topic 5 - on the wild side Flashcards
ecosystem definition
all the organisms living in a particular area, as well as all the non living elements of that particular environment
community definition
all of the populations of all the organisms living in a particular habitat at a particular time
population definition
all of the organisms of a particular species living in a particular habitat at a particular time
habitat definition
the place where an organism lives
examples of biotic factors
- availability of food: more food means organisms have a higher chance of surviving and reproducing thus populations can increase
- new predators: ecosystem may become unbalanced
- new pathogens: no immunity or resistance so populations may die out
- competition
examples of abiotic factors
- light intensity
- temperature
- moisture levels
- wind direction and intensity
what is ecological niche
- the species particular role in a habitat
- consists of its biotic and abiotic factors within the environment
- species distribution and abundance depends on the number and type of ecological niches available
what is the niche concept
states that only one organism can occupy each niche in a given habitat at a given time - if two species have a niche that overlaps, the best adapted will out compete the others in surviving to reproduce
succession definition
the change in species inhabiting an area over time. brought about by changes to the environment made by organisms colonising it themselves
when does primary and secondary succession occur?
primary: when an area previously devoid of life is first colonised by communities of organisms - soil must be established before more complex organisms can grow
secondary: occurs with existing soil that is clear of vegetation. this may occur after an event such as a forest fire
what are pioneer species and what do they do
- give an example
- the area is first colonised by pioneer species , which are adapted to survive in harsh conditions
eg lichen - these species can penetrate rock surface and break it down into grains.
what is humus
- as organisms die, they are decomposed by microorganisms, thus adding humus which is the organic component of soil
- this leads to the formation of soil, which makes the environment suitable for complex organisms
what is a climax community
- the most productive, self sustaining and stable community of organisms that the environment can support, usually with one or two species
speciation definition
when two reproductively isolated organisms can no longer interbreed to produce fertile offspring
chloroplast structure
- stacks of thylakoid membranes, called grana, which contain chlorophyll, arranged as photosystems. this is the site of the light dependant stage of photosynthesis
- contains stoma, which is the fluid surrounding the grana. stoma contains all the enzymes required for the light independent stage
- chloroplast envelope: controls movement of substances
- starch granules: store products of photosynthesis
net primary productivity (NPP) definition
the rate at which energy from the sun is converted into the organic molecules that make up new plant biomass
why is some energy lost at each trophic level?
- undigested matter
- respiration
- metabolic waste products eg urea
how is chloroplast structure related to its function
chloroplast envelope: double membrane which encloses chloroplast, keeps all components needed for photosynthesis close together. transport proteins inside inner membrane control flow of molecules between stroma and cytoplasm
stroma: gel like fluid which contains enzymes that catalyse the reactions for photosynthesis
DNA: contains genes which code for some proteins used in photosynthesis
Ribosomes: enable translation of proteins
thylakoid membrane: space between the two membranes known as the thylakoid space, in which conditions differ from stroma eg so a protein gradient can be developed. the space has a very small volume so protein gradient can develop quickly
grana: large surface area for maximum light absorption. also provide more membrane area for proteins such as electron carriers and ATP synthase enzymes, to enable the production of ATP
photosystems: two types = 1 and 2 which contain a different combination of photosynthetic pigments. each photosystem absorbs lights of a different wavelength, maximising light absorption.
photosynthesis equation
co2 + water = glucose + oxygen
why is ATP required by all living organisms
- for building new molecules from the products of digestion during anabolic reactions
- to move substances across cell membranes in active transport or to move substances within cells
- for muscle contraction
- in the conduction of nerve impulses
describe ATP’s structure
- it is a type of nucleic acid
- it is a phosphorylated nucleotide, consisting of a nitrogenous base (adenine), a sugar (ribose) and three phosphate groups
how are ADP and AMP created
ADP: removal of one phosphate from ATP
AMP: removal of two phosphates from ATP
how is ATP produced
what is the equation
- is produced during respiration by the addition of inorganic phosphate (Pi) to adenosine diphosphate (ADP).
