to electron carrier and the energy lost in used to synthesise ATP
what happens during the chemiosmotic theory
- protons are pumped from stroma to thylakoid using energy released in the photolysis of water by a proton carrier creating conc. grad.
- photolysis of water also produced H+ which further increases the conc. inside the thylakoid membrane
- protons diffuse through the ATP synthase channel proteins causing the enzyme to change shape
what happens after chemiosmotic theory
- protons diffuse out of the thylakoid space through the ATP synthase channel protein and are taken up by NADP
- reduced NAPD is the main product of light dependent reaction
- reduced NAPD enters the light independent state taking its electrons from the chlorophyll molecules
processes in order of the light dependent reaction
- photoionisation
- electron carriers
- electron transfer chain
- the chemiosmotic theory
how many turns of the calvin cycle is needed to make a glucose
6
outline the calvin cycle
- CO2 diffuses into the leaf and is dissolved in water around the walls of the mesophyll cells and then diffuses through to the chloroplasts stroma
- carbon dioxide reacts with ribulose biphosphate catalysed by rubisco to form 2 molecules of glycerate-3-phosphate
- reduced NADPH is used to reduce glycerate-3-phosphate to triose phosphate using energy from 2 ATP to form 2 ADP
4.NADP returns to light dependent stage - triose phosphate molecules are converted to organic substances that the plant requires like starch, amino acids
- 5 of the triose phosphate molecules are used to regenerate ribulose biphosphate using ATP
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 its shortest supply
define respiration
a series of controlled reactions in which energy is transferred from organic compounds to ATP
what is the order of the processes of respiration
- glycosis
- the link reaction
- the Krebs cycle
4.oxidative phosphorylation
what happens in glycosis
- glucose is phosphorylated by ATP being hydrolysed to form phosphorylated glucose to make it more reactive to lower activation energy for the enzyme controlled reactions
- lysis of phosphorylated glucose occurs and it splits into two molecules of triose phosphate
- oxidation of triose phosphate and hydrogen is removed and received by NAD to produce NADH
- enzyme controlled reactions convert triose phosphate into another 3 carbon molecule called pyruvate and in the process 2 molecules of ATP are produced
what occurs in the link reaction
- the pyruvate is oxidised by enzymes to produce acetate and it loses CO2 and 2 H
- hydrogens lost are then accepted by NAD to form reduced NADH
- the acetate combines with CoA to produce acetyleCoA
what happens in the Kreb cycle
- acetyle CoA combines with 4 carbon molecule to produce citrate a 6 carbon molecule
- citrate loses 2 CO2 and H to give a 4 carbon molecule called oxaloacetate and a single molecule of ATP is produced
- oxaloacetate can now combine with acetyleCoA to begin cycle again
what happens in oxidative phosphorylation
- H atoms produced in glycosis and the Krebs cycle combine with NAD and FAD causing them to be reduced and then donate the electrons from the H atoms to the first molecule in the transfer chain
- electrons pass through electron chain in ox/red reactions and energy is released and used in active transport of protons across the inner mitochondrial membrane and into the inner membrane space
- protons accumulate creating a conc. gradient meaning they diffuse back through the matric via ATP synthase
- electrons combine with the protons and oxygen to form water
compare and contrast photosynthesis and respiration
- respiration happens in mitochondria and photosynthesis happens in the thylakoid membrane
- electron transfer chain is used to release bursts or energy in both
- Produce ATP by the Hydrogen diffusing through ATP synthase
- in photosynthesis you are converting light energy into ATP whereas in respiration you are converting chemical energy into ATP
what are the stages of anaerobic respiration in plants
glycolysis
ethanol fermentation
what are the stages of anaerobic respiration in animals
glycolysis
lactate fermentation
compare and contrast aerobic and anaerobic respiration
- in aerobic respiration the electron transfer chain releases small amount of energy whereas in anaerobic respiration the electron transfer chain isn’t functional as there is no final electron acceptor
- in aerobic respiration ATP is produced from the the Krebs cycle, glycolysis and oxidative phosphorylation whereas in anaerobic respiration it is only produced from glycolysis
-NAD and FAD are oxidised in both
- CO2 is produced in both
- in aerobic respiration the products are CO2 and water whereas in anaerobic respiration it is CO2 and lactate/ethanol
- aerobic takes place in mitochondria and cytoplasm whereas anaerobic takes place in the cytoplasm only
what is biomass
Biomass is the total mass of living material in a specific area at a given time
how do you measure biomass
Measured using dry mass per grams squared/ grams cubed in a given time using calorimetry
how does calorimetry work
Chemical energy store in dry mass can be estimated using calorimetry by weighing sample of dry mass and burning it in excess oxygen within a sealed container and the container is called a bomb. The bomb is surrounded by a water bath and the heat of combustion causes rise in temperature.
