Topic 5 Ford Flashcards

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1
Q

What is photosynthesis used for?

A
  • growth as it can make new molecules e.g. DNA, proteins, cellulose
  • respiration as it releases glucose and energy within glucose that can be used for other reactions
  • stored as starch
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2
Q

What are the two main stages of photosynthesis?

A

the light dependent reactions and the light independent reactions (Calvin cycle)

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3
Q

Phosphorylation

A

adding phosphates to a molecule

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4
Q

Lysis

A

splitting up/ breaking

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5
Q

Synthesis

A

making something

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6
Q

Photo

A

light

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7
Q

Hydro

A

water

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8
Q

What is ATP?

A

Adenosine Triphosphate - is the universal energy transfer molecule in a cell

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9
Q

Uses of ATP:

A
  • active transport
  • respiration (glycolysis)
  • anabolic processes
  • movement: muscle and spindle action
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10
Q

Oxidation

A

loss of electrons - lose hydrogen releasing energy

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11
Q

Reduction

A

gain of electrons - gain hydrogen absorbing energy

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12
Q

Redox reactions

A

a series of reduction and oxidation reactions

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13
Q

What is the co-enzyme used in photosynthesis?

A

NADP (P –> Photosynthesis)

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14
Q

What is the purpose of NADP?

A

its job is to carry hydrogen

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15
Q

Why are leaves green?

A

Leaves are green because with white light all are blocked apart from green light which is reflected. Leaves turn red/ orange/ yellow in Autumn because the chlorophyll is being broken down into other pigments so you see other colours

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16
Q

What are pigments?

A

substances that absorb visible light - chloroplasts contain a mixture of different pigments

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17
Q

Where are chlorophyll molecules found in the chloroplast?

A

in the photosystems in the membranes

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18
Q

What is a photosystem?

A

a group of light absorbing pigments

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19
Q

Where do the light dependent reactions happen?

A

in the Thylakoid membrane

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20
Q

Where do the light independent reactions happen?

A

in the stroma

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21
Q

Overview of light dependent

A
  • light strikes chlorophyll
  • 2 electrons are excited
  • 2 electrons move along the electron transport chain in a series of redox reactions
  • the energy released from this turns ADP + Pi –> ATP
  • water undergoes photolysis causing 2 electrons to replace the ones in the photosystem
  • hydrogen from the water and electrons from transport chain are used to reduce NADP
  • oxygen is a waste product
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22
Q

Overview of light independent

A
  • carbon dioxide combines with RuBP
  • this is catalysed by RuBISCO and forms a 6 carbon compound
  • this is unstable so immediately breaks down to form two 3 carbon compounds of GP
  • the 3 carbon compound GP turns into GALP by using energy (a phosphate) from ATP and the hydrogen from NADPH
  • some of the GALP can be removed to make hexose sugars and other organic molecules and the rest will continue in the cycle to be rearranged to form RuBP again
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23
Q

Why is light independent reactions a better term than dark reactions?

A

because they can happen in the light and the dark (unlike the light dependent - only in light)

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24
Q

What is carbon fixation?

A

when carbon dioxide combines with RuBP to form GP

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25
Q

What would happen to the Calvin cycle if a plant was denied light?

A

it would continue as normal until a point when the light dependent reactions can’t happen anymore, once the light dependent stops the Calvin cycle will stop as their will be no ATP or NADPH - nothing happens to RuBP and GP levels

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26
Q

What will happen if CO2 levels fall?

A

the GP levels will fall and RuBP levels will rise as it stays constant but less is being used to make GP but GP is turning into GALP

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27
Q

What factors affect/ limit photosynthesis? How?

A
  • temperature - can denature the proteins
  • light intensity - can affect the light dependent reactions so more/less ATP and NADPH being made and available for use
  • CO2 concentration - affects the Calvin cycle
28
Q

What organic substances can the Calvin cycle be the starting point for?

A
  • hexose sugars
  • starch
  • lipids (fatty acids from GP)
  • proteins (some amino acids can form from GALP)
29
Q

Chlorophyll only…

A

…absorbs certain wavelengths

30
Q

Why does not all light reaching Earth hit plants?

A

some will hit buildings

31
Q

How much of light reaching the plant is absorbed?

A

40%

32
Q

What happens to light (energy) reaching the plant?