ADP + Pi = ATP - the breakdown of glucose in respiration releases the energy needed to phosphorylate ADP
the removal of a phosphate group is known as…
dephosphorylation
what does the hydrolysis of ATP release
what is the equation
what is it catalysed by
- releases an inorganic phosphate as well as a small amount of energy which can be used by the cell
- ATP = ADP + Pi
- catalysed by the enzyme ATPase
- the ADP and inorganic phosphate produced by the hydrolysis of ATP can be recycled to make more ATP
- ADP + Pi = ATP
what are the two distinct stages of photosynthesis and where do they take place
- the light dependant reactions (rely on light directly)
- the light-independent reactions (rely on the products of light-dependant reactions)
- both take place within the chloroplast
- the light-dependent reactions take place across the thylakoid membrane
- light independent reactions take place in the stroma
what can the products of photosynthesis be used for
glycerate 3-phosphate (GP) is used to produce…
1. amino acids which can be used for protein synthesis
2. fatty acids which form the tails of lipid molecules
glyceraldehyde 3-phosphate (GALP) is used to produce…
1.hexose sugars which can be converted into sucrose for transport in the phloem or joined together to make starch and cellulose
2. glycerol for building lipid molecules
3. nucleic acids which form the basis of DNA and RNA
primary productivity definition
the rate at which producers convert light energy into chemical energy
gross primary productivity definition
the rate at which chemical energy is converted is converted into carbohydrates during photosynthesis in plants
NPP equation
NPP = GPP - R
net productivity
rate at which energy is converted into biomass in the body of a consumer
why is energy lost in producers
- light passes through leaves
- light is reflected away
- light hits non photosynthetic parts of a plant eg bark
- light is a mixture of wavelengths and only certain wavelengths are absorbed in photosynthesis
- release of energy in respiration
energy efficiency equation
energy efficiency = (net productivity divided by energy received) times 100
how does evolution via natural selection work
- variety of phenotypes exist within a population due to random mutation
- an environmental change occurs and a result selection pressure changes
- some individuals possess advantageous alleles which give them a selective advantage and allow them to survive and reproduce
- advantageous alleles are passed on to their offspring
- over time, frequency of alleles in a population change
what is allopatric speciation and what does it lead to
- occurs when populations of a species become separated from each other by geographical barriers
- this leads to no gene flow taking place, which changes allele frequencies. if enough change occurs between the two populations then they eventually will no longer be able to breed with each other and produce fertile offspring and so are SEPARATE SPECIES
what is sympatric speciation and what does it lead to ?
- isolation caused by non-geographic factors such as seasonal and behavioural.
- leads to SEPARATE SPECIES
how are theories validated by the scientific community
- reading scientific journals: journals will be read and evaluated by many other scientists working the field of study (peer review) and published studies can be repeated to check that their results are reliable
- attending scientific conferences: scientists can present their findings for questions and discussion
what evidence do we have for evolution
- the fossil record
- real life observations eg antibiotic resistance
- molecular evidence
how can we find evidence from protein sequences
- this is called proteomics
- as the order of amino acids is determined by the DNA base sequence of the gene that codes for a protein, amino acid sequences can be used to determine evolutionary relationships in the same way as DNA sequences.
how can we find evidence from gene sequences
- this is genomics
- the level of similarity between base sequences can give a measure of how long ago two species diverged from each other during speciation eg genes with similar base sequences are likely to have diverged recently
what are the useful products of the light dependant reaction
ATP and NADPH
what is the location of the photosynthetic pigments
the grana/ thylakoid membrane
climate definition
weather conditions in a region over a long period of time
how can atmospheric carbon dioxide be used as evidence to climate change
- since the industrial revolution, atmospheric co2 levels have risen to the highest in earths history
- data show a correlation between changing atmospheric co2 and temps over thousands of years
- co2 is also released into the atmosphere when natural stores of carbon are damaged or destroyed by humans: these carbon stores are known as the carbon sinks
what can be used as evidence for the causes of climate change
atmospheric co2 levels
average global temps
changing plant communities
records of tree growth
how can average global temperatures be used as evidence for climate change
- Thermometers can be used to measure air temperature, and thermometer records from different places around the world over extended periods of time can be put together to show average global temperature change over time
- records from mid 1800’s show an overall trend of increasing temp.
how can pollen grains preserved in peat bogs be used as evidence for climate change
- under waterlogged, acidic conditions dead plant matter accumulates and becomes compacted forming PEAT
- peat builds up in layers, the peat becomes older as you dig down
- peat cores can be taken from a bog and the layers can be analysed to assess the pollen grains
- pollen grains can be observed under a microscope.
