Topic 5 Biology Flashcards

1
Q

Structure of a chloroplast

A

LOOK ON GOOD NOTES

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2
Q

Structure and function

A

Granum - made up of many layers of thylakoid membrane
- Increases surface area for light absorption.
Thylakoid membrane contains chlorophyll for absorbing light.
Electron carrier molecules are also found in the thylakoid membrane to generate ATP.

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3
Q

Chlorophyll

A

Absorbs light most strongly in the blue portion of the electromagnetic spectrum, followed by the red portion.
Poor absorber of green and near - green portions of the spectrum, hence the green colour.
First isolated and named by Joseph Bienaime Caventou and Joseph Pelletier in 1817

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4
Q

ATP synthesis - light dependent stage

A

Location - Thylakoid Membrane
Energy from light excites electron on the chlorophyll molecule
Which then pushes an electron away from it to a carrier in the thylakoid membrane
Electron moves thru a series of electron carriers (electron transport chain)
Each time it moves it gives out a bit of energy, which is used to create ATP

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5
Q

ATP and reduced NADP synthesis

A

The electron passes along the carriers in the thylakoids membrane which releases energy needed to convert ADP and PI to ATP.
——> photophosphorylation
Called the electron transport chain
These electrons can replace the missing electrons from the chlorophyll so it is ready to use again. Cyclic phosphorylation
Or the elections may also combine with oxidised NADP to make reduced NADP - non cyclic phosphorylation.
In this case chlorophyll’s electrons are replaced by splitting water using energy from light - Photolysis

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6
Q

Electron transport chain

A

The electron is passed down a series of electron carriers in the thylakoid membrane releasing energy at each stage.
The energy is used to pump H+ (protons) into the thylakoid space using proton pumps creating a proton gradient.
The protons then flow back into the stroma via facilitated diffusion via an ATP synthase enzyme
—> AKA ATP synthatase and sometimes ATPase
Uses the flow of H+ to provdide energy to combine ADP + Pi —> ATP
Chemiosmosis

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7
Q

8 stages of the light dependent stage

A

Stage 1 : light energy is absorbed by chlorophyll. Electrons in chlorophyll excited.
Stage 2 : Electrons are lost from the chlorophyll molecule and are transferred between electron carriers in the thylakoid membrane.
Stage 3 : Energy released during the transfer of the electrons along the electron transport chain is used to synthesise ATP. photophosphorylation
Stage 4 : H+ ions are pumped into the thylakoid space and flow into the stroma via ATP synthase enzyme (making ATP)
Stage 5 : Water molecules in the thylakoid space a split into electrons, hydrogen ions and oxygen using energy from light. ( photolysis)
Stage 6 : The electrons from water replace the electrons lost from the chlorophyll molecule to the electron transport chain.
Stage 7 : NADP is reduced by the addition of electrons that pass along the electron transport chain and hydrogen ions.
Stage 8 : Oxygen from the splitting of water is lost as a waste product.

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8
Q

Light dependent reaction products

A

ATP transfers energy and reduced NADP transfers hydrogen to the light independent reaction
Also during the process H2O is oxidised to O2

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9
Q

Photophosphorylation and photolysis

A

In the LD reaction, the light energy absorbed by the photosystems is used for three things :
- Making ATP from ADP and Pi - photophosphorylation
- Making reduced NADP from oxidised NADP
- Splitting water into protons (H+ ions), electrons and oxygen - photolysis

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10
Q

5.1 Understand the terms ecosystem, community, population and habitat.

A

Ecosystem - a community and its interactions with the non living parts of its habitat
Community - multiple populations living and interacting in the same area
Population - all of the individuals of one species living in a habitat
Habitat - the place where an organism lives

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11
Q

5.2 Understand that the numbers and distribution of organisms in a habitat are controlled by biotic and abiotic factors BIOTIC FACTORS

A

Biotic factors - living factors that influence populations within their community

Come about as a result of the activity of other organisms e.g.
- predation
- food availability
- Intraspecific community
- Interspecific community
- Cooperation between organisms
- Parasitism
- Disease

