Section 5 Energy Flashcards
What is the main source of energy for an ecosystem?
Sunlight
What is the role of producers, consumers, decomposers, in an ecosystem?
producers = plants, perform photosynthesis, use light energy to make biological molecules
consumers = animals, cannot make their own biological molecules, need to eat plants (primary consumers) or other animals (secondary/tertiary consumers) to obtain biological molecules
decomposers = bacteria and fungi, perform saprobiotic decomposition,
release enzyme onto dead plants/dead animals/animal waste (organic matter) breaking them down to obtain biological molecules
Why do producers (plants) need biological molecules?
Glucose = respiration, store as starch, make cellulose
Amino Acids = make proteins e.g. enzymes
Fatty Acid & Glycerol = make triglyceride as energy store, make phospholipid for membranes
Why do consumers (animals) need biological molecules?
Glucose = respiration, store as glycogen
Amino Acids = make proteins e.g. enzymes
Fatty Acid & Glycerol = make triglyceride as energy store and insulation/protection, make phospholipid for membranes
Why do decomposers (bacteria/fungi) need biological molecules?
Glucose = respiration
Amino Acids = make proteins e.g. enzymes
Fatty Acid & Glycerol = make phospholipid for membranes
How do organisms carry energy?
Main Source = Glucose
Stored as Starch in plants and Glycogen in animals
Alternative Source = Lipids/Fats/Triglycerides and Proteins
How does energy move through an ecosystem?
by the food chain, begin with producer and then moves onto primary consumer, then secondary consumer, then tertiary consumer – with decomposers occurring at each stage (trophic level).
Why is all the light energy not utilised by plants in photosynthesis?
only 2% is used in photosynthesis – of the rest, a certain part misses the chloroplast, the other parts would be reflected or the wrong wavelength
Why is energy lost along a food chain?
not all the glucose made by producers is stored as starch or used to build biomass, as a certain part is lost in respiration (as heat)
not all the stored energy in the plant is transferred to primary consumers as certain parts of the plant are inedible and indigestible (available to decomposers)
of the energy the primary consumer obtains, a certain amount is used in respiration, the rest is stored as glycogen and used to build biomass
not all this stored energy is transferred to secondary consumers due to inedible parts and indigestible parts (available to decomposers)
only 10% of energy is transferred from producer to primary consumer
only 20% of energy is transferred from consumer to consumer
the losses are due to respiration, inedible parts, indigestible parts
higher proportion is transferred from consumer to consumer because consumers are more edible and digestible, producers are made up of cellulose
the higher consumers have the highest respiratory losses as they have increased movement (hunt for food)
Effect of energy loss on a food chain?
places a limit on the length of a food chain, those at the higher trophic levels (just quaternary consumers) would not obtain enough energy from the food it consumes
What is Productivity?
Productivity = Amount of Glucose/Energy available to organism
Primary Productivity = Amount of Glucose/Energy available in Plants
Secondary Productivity = Amount of Glucose/Energy available in Animals
Net Productivity = Gross Productivity – Respiratory [and Faeces] Losses
Gross Primary Productivity is amount of glucose made by plant in photosynthesis,
Net Primary Productivity is amount of glucose stored as starch after respiration
Gross Secondary Productivity is amount of glucose consumed by animal,
Net Secondary Productivity is amount of glucose stored as glycogen after respiration
in all cases, net productivity is the glucose/energy available to organisms at next stage of food chain
respiratory losses are higher in consumers then producers due to movement
and respiratory losses are higher in secondary/tertiary/quaternary consumers then primary consumers as they move more to hunt for food
and respiratory losses are higher in consumers that have to maintain a constant body temperature (endotherms)
What does a Pyramid of Number represent?
number of each type of organism at each trophic level – the numbers decrease as we move up trophic levels due to the loss of energy (not as many individuals can be supported)
can look inverted when it does not take into account mass (e.g. 1 oak tree or millions of fleas)
What does a Pyramid of Biomass represent?
biomass of each type of organism at each trophic level
biomass = mass of living tissue (based on dry mass, water excluded)
biomass includes biological molecules, organelles, cells, tissues, organs
units for biomass (g per m2 for land based animals,
g per m3 for water based animals)
so as we move along a food chain (up trophic levels) there is a loss of energy due to respiration/inedible parts/indigestible parts, so there is less energy to build biomass, so biomass decreases
What does a Pyramid of Energy represent?
amount of energy found at each trophic level
as before, loss of energy occurs along a food chain (respiration, inedible parts, indigestible parts)
What are the units for energy?