- because the pollen grains of each plant species are unique to that plant, the plant species that were growing around the bog at different points in time can be identified
- Different plant species grow under different climatic conditions, so the plants present at different times can be used a measure of the climate at that time
how can dendrochronology be used as evidence for climate change
- tree trunks grow in diameter each growing season as they produce more vascular tissue
- This vascular tissue grows in a ring around the outside of the trunk
- Light coloured rings are produced by fast growth during warmer spring and summer months and dark coloured rings form as a result of slow autumn growth, meaning that one light ring and one dark ring together represent a full year’s growth in a tree
- Trees grow faster when conditions are warmer, so the rings that form during warm years are wider than the rings that form during cool years
- Analysis of the width of tree rings can provide a measure of climate during each year of growth
what is extrapolating from data (climate change)
using existing data related to global warming to make predictions about global temperatures in the future
what can global warming predictions be used for
planning for the future eg building flood defences,funding scientific research
encourage people to change their activities eg reduce burning of fossil fuels, reduce meat consumption
what are the limitations to models based on extrapolated data (climate)
- IPCC has produced models based on several emissions scenarios, but we don’t know which is most likely
- we do not know whether future technologies will be successful
- it is unknown exactly how atmospheric gas concentrations might affect global temps
- global climate patterns are complex and therefore predictions are dificult
what are the impacts of climate change
- weather events becoming more extreme
- changes to ocean currents
- changes in patterns of rainfall
evidence for the impacts of climate change
- warming climates cause animals to move towards the poles or higher altitudes - this may lead to decreased biodiversity, as species try to outcompete each other. other species may not be able to change their distribution fast enough and become extinct
- water availability in some habitats is changing : Changes to rainfall patterns can be devastating to species that rely on seasonal rains for their survival, Some species may no longer be able to survive in their habitat due to a lack of rainfall
- seasonal cycles are changing
- polar ice and glaciers are retreating: this may affect water supplies of surrounding wildlife
- sea levels have been rising faster: increased risk of flooding
explain the carbon cycle:
- carbon is present in the atmosphere in the form of co2
- co2 is removed from the atmosphere by producers during photosynthesis
- carbon is transferred to and between consumers as a result of feeding
- carbon is transferred back into the atmosphere by both plants and animals as a result of respiration
- Carbon dioxide can also be removed from the atmosphere by dissolving in the oceans
- Dissolved carbon can be taken in by marine plants when they photosynthesise or by other marine organisms as they build calcium carbonate exoskeletons
- When living organisms die their tissues are broken down by decomposers such as bacteria and fungi
- Any living tissue that is not fully decomposed can go towards the formation of peat or fossil fuels over millions of years; carbon can be stored in these sinks for long periods
- The combustion of peat and fossil fuels releases carbon dioxide back into the atmosphere
how can biofuels be used to reduce climate change
-these fuels are made from recently living plant biomass
- biofuels can be used in the same way as fossil fuels, releasing co2
arguments in favour of biofuels
- cheaper than oil
- “carbon neutral” meaning they can only release carbon that was recently removed from the atmosphere when the plants were alive
- renewable source of energy
arguments against biofuels
- still release co2
- The vast amounts of land required to grow biofuels could otherwise have been used for food production
- Creating land for biofuel growth often involves the loss of other types of habitats e.g. rainforest; this is bad for biodiversity
- Cutting down mature trees to create land for biofuel growth reduces the removal of carbon from the atmosphere by photosynthesis
how can humans increase the global rates of photosynthesis
- stopping destruction of forests
- planting trees
explain the greenhouse effect
- when radiation from the sun hits the earth, it is radiated back from the earth’s surface
- a greenhouse gas is a gas that absorbs this re-radiated radiation, trapping it in the earth’s atmosphere
- the greenhouse effect is important to ensure that Earth is warm enough for life
