Topic 5 Flashcards
Define Habitat
The place where an organism lives
Define Population
All the organisms of one species in a habitat
Define Population Size
The number of individuals of one species in a particular area (same as abundance)
Define Community
Populations of different species in a habitat
Define Abiotic
Non living features of the ecosystem - chemical and physical factors
Define Biotic
Living features of an ecosystem - the factors influenced by organisms
Define Abundance
The number of individuals of one species in a particular area (same as population size)
Define Distribution
Where a species is within a particular area
Name three or more abiotic factors affecting population size
Amount of light Amount of water Amount of space Temperature of surroundings Chemical composition of surroundings
Name the biotic factors affecting population size
Interspecific competition
Intraspecific competition
Predation
Define Interspecific Competition
When organisms of different species compete for the same resources
What resources do organisms compete for?
Food sources, habitats, water, space, light
Define Intraspecifc Competition
When organisms of the same species compete for the same resources. Resources become limiting, population begins to decline, less competition so grows again
What is carrying capacity?
The maximum stable population size of a species than an ecosystem can support
What is the maximum stable population size of a species than an ecosystem can support called?
The carrying capacity
Define Predation
Where an organism kills and eats another organism
Name the abiotic factors affecting distribution of organisms
Aspect, light intensity, salinity, temperature
Name the biotic factors affecting distribution of organisms
Interspecific competition - organism outcompete in an area by another
What is a niche?
The role of a species within its habitat
How many species can occupy a niche?
One
How does the concept of a niche explain species abundance?
Species occupying similar niches will compete for resources so fewer individuals of each can survive
How does the concept of a niche explain species distribution?
Can only exist in habitats where the conditions that comprise their role exist.
When do you count a square in a quadrat for percentage cover?
When more than half covered
Which plants do you record with a pin quadrat?
Every plant the pin touches
What is a transect used for?
Investigating distribution of plants in an area
How do you investigate the distribution of plants in an area?
Use a transect
What are the three types of transect?
Line, belt and interrupted
What is a line transect?
A line is placed along the transect and all the species that touch it are recorded
What is a belt transect?
Data is collected along the transect using frame or point quadrats
What is an interrupted transect?
Data collected at intervals along the transect rather than investigating the whole transect
What abiotic factors can you measure?
Temperature Rainfall Humidity Oxygen availability Light intensity pH Soil moisture Relief (height changes of surface) Slope angle Aspect
How do you measure temperature?
Thermometer
How do you measure rainfall?
Rain gauge
How do you measure humidity?
Hygrometer
How do you measure oxygen availability?
Oxygen sensor
How do you measure light intensity?
Light sensor
How do you measure pH?
pH probe
How do you measure moisture content?
Mass measured before and after drying, as percentage
How do you measure relief?
GPS/contour lines
How do you measure slope angle?
Clinometer
How do you measure aspect?
Compass
What is succession?
The process by which an ecosystem changes over time
What is primary succession?
Happens on newly formed or exposed land. No soil or organic matter to start with, just bare rock
What is secondary succession?
Happens on land cleared of all plants, but with soil remaining.
What are the stages of succession called?
Seral stages
How does primary succession progress?
- Seeds and spores blown in
- Pioneer species change the abiotic conditions, making them less harsh
- Pioneers die, decompose to humus - forms a basic soil
- New organisms can move in and grow
- Die, increase volume and mineral content of soil
What are the first species to grow on bare land called?
Pioneer species
What is the difference between primary and secondary succession?
As there is already soil, secondary starts at a later seral stage.
What is the final seral stage called?
A climax community
What is a climax community?
The ecosystem is supporting the most complex and largest community of plants and animals it can
What is photosynthesis?
Process whereby energy from light breaks the strong bonds in water and combines hydrogen with CO2 to form glucose. O2 is released into the atmosphere
How is ATP formed?
An inorganic phosphate is added to an ADP molecule using energy from a reaction like respiration using the enzyme ATP synthase
How does ATP store energy?
Chemical energy in the phosphate bond
What enzyme catalyses ATP formation?
ATP synthase
How does ATP release energy?
Broken down into ADP and inorganic phosphate. ATPase acts as catalyst.
What is the catalyst for the break down of ATP?
ATPase
What kind of reaction is the breakdown of ATP?
Hydrolysis
What kind of reaction is the formation of ATP?
Phosphorylation
What is phosphorylation?
Adding phosphate to a molecule
What is photophosphorylation?
Adding phosphate to a molecule using light
What is photolysis?
