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a level biology > Topic 5: On the Wild Side > Flashcards

Topic 5: On the Wild Side Flashcards

1
Q

define habitat

A

the place where an organism lives

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2
Q

define population

A

organisms of the same species living in a habitat

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3
Q

define community

A

all the different populations of different species living in a habitat

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4
Q

define niche

A

the role an organism plays in a habitat

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5
Q

define abiotic

A

non-living elements of an organisms habitat

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6
Q

define biotic

A

the living elements of an organism’s habitat

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7
Q

define succession

A

the process by which communities of organisms colonise an area, then over time, are replaced by others that are usually more varied

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8
Q

define ecosystem

A

the interaction of living organisms with abiotic factors

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9
Q

give examples of biotic factors and their influence

A

new predators - in a balanced ecosystem predators catch enough prey to survive but not so much that they wipe out a population but a new predator could cause imbalance

competition - if two species compete for one resource and one is better adapted, the other will decrease in size until there are too few to successfully breed

new pathogens - the populations living in an ecosystem would likely have no immunity or resistance and their population would likely decrease or die out

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10
Q

give examples of abiotic factors and their influence

A

light intensity - more light increases rate of photosynthesis, increasing rate of growth

carbon dioxide concentration - photosynthesis rate increases with more CO2, increasing rate of growth

soil pH - affects enzymes

can add

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11
Q

describe primary succession

A
  • pioneer species colonises bare land; seeds and spores are blown in by the wind and begin to grow
  • harsh abiotic conditions eg. no soil for water retention, only pioneer species can survive
  • pioneers change the conditions by dying and microorganisms decompose the humus to form soil and roots stop existing land from getting blown away
  • less hostile conditions and the basic soil can retain water, grasses and small plants adapted to shallow/nutrient-poor soil arrive, their roots form a network to keep the soil in place
  • new species change the env. and make it less suitable for the previous species
  • soil becomes deeper and more nutrient-dense, biodiversity increases
  • the final species to colonise becomes the dominant species, forming a climax community
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12
Q

outline secondary succession

A

as there is already a soil layer, it starts at a later stage to primary succession
the pioneer species in secondary succession are larger plants

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13
Q

what is the equation for photosynthesis

A

6CO2 + 6H2O –> C6H12O6 + 6O2

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14
Q

define phosphorylation

A

adding phosphate to a molecule
ADP is phosphorylated to ATP

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15
Q

define photophosphorylation

A

adding phosphate to a molecule using light

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16
Q

define photolysis

A

the splitting of a molecule using light energy

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17
Q

define hydrolysis

A

the splitting of a molecule using water, ATP is hydrolysed to ADP

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18
Q

how is ATP used as an energy source in cells

A
  • cells can’t directly get energy from glucose, so it is broken down in respiration, releasing energy to photophosphorylate ADP, forming ATP
  • this reaction is catalysed by ATP synthase and the energy is stored as chemical energy in the phosphate bond
  • ATP diffuses to the part of the cell that needs energy and is broken down back into ADP and inorganic phosphate via hydrolysis, releasing chemical energy from the phosphate bonds to be used by the cell - the reaction is catalysed by ATPase

the ADP and inorganic phosphate are recycled and the process restarts

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19
Q

label this chloroplast

A
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20
Q

what is the structure and function of the chloroplast envelope

A

it is a double membrane that helps to keep the reactants for photosynthesis close to their reaction sites

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21
Q

what is the structure and function of thylakoids

A

they are filled with ATP synthase and have a large surface area to allow as much light energy to be absorbed as possible

they are stacked into grana to have a large surface area and absorb max light

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22
Q

what is the structure and function of a thylakoid membrane

A

they contain photosynthetic pigments and chlorophyll that can absorb various wavelengths of light, the pigments are attached to proteins and collectively called a photosystem

there are 2 photosystems: photosystem I and photosystem II

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23
Q

what is the structure and function of the stroma

A

it is a gel -like substance surrounding the thylakoids that contains all enzymes, sugars and organic acids required for the light independent reaction to take place