kJ/m2 /year
What is photosynthesis?
using light energy to make glucose (and other biological molecules)
occurs in plants and algae (both have chloroplast)
Adaptation of plant for photosynthesis?
leaf located near top of plant = closer to light
leaf is thin and wide = large surface area for light, short diffusion distance for CO2
has many veins = connect to xylem to bring in water
has stomata for gas-exchange (CO2/O2)
has air spaces to support ease of gas-exchange
palisade cells located near top of leaf close to the light
palisade cells are large = large surface area for light
palisade cells have a thin cell wall = short diffusion distance for CO2
palisade cells contain many chloroplasts (site of photosynthesis)
palisade cells have a large vacuole = pushes chloroplast to edge of cell closer to light
Structure of chloroplast?
site of photosynthesis
has a double membrane (outer and inner)
contains discs called thylakoids (contain chlorophyll)
a stack of thylakoids = granum
thylakoids are surrounded by a fluid material called stroma
How does photosynthesis take place?
In 2 stages
light dependent stage = on thylakoids, makes ATP and reduced NADP
light independent stage = in stroma, uses the ATP and reduced NADP to make glucose
Describe the light dependent stage?
light hits chlorophyll
chlorophyll absorbs the light if correct wavelength
electrons become excited and are lost from the chlorophyll (photoionisation)
electrons enter an electron carrier system
electrons move down the system releasing energy
this pumps protons from stroma into thylakoid space
protons accumulate in thylakoid space, then diffuse back into stroma
they pass though ATP Synthase which joins ADP and Pi to make ATP (mechanism = chmeiosmosis, process = photophosphorylation)
the electron ends up by joining with NADP to form reduced NADP
light also hits water
causes photolysis (breakdown of water due to light)
forms: H+, e-, O2
the H+ joins with the reduced NADP (now carries a hydrogen atom: H+ and e-)
the e- replaces electrons lost from chlorophyll
O2 given off as waste
Describe the light independent stage?
involves the calvin cycle
RuBP (5 carbon) joins with CO2 to make 2 lots of GP (3 carbon)
the GP is reduced into TP (3 carbon)
this uses energy from ATP and hydrogen atom from reduced NADP
the TP can be used to reform RuBP (uses energy from ATP)
the TP can also be used to form glucose (carbohydrate)
GP can also be used to form amino acids (proteins) and fatty acids
TP can also be used to form glycerol
fatty acids and glycerol will form a lipid
photosynthesis/calvin cycle = produces all the main biological molecules
What are the limiting factors of photosynthesis?
Amount of C02 (Concentration)
Amount of light intensity
The temperature
Effect of light limiting the calvin cycle
RuBP increases
Gp decreases
How do you measure the rate of photosynthesis?
You measure the amount of CO2 used or measure the amount of oxygen in a certain amount of time.
Or you use a photosynthometer.
What is the structure of ATP?
Adenosine triphosphate ( 1 Adenosine linked to 3 phosphates)
MAIN ENERGY CARRIER MOLECULE
Formed by joining ADP to a phosphate (+energy used) (Condensation reaction using ATP synthase)
On breakdown (ATP to ADP + Pi (+energy released)(Hydrolysis reaction using enzyme ATPase)
Energy released after breakdown is delivered to wherever required.
What are the 3 ways ATP can be formed?
1) Phosphorylation (Light dependent stage of photosynthesis)
2) Substrate-level phosphorylation (glycolysis and krebs cycle of respiration)
3) Oxidative phosphorylation (electron transport chain of respiration)
Why is ATP a suitable source of energy in the body?
It’s an immediate source of energy- only ONE BOND needs to break to release energy (Also a VERY WEAK bond)
It’s also a manageable source as it releases small source amount of energy.
Uses of ATP (made by respiration) in organisms?
Protein synthesis Organelle synthesis DNA replication Cell division Active transport metabolic reactions movement (muscle contractions) Maintaining body temperature
What is respiration?
Releasing energy from glucose to make ATP
ATP will provide energy for life processes
Occurs in all living things
ATP can be made by substrate level phosphorylation and oxidation phosphorylation
What are the 2 types of respiration?