We know SHC of water and so we can calculate the energy released from the burnt biomass
what is the use of these things in calorimetry
1. thermometer
2. water
3. ingition wires
4. oxygen atmosphere
5. stirrer
- Thermometer- used to measure temp change of water
- Water- to measure the thermal energy transferred and we know SHC
- Ignition wires- to ignite the sample when its inside the bomb chamber and start reaction and measure how much energy you have put in so you can subtract it
- Oxygen atmosphere- to ensure complete combustion of carbon
- Stirrer- to ensure that the temperature of the water is uniform throughout container
what are the 7 uses of glucose in a plant
- Energy source for respiration
- Respiration which is then used to turn sugars, nitrates and other nutrients into amino acids to make proteins
- Repair and replacement of damaged parts
- Make fats and oils
- Energy storage as sucrose in fruit
- Energy stored as starch in leaves
- To make cellulose and maintain cell wall structure
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 other organisms rather than using the energy from sunlight
what are saprobionts
group of organisms that break down the complex materials in dead organisms into simple ones and they release valuable minerals and elements that can be absorbed by plants and recycled
what is a food chain
Food chain describes a feeding relationship where the producers are eaten by primary consumers and in return these are eaten by secondary consumers and etc.
what is each stage of the food chain referred too
trophic level
what are the 4 reasons why most of the suns energy is not converted into organic matter
Over 90% of the sun’s energy is reflected back into space by clouds, dust or absorption in the atmosphere
Not all wavelengths of light can be absorbed and used for photosynthesis
Light may not fall on a chlorophyll molecule
There could be other limiting factors like temperature and carbon dioxide limiting the rate of photosynthesis
what is gross primary production (GPP)
The total energy quantity of the chemical energy store in plant biomass in a given area or volume in a given time
what is net primary productivity
The chemical energy store which is left when losses to respiration have been taken into account and is available to the plant for growth and reproduction but is also available to other trophic levels in the ecosystem like consumers and decomposers
4 reasons why is there so much energy lost in a food chain
- Some of the organisms isn’t consumed
- Some parts are consumed but cannot be digested
- Some of the energy is lost in excretion
- Some energy losses occur as heat from respiration and are lost to the environment
what is the equation for net production
N = I - (F + R)
N = net production
I = chemical energy store of ingested food
F= energy lose in faeces and urine
R= energy lost in respiration
4 ways farmers reduce energy losses and increase yeilds
Movement is restricted: less energy is used in muscle contraction so more for growth
Kept indoors in the warm: reduce heat loss from the body trying to keep warm
Feeding is controlled: animals receive the optimum amount and type of food for max growth so no wastage
Kept same from predators: so, there is no loss to other organisms in the food web
what are the ethical problems with reducing energy losses
It can cause stereotypical behaviour that are repeated patterns of behaviour that have no apparent purpose like self-mutilation, feather pecking and tail biting
what are the four ways you can simplify food webs
Removing weeds: weeds compete for crop water, mineral ions, space and light as these resources are often limited and the amount taken by the weeds is reducing the availability to the crop and reduce yield
Remove insect pests: insects may damage the leaves on the crop and their ability to photosynthesise reducing yield
Avoiding monoculture: many crops are now grown on a large scale individually which enables insects’ pests and fungal pests to spread easily, and mineral ions are depleted in the soil needing to be replaces by fertilisers, so we grow multiple different crops on the same field.
Removing pests on domesticated animals using pesticides: pests may cause disease, and the animals therefore may not grow as rapidly or may be unfit for human consumption all of which reduced productivity, so we remove them.
what are pesticides useful for
Used to increase productivity by killing pests and reducing loss to other organisms in the food web so we get more.