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24
Q

outline the light-dependent reaction in photosynthesis

A

it needs light energy and takes place in the thylakoid membranes of chloroplasts

photosynthetic pigments in photosystems absorb light energy and convert it to chemical energy

  • Light energy excites electrons in the chlorophyll to a higher energy level
  • electrons release energy as they are passed along the electron transport chain
  • energy released is used to pump hydrogen ions across the thylakoid membrane, which then diffuse back again via ATP synthase, adding an inorganic phosphate group to ADP, forming ATP via photophosphorylation
  • light energy splits water into protons (H+), electrons and oxygen
  • the electrons are used in the ETC
  • NADP is reduced to form reduced NADP

ATP transfers energy and reduced NADP transfers hydrogen to the light-independent reaction

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25
Q

what products of the light-dependent reaction are used in the light-independent reaction in photosynthesis

A

ATP and reduced NADP from the light-dependent reaction supply the energy and hydrogen to make glucose from CO2

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26
Q

does the light dependent or independent reaction include photophosphorylation

A

the light dependent reaction
it includes two types; cyclic and non-cyclic
both processes produce different products
cyclic - ATP
non-cyclic - ATP and reduced NADP

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27
Q

explain non-cyclic photophosphorylation

A
  1. light energy is absorbed by PSII, it excited electrons in chlorophyll making them move to a higher energy level
    the high energy electrons then move along the electron transport chain to PSI
  2. the electrons that leave PSII and move along the electron transport chain have to be replaced
    light energy splits water into protons (H+ ions) and oxygen ; this is photolysis
    reaction: H2O –> 2H+ + 2e- + 0.5O2
  3. as the excited electrons move along the electron transport chain, they lose energy
    the energy is used to transport protons into thylakoids so the thylakoid has a higher proton concentration that the stroma; forming a proton gradient across the membrane
    protons move down this concentration gradient into the stroma via ATP synthase (enzyme)
    the energy from this movement combines ADP and inorganic phosphate to form ATP
  4. light energy is absorbed by PSI, exciting the electrons again to an even higher energy level
    the electrons are transferred to NADP along with a proton (H+) from the stroma, to form reduced NADP

add revision guide pics or toher

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28
Q

explain cyclic photophosphorylation

A

uses only PSI

  • light hits PSI and electrons are excited to a higher energy level and leave the photosystem
    these move along the electron transport system, releasing energy as they do so
  • this energy released allows H+ ions to be actively transferred from a low concentration in the stroma to a high concentration in the thylakoid membrane
  • H­­+ ions diffuse back across the thylakoid membrane into the stroma via ATP synthase enzymes embedded in the membrane
  • The movement of H­­+ ions cause the ATP synthase enzyme to catalyse the production of ATP
  • the electrons rejoin PSI at the end of the electron transport chain
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29
Q

what is chemiosmosis

A

the process where the movement of H+ ions across a membrane generates ATP, it occurs in photosynthesis and respiration

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30
Q

what organic substances are made by the products of the calvin cycle

A

carbohydrates
lipids
amino acids
nucleic acids

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31
Q

how are carbohydrates made from the products of the calvin cycle

A

simple sugars like glucose - made by joining two GALP molecules

polysaccharides like starch/cellulose - made by joining hexose sugars together in different ways

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32
Q

how are lipids made from the products of the calvin cycle

A

GP is synthesised to form fatty acids
GALP is synthesised to form gLycerol
lipids are then made from glycerol and fatty acids