Aerobic (with oxygen)
Anaerobic (without oxygen)
Describing Aerobic respiration (LONG)
occurs in 4 stages: Glycolysis, Link Reaction, Krebs Cycle, Electron Transport Chain
glycolysis takes place in cytoplasm of the cell
link reaction and krebs cycle take place in matrix of mitochondria
electron transport chain takes place on inner membrane of mitochondria (cristae)
the main job of the first 3 stages are to provide reduced NAD and reduced FAD for the last stage, this is where most of the ATP is made by oxidative phosohorylation
GLYCOLYSIS
uses glucose to produce 2x pyruvate, 2x ATP, 2x reduced NAD
pyruvate enters link reaction
ATP made by substrate-level phosphorylation
reduced NAD used in ETC
LINK REACTION
link reaction
uses pyruvate to produce acetylcoenzyme A, reduced NAD, CO2
pyruvate + coenzyme A + NAD = acetylcoenzyme A + reduced NAD + CO2
acetylcoenzyme A used in krebs cycle
reduced NAD used in ETC
CO2 given off as waste
KREBS CYCLE
uses acetylcoenzyme A to produce 3x reduced NAD, 1x reduced FAD, 1x ATP, 2x CO2
reduced NAD and reduced FAD used in ETC
ATP made by substrate-level phosphorylation
CO2 given off as waste
ELECTRON TRANSFER CHAIN
reduced NAD and reduced FAD release the hydrogen atom (H+/e-) they are carrying
the H+ build up in the matrix of the mitochondria
the e- enter the ETC
the electron (e-) moves along the chain releasing energy, this pumps the protons (H+) from the matrix into the intermembranal space
the H+ build up in the intermembranal space, then diffuse back into the matrix via a transport protein carrying ATP Synthase enzyme
this leads to the production of ATP = oxidative phosphorylation
oxygen is used as a final electron acceptor and proton acceptor
it removes the electron from the end of the ETC, so the ETC can continue
it removes the proton from the matrix, hence maintaining concentration gradient
it becomes water
Describe anaerobic respiration?
no oxygen present, so no final electron acceptor and proton acceptor
ETC stops
Krebs Cycle and Link Reaction also stop as NAD amd FAD are not reformed in ETC
Glycolysis can continue as it reforms its own NAD
so Anaerobic Respiration only relies on Glycolysis (making 2x ATP by substrate-level phosphorylation
NAD is reformed from the reduced NAD made in glycolysis
the reduced NAD donates its hydrogen atom (H+/e-) to pyruvate to reform NAD
in animals the pyruvate becomes lactate (lactic acid)
in plants/yeast the pyruvate becomes ethanol and CO2
How to measure the rate of respiration?
Measure amount of O2 used or measure amount of CO2 produced, certain time
One method=respirometer
What are the respiratory substrates?
Carbohydrates all forms of carbohydrates are turned into glucose
Proteins, excess amino acids are converted into keto acid
Lipids, provided fatty acids and glycerol
What are the uses of nitrogen in organisms?
Used to make amino acids and proteins and
Used to make nitrogenous bases in DNA
Describing the nitrogen cycle (LONG)
nitrogen present in the atmosphere as nitrogen gas (N2)
N2 cannot be absorbed by plants, they can only absorb Nitrate ions (NO3-)
N2 converted into Ammonium Ions (NH4+) by nitrogen fixation by nitrogen-fixing bacteria
there are 2 types of NFB: mutualistic and free-living
mutualistic NFB are found in the root nodules of leguminous plants, they place the NH4+ ions directly in the roots – these plants can use this to make AA and nucleotides
free-living NFB are found in the soil – they place NH4+ ions in the soil
NH4+ ions cannot be absorbed by plants therefore is converted into NO3- by nitrification by nitrifying bacteria
Ammonia ions (NH4+) into Nitrite ions (NO2-) into Nitrate ions (NO3-)
the NO3- ions will be absorbed by plants to make AA/proteins and nucleotides/DNA
consumers can eat the plant to obtain the AA and nucleotides
organic material (dead plants, dead animals, animal waste) are broken down by saprobiotic decomposers, this releases Ammonia ions (NH4+) back into the soil by a process called ammonification
Nitrate ions (NO3-) can be converted back into Nitrogen gas (N2) by denitrification by denitrifying bacteria – they work in anaerobic conditions (when the field is waterlogged and all the air spaces in the soil are filled with water)
What is phosphorous used for in organisms?
Used to make phospholipid
Used to make DNA
Used to make ATP
Describing the phosphorous cycle (LONG)
phosphorous present in sedimentary rock as phosphate ions (PO43-)
when sedimentary rock erodes, leaves soil containing PO43-)
plants absorb PO43-) to make phospholipid/DNA/ATP
consumers eat plants to obtain phospholipid/DNA/ATP
organic material (dead plants, dead animals, animal waste) are broken down by saprobiotic decomposers, this releases Phosphate Ions (PO43-) back into the soil
(if soil sediments and hardens, over time, it returns to a rock state)
Agricultural ecosystem?