- increasing levels of co2 and methane are entering the atmosphere as a result of human activities, leading to increased rate of atmospheric warming
how can methane be linked to climate change
- greenhouse gas
- released from guts of ruminant mammals
- landfill sites release methane when organic matter such as food waste decomposes
- extraction of fossil fuels from underground releases methane
how do changes to enzyme activity resulting from changing global temps affect living organisms
- Some chemical reactions take place faster at higher temperatures
- Photosynthesis is essential for converting carbon dioxide into carbohydrates, the process which produces food for producers and other organisms higher up the food chain; it relies on the function of proteins in the electron transport chain and that of enzymes such as rubisco
Some chemical reactions are slowed down at higher temperatures :
At high temperatures plants carry out a reaction called photorespiration at a faster rate; this reaction uses the enzyme rubisco and so slows down photosynthesis
- This can reduce crop yields as temperatures rise
Some fish eggs have been shown to develop more slowly at higher temperatures
Many species’ successful egg development is dependent on temperature, with impacts such as
Extreme temperature fluctuations can reduce hatching rates in some invertebrates
The sex of the young inside the egg of some species is determined by temperature, so increasing temperatures can affect the sex ratios in a species
species may have to change their distribution in response to changing temperatures in order to survive
how to evaluate data?
- consider how good the evidence is
- find out whether the statement comes from a trustworthy source
- people may have a personal interest or bias
explain how differences can be shown to be statistically significant
- find mean values
- use a t test/ calculate a t value
- calculated t value needs to be greater than the critical value
what happens to bare rock to allow the growth of trees
- bare rock colonised by pioneer species
- pioneer species break up the rock
- dead plants add humus as they decompose
- trees will be able to grow as the soil becomes deeper
describe how starch is formed from the products of the light independent reactions of photosynthesis
- two GALP used to produce a glucose molecule
- glucose molecules are joined together by glycosidic bonds to form starch
- by condensation reaction
- producing amylose and amylopectin
what is the role of photosynthesis in the carbon cycle
carbon dioxide is reduced to form organic molecules
explain why an increase in co2 concentration affects the growth of plants in glasshouses
- carbon dioxide is a limiting factor
- carbon dioxide is fixed to produce GALP
- therefore increased co2 results in more glucose being produced
- which leads to a greater rate of growth
state the location of chlorophyll
thylakoid membrane
what is the name of the enzyme used by plants to fix co2
rubisco
Explain the importance of RUBISCO to the productivity of an ecosystem
- fixes inorganic carbon
- allowing formation of organic molecules by the calvin cycle
- these organic molecules allow transfer of energy to next trophic level
Explain the relationship between the structure and functions of a granum in
photosynthesis
- granum is formed from many layers of thylakoid membranes to increase surface area for absorbing light
- thylakoid membranes contain chlorophyll to absorb light
- electron carrier molecules in thylakoid membrane involved in ATP production
why does burning wood chips not increase co2 to the atmosphere in the long term
- co2 produced by burning wood replaces that absorbed by the trees
- trees absorb co2 for photosynthesis
- new trees are grown to replace those that are cut down
- therefore no net increase in co2
how does one species evolve into two
- speciation
- different selection pressures in different habitats
- animals that survive pass on beneficial alleles to the offspring
- reduced gene flow between populations
- random mutations responsible for variation
how can reforestation be used to minimise climate change
- new trees
- resulting in net uptake of co2
- thus reducing co2 in the atmosphere
how can the hardy weinburg equation be used to provide evidence for changes in a population
- calculate the allele frequencies in the population
- regular sampling over a period of time
explain why the value for GPP is lower than the light energy available to the ecosystem
- not all of the light falls on the leaves
- some of the light is reflected
- some of the light misses the chloroplasts
- some of the light is the wrong wavelength
explain why respiration affects the production of biomass
glucose used in respiration to provide energy
because the more glucose used in respiration, the less available for the production of biomass
the main reason that carbon dioxide acts as a greenhouse gas is because it….