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33
Q

how are amino acids made from the products of the calvin cycle

A

they can be made from GP

34
Q

how are nucleic acids made from the products of the calvin cycle

A

the sugar in RNA (ribose) is made using GALP

GALP is also used to make DNA

35
Q

what is the calvin cycle also known as

A

light independent reaction
carbon dioxide fixation

36
Q

outline the calvin cycle

A
  1. CO2 enters leaf via stomata and diffuses into chloroplasts Stroma
    CO2 combines with RuBP (5C) (ribulose bisphosphate) and this is catalysed by the enzyme RUBISCO to form an unstable 6C
    this quickly breaks down into 2 lots of GP (glycerate 3-phosphate), a 3C compound
  2. 2ATP (from the light dependent reaction) is hydrolysed and NADPH is used to get H to turn GP into GALP, both of which as 3C compounds
    some GALP —> converted to useful organic compounds eg. glucose
    some GALP —> continues in calvin cycle to regenerate RuBP
  3. there are 2 GALP molecules with 6C overall
    5C/6C are used to regenerate RuBP using ATP
    so only 1C is left to make glucose
    so 1/6 of a glucose molecule is produced every Calvin Cycle turn
    which means 6 turns = 1 glucose molecule
37
Q

what is a producer

A

the first trophic level in a food chain because it produces it’s own food

38
Q

define biomass

A

the mass of living material in an organism, it’s what gets passed on between trophic levels

39
Q

why is not all sunlight used by plants for photosynthesis

A

some light may be:
- wrong wavelength
- reflected off the leaf
- transmitted through the leaf
- hit a part of the leaf that can’t photosynthesise

40
Q

define net primary productivity (NPP)

A

the biomass, it is what the producer passes on to the primary consumer

41
Q

what is gross primary productivity (GPP)

A

the quantity of energy that an organism takes in, some of which is lost in plant respiration

42
Q

what is the calculation for net primary productivity

A

NPP = GPP - respiratory loss

43
Q

why is not all energy from an animal passed on to the next trophic level

A

not all parts are consumed and some can’t be digested ; eg. bones/ tendons and ligaments
some of the energy of the animal would have been used for it’s own metabolic processes like respiration

44
Q

what is the calculation for net productivity and when is it used

A

net productivity = gross productivity - respiratory loss

with animals

45
Q

define climate change

A

the change in weather patterns in a particular area over a period of time eg. more monsoons/ global warming/ changing rainfall patterns

46
Q

outline dendrochronology and how it’s used

A

dendrochronology - method of assessing a tree’s age by using it’s tree ring

scientists take cores through tree trunks and date each ring by counting back from when the core was taken
the thickness of the rings indicate the climate; a thicker ring means better climate
eg. warmer/less wind/light rain etc.

47
Q

outline pollen in peat bogs and how it’s used

A

pollen is often preserved in peat bogs (due to the acidity and anaerobic nature), the bogs accumulate in layers so the age of preserved pollen increases with depth

  1. scientists take cores from peat bogs and extract pollen grains from differently aged layers
  2. they identify the plan species the pollen came from
    only mature plant species produce pollen so samples only show the successful species from that time
  3. the species is then compared to the climate that the species thrives in today
  4. this is thought to be the climate at that time
48
Q

how have temperature records been kept

A

since the 1850’s temperature has been measures worldwide using thermometers
gives a reliable, short-term record of climate change

49
Q

define species

A

a group of organisms with similar physiological features that can breed together to produce fertile offspring

50
Q

how can plants use hexose sugars

A
  • be respired to release energy
  • convert into starch for storage
  • convert into cellulose for cell wall structure
  • convert into sucrose for transport
51
Q

how can dendrochronologists learn about the climate going beyond the lifespan of living/recently chopped trees

A

examine fossilised trees
examine ancient objects made of wood eg. building parts/ furniture

52
Q

what are ice cores and how are they used

A

ice forms from the compaction of snow, so it contains tiny bubbles of air from the era when it was formed

The gas content of the trapped air bubbles can be analysed for gas content and compared to the present-day atmosphere

53
Q

why has ocean warming increased carbon dioxide

A

because it’s less soluble in warm water than cold water

54
Q

why might a woman piece of data be bad or not good to use for a future trend etc.

