Module 5: Energy Flashcards
source of energy for an ecosystem
sunlight
role of producers
photosynthetic organisms
plants
use light energy to make biological molecules
role of consumers
animals can't make their own biological molecules eat plants (primary consumer) eat other animals (secondary/tertiary) to obtain biological molecules
decomposers
bacteria and fungi
perform saprobiotic decomposition
release enzyme onto dead plants/animals/animal waste
breaking them down into organic matter
why do producers/plants need biological molecules
glucose-respiration, store as starch, make cellulose
amino acids- make proteins (enzymes)
fatty acid and 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 (enzymes)
fatty acids and glycerol-make triglyceride as energy store and insulation/protection, make phospholipid for membranes
why do decomposers need biological molecules
glucose-respiration
amino acids-make proteins (enzymes)
fatty acids and glycerol-make phospholipid for membranes
how do organisms carry energy
main source- glucose
stored as starch in plants
stored as glycogen in animals
alternative source-lipids/fats/triglycerides and proteins
how does energy move through an ecosystem
by the food chain
producer-primary consumer-secondary-tertiary
decomposers occur at each trophic level
why is all the light energy not utilised by plants in photosynthesis
only 2% is used in photosynthesis
rest of light: some misses chloroplast, others reflected by the wrong wavelength
why is energy lost along a food chain
respiration
inedible and indigestible parts of plants
stored as starch/glycogen
used to build biomass
10% producer to primary
20% consumer to consumer
consumers more digestible as they aren’t made up of cellulose
higher consumers have higher respiratory losses as they hunt
effect of energy loss on a food chain
places a limit on the length of a food chain, those at higher trophic levels (quaternary) wouldn’t obtain enough energy from the food it consumes
productivity
amount of glucose/energy available to an organism
primary productivity
amount of glucose/energy available to plants
secondary productivity
Amount of glucose/energy available in animals
Net primary productivity equation
Gross productivity - respiratory losses
Gross primary productivity
Amount of glucose made by a plant in photosynthesis
What is net primary productivity
Amount of glucose stored as starch after respiration
Gross secondary productivity
Amount of glucose consumed by animal
Net secondary productivity
Amount of glucose stored as glycogen after respiration
When are respiratory losses higher
In consumers than producers due to movement
Higher in secondary/tertiary/quaternary consumers as they move more to hunt for food
Higher in consumers that have to maintain constant body temperature (endotherms)
What does a pyramid of number represent
Number of each type of organism at each trophies level- numbers decrease as we move up trophic levels due to loss of energy (not as many can be supported)
Can look inverted when it doesn’t take mass into account
What does a pyramid of biomass represent
biomass of each type of organism at each trophic level
Move up food chain loss of energy due to respiration/inedible parts/indigestible parts so less energy to build up biomass so biomass decreases
Biomass
Mass of living tissue (based on dry mass, water excluded)
g per m2 for land based or g per m3for water based
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
How is energy lost in a food chain
Respiration
Inedible parts
Indigestible parts
Units for energy
kJ/m2/year
What is photosynthesis
Uses light energy to make glucose
Occurs in plants and algae
Adaptation of plant for photosynthesis
Leaf at top of plant=closer to light
Thin and wide= large SA, short diffusion distance
Veins= connect to xylem
Stomata=gas exchange
Palisade cells= top of leaf, large,thin cell wall, many chloroplasts and large vacuole (pushes chloroplasts to edge of cell closer to light)
Structure of chloroplasts
Site of photosynthesis Double membrane Thylakoids discs Stacks of thylakoids=granum Thylakoids surrounded by fluid called stroma
2 stages of photosynthesis
Light dependent
Light independent
Light dependent brief
On thylakoids
Makes ATP
reduced NADP
Light independent brief
In stroma
Uses ATP and reduced NADP
makes glucose
Light dependent stage
Light strikes chlorophyll and is absorbed
Pair of electrons become excited and leave chlorophyll (photoionised)
Electrons enter ETC, move down system releasing energy
Protons from stroma into thylakoid space
Protons accumulate in thylakoid space, diffuse back into stroma