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12
Q

5.2 Understand that the numbers and distribution of organisms in a habitat are controlled by biotic and abiotic factors ABIOTIC FACTORS

A

Non-living factors that influence populations within their community

E.g.
- Light intensity and wavelength
- Temperature
- Turbidity, or cloudiness, of water
- Humidity
- Soil or water pH
- Soil or water salinity
- Soil composition
- Oxygen and carbon dioxide concentration

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13
Q

5.3 Understand how the concept of niche accounts for distribution and abundance of organisms in a habitat.

Definition of niche

A

Niche - the role of a species within its habitat

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14
Q

Important information about niches

A
  • No two species can fill the same niche within a habitat
    • If this happens the two species will be in direct competition, and one of the two species will out-compete the other, causing it to due out in the particular habitat.
  • Can sometimes seem as though species are occupying the same niche, but there will still be subtle differences in their role; e.g. they might feed at different times of day, or have different food sources.
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15
Q

Abundance

A

The niche filled by a species determines its abundance within a habitat.

Definition : The number of individuals of a particular species living in a habitat.

  • If two species occupy a similar niche within a habitat, they will be competing with each other, so their populations will be smaller, and their abundance will therefore be lower.
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16
Q

Distribution

A

The niche filled by a species determines its distribution.

Definition : where a species lives

Species can only survive in habitats to which they are well adapted; if they are not well suited to a habitats biotic and abiotic factors then they will move to a more suitable habitat and their distribution will change.

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17
Q

Core practical 10 : Carry out a study on the ecology of a habitat, such as using quadrats and transects to determine distribution and abundance of organisms, and measuring abiotic factors appropriate to the habitat.

A

Change
• Position of the quadrat along the transect. Regular intervals should be used along the transect (e.g. every 2
meters).
Repeat
• Repeat many times (at least 10) in each area/for each transect, calculate mean, discard anomalies, times mean amount in one quadrat by the number of quadrats that fit in the total area. Calculate standard deviation
Measure
• Dry mass, percentage cover, length/width, species richness, within quadrat & use as an estimate for the area
• Stats test to look for differences – T test for random sampling of 2 areas, Correlation coefficient for transect
Same
• Time of day, direction of transect, size of quadrat, method of sampling (e.g. kick sampling with the same force, for the same time), measure abiotic factors
Safety
• Don’t throw quadrats, sun protection, wear shoes in rivers to protect from infection

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18
Q

5.4 Understand the stages of succession from colonisation to a climax community

A

Succession - change in species inhabiting an area over time. It is brought about by changes to the environment made by the organisms colonising it themselves.

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19
Q

Primary succession

A

Occurs when an area previously devoid of life is first colonised by communities of organisms; for instance, after the eruption of a volcano - soil must first be established before more complex organisms can grow.

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20
Q

Secondary succession

A

Occurs with existing soil that is clear of vegetation. This may occur after an event such as a forest fire.

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21
Q

Pioneer species

A
  • Area that is first colonised.
  • e.g lichens, when are adapted to survive in harsh conditions (where other species would not survive)

Example - these species can penetrate rock surface and break it down into grains. Similarly their roots can hold together sands with a loose; shifting structure.

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22
Q

Humus

A

The organic component of soil.

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23
Q

Climax community

A
  • organisms are decomposed over time
  • the soil becomes richer in minerals, thus enabling larger, more varied and more productive plants such as shrubs to survive.
  • CLIMAX COMMUNITY established - this is the most productive, self-sustaining and stable community of organisms that the environment can support, usually with only one or two species.
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24
Q

5.5 Understand the overall reaction of photosynthesis as requiring energy from light to split apart the strong bonds in water molecules, storing the hydrogen in a fuel (glucose) by combining it with carbon dioxide and releasing oxygen into the atmosphere.

A

Carbon dioxide + Water ——> Glucose + Oxygen

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25
Q

5.6 Understand how phosphorylation of ADP requires energy

A
  • ATP is produced during respiration by the addition of inorganic phosphate (Pi), a type of phosphate group, to adenosine diphosphate, or ADP.

