Topic 5 - On the wild side Flashcards
Define abiotic and biotic factors and give 3 examples of each
Biotic factors are interactions between living organisms e.g. :
Predation
Grazing
Disease
Intraspecific competition
Interspecific competition
Abiotic factors are measurable non-living characteristics of the environment e.g. :
Light intensity
Temperature
Amount of Rainfall
Average wind speed
Define edaphic factors and give 2 examples
Edaphic factors are abiotic factors that relate to the soil e.g.:
Water content
Compaction
Organic matter content
Grain size
Named nutrient (e.g. nitrate) conc
pH
Describe how to carry out a study on the ecology of a habitat using randomly placed quadrats to assess the abundance of organisms.
Lay a grid over the area to allow quadrats to be placed using random coordinates.
Count the number of individuals of the species of interest or estimate percentage cover of the species of interest.
Repeat the process 20 times. Calculate a mean percentage cover or mean number of individuals per m2.
In order to investigate (factors that affect) the abundance of organisms measurements of abiotic factors need to occur at each quadrat as well – e.g. soil temperature, light intensity, pH of soil, water content of soil, nitrate content of soil etc.
Describe how to carry out a study on the ecology of a habitat using transects to assess the distribution and abundance of organisms.
Place a tape measure across the area being investigated (from one end of the abiotic gradient to the other – e.g. out from the woodland edge, or pond edge, or low water mark) – this is the transect line.
Use a quadrat to sample systematically along the transect – either continuously with no gaps between quadrat locations (a belt transect) or every metre or few metres (an interrupted belt transect).
In each quadrat either count the number of individuals or estimate percentage cover
Do 10 transects in the area being investigated to create a mean value for each distance along the quadrat.
In order to investigate (factors that affect) the distribution and abundance of organisms measurements of abiotic factors need to occur at each quadrat as well – e.g. soil temperature, light intensity, pH of soil, water content of soil, nitrate content of soil etc.
Understand whether random quadrating or laying transects is appropriate for a particular investigation in a particular environment.
Random Quadratting (a form of random sampling) - measures abundance, in a uniform environment
Transects (a form of systematic sampling) - measures distribution and abundance, along with abiotic gradient.
Both use quadrats as a way of creating a fixed area to sample. This allows a direct comparison to be made between different locations.
Quadratting as a form of sampling is quick so many repeats can be done to improve the reliability of the findings.
Define succession, primary succession, secondary succession, deflected succession, pioneer species and climax community
TERM
DEFINITION
Succession
The predictable change in the species present in a community of organisms over time
Primary succession
Succession (from pioneer species to climax community) that occurs where life wasn’t present before, e.g. bare rock
Secondary succession
Succession (from recolonisation to climax community) that occurs where life used to be present recently, e.g. bare soil
Deflected succession
Succession that is prevented from reaching a climax community, e.g. by grazing
Pioneer species
The first species that colonise an area – they are able to withstand harsh abiotic factors
Climax community
The final stage of succession. It is a stable community which cannot be outcompeted by another community unless conditions change.
Understand how succession occurs from colonisation to a climax community
The first species to colonise is the pioneer species, and this changes the abiotic conditions of the habitat making it more suitable to different species of organisms to now colonise.
Pioneer species can survive harsh abiotic conditions but get outcompeted by other species once the conditions are suitable for them to survive.
As conditions get more and more favourable different species can now survive and they outcompete the earlier species.
As the succession progresses the species diversity tends to increase for both animals and plants. The final community of species, which in theory will now not change, is called the climax community.
As plants die and decompose they add organic matter to the soil. This increases the depth of the soil, increases the volume of water the soil can hold and increases the nutrient / nitrate content of the soil.
Define oxidation and reduction in terms of oxygen, hydrogen atoms and electrons
Oxidation - gain of oxygen, loss of hydrogen, loss of electrons
Reduction - loss of oxygen, gain of hydrogen, gain of electrodes
OIL RIG - Oxidation is loss, reduction is gain
Describe what the simple sugar product from photosynthesis may be used for
The first carbohydrate product is GALP. This is a 3 carbon carbohydrate (triose).