absorbs infrared radiation reflected by the surface of the earth
Explain how studying pollen grains in peat bogs can provide evidence of climate change (4 marks)
- pollen preserved in peat bogs
- a plant species can be identified from its pollen
- climate affects the type of plants growing
- depth of peat correlated with period of time since pollen was produced
- changes in pollen over time indicate changes in climate
how to calculate the temperature coefficient (Q10)
rate at higher temp/ rate at lower temp
what is meant by the term Q10 temperature coefficient
the ratio of the rate of an enzyme reaction taking place at different temperatures differing by 10 degrees celsius
null hypothesis definition
there is no statistically significant difference
explain how ice cores can give clues about changes to the earths atmosphere over a long period of time
- ice forms from the compaction of snow
- so the ice has tiny bubbles of trapped air from the era it formed
name two principle greenhouse gases and why are atmosopheric levels of those gases increasing
co2 and methane
- co2 is increasing due to respiration, burning of fossil fuels and deforestation
- methane is increasing due to livestock farming, landfill sites and Melting of ice caps releasing trapped methane gas from the permafrost;
why does ocean warming cause an increase in co2
co2 dissolved in the oceans is lesssoluble in warm water than in colder water
how may global warming allow photosynthesis in plants to improve
- higher temp cause cause increased reaction rates
- more efficient enzyme catalysed reactions
- increased co2 concentration in the air could benefit plants
- so more carbon is fixed into biomass again
explain the climatic impact of underground peat fires.
why do peat fires occur more frequently when areas of peat bogs are dried out?
- co2 is emmitted contributing to climate change
- fire spreads quicker through dry peat.
why are there yearly fluctuations in co2 concentration
- plants remove co2 from the atmopshere during photosynthesis
- there are seasonal fluctuations in the rate of photosynthesis
state three sources of atmopsheric greenhouse gases
- naturally occuring wildfires
- use of artificial fertilisers
- peat bog loss
anthropogenic climate change
The atmospheric warming for which humans are thought to be responsible
species definition
- a group of organisms which similar biochemical features
- that are able to produce fertile offspring
what does a q10 value of less than one indicate
- enzyme is denatured
- therefore no increase in the formation of enzyme-substrate complexes
Devise an investigation to investigate the effect of temperature on the rate of an
enzyme-catalysed reaction, to include Q10
eg…
1. Grind a known mass of peas in distilled water and place in a boiling tube.
2. Add 5cm of hydrogen peroxide solution to the peas.
3. Fit the syringe into a delivery tube and the delivery tube into the boiling tube with
a bung.
4. Place the boiling tube into a water bath at a known temperature.
5. Time for a set length of time e.g. 5 minutes. Measure the volume of gas
produced at regular intervals e.g. 30 seconds.
6. Repeat the experiment at different temperatures.
explain the impact of cutting down trees on climate change
- less photosynthesis
- more co2 remains in the atmosphere
- co2 is a greenhouse gas therefore more heat energy is trapped in the atmosphere
- increasing atmospheric temperature
how can differences be shown to be statistically significant
-calculate mean
- use a t test
- t value needs to be greater than the critical value
how do biofuels reduce global warming
- burning fossil fuels releases co2 which is a greenhouse gas
- however….
- co2 is taken in for photosynthesis during production of plants for biofuels
- therefore there is no net change of carbon dioxide in the atmosphere when biofuels are burnt
why might the value for GPP be high
- fast photosynthesis
- high nutrient levels
- high temperatures and light intensity
Describe and explain how global warming could affect plant species
- loss of species/extinction of species
- change of distribution of species
- changes in the number of plant species
-temp may become too hot for species - increase co2 results in more photosynthesis
role of photosynthesis in the carbon cycle
carbon dioxide is reduced to form organic molecules
difference between interspecific competition and intraspecific competition
inter: between species for the same resources
intra: competition for the same resources within the same species