ADP + Pi → ATP

ADP contains two phosphate groups, hence diphosphate
The breakdown of glucose in respiration releases the energy needed to phosphorylate ADP

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26
Q

ATP

A

Adenosine Triphosphate - used to transfer and supply energy within cells
- Known as the universal energy currency
- ATP diffuses within cells to where it is needed.

Type of nucleic acid and it structurally very similar to the nucleotides that make up DNA and RNA.
- Phosphorylated nucleotide
- consists of a nitrogenous base, a sugar, and a single phosphate group.
- ATP contains three phosphate groups, hence triphosphate

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27
Q

Hydrolysis of ATP provides an immediate supply of energy for biological processes.

A

The hydrolysis, or breakdown, of ATP releases an inorganic phosphate as well as a small amount of energy which can be used by the cell

ATP → ADP + P

  • The removal of a phosphate group is known as dephosphorylation
  • The hydrolysis of ATP is catalysed by the enzyme ATPase
  • The ADP and inorganic phosphate produced by the hydrolysis of ATP can be recycled to make more ATP.
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28
Q

5.7 Understand the light-dependent reactions of photosynthesis including how light energy is trapped by exciting electrons in chlorophyll and the role of these electrons in generating ATP, reducing NADP in photophosphorylation and producing oxygen through photolysis of water.

A
  • take place across the thylakoid membrane
  • use of light energy to excite electrons in chlorophyll.
  • photolysis/splitting of water to produce oxygen, electrons, and hydrogen ions.
  • electrons used in the electron transport chain/ to replace those lost in chlorophyll
  • generation of ATP/photophosphorylation
  • reduction of NADP
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29
Q

Products of the light dependent reaction

A
  • ATP —> used by the enzyme converting GP to GALP/ GALP to RuBP
  • Reduced NADP - used to convert GP to GALP
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30
Q

5.8 i) Understand the light-independent reactions as reduction of carbon dioxide using the products of the light-dependent reactions (carbon fixation in the Calvin cycle, the role of GP, GALP, RuBP and RUBISCO).

A
  • Calvin cycle
  • rely on the products of the light-dependent reactions ATP/reduced NADP
  • takes place in the stroma
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31
Q

Light independent steps

A

There are three main steps within the light-independent reactions

  1. Carbon dioxide is combined with ribulose bisphosphate (RuBP), a 5-carbon
    (5C) compound; this yields two molecules of glycerate 3-phosphate (GP), a 3-
    carbon (3C) compound.
  2. GP is reduced to glyceraldehyde 3-phosphate (GALP), another 3C
    compound, in a reaction involving reduced NADP and ATP.
  3. RuBP is regenerated from GALP in reactions that use ATP.
32
Q

ii) Know that the products are simple sugars that are used by plants, animals and other organisms in respiration and the synthesis of new biological molecules (polysaccharides, amino acids, lipids and nucleic acids). (CHECK)

A

Produce complex organic molecules such as
- starch for storage
- sucrose for transport
- cellulose for making cell walls

33
Q

CORE PRACTICAL 11:
Investigate photosynthesis using isolated chloroplasts (the Hill reaction).

A

Change
• Combination of leaf extract, supernatant, isolation medium and DCPIP
Organism
• Same species - spinach (Chloroplast extracted), genetically identical clones or same plant, same part of plant, same age
Repeat
• Repeat 4 times at each condition, calculate mean, discard anomalies, calculate standard deviation
Measure
• Time how long it takes to decolourise the DCPIP in each tube
Same
• Distance from light, time in light, same volume of filtrate, volume of isolation fluid
Safety
• DCPIP - skin irritation, serious eye irritation, harmful if swallowed. Don’t handle electrical equipment/bulbs with

34
Q

RESULTS

A

Tube 1 (leaf extract + DCPIP) colour changes until it is the same colour as tube 4 (leaf extract + distilled water).
• This is due to the light dependent reaction reducing DCPIP

• Tube 2 (isolation medium + DCPIP) no colour change.
• This shows that the DCPIP does not decolourise when exposed to light.