The splitting of a molecule using light
What is hydrolysis?
The splitting of a molecule using water
What is a coenzyme?
A molecule that aids the function of an enzyme
How do coenzymes work?
By transferring a chemical group from one molecule to another
What is the coenzyme in photosynthesis?
NADP
What does NADP do?
Transfers hydrogen from one molecule to another in photosynthesis
Where does photosynthesis take place?
In the chloroplasts of plant cells
What are chloroplasts? What are their structure?
Small, flattened organelles found in plant cells. They have a double membrane called the chloroplast envelope. Contains thylakoids stacked in structures called grana. Grana are linked by bits of thylakoid membrane called lamellae. Chloroplasts contain photosynthetic pigments
What is the chloroplast envelope?
The double membrane of a chloroplast
What are thylakoids?
In chloroplasts. Fluid filled sacs
What are grana?
In chloroplasts. Stacks of thylakoids.
What links grana?
Bits of thylakoid membrane called lamellae
What are lamellae?
Bits of thylakoid membrane linking grana
Examples of photosynthetic pigments?
Chlorophyll a and b, carotene.
What do photosynthetic pigments do?
Coloured substances that absorb light energy for photosynthesis
Where are photosynthetic pigments found?
Attached to proteins in thylakoid membrane
What is a photosystem?
Photosynthetic pigment joined to protein
What is the stroma?
Gel like substance surrounding thylakoids within inner membrane of chloroplasts
What does the stroma contain?
Enzymes, sugars, organic acids, oil droplets storing non-carbohydrate organic material
What are the two stages of photosynthesis?
The light dependant and light independent reactions
Where does the light dependant reaction take place?
In the thylakoid membranes of chloroplasts
Where does the light independent reaction take place?
Stroma of chloroplasts
Other name for the light independent reaction?
The Calvin cycle
What is the Calvin cycle?
The light independent stage of photosynthesis
What is light energy absorbed by photosystems used for the in the light dependent reaction?
1) Making ATP (photophosphorylation)
2) Making reduced NADP from NADP
3) Splitting water into protons, electrons and oxygen (photolysis)
What are the two types of photophosphorylation in the light dependent reaction?
Cyclic and non cyclic
What links photosystems together?
Electron carriers
What are electron carriers?
Proteins that transfer electrons
What does non cyclic photophosphorylation produce?
ATP, reduced NADP and oxygen
What happens in non cyclic photophosphorylation?
1) Light energy excites electrons in chlorophyll
2) Photolysis of water produces protons, electrons and O2
3) Energy from excited electrons makes ATP
4) Energy from excited electrons generates reduced NADP
Explain the step ‘light energy excites electrons in chlorophyll’
- Light energy absorbed by PSII
- Light energy excites electrons in chlorophyll
- The electrons move to a higher energy level
- High energy electrons move along electron transport chain to PSI
Explain the step ‘photolysis of water produces protons, electrons and O2’
- Light energy splits water into protons, electrons and oxygen
- The electrons replace those excited in PSII
Explain the step ‘energy from excited electrons makes ATP’
- Electrons lose energy as they move along the electron transport chain
- This energy transports protons into the thylakoid, giving it a higher conc than the stroma, forming a proton gradient across the membrane
- Protons move down gradient into stroma via ATP synthase enzyme. Energy from this movement combines ADP and Pi
Explain the step ‘generates reduced NADP’
- Light energy absorbed by PSI excites electrons to an even higher energy level
- Electrons are transferred to NADP along with a proton from the stroma to form Reduced NADP
Explain cyclic photophosphorylation
Excited electrons pass down the electron transport chain from PSI back to PSI, forming only small amounts of ATP in the process.
What are the three key stages of the Calvin cycle?
1) Carbon dioxide is combined with RuBP to form two molecules of GP
2) ATP and reduced NADP are required for the reduction of GP to GALP
3) RuBP is regenerated
Explain the first step of the Calvin cycle
- CO2 enters leaf through stomata and diffuses into the stroma of chloroplasts
- CO2 combined with RuBP (5C) which creates 6C that quickly breaks down to 2 GP (3C)
- Reactions of CO2 and RuBP catalysed by rubisco
Explain the second step of the Calvin cycle
- ATP provides energy to reduce GP to GALP (3C)
- Reduction requires H+ from reduced NADP, recycled to NADP
- GALP converted to useful compounds eg. glucose
Explain the third step of the Calvin cycle
- 5 out of 6 GALP molecules used to regenerate RuBP
* Regeneration uses rest of ATP from light-dependant reaction
How many turns of the Calvin cycle to produce one glucose molecule?