A
  • only one set of data (reference location, species etc.)
  • no statistical tests to see if the results were significant
  • error bars not present
  • no mean so no repeats
  • not enough data collected
  • fluctuation
  • can’t assume a trend would continue
55
Q

why is peer review important in science

A
  • determine whether the research falls within the scope of the (scientific) journal being submitted to
  • ensure experiment is repeatable
  • check results were analysed appropriately
  • prevent the publication of flawed scientific research
56
Q

how do you calculate efficiency of biomass transfer

A

Efficiency of biomass transfer = (biomass transferred/biomass intake) x 100

aka biomass of B/biomass of A

57
Q

why does more of the sun’s radiation reach the earth than goes back into space

A

Shortwave radiation reaches Earth, longwave radiation is re-emitted by Earth

  • Very little shortwave radiation from the sun is absorbed by greenhouse gases in Earth’s atmosphere
  • Most of the re-emitted longwave radiation is absorbed by greenhouse gases
58
Q

sources of greenhouse gases

A
  • cattle farming
  • respiration
  • peat bog degradation
  • use of artificial fertilisers
59
Q

how do greenhouse gases affect the climate

A

they trap infrared radiation/heat energy in the atmosphere, causing temperatures to increase

60
Q

what is Q10 temperature coefficient

A

the ratio of the rate of an enzyme reaction taking place at two temperature differing by 10˚C/K

higher/lower

61
Q

how can forests be managed sustainably

A
  • replace trees that are cut down with rapidly growing trees
  • cut down the older trees
62
Q

what is the consequence of chopping down trees

A
  • less photosynthesis, so less CO2 is fixed and more is in atmosphere
  • CO2 is a greenhouse gas, so more infrared radiation will be trapped in the atmosphere, increasing temperatures
63
Q

is CO2 reduced/oxidised in photosynthesis

A

CO2 is reduced to form organic molecules

64
Q

where is chlorophyll found in a chloroplast?

A

in the thylakoid membrane

65
Q

outline how you could study the Hill reaction

A

Hill reaction: PSI in LDR NADP is reduced and O2 is released from water

  1. cut some leaves (eg. spinach) into pieces, removing any tough stalks
  2. using a pestle and mortar, grind the leaf pieces up with some chilled isolation solution (sucrose, KCl, phosphate buffer, pH7)
  3. filter the liquid into a beak via a funnel lined with muslin cloth, transfer the liquid to centrifuge tubes and centrifuge at high speed for 10 minutes to allow chloroplasts to gather at the base of each tube in a ‘pellet’
  4. get rid of the liquid at the top, leaving the pellets at the bottom. re-suspend the pellets in a fresh, chilled isolation solution - this is the chloroplast extract and should now always be stored on ice
  5. set up a colorimeter with a red-filter and zero it with a cuvette containing the extract and distilled water
  6. set up a test tube rack at a set distance from a bench lap and switch on the lamp
  7. put a test tube in the rack, add a set volume of chloroplast extract and DCPIP, mix together
  8. take a sample and add to a clean cuvette immediately, measuring absorbance with the colorimeter
  9. repeat every 2 minutes for the next 10 minutes
  10. repeat experiment 2x more, controlling distance from light, time etc.
66
Q

explain the results that should be seen from the Hill reaction cp

A

The hill reaction occurs in photosystem I, during the light dependent stage of photosynthesis where NADP acts as a proton acceptor from split water, forming NADPH and O2 is released

the rate of this reaction can be investigated using a redox indicator dye (eg. DCPIP) to isolated chloroplasts
the dye can act like NADP and act as an e- acceptor, getting reduced
the reduction of the dye will show a colour change (DCPIP goes blue –> colourless); the rate of colour change can be measured to calculate the rate of the hill reaction