A
  • reflected
  • pass straight through
  • absorbed
  • energy not absorbed by chlorophyll but used in evaporating water from leaves
33
Q

GPP - Gross Primary Productivity

A

the rate at which energy is taken in into organic molecules (e.g. glucose)
energy per area per year - Jm-2y-1

34
Q

NPP - Net Primary Productivity

A

the rate at which energy is transferred into the organic molecules that makes up the new plant biomass

35
Q

Efficiency of Photosynthesis =

A

(GPP / amount of light striking the plant) *100

36
Q

NPP =

A

GPP - R

37
Q

Succession

A
  • the change in one ecological community to another over time
  • the gradual change in a community over time
38
Q

Habitat

A

a place with a distinct set of conditions where an organism lives

39
Q

Population

A

a group of individuals of the same species found in an area at that time

40
Q

Community

A

different populations sharing a habitat/ ecosystem at a particular time

41
Q

Primary succession

A

formation of a habitat where no community has been before - bare rock, sand, open water (occurs when organisms colonize a lifeless habitat)

42
Q

Secondary succession

A

when an existing community has been cleared - fire, tsunami, war, ploughed field (occurs when organisms recolonize a devastated ecosystem)

43
Q

Pioneer species

A

the first organisms to colonise a habitat

44
Q

Climax community

A

a stable community that remains unchanged

45
Q

Deflected succession

A

takes another route along succession so it doesn’t reach its climax community - often human activity preventing succession running its course

46
Q

Why can only a few pioneer species colonise the sand?

A
  • lack of nutrients
  • salinity, high salt
  • pH, alkaline
  • wind, sand moves
  • dry conditions
47
Q

As you move from the sand dunes to the woodland what happens to animal diversity? Why?

A

the animal diversity increases, this is because there is less extreme conditions and they’re able to create more niches

48
Q

Why do pioneer species not end up in the climax community?

A

because they don’t have adaptations for it and can’t compete very well

49
Q

What happens to the species richness and species diversity in a climax community?

A

the species richness - increases as increased biodiversity

the species evenness - normally one dominant species so not very even

50
Q

What happens during succession?

A

The organisms within an ecosystem change its abiotic conditions. The better adapted organisms colonize the area, replacing current inhabitants

51
Q

Interspecific

A

between different species (Internet - everyone)

52
Q

Intraspecific

A

between the same species (Intranet - school network)

53
Q

Pioneer community features

A
  • harsh environment
  • extreme abiotic conditions
  • poor competitors
  • low organic matter (living things)
54
Q

Climax community features

A
  • high species diversity
  • little tolerance of abiotic extremes
  • stable environment
  • good competitors
55
Q

High stress

A

exposure to difficult conditions

56
Q

How could you sample species distributions with an environmental gradient? Random

A

Stratified random sampling - dividing the area into strata on the basis of obvious variation within it such as vegetation changes, fixed distances, fixed heights. Within each strata random sampling by x,y co-ordinates or random walking

57
Q

How could you sample species distributions without environmental gradient? Random

A

Grid method, a grid is laid out and random numbers are used as x,y co-ordinates. Alternatively, pacing the random numbers can be done from a fixed starting point

58
Q

How could you sample species distributions with an environmental gradient? Systematic

A

Transect - A line transect, sampling may be continuous or interrupted along the line. Continuous belt transect, rolling a quadrat over measuring everything along the transect length. Interrupted belt transect, quadrats set out at regular intervals

59
Q

Environmental gradient

A

a gradual change in an abiotic factor e.g. light intensity, pH, salinity, soil moisture

60
Q

How could you sample species distributions without environmental gradient? Systematic

A

Grid method, a grid is laid out and data is recorded at regular intervals across the grid

61
Q

Qualitative recording

A

presence or absence of species in a quadrat

62
Q

Quantitative recording

A
  • Density
  • Percentage cover
  • Frequency
63
Q

Density recording

A

density is a count of the number of individuals of a species per unit area

64
Q

Frequency recording

A

frequency is the probability or chance of finding a species in a given area - divided quadrat - presence or absence is recorded for each species in a sub-unit

65
Q

Percentage cover

A
  • direct estimate with an open quadrat
  • Scales: Braun-Blanquet, Domin, ACFOR
  • Divided quadrat: estimate the number of squares a species would fully occupy
  • Point quadrat: number of hits *10
66
Q

Why does algae look different colours?

A

Because in water different wavelengths of light pass through them. All photosynthesise and different pigments are picked out and used depending on the water so different colours are made