• Tube 3 (leaf extract + DCPIP in the dark) no colour change.
• It can therefore be inferred that the loss of colour in tube 1 is due to the effect of light on the extract.

• Tube 4 (leaf extract + distilled water) no colour change.
• This shows that the leaf extract does not change colour in the light. It acts as a colour standard for the leaf extract on its own.

• Tube 5 (supernatant + DCPIP) no colour change
• The supernatant does not contain chloroplasts, so there is no reduction of DCPIP, this proves chloroplasts are needed to
release the electron
• The results should indicate that the light-dependent reactions of photosynthesis are restricted to the chloroplasts that have been extracted.

35
Q

5.9 Understand the structure of chloroplasts in relation to their role in photosynthesis.

A

LOOK AT ON NOTION FOR PHOTO

36
Q

STRUCTURE/FUNCTION OF A CHLOROPLAST

A

Thylakoid membranes (grana/granum) - contain photosynthetic pigments, such as chlorophyll, arranged as photosystems. (Light dependent stage)

Stroma - fluid surrounding the grana. Contains all the enzymes required for the light independent stage.

Chloroplast envelope - controls movement of substances in and out of the organelle. Their double membrane supports the endosymbiotic theory.

Starch granules - store the products of photosynthesis.

Outer membrane/inner membrane

37
Q

5.10 i) Be able to calculate net primary productivity.

A

Net productivity = gross productivity - respiratory loss

38
Q

ii) Understand the relationship between gross primary productivity, net primary productivity and plant respiration.

A

—> Gross primary production - The total quantity of energy that the plants in a community convert too glucose.
—> Net primary production - The left over glucose that is used for growth, resulting in an increase in biomass.

  • Plants use 25-50% of this energy as respiration, leaving little to be stored as organic molecules that makeup up the plant biomass. The rate at which they do this is called the NPP.
  • Respiratory losses
    -Releases energy.
    -Energy can be given off as heat.
    -Or used in movements, opening of flowers, metabolic processes.
    -Carbon is given out as carbon dioxide to the environment - so no longer part of the plant’s biomass.
  • At night/in the dark plants only respire, so this value is often given to represent R in exam questions.
  • An increase in biomass represents NPP.
39
Q

5.11 Know how to calculate the efficiency of biomass and energy transfers between trophic levels.

A

Efficiently = net production/energy received x 100

Energy transfer = energy available after the transfer/energy available before the transfer x 100

40
Q

Limiting factors in photosynthesis

A

—> Temperature, carbon dioxide, light and water.

41
Q

Reasons for the different NPPS in different geographical areas

A
  • Higher temperature, so it is not a limiting factor in photosynthesis
  • Constant/no/little seasonal change
  • Higher plant density due to soil quality
  • Higher water availability/rainfall
  • Evergreen plants versus deciduous temperature trees have no leaves for part of the year
  • More light (energy) / intensity
42
Q

5.12 Understand the 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.

A
  • Ice core analysis
  • Pollen in peat bogs
  • Temperature records
  • Dendrochronology
  • Carbon dioxide levels
43
Q

Ice core analysis

A
  • Bubbles in the ice core preserve actual samples of the world’s ancient atmosphere, which can be analysed.
  • Also preserve annual layers, seasonal differences in the snow properties create layers - just like rings in trees.
  • Melt layers are related to summer temperatures. More melt layers indicated warmer summer air temperatures. Formed when the surface snow melts, forming bubble - free ice layers, visible in the ice core.
44
Q

Pollen in peat bogs

A
  • Pollen is often preserved in peat bogs (acidic wetland areas) which accumulate in layers so age of preserved pollen increases with depth.
  • Take cores and extract pollen grains from different aged layers then identify plant species the pollen came form
  • Species vary with climate so pollen will vary as climate changes over time.
    (Look at photo on notion)
45
Q

Temperature records

A
  • Measured using thermometers
  • Reliable but short-term record
  • General trend/fluctuations
46
Q

Dendrochronology

A
  • Age of tree using tree rings
  • One ring = One year
  • Thickness of ring depends on climate
  • Warmer = thicker as growth is better
  • Colder = thinner
  • Take cores and analyse
47
Q

Carbon dioxide levels

A
  • Increasing levels of carbon dioxide in the atmosphere are believed to contribute towards climate change
  • Due to carbon dioxide being a greenhouse gas
  • Involved in the greenhouse effect
48
Q

What is climate change caused by human beings called?