If you join 2 GALPs together you can make a hexose (has 6 carbons) such as glucose. Many glucoses could be joined to make amylose, amylopectin or cellulose.
Name the other important molecules that plants need to produce from the products of photosynthesis, and identify which other elements will also be required to synthesise them.
The carbohydrates could be made into plant lipids (also made of just carbon, hydrogen and oxygen).
If a source of nitrogen is available (e.g. nitrates from the soil) then amino acids / proteins, or nucleic acids (DNA, RNA) could be made.
For some amino acids there needs to be a source of sulphur too.
State where the light dependent and light independent reactions occur within a chloroplast and describe why they should be in that location
Light dependent reactions = Thylakoid membranes of thylakoids/grana
Embedded in a membrane so that electrons can pass from one electron carrier to the next in an ordered way.
Light independent reactions = Stroma
A series of enzyme controlled reactions in the stroma so that the products of one reaction can diffuse and collide with an enzyme of the next reaction and so on.
Define gross primary productivity, biomass and net primary productivity
Gross primary productivity = the rate at which energy is converted into organic matter in plants.
It is all the organic matter produced in photosynthesis and is measured in kilojoules per metre squared per year (kJ/m2/y or kJ.m-2.y-1).
Biomass = the mass of organic matter contained in an organism
Net primary productivity = the rate at which organic matter accumulates as plant biomass.
It is the organic matter left over from GPP after some has been used in respiration.
Suggest suitable units for measuring gross primary productivity
kJ/m2/y or kJ.m-2.y-1
Kilojoules per metre square per year
(energy, area, time)
Carry out calculations of net primary productivity and explain the relationship between gross primary productivity, net primary productivity and plant respiration
GPP – R = NPP
Gross Primary Productivity (GPP) - Respiration (R) = Net Primary Productivity (NPP)
You need to be able to rearrange this equation and use information given to you in exam questions to work out GPP, R or NPP.
Calculate the percentage efficiency of photosynthesis and of energy transfers between trophic levels
Percentage efficiency of photosynthesis
GPP / Total amount of energy falling on a leaf x 100
Percentage efficiency of energy transfers between trophic levels
Biomass of trophic level / Total amount of energy eaten x 100
Calculate the percentage efficiency of photosynthesis and of energy transfers between trophic levels
Percentage efficiency of photosynthesis
GPP / Total amount of energy falling on a leaf x 100
Percentage efficiency of energy transfers between trophic levels
Biomass of trophic level / Total amount of energy eaten x 100
Describe how some energy fails to get passed on between primary consumers and secondary consumers
Not all the energy the secondary consumer eats (i.e. biomass of the primary consumer) is converted into biomass (in the secondary consumer) due to:
Energy being lost as heat from respiration for locomotion, maintenance of internal body temperature (in warm blooded animals), protein synthesis, mitosis etc.
Some of the biomass of the previous trophic level is indigestible
Excretion of nitrogenous waste
Some of the biomass of the primary consumer might be inedible (e.g. because it’s toxic)
Analyse and interpret different types of evidence for climate change and its causes (including records of carbon dioxide levels, temperature records, pollen in peat bogs and dendrochronology) recognising correlations and causal relationships
The concentration of CO2 in the atmosphere in the past can be determined from bubbles of air trapped in extracted ice cores.
Long temperature record sequences exist for a number of places around the world (e.g. England from 1659). The only concern is with the reliability of the measuring equipment used in the past.
Analysis of pollen in peat bogs gives an indication of their relative abundance and climate at the time of their production.
Analysis of the width of tree rings (dendrochronology) gives information about the climate at the time the ring was formed. The outermost ring corresponds to the most recent year of growth.
A correlation occurs when two variables change at the same time but the change is one is not directly caused by the other.
A causal relationship occurs when the change in one variable is as a direct result of the change in another variable.
Explain why pollen in peat bogs is useful for reconstructing past climates
In the anaerobic and acidic conditions that exist in a peat bog the decay of plant matter is slowed down or stopped altogether. Pollen grains are particularly well preserved.