Pass through ATP synthase channel (chemiosmosis) which joins ADP and Pi to ATP, photophosphorylation
Electron joins NADP to form reduced NADP
light strikes water molecule
Causes photolysis
Forms H+, e- and O2
H+ joins reduced NADP (carries hydrogen atom)
e- replaces electrons lost from chlorophyll
O2 is waste
Light independent stage
Involves Calvin cycle
RuBP (5C) joins CO2 to make 2 glycerate 3 phosphate (GP)
GP reduced to triose phosphate (TP)
Uses energy from ATP and hydrogen atom from reduced NADP
TP can be used to reform RuBP (uses energy from ATP)
TP used to form glucose
GP used to form amino acids and fatty acids
TP used to form glycerol
Fatty acids and glycerol form lipid
process of chemiosmosis
pumping protons through special channels in the membranes of the mitochondria
from inner to outer compartment
establishes a H+ gradient
after gradient is established, proteins diffuse down gradient using ATP synthase channel
limiting factors for photosynthesis
light
CO2
temperature
increase any of these then the rate of photosynthesis increases
effect of limiting light on the calvin cycle
RuBP decreases- being converted into GP but not being reformed from TP (no ATP)
GP increases- not converted into TP (no ATP/reduced NADP) but is being formed from RuBP
effect of limiting CO2 on the calvin cycle
RuBP increases- not converted into GP (no CO2) but is being reformed from TP
GP decreases- not being formed from RuBP (no CO2) but being converted into TP
products of the light dependent reaction
ATP
NADPH
products of the light independent reaction
glucose
NADP+
ATP
inorganic phosphate
what is the compensation point in plants
point in the day (light intensity) when the CO2 taken in by photosynthesis equals the amount given out by respiration= no net gas exchange
at low light intensity: rate of respiration > rate of photosynthesis (CO2 released)
at high light intensity: rate of photosynthesis> rate of respiration (CO2 absorbed)
how to measure the rate of photosynthesis
measure amount of CO2 used or measure amount of O2 produced, in a certain time
use a photosynthometer
how does a photosynthometer work
measures amount of O2 produced
uses aquatic plants as the O2 produced can be observed and collected
plant is surrounded in sodium hydrogencarbonate solution (CO2 source)
plant is kept in darkness before experiment begins (remove all O2)
as experiment runs O2 will be produced, collect in a capillary tube
amount collected can be measured , converted into a volume by multiplying length of oxygen bubble by pi r^2
volume O2 collected can be divided by time to find rate of photosynthesis
structure of ATP
adenosine triphosphate 1 adenosine, 3 phosphates energy carrier molecule ADP + Pi (+energy used) -> ATP condensation reaction using ATP synthase carries energy in its bonds ATP-> ADP + Pi (+energy released) hydrolysis reaction using ATP hydrolase (ATPase)
what is GP
glycerate 3 phosphate
what is TP
triose phosphate
how can ATP be formed
photophosphorylation (light dependent stage of photosynthesis)
substrate-level phosphorylation (glycolysis and krebs cycle of respiration)
oxidative phosphorylation (electron transport chain of respiration)
what makes ATP (from respiration) a good source of energy
immediate= need to only break one bond to release energy, bond is weak manageable= releases small amount of energy
uses of ATP (made in respiration) in organisms
proteins synthesis organelle synthesis DNA replication cell division active transport metabolic reactions movement maintaining body temperature
what is respiration
releasing energy from glucose to make ATP
ATP will provide energy for life processes
occurs in all living organisms
ATP can be made by substrate level phosphorylation (glycolysis and krebs cycle) and oxidative phosphorylation (electron transport chain)
2 types of respiration
aerobic
anaerobic
4 stages of aerobic respiration
glycolysis
link reaction
krebs cycle
oxidative phosphorylation
glycolysis
occurs in cytoplasm
glucose is phosphorylated to make it more reactive (uses 2 ATP)
glucose is split into 2 triose phosphates
hydrogen is removed and reduced NAD
triose phosphate turned into pyruvate, regenerates 2 ATP
uses glucose to produce 2x pyruvate, 2x ATP and 2x reduced NAD
pyruvate enters link reaction
ATP made by substrate-level phosphorylation
reduced NAD is used in ETC
link reaction
occurs in matrix of mitochondria
pyruvate oxidised to acetate, decarboxylated and dehydrogenated
2x H reduce NAD
acetate combines with coenzyme A to produce acetyl co enzyme A
pyruvate + coenzyme A + NAD -> acetylcoenzyme A + reduced NAD + CO2