A

Anthropogenic

49
Q

5.13 Understand the causes of anthropogenic climate change, including the role of greenhouse gases (carbon dioxide and methane) in the greenhouse effect.

A
  • Human activity enhances greenhouse effect= absorbing outgoing energy so that less is lost to space= too much greenhouse gas in atmosphere means the planet warms up
50
Q

Carbon dioxide (greenhouse gas)

A

—> CO2 concentration increases due to more fossil fuels being burnt/destruction of natural sinks (that keep CO2 out of atmosphere by storing carbon).
—> CH4 is increasing because more methane is released into the atmosphere (more fossil fuels extracted, more decaying waste, more cattle which give off methane as waste gas/released from natural stores too.
—> Burning fossil fuels, farming, deforestation, increased atmospheric concentrations of CO2 and CH4 increases global warming.

51
Q

WHAT IS THE GREENHOUSE EFFECT?

A
  • Solar radiation passes through the atmosphere
  • Some is absorbed by the earth’s surface and warms it
  • Some thermal/infrared energy is reflected off the surface of the earth
  • This has a lower frequency, so less energy
  • Some will pass out through the atmosphere back into space
  • Some is reflected back to earth by greenhouse gases - carbon dioxide, water vapour and methane
  • This warms the surface of the earth even more
52
Q

DIFFERENCE BETWEEN GLOBAL WARMING, CLIMATE CHANGE AND THE GREEN HOUSE EFFECT?

A
  • Greenhouse effect is what you have just described.
  • Climate change is a change in the earth’s weather conditions over time.
  • Global warming is shown by studying the earth’s temperature in many locations.
  • We can see the average surface temperature is increasing.
53
Q

5.14 i) Understand that data can be extrapolated to make predictions and that these are used in models of future climate change.

A
  • Use of extrapolation to model climate change - shows the consequences of global warming could be extremely serious for humans and global biodiversity if we continue with current human activities.
  • If we want to limit the consequences of global warming it is essential that we act quickly to reduce carbon emissions and increase the rate at which carbon is removed from the atmosphere.
54
Q

ii) Understand that models for climate change have limitations. (LOOK AT NOTION)

A

Predicting the future - extrapolation

Why don’t all models predict the same outcome?

  • Fluctuations on both graphs/ eq
  • Natural fluctuations
  • Assumes present trend continues
  • Line not based on long enough series of data
  • Older data may be less accurate / reliable
  • Conflicting evidence
55
Q

What is a carbon sink?

A

An area that removes more carbon than it releases.

56
Q

How can we predict the future?

A
  • Dendrochronology, ice core, peat bogs
  • Past records and extrapolation
57
Q

Why do people disagree about the future?

A
  • Uncertainty about the past
  • Natural fluctuations
  • Uncertainty about the sun
  • Scientific bias
58
Q

5.15 Understand the effects of climate change (changing rainfall patterns and changes in seasonal cycles) on plants and animals (distribution of species, development and life cycles).

CHANGING RAINFALL PATTERNS

A
  • Affect development and life cycle of organisms
  • Will affect distribution of species
59
Q

CHANGES IN SEASONAL CYCLES

A
  • Change timing of seasons
  • Organisms are adapted to timings of the season and the changes that happen
  • Will affect development and life cycle of organisms
  • Will affect distribution of species
60
Q

5.16 Understand the effect of temperature on the rate of enzyme activity and its impact on plants, animals and microorganisms.