a graph of absorbance against time can help to visualise these results

67
Q

how could the effect of temperature on seedling growth rate be studied

A
  1. last seedlings of the same species and age in soil trays, measuring the height of each
  2. put the trays in incubators at different temps
  3. ensure other variables are controlled (water content of soil, light intensity, CO2 conc etc.)
  4. after a period of incubation record the change in height of each seedling
  5. calculate the average growth rate by doing: avg seedling height change / incubation period
68
Q

how could the effect of temperature on brine shrimp hatch rate be studied

A
  1. put an equal number of brine shrimp eggs in water baths at diff temps (10, 20…)
  2. control all other variables in each water bath (water volume, salinity, O2 conc)
  3. record the no. of hatched brine shrimp every 5 hrs
  4. calculate hatching rate using
    no. hatched brine shrimp water bath / number of hours
69
Q

how can the effect of temperature on enzyme catalysed reactions be studied

A
  1. set up boiling tubes with the same volume and concentration of hydrogen peroxide, adding equal volumes of a suitable buffer solution to each tube
  2. set up the apparatus as shown in the diagram
  3. put each boiling tube in a water bath (10, 20, 30 etc.) along with another tube containing catalase
  4. add the same volume and conc of catalyse t each boiling tube, quickly attaching the bung and delivery tube
  5. record the O2 produced every 10 seconds in the first minute, using a stopwatch to measure time

plot a graph and draw a tangent at 0 to get initial rate!!!

70
Q

outline transects and how they’re used

A

belt transect: data is collected along the transect, using frame quadrants placed next to each other

71
Q

outline how climate change could be reduced

A

biofuels:
fuels made from biomass (material that is/was recently living) eg. crops
they are a sustainable resource and when they are burnt they don’t increase atmospheric CO2 concentration

reforestation:
CO2 is fixated into carbon compounds and stored in trees as plant tissues

72
Q

how might people disagree on methods of reducing climate change

A

biofuels:
famers might support because governments might fund crop farming for them

drivers might support because bio-fuels can be cheaper than oil-based

consumers might oppose because using farmland for fuel could cause food shortage

conservationists might oppose because forests have been cleared to grow biofuel crops

73
Q

outline how you would study various abiotic factors in a given habitat

A

climate: temperature using a thermometer

oxygen availability: (only done in aquatic habitats) an oxygen sensor can measure the amount of O2 dissolved in the water

solar input: light sensor

edaphic factors (soil conditions): mix a sample of soil with water and a pH indicator solution

topography: measure relief using height reading at different points using a GPS

74
Q

why is a cold buffer solution and sucrose used in studying the hill reaction

A

cold and buffer stops enzyme denaturation
sucrose stops osmotic water loss from chloroplasts

75
Q

is NADPH formed in cyclic or non-cyclic photophosphorylation

A

non-cyclic
sooooo Non-cyclic = NADPH

76
Q

what should you mention when talking about glucose –> starch

A

forming glycosidic bonds between glucose molecules via condensation reactions

77
Q

where does the light dependant vs independent reaction take place

A

dependent: thylakoids
independent: stroma

78
Q

why is CO2 linked to plant growth

A

CO2 is fixed to produced GALP which is used to form carbs etc. this leads to increased growth ratw

79
Q

outline a method to study the species’ present in two different areas

A
  • randomly generated coordinates via random no. generator
  • quadrat 10 times MINIMUM in each place
  • count the species in each quadrat
  • calculate the total species in the given area
  • calculate mean and standard deviation for each one
80
Q

why do plants have less net emissions than meat

A

they remove CO2 from the atmosphere and use it to produce organic compounds via photosynthesis

animals respire more than plants and sometimes produce methane

81
Q

why is deforestation bad

A

cuts down trees which are carbon sinks
burning of these trees releases CO2 into the atmosphere
without trees there’s less photosynthesis to remove CO2 from the atmosphere

82
Q

how do pioneer species change bare rock

A

eg. lichens
help to slowly brew apart the surface and the fragmented rock plus the humus after the plant dies forms a basic soil layer

a level biology (13 decks)

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