acetylcoenzyme A is used in Krebs
reduced NAD used in ETC
CO2 is given of as waste
krebs cycle
occurs in the matrix of the mitochondria
acetyl coenzyme A from link combines with 4 carbon molecule
dehydrogenated and decarboxylated twice
to reform 4 carbon molecule
hydrogen reduces NAD and FAD
uses acetylcoenzyme A to produce 3x reduced NAD, 1 x reduced FAD, 1x ATP, 2x CO2
reduced NAD and reduced FAD are used in ETC
ATP is made by substrate-level phosphorylation
CO2 given off as waste
oxidative phosphorylation/ETC
takes place on the inner membrane of the mitochondria (cristae)
hydrogen atoms produced in glycolysis and krebs combine with coenzymes NAD and FAD
donate H to ETC
down ETC with redox reactions
energy released causes active transport of protons across inner mitochondrial membrane and into inner-membranal space
accumulate in inner-membranal space before diffusing back into matrix through atp synthase channels
at the end of the chain electrons protons and oxygen combine to form water
oxygen is the final acceptor
Anaerobic respiration
no oxygen present so no final electron acceptor
Electron transport chain stops
Krebs and link also stop as NAD and FAD aren’t reformed
Glycolysis continues as it forms its own NAD
anaerobic respiration only relies on glycolysis (2 ATP by substrate level phosphorylation)
NAD reformed from reduced NAD made in glycolysis
Reduced NAD donates hydrogen atom H+/e- to pyruvate to reform NAD
In animals pyruvate becomes lactate (lactic acid)
In plants/yeast pyruvate becomes ethanol and CO2
How to measure rate of respiration
Measure amount of O2 used or measure amount of CO2 produced in a certain time
Respirometer
How does respirometer work
Measure amount of gas exchange taking place between organism and air in a test tube
Test tube connected to manometer
Organism more O2 in then air in test tube decreases, less pressure so liquid moves towards test tube
Organism more CO2 out, more pressure so liquid moves away
Amount/volume by which coloured liquid moves represents volume of gas taken in/given out
What are respiratory substrates
Carbohydrates are turned into glucose
Proteins, excess amino acids converted into keto acid (turned into pyruvate and intermediates of krebs)
Lipids turn into fatty acids which turn into acetyl co enzyme a, glycerol turns into triode phosphate
Value of nitrogen to organisms
Amino acids
Proteins
Nitrogenous bases in DNA
nitrogen cycle
nitrogen fixation:
- nitrogen gas to nitrogen-containing compounds
- uses free living nitrogen fixing bacteria and mutualistic nitrogen-fixing bacteria
- free-living: reduce gaseous nitrogen to ammonia, manufacture amino acids, release nitrogen rich compounds when they die and decay
- mutualistic: live in nodules on roots, obtain carbohydrates from plant and plant acquires amino acids from bacteria
ammonification:
- organic material broken down by saprobiotic decomposers
- releases NH4+ back into the soil
nitrification:
- uses nitrifying bacteria, require oxygen so in soil with lots of air spaces
- ammonium to nitrate ions
- oxidation of ammonium to nitrite(NO2-)
- nitrite to nitrate (NO3-)
denitrification:
- nitrate back to nitrogen gas by denitrifying bacteria
- anaerobic conditions
- waterlogged field and all air spaces filled with water
value of phosphorus to organisms
phospholipids
DNA
ATP
Describe the phosphorus cycle
Phosphorus present in sedimentary rocks as phosphate ions
When sedimentary rocks erodes leaves the soil containing the phosphate ions
Plants absorb the ions to make phospholipids/DNA/ATP
Consumers eat plants to obtain the phospholipids/DNA/ATP
Organic material is broken down by Sa probiotic decomposers, releasing the phosphate ions back unto the soil
Over time the soil sediments and hardens returning to a rock state
What are mycorrhizae
Fungi inn the roots of plants to support uptake of scarce materials like phosphate ions
Agricultural ecosystem
Description for farming ecosystems
Aim of farms is to grow crops and raise animals
Grow crops to sell and feed farm animals
Raise animals to sell meat and other resources
How are crops intensively farmed for high yield
Select suitable location
Clear area of plants and animals
Selectively breed the corp
Use greenhouse to provide high levels of light,CO2 and temperature
Provide water by irrigation
Add fertilizers
Control pests
Polyculture/ crop rotation (so minerals don’t become depleted)
Ploughing (add air spaces to soil so bacteria can aerobically respire)
What are pests
Organisms that harm plants/ crops