A

—> Increase in temp=more kinetic energy=molecules move faster=more successful collisions.
—> Temp too high=denature=change in shape of active site=no longer fits substrate.
—> Metabolic reactions are controlled by enzymes=high temp high metabolic rate high rate of growth=go through life cycle faster e.g. photosynthesis faster.
—> Temp too high=slower life cycle.
—> Will affect distribution of species as ideal conditions necessary for survival.

61
Q

EVOLUTION

A
  • Changes in the heritable characteristics of organisms over generations
62
Q

5.17 Understand how evolution (a change in the allele frequency) can come about through gene mutation and natural selection.

A
  1. Variation is present in a population.
  2. Selection pressures affect a population.
  3. Those with advantageous alleles are more likely to survive and reproduce.
  4. Advantageous alleles are passed to offspring.
  5. Advantageous alleles become more frequent in the population.
63
Q

Explain the similarities and differences between natural selection and evolution. Can you believe in evolution without natural selection.

A

Both due to variation in genetic material.

Evolution
- change in allele frequency over time

Natural selection
- change in allele frequency over time due to selection pressures in the environment.
- some are more adapted to survive then others so reproduce and pass on their advantageous alleles

64
Q

5.18 Understand the role of the scientific community (scientific journals, the peer review process, scientific conferences) in validating new evidence, including proteomics and genomics, that supports the accepted scientific theory of evolution.

A
65
Q

X

A
66
Q

X

A
67
Q

5.19 Understand how isolation reduces gene flow between populations, leading to allopatric or sympatric speciation.

A
68
Q

xx

A
69
Q

X

A
70
Q

X

A
71
Q

CORE PRACTICAL 12:
Investigate the effect of temperature on the initial rate of an enzyme-catalysed reaction, to include Q10.

A

Change
• Temperature, using water bath 0 - 65
Organism
• Same species, same batch, same age, same mass
Repeat
• Repeat 4 times at each temperature, calculate mean, discard anomalies, calculate standard deviation
Measure
• The volume of Oxygen produced in 30 seconds initial rate of reaction
• RATE divide by time to get the rate of oxygen production cm3/s
• Q10 Rate at temp+10/rate at temperature
• Stats test – Correlation Coefficient
Same
• volume of hydrogen peroxide, time to acclimatize in water bath before recording volume, concentration of hydrogen peroxide,
• volume of distilled water used to macerate tissue, maceration time & technique

72
Q

CORE PRACTICAL 13:
Investigate the effects of temperature on the development of organisms (such as seedling growth rate, brine shrimp hatch rates).

A

Change
• Temperature, using water bath 10 - 40 (NOT ABOVE 40 - ethics)
Organism
• Brine shrimp, Same species, genetically identical clones or same parents, same age/stage of development
Repeat
• Repeat 4 times at each temperature, calculate mean, discard anomalies, calculate standard
deviation
Measure
• Number of brine shrimp which have hatched each day for 2 weeks, shine a light on the beaker and
count the number of moving objects in the water
Same
• Length of time allowed for development, nutrients and concentration of salt in the water, same volume of water, same number of eggs at each temperature

73
Q

Brine shrimp welfare

A
  • Hatched shrimp should be returned to a suitable environment that replicates their natural habitat at the end of the experiment.
  • Any handling and transfer of hatched shrimps should be carried out gently and quickly.
  • Dangerously high temperatures should not be used.
  • Any bright lamp used for observation should be switched off when not in use.
74
Q

5.20 Understand the way in which scientific conclusions about controversial issues, such as what actions should be taken to reduce climate change or the degree to which humans are affecting climate change, can sometimes depend on who is reaching the conclusions.

A

Reliable data
Bias/ lack of objectivity/ funding
Scientific evidence
E.g. Farmers supporting increase in use of biofuels due to government funding/ drivers may support this too as cheaper than oil-based fuels/ consumers disagree because it leads to food shortages.

75
Q

5.21 Understand how knowledge of the carbon cycle can be applied to methods to reduce atmospheric levels of carbon dioxide.

A
76
Q

xx

A
77
Q

5.22 Understand how reforestation and the use of sustainable resources, including biofuels, are examples of the effective management of the conflict between human needs and conservation.

A