Six
How many ATP/rNADP for one glucose in the Calvin cycle?
18 ADP
12 rNADP
How is the structure of a chloroplast adapted for photosynthesis?
- Chloroplast envelope keeps reactants for photosynthesis close to reaction sites
- Thylakoids have large surface area to absorb light
- Lots of ATP synthase in thylakoid membranes to produce ATP
- Stroma contains all the reactants and enzymes for light-independent reaction
How much energy is passed to the next trophic level?
10%
Where does the energy not passed to the next trophic level go?
- Some light is not absorbed/reflected/passes through leaves
- Some light hits not photosynthesising parts of the plant
- Some parts of food can’t be eaten eg. bones and roots
- Some part indigestible and pass out as faeces
- Lost in ‘respiratory loss’ e.g. body heat
What is gross productivity?
The total energy taken in by an organism
What is net productivity?
The total energy available to the next trophic level
How is net productivity calculated?
Gross productivity - respiratory loss
Impact of warm temperature on tree rings?
Thicker when warmer
How do you tell climate from peat bogs?
Preserves pollen in age order, pollen shows type of plants successful at a time
How is CO2 increasing in the atmosphere?
Burning fossil fuels, deforestation, burning trees, or when broken down by decomposers
How is methane increasing in the atmosphere?
Extraction of fossil fuels, decaying waste, more cattle, thawing permafrost
What are the effects of global warming?
Rising temperature, changing rainfall patterns, seasonal cycles
Effects of rising temperature?
- Affects metabolism of all organisms
- Rate of growth and speed through lifecycles increase, or the opposite for some organisms
- Species move to other locations for ideal temperature, affecting distribution
Effects of changing rainfall patterns?
- Affect lifecycles of some organisms
* Affect distribution as rainfall conditions stop being ideal - desert areas may expand etc
Effects of changing seasonal cycles?
- Changes lifecycles of some organisms
* Changes distribution of some organisms
How to investigate effect of temperature on seedling growth rate
- Plant seedling in soil trays and measure the height of each seedling
- Incubate trays at different temperatures
- Make sure other variables are the same
- Record change in height after period of time
- Calculate average growth by:
avg. change in seedling height in tray/incubation period
How to investigate effect of temperature on brine shrimp hatch rate
*Put equal number of eggs in water baths at different temperatures
*Keep all other variable the same
*Record number of hatched eggs every 5 hours
*Calculate hatch rate by:
number of hatched shrimp/number of hours
What two methods are there of reducing atmospheric CO2 concentration?
Biofuels and reforestation
What are biofuels?
Fuels produced from living or recently living materials
How do biofuels reduce CO2 conc?
No net increase when burnt because amount released is same as amount taken in when material was growing. Therefore by replacing fossil fuels stops the increase
What is reforestation?
Planting new trees in existing forests which have been depleted
How does reforestation reduce CO2 conc?
More trees mean more CO2 is removed by photosynthesis, converted to carbon compounds and stored, so less in the atmosphere
Limitations of climate change models?
- Don’t actually know how emissions will change
- Don’t know how much each scenario would increase temperature by
- Change in CO2 conc due to natural causes not known
- Don’t know what attempts there will be at managing CO2 conc, nor how successful they will be
What is a gene pool?
The complete range of alleles present in a population
What causes new alleles to appear?
Mutations in genes - changes in base sequence of DNA that occur during DNA replication
What is allele frequency?
How often alleles occur in a population
What is evolution?
A change in allele frequency in a population over time
How does evolution occur through natural selection?
- Some individuals better adapted because of their alleles
- More likely to survive, reproduce and pass on their genes
- More individuals in next generation have allele
- Frequency increases, this is evolution
How does reproductive isolation lead to speciation?
Species are organisms that can reproduce to create fertile offspring and are not isolated in place, time or behaviour. Reproductive isolation means they change so much they are incompatible
What causes reproductive isolation?
Population divided by physical barrier
Conditions different on either side
Natural selection takes different paths
Allele frequencies in each population differ
DNA evidence for evolution?
Organisms that have diverged from one another more recently have more similar DNA
Proteomics as evidence for evolution?
Related organisms have similar amino acid sequences. More recent divergence should have more similar proteins, and this is the case.
What is proteomics?
Study of proteins
Three ways scientists share and discuss work?
Scientific journals
Peer review
Conferences