Other plants e.g. weeds act as competitors, insects eat the plant and fungi cause disease
How can pests be controlled
Pesticides or biological control
What are pesticides
Chemical sprays that kill the pest
Weeds= herbicide
Insects= insecticide
Fungi= fungicide
Advantages of using pesticides
Fast acting
Can control the area covered
Disadvantages of using pesticides
Non-specific
Non- biodegradable which leads to bioaccumulation and toxicity in the higher trophic levels
Pest may be resistant
Needs to be reapplied
What is biological control
Using predators or parasites to the pest
Advantages of using biological control
Specific
Doesn’t cause bioaccumulation
Pests do not develop resistance
Doesn’t need to be reappplied
Disadvantages of using biological control
Slow acting
May become a pest itself
Can’t control the area covered
What is bioaccumulation
Pesticides aren’t biodegradable
Remain stored in the organisms tissues
They accumulate up the trophic levels
Toxic to the consumers at higher trophic levels
What is an integrated pest control system
Makes use of both pesticides and biological control
Keep some native trees
Monitor area for pests
Mechanically remove pests if present
Initial dose of pesticide is 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 fertilizers provide
Nitrate= make amino acids and nitrogenous bases Phosphates= make ATP, DNA and phospholipids Magnesium= make chlorophyll
2 types of fertilizers
Natural
Artificial
Natural fertilizers
Applying dead plants/animals/animal waste
Decomposed leading to ammonifiation, followed by nitrification to provide source of no3-
Artificial fertilizers
Spraying on concentrated solutions of the minerals
Natural vs artificial fertilizers
Natural= reduced risk of leaching/eutrophication bu slower release of minerals Artificial= faster release of minerals and higher concentration but risk of leaching/eutrophication and lowers the water potential of the soil so plant absorbs less water by osmosis
Benefit of ploughing
Increases amount of air spaces in the soil
Supports aerobic respiration of decomposers and bacteria involved in the nitrogen cycle
Eutrophication process
If large amounts of chemical fertilizers are sprayed onto fields and heavy rainfall occurs the fertilizer may leach into local water sources
Fertilizer will travel and build up in ponds or lakes
Mineral will be absorbed and used by algae
Leads to an increase growth of algae=algal bloom
Algae grows on the upper surface of the water which prevents light reaching the plants at the bottom of the water
Light becomes the limiting factor so no photosynthesis
Plants die
Provide more nutrients to saprobiotic decomposers so they increase in number
Aerobically respire so oxygen becomes the limiting factor
Fish unable to respire so die
Provides more nutrients
Oxygen concentration too low so water turns putrid
Deforestation impact on crop farming
Reduces species diversity
Reduces plant species diversity
Less habitats and food sources
Reduces animal species diversity
Monoculture impact on crop farming
One type of plant
Depletes certain nutrients in the soil (no time provided for nutrient levels to recover)
Selective breeding impact on crop farming
Reduces genetic diversity of crop
Reduces variation and reduces the ability to adapt to changes in the environment
Pollution impact on crop farming
Bioaccumulation of pesticides
Eutrophication from chemical fertilizers
Reducing the environmental impact of crop farming
Keep some native trees (species diversity)
Keep hedgerows (species diversity and absorb chemical fertilizers reducing eutrophication)
Polyculture (grow different crops at different times of the year, allows depleted nutrients in the soil to recover)
Keep seeds of wild crop (maintain genetic diversity, use if the environment changes)
Uses biological control for pests an natural fertilizers for minerals
How are animals intensively reared in farming
Selectively bred
Given predigested food (enzymes added) with high protein and high energy levels
Given antibiotics and vaccinations
Given steroid hormones
Restricted movement andrkept warm to reduce energy levels
Natural ecosystem
Light energy source High biodiversity High species diversity High genetic diversity Low productivity Nutrient recycled Competition/predators control pests Reaches climax community
Artificial ecosystem (farming)
Light and food for farmer and fossil fuel for machines as energy sources Low biodiversity Low species diversity Low genetic diversity High productivity Nutrients are added via fertilizers Pesticides/biological control to control pests Prevent climax community being reached