Description for farming ecosystems
Aim of farms is to grow crops and raise livestock
Grow crops to sell and feed farm animals
Raise animals to sell meat and other resources.
How are crops farmed intensively for high yield?
select suitable location (sunlight, water, minerals)
clear area of plants and animals (deforestation – removes competition/pest)
selectively breed crop
use greenhouse to provide high levels of light, CO2, temperature
provide water by irrigation
add fertilisers (provides minerals = nitrate, phosphate, magnesium)
control pests
polyculture/crop rotation (ensures mineral levels in the soil do not become depleted)
ploughing (adds air spaces to soil, so bacteria involved in nutrient cycles can aerobically respire)
What are pests?
Organisms that harm plants/ crops
E.G. Other plants acting as competitors, insects eat the plants, fungi causing disease.
How can pests be controlled?
Pesticides or biological control
What are pesticides?
Chemical sprays that kill the pest
E.G. For weeds= herbicide
Insects=Insecticide
Fungi=fungicide
Pros and cons of using biological control.
ADVANTAGES specific does not cause bioaccumulation pests do not develop resistance does not need to be reapplied
DISADVANTAGES
slow acting
may become a pest itself
cannot control area covered
What is bio accumulation?
.
Pesticides are not biodegradable
They remain stored in organisms tissues
They then accumulate up the trophic levels
They are toxic to consumers at higher trophic
What is an integrated pest control system?
makes use of both pesticides and biological control – the aim is to reduced the amount of pesticide used, as the pesticide harms food chains and ecosystems
process:
keep some native trees (will act as natural habitats to natural biological controls)
monitor area for pests
mechanically remove pests if present
initial dose of pesticide – fast acting
then apply biological control – will increase in number over time and provide long term control
reapply pesticides whenever there is an uncontrollable outbreak
What minerals do fertilisers provide?
nitrate = make AA, make nitrogenous bases
phosphate = make ATP, DNA, phospholipids
magnesium = make chlorophyll
What are the 2 types of fertiliser?
Natural= Reduced risk of leaching/ eutrophication
Artificial= = faster release of minerals and higher concentration but risk of leaching/eutrophication and lowers water potential of soil
What is eutrophication? (LONG)
if large amounts of chemical fertilisers are sprayed onto fields and heavy rainfall occurs, the fertiliser may leach into local water sources
the fertiliser will travel and build up in ponds or lakes
the mineral (e.g. nitrates to make AA) will be
absorbed and used by Algae
this will lead to an increase growth of algae = algal bloom
the algae grows on the upper surface of the water, this prevents light reaching the plants at the bottom of the water
these plants cannot photosynthesise, so die
these provide more nutrients to saprobitoic decomposers, so these increase in number
the decomposers will aerobically respire, using up the oxygen in the water
therefore fish die as less oxygen is available
Environmental impacts of crop farming
DEFORESTATION = reduces species diversity, reduces plant species diversity, less habitats and food sources, reduces animal species diversity
MONOCUTLURE = one type of plant/crop grown, depletes certain nutrients in the soil (no time provided for nutrient levels to recover)
SELECTIVE BREEDING = reduces genetic diversity of crop (reduces variation, reduces ability to adapt to changes in the environment)
POLLUTION = bioaccumulation of pesticides, eutrophication from chemical fertilisers
Reducing environmental impact of crop farming
keep some native trees (helps to maintain species diversity)
keep hedgerows (help to maintain species diversity + absorb chemical fertilisers reducing eutrophication)
polyculture (grow different crops at different times of the year, allows depleted nutrients to recover in the soil)
keep seeds of wild crop (maintain genetic diversity, use if environment changes)
use biological control for pests & natural fertiliser for minerals
How are animals (domestic livestock) intensively reared in farming?
Selectively bred
Given predigested food with additional enzymes
Given antibiotics and vaccinations
Given steroid hormones
Restricted movement and kept warm (reducing energy loss)
Natural ecosystem vs agricultural ecosystem (LONG)
NATURAL= light source, AGRICULTURAL= light+food for farmer+ fossil fuel for machines
NATURAL= high biodiversity, AGRICULTURAL= low
NATURAL= high genetic diversity, AGRICULTURAL= low
NATURAL= low productivity, AGRICULTURAL=high
NATURAL= nutrients recycled, AGRICULTURAL= nutrients added (fertilisers)
NATURAL= competition/predators control pests, AGRICULTURAL= pesticides/ biological control
NATURAL= reaches climax community, AGRICULTURAL= prevent climax from being reached