what is the problem with using pesticides
insecticides do kill and harm useful insects and well as harmful ones
what do organic farmers do to increase productivity
They find natural predators of the pest that doesn’t eat the crop as well or reduce productivity
You can also find something to grow around your crop that the predator doesn’t like e.g. garlic, strong onions
what is the calculation for efficiency of energy transfers and what are the units
Percentage efficiency = energy available after the transfer/ energy available before the transfer
Units: Kj/m2/year
what is the use of nitrogen mineral
making biomolecules like proteins
what is the use for phosphorus mineral
making roots
what is the sue for potassium mineral
making fruit and flowers
what is the use of magnesium minerals
making chlorophyll
what are the 3 main sources of minerals
Rocks: mineral rocks are slowly dissolved by acidic rainwater and the minerals are washed into soil
Natural fertilizers: animal faeces, the decay of dead plants/animals return minerals to soil
Artificial fertilizers: contain a readymade mixture of the mineral needed by plants
what are saprotrophs
Saprotrophs are a form of decomposer but digest internally such as earth worms, millipedes, dung beetles as they eat decaying plants and animal matter in the soil
what is the role of mycorrhizae
Acts as a sponge and holds water and minerals in the roots and this enables the plants to resist drought and take up ions more readily and the fungi gets organic compounds like sugars and amino acids from the plant
explain the steps of the phosphorus cycle
- rocks weather and erode helping phosphate ions dissolve in soil available for plants
- the phosphate ions are then passed into the animals which feed on the plants
- excess phosphate ions are excreted by animals and accumulate into waste material
- when animals and plants die the decomposer break them down releasing them into water or soil and some remain in the animal or plant like bones or shells
- decomposers release phosphate ions in excreta and dissolved out of rocks are transported by streams and rivers where they form sedimentary rocks
what are the uses of phosphate ions
RNA, DNA, Phosphorylation, ATP and phospholipids
use of nitrogen
nucleic acids, RNA , amino acids, DNA and fertilisers
sources of nitrogen
atmosphere, soil, plants
what are the properties of nitrogen that help with the nitrogen cycle
very soluble , easily leach through the soil
what are teh 4 main steps of nitrogen cycle
- Ammonification
- Nitrification
- Nitrogen fixation
- Denitrification
what happens in ammonification
- ammonia is produced from organic nitrogen containing compounds
- saprobionts feed on faeces and dead organisms material releasing ammonis which then forms ammonium ions in the soil
what happens in nitrification
- Nitryfying bacteria convert ammonium ions into nitrate ins and this is an oxidarion reaction so oxygen required to do this therefore soil with air spaces is required for higher yields
what happens in nitrogen fixation
Nitrogen gas is converted into nitrogen containing compounds and this can be done industrially and naturally
Free living nitrogen fixing bacteria reduce gaseous nitrogen to ammonia and use this to make amino acids
Mutualistic nitrogen fixing bacteria which live in nodules on the roots of leguminous plants like peas and beans and obtain carbs and amino acids from the plants
what happens in denitrification
When soil is waterlogged and has low O2 conc fewer aerobic nitrifying and nitrogen fixing bacteria are found and there is an increase in anaerobic denitrifying bacteria
They convert soil nitrates into gaseous nitrogen
why do we use fertilisers
Fertilisers contribute to the ecosystem to increase efficiency of energy transfers along food chains and therefore increase productivity
what are the 2 types of fertilisers
Natural fertilisers : dead and decaying remains of plants and animals and animal waste
Artificial fertilisers: mined from rocks and deposits and converted into different forms and blended together to give the balance of minerals for a particular crop . Compounds contain nitrogen, phosphorus and potassium are almost always present
what are the 3 main issues with fertilisers
1.Reduced species diversity and the nitrogen rich soils favour the growth of grasses, nettles and other rapidly growing species and these outcompete other species which die as a result
2.Leaching leads to pollution of watercourses
3.Eutrophication caused by leaching fertiliser into watercourses
what is leaching
Leaching is a process by which nutrients are removed from the soil and rainwater will dissolve any soluble nutrients such as nitrate ions and carry them deep into the soil beyond the reach of the plant roots
The leached nitrate ions will find their way to a river and stream and eventually drain into lakes or oceans and would have a harmful effect on humans if it is a source of drinking water
what is the process of eutrophication
- nitrogen is the limiting factor for plant and algal growth
- nitrogen concentration increases due to leaching, leading to more algae and plants
3.algae grows on the surface of the water and becomes very dense reducing light that reaches the bottom on the water as it absorbs the light - light is now the limiting factor and plants and algae now die that are deeper
- due to the dead plants the saprobiont population increases as they have plants to feed on meaning there is a higher demand for oxygen now
- oxygen then becomes a limiting factor and the other organisms like fish will die
- Without aerobic respiration organisms there is less competition for the anaerobic organisms whose populations increase
- Anaerobic organisms further decompose dead material releasing more nitrates and toxic wastes like hydrogen sulphide which makes water putrid
