topic 5 Flashcards
5.1 What is the definition of an ecosystem
all organisms living in a particular area including abiotic factors
5.1 What is the definition of a community
all of the organisms of different species that live in the same habitat and interact with each other
5.1 What is the definition of a population
all the organisms of one species in a habitat
5.1 What is the definition of a habitat
a place where an organism lives
5.2 How is population controlled by abiotic factors?
- amount of light
- water or space available
- temperature of their surrounding
ideal conditions: faster growth and successful reproduction > don’t have to use as much energy maintaining body temp (energy used for growth and reproduction)
5.2 How is distribution controlled by abiotic factors? (examples)
- organisms can only exist where the abiotic factors they survive in exist
- south-facing slopes have the greatest solar input so lots of plants grow there
- plants don’t grow near shoreline because soil is too saline
5.2 How is population controlled by biotic factors?
- Interspecific Competition
- Intraspecific Competition
- Predation
5.2 What is interspecific competition?
- where organisms of different species compete with each other for the same resources
- resources that species compete for will be reduces (less available)
- limited sources
- less energy for growth and reproduction
- lower population sizes
5.2 What is intraspecific competition?
- when organisms of the same species compete with each other for the same resources
- population increases when resources are plentiful (more organisms for competing for same space and food)
- eventually limited (population declines)
- fluctuating population
- carrying capacity: maximum stable population size of a species that an ecosystem can support
5.2 What is predation?
- where a predator kills and eats the prey
- population sizes of predators and preys are interlinked
- as prey population increases, predator population grows
- prey population decreases (too many predators)
- less food for predators, predator population decreases
5.2 How is distribution affected by biotic factors?
- interspecific competition (if 2 species are competing and one is better adapted than the other, the well adapted species will be out competed)
5.3 What is a niche?
- role of a species within its habitat in an ecosystem
- the interrelationship of a species with all biotic and abiotic factors affecting it
5.3 Explain why species cannot occupy the same niche (4)
- competitive exclusion
- interspecific competition
- two species compete for the same resources
- natural selection
- passing of advantageous alleles will outcompete other
- survive at the expense of other speices
- reporduce
5.3 Distribution of species (niche concept)
- organisms can only exist in habitats where all the conditions that make up their role exist
5.3 Abundance of species (niche concept)
- two species occupy similar niches compete
- fewer individuals of both species survive in the area
5.4 Define primary and secondary succession
primary succession
- where organisms grow where there has been no previous growth in the area
- moves through a series of stages to climax community
secondary succession: organisms grow where there has been a previous population
5.4 Define pioneer species
- first species to colonise an area
- specially adapted to cope with harsh conditions
- changes abiotic conditions (they die and microorganisms decompose forming basic soil)
5.4 Define climax community
ecosystem supports the largest and most complex community of plants and animals it can (does not change)
5.4 Understand the stages of succession from colonisation to a climax community
- pioneer species colonise a new land surface (primary succession)
- these species change abiotic conditions
- makes conditions less hostile
- new species change the environment
- secondary succession occurs
- different species are better adapted and outcompete the existing species
- biodiversity increases
- climax community
5.5 Overall reaction of photosynthesis
6CO2 + 6H2O + energy –> C6H12O6 + 6O2
5.5 Define phosphorylation
adding phosphate to a molecule
ADP is phosphorylated to make ATP
5.5 Define photophosphorylation
adding phosphate to a molecule using light
5.5 Define photolysis
splitting of molecule using light energy
5.5 Define hydrolysis
splitting of molecule using water
ATP hydrolysed to ADP
5.5 Photosynthesis 2 step process
- Light dependent reaction (water is split and ATP + NADPH are made) - in granae
- Light independent reaction (ATP and NADPH is used to make glucose) - in stroma
5.6 ATP
ATP –> ADP + Pi (inorganic phosphate) + energy
- photophosphorylation
- made in LDR from using energy from light
- ATP used as a source in LIR
- hydrolysis breaks ATP to ADP and Pi (recycled and used again)
- energy released used by the cell
5.7 Light dependent reactions (LDR) - thylakoid membrane
- Energy from light rises two electrons in each chlorophyll molecule to a higher energy level to make them ‘excited’.
- Electrons leave excited chlorophyll and pass through electron carrier molecules in electron transport chain
- Electrons from photosystem 2 chlorophyll travel to carriers through oxidation and reduction reaction, and the energy lost is used for ATP synthesis - photophosphorylation.
- Electrons from PSII replace those lost in PSI chlorophyll.
- Electrons lost in PSII must be replaced for electron transport chain to continue.
- In thylakoid space, enzyme catalysis photolysis (split of water) to make O2, H+ and e-.
- These electrons replace those lost in PSII, H+ ion concentration in thylakoid space increases.
- Electrons from PSI chlorophyll in electron transport chain combine with NADP and H+ to make reduced NADP.
5.8 Light independent reactions (LIR) - in the stroma
- Carbon Dioxide combines with RuBP (5-carbon) which is catalysed by RuBISCO.
- 6-carbon compound formed is unstable and breaks down into 2x 3-carbon molecules GP.