Pollen from peat is useful for reconstructing past climates because:
Wind-pollenated plants produce vast amounts of pollen so some is likely to be preserved
Pollen is only produced by mature trees so they would be surviving successfully in the climate.
Pollen has a tough outer coating that is very resistant to decay.
Each species of plant has a distinctive type of pollen, allowing identification of the plant species they came from.
Peat forms in layers, the deeper the layer, the older the peat. 14C-dating allows the age of a particular peat layer to be established.
Plant species have specific ecological conditions in which they flourish best. So if pollen is found from a plant species that favour warm climatic conditions, it can be inferred that the peat was laid down when the climate was warm.
Explain how dendrochronology provides information about past climates
Every year trees produce a new layer of xylem
vessels by cell division of cells underneath the bark.
The diameter of the vessels varies depending on the
season in which they grew. Wide vessels are
produced in spring (warm and wet conditions) as the
tree is growing quickly. Narrower vessels are formed
in summer. Little, if any, growth occurs in the autumn/winter. These different widths of xylem vessels create a pattern of rings across a trunk.
The width of the rings indicates the climatic (growth) conditions of the time period. Favourable conditions (warm and/or wet) will result in wider tree rings than unfavourable conditions (cold and/or dry)
Understand the effects of changing rainfall patterns and changes in seasonal cycles on organisms (distribution of species, development and life cycles).
Climate change is likely to mean that rainfall patterns change. For example the USA may receive less rainfall whereas Canada may get more.
As such crops may now grow better in Canada and worse in the USA, effecting the yield for their farmers.
For seasonal cycles, it may be that caterpillars start hatching from butterfly eggs earlier in the Spring due to warmer atmospheric conditions. When the migrating birds arrive to nest, their eggs now hatch at a time when the caterpillars should be at maximum availability, but that time has already past, so there is not enough food to feed their chicks. The bird populations decline.
Explain the effect of increasing temperature on the rate of enzyme activity in plants, animals and micro-organisms
Most biochemical reactions (reactions occurring in living organisms) involve enzymes.
Enzymes are biological catalysts. They increase the
rate of a reaction by lowering the activation energy of
the reaction. Enzymes are not used up in the reaction.
A change in temperature will effect the rate of enzyme-controlled reactions. Up to an optimum temperature an increase in temperature will increase the rate of enzyme activity. Any further increase in temperature beyond the optimum temperature will decrease the rate of enzyme activity.
Explain why enzyme-controlled reactions increase as temperatures increase up to the optimum
At low temperatures the rate of reaction
is slow because the enzyme and substrate
move slowly and do not collide very often.
As temperature increases the kinetic energy
of the enzyme and substrate increases and
There are more collisions between them.
The substrate binds the enzyme’s active site more frequently and the rate of reaction increases.
Describe how to investigate the effects of temperature on the development of organisms (e.g. seedling growth, brine shrimp hatch rates)
Seedling growth rate
Measure the height of seedlings at the start of the investigation
Incubate seedlings at different temperatures (in incubators) for an appropriate time period (days).
Ensure all other variables are constant (e.g. water content, light, CO2 concentration)
Record the change in height of each seedling.
Average growth rate = Average change in seedling height in each tray
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Incubation period
Brine Shrimp hatch rate
Put an equal number of brine shrimp eggs in water baths set at different temperatures
The relationship between temperature and the development of organisms is causal if all
other variables have been controlled.
Incubate for an appropriate amount of time (hours)
Control all other variables for each water bath (e.g. volume and salinity of water, O2 concentration)
Record the number of hatched eggs in each water bath after a set period of time (e.g. every 5h)
Hatch rate =
Describe the greenhouse effect
Draw a diagram showing the inputs and outputs of the light dependent and independent reactions of photosynthesis
Draw a diagram of a chloroplast, label its internal structures and annotate with the functions of these structures
Draw a flow chart of the sequence of events in the light-dependent reactions of photosynthesis
Draw a diagram that describes what happens to light reaching a leaf’s surface
Draw a diagram of the Calvin cycle (light independent reactions) (with GP, GALP, RuBP, RUBISCO), tracking the number of carbon atoms and annotate with the events that are occurring at each stage