- GP is reduced to make GALP, and the hydrogen for reduction comes from reduced NADP and ATP provides the energy.
- 2/12 GALPS are used to make hexose (glucose) which can be converted into amino acids/lipids…
- 10/12 GALPS are used to make RuBP.
5.8 Calvin Cycle
- CO2 combines with RuBP (catalysed by RUBISCO)
- forms a 6 carbon compound which is unstable so it breaks down to two 3 carbon molecules GP
- GP reduces to form GALP (H comes from reduces NADP from LDR, ATP from LDR provides energy to this reaction)
- 2/12 GALP: creates glucose which can be converted into organic compounds
- 10/12 GALP: recreates RuBP (photophosphorylation using ATP from LDR)
5.8 What is carbon fixation?
process where inorganic carbon is added to an organic molecule
RuBP + CO2 –> 2 GP
5.8 Role of GP
5.8 Role of GALP
- makes glucose and other useful organic substances
5.8 Role of RuBP
5.8 Role of RUBISCO
- catalyses the reaction where CO2 combines with RuBP
- catalyses carbon fixation
5.8 Fate of sugars made in photosynthesis
- used in respiration: reduce CO2, H2O and energy
- polysaccharides: starch (storage molecule), cellulose (cell wall)
- nucleic acid: DNA and RNA
- amino acids: to make proteins
- lipids: waterproofing and storage
5.9 Structure of a chloroplast (double membrane)
- smooth outer membrane: freely permeable to molecules (CO2, H2O)
- smooth inner membrane: contains many transporter molecules (membrane proteins - regulate transport of substances)
- starch grain: stores products of photosynthesis
- DNA loop: chloroplast contains genes of protein
- thylakoid membrane: system of interconnected flattened fluid filled sacs (LDR takes place)
- stroma: fluid surrounding thylakoid membrane (contains enzymes for LIR)
- thylakoid space: fluid within thylakoid membrane sacs (contains enzymes for photolysis)
- granum: stack of thylakoids (ATP synthase to produce ATP LDR)
5.10 Formula of net primary productivity (NPP)
NPP = GPP - R
unit: kJ/m^2/year
5.10 What is productivity?
rate at which energy is added to the bodies of organisms in the form of biomass
5.10 What is net primary productivity?
amount of energy available to the next trophic level
(on a graph) calculate the gradient
5.10 What is gross primary productivity?
rate at which energy is needed into organic molecules in plants
5.10 What is respiration?
plants use this energy in respiration
5.11 What is biomass?
amount of matter stored in bodies of a group of organisms
5.11 Formula to calculate efficiency of energy transfer
energy transfer = (energy available after transfer / energy available before transfer) x 100
5.21 Understand how knowledge of the carbon cycle can be applied to methods to reduce atmospheric levels of carbon dioxide
- absorbed by plants (photosynthesis)
- passed onto animals (when they eat plants) and decomposers (when they eat dead organic matter)
- returned to atmosphere through respiration
- turned into fossil fuels
- carbon in fossil fuels released as CO2 when burnt (combustion)
5.12 What is climate change?
significant change in weather of a region usually over a period of several decades
- natural variations caused by humans
5.12 Evidence of Climate Change: Temperature Records
> reliable but short-term record of temperature change
5.12 Evidence of Climate Change: Dendrochronology (tree rings)
- method for figuring out how old a tree is using tree rings
- thickness of the ring depends on the climate
- warmer: thicker rings
- cores of tree trunks: dates each ring by counting them back
5.12 Evidence of Climate Change: Pollen in peat bogs
- shows how temperature has changed over thousands of years
- pollen preserved in peat bogs
- accumulate in layers so age of the preserved pollen increases with depth
- gradual increase in pollen from a plant: more successful in warmer climates = rise in temperature
5.12 Evidence of Climate Change: Recognising correlations and causal relationships
correlation: relationship between two variables
causal relationships: one change in variable causes a change in the other variable
- describe the data
- draw a conclusion
5.13 Anthropogenic climate change
- caused by human activity (enhances greenhouse effect
5.13 Anthropogenic: Carbon dioxide
- CO2 increasing: more fossil fuels burnt, destruction of natural carbon sinks, decomposers respire
5.13 Anthropogenic: Methane
- methane increasing: more fossil fuels extracted, decaying waste, cattles give off waste gas, natural stores (frozen ground)
5.14 Extrapolated data
- used to make predictions of how greenhouse gas emissions might change
1. minimum emissions in which greenhouse gas conc peak and then reduce
2. stabilising scenarios in which emissions increase and eventually level off
3. maximum emissions showing the worst case scenario of climate change
5.14 Limitations of extrapolated data
- not sure which emission scenario is most accurate
- not sure how many emissions cause the global temperature to rise by
- climate change affected natural causes isn’t known
- complex feedback systems involved
5.15 Effects of climate change: changing rainfall patterns
- some areas get more rain, some get less
- affects development ad life cycles of some organisms
- affects distribution of some species
5.15 Effects of climate change: changing seasonal cycles
- changes timing of seasons
» changes in temperature, rainfall, availability of food - affect development and life cycles of some organisms
- affect distribution of species
