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topic 5 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

structure of chloroplasts

A

-thylakoid membrane- folded membranes which contain chlorophyll and electron carrier proteins embedded within these membranes. Involved in the LDR.
-stroma- fluid centre which contains enzymes involved in the LIR
-inner and outer membrane- control what can enter and leave the organelle

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2
Q

where does the LDR occur and what is its purpose

A

on the thylakoid membranes
light energy and water are used to create ATP and reduced NADP which are needed for the LIR

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3
Q

what are the 4 key stages of LDR

A

photoionisation of chlorophyll
production of ATP and reduced NADP
chemiosmosis
photolysis

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4
Q

describe photolysis

A

light energy is absorbed by chlorophyll and splits water into oxygen, H+ and e-
H2O –> 1/2O2 + 2e- + 2H+
the H+ is picked up by NADP to form NADPH and is used in the LIR
the e-s are passed along a chain of electrons carrier proteins
the oxygen is either used for respiration or diffuses out of the leaf through the stomat

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5
Q

describe photoionisation of chlorophyll

A

light energy is absorbed by the chlorophyll and this results in electrons becoming excited and raising up an energy level to leave chlorophyll
some of the energy from the released electrons is used to make ATP and reduced NADP in chemiosmosis

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6
Q

describe chemiosmosis

A

the electrons that gained energy and left the chlorophyll move along a series of proteins embedded within the thylakoid membrane
as they move along, they release energy and some of this is used to pump the protons across chloroplast membranes
an electrochemical gradient is created-high in thylakoid space and low in stroma so the protons diffuse across the membrane through the enzyme ATP synthase which results in the production of ATP
the protons combine with the co-enzyme NADP to become reduced NADP

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7
Q

where does the LIR/ calvin cycle occur

A

in the stroma
contains the enzyme rubisco which catalyses this reaction

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8
Q

what are the products and reactants of the calvin cycle

A

uses CO2, reduced NADP and ATP to produce a hexose sugar

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9
Q

describe the LIR/ calvin cycle

A

-CO2 reacts with RuBP to form 2 molecules of GP, a 3 carbon compound. this reaction is catalysed by rubisco
-GP is reduced to triose phosphate using energy from ATP and by accepting a H from reduced NADP
-one of the carbons from triose phosphate leaves the cycle each turn to be converted into useful organic substances
-the rest of the molecule is used to regenerate RuBP with energy from ATP
-glucose is the product and can join to form di/polysaccharides or can be converted into glycerol and combine with fatty acids to make lipids for the plant

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10
Q

what are the limiting factors for photosynthesis

A

temperature
CO2 concentration
light intensity

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11
Q

what are the limiting factors for photosynthesis

A

temperature
CO2 concentration
light intensity

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12
Q

what are common agricultural techniques to remove limiting factors

A

-artificial lighting
-heating
-burning fuel to produce CO2
-must be cost effective

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13
Q

4 stages of aerobic respiration

A

glycolysis (cytoplasm)
link reaction (mitochondrial matrix)
krebs cycle (mitochondrial matrix)
oxidative phosphorylation (cristae)

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14
Q

what steps are in involved in glycolysis

A

-phosphorylation glucose to glucose phosphate using ATP
-the production of 2x triose phosphate
-oxidation of triose phosphate to produce pyruvate with a net gain of ATP and reduced NAD
-

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15
Q

describe glycolysis

A

glucose is phosphorylated into hexose bisphosphate using 2x ATP
this then splits into 2x triose phosphate
triose phosphate is oxidised forming 2x pyruvate
2x NAD picks up H to form 2x reduced NAD
4 ATP are prodcuced

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16
Q

what are the products of glycolysis

A

2x pyruvate
net gain of 2 ATP
2x NADH

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17
Q

describe the link reaction

A

the pyruvate made in glycolysis is oxidised to acetate
NAD picks up the hydrogen and become reduced NAD
acetate then combines with coenzyme A

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18
Q

what are the products for the link reaction

A

the link reaction occurs twice for every glucose molecule as 2 pyruvate molecules are made from every glucose molecule in glycolysis
-2 molecules of acetyl coA (goes to Kreb’s cycle)
-2 CO2 molecules (waste product)
-2 molecules of reduced NAD (goes to oxidative phosphorylation)

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19
Q

describe kreb’s cycle

A

acetyl coA from the link reaction reacts with a 4-C moleucle to form a 6-C molecule
coA goes back to the link reaction to be used again
the 6C compound undergoes a series of enzyme controlled redox reactions involving decarboxylation and dehydrogenation occur where CO2 and hydrogen is removed
the H is used to produce reduced NAD
one molecule of reduced FAD and 2 of reduced NAD are produced
ATP is also produced

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20
Q

what are the product’s per kreb’s cycle

A

3x reduced NAD
1x reduced FAD
1x ATP
2x CO2
it is double the amount per glucose

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21
Q

describe oxidative phosphorylation

A

as reduced NAD and FAD are oxidised, they release a H atom which splits into a proton and electron
the e-s move down the electron transport chain, losing energy at each carrier
the energy is used by electron carriers to pump protons from the mitochondrial matrix to the intermembrane space
the conc of protons is now higher there, so an electrochemical gradient is formed
protons move back down the EC gradient into the matrix via ATP synthase so ATP is produced
(chemiosmosis)
in the matric at the end of the transport chain, the protons, electrons and O2 combine to form water
oxygen is the final e- acceptor

22
Q

where does anaerobic respiration occur

A

the cytoplasm of a cell

23
Q

how does anaerobic respiration occur in animals

A

the pyruvate produced in glycolysis is reduced to form lactate in animals by gaining the hydrogen from reduced NAD
this oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced

24
Q

how does anaerobic respiration occur in plants and microbes

A

the pyruvate produced in glycolysis is reduced to form ethanol and carbon dioxide in plants and microbes gaining the hydrogen from reduced NAD
this oxidises NAD so that it can be reused in glycolysis and ensure more ATP is continued to be produced

25
Q

compare the efficiency of aerobic and anaerobic respiration

A

-1 reduced NAD can result in a yield of 3 ATP molecules whereas 1 reduced FAD can result in a yield of 2 ATP molecules
-therefore the total yield of ATP from one glucose molecule in aerobic respiration is 38 molecules of ATP
-aerobic respiration is about 32% efficient due to some protons leaking across the mitochondrial membrane during oxidative phosphorylation, ATP being used to actively transport pyruvate and NADH into the matrix and because some energy is lost as heat
-anaerobic respiration is less efficient because only 2 ATP molecules are produced per glucose molecule

26
Q

what are the producers in a food web in an ecosystem

A

plants are the producers as they are able to produce their own carbohydrates using carbon dioxide in the atmosphere or water

27
Q

where is energy lost between each trophic level

A

-respiration and excretion
-the remaining energy is used to form the biomass

28
Q

how to measure biomass

A

-mass of carbon
-dry mass of tissue per given area

29
Q

what is gross primary production

A

the chemical energy store in plant biomass, in a given area or volume. It is the total energy resulting from photosynthesis

30
Q

what is net primary production

A

the chemical energy store in plant biomass taking into account the energy that will be lost due to respiration

31
Q

equation for NPP

A

NPP=GPP-R

32
Q

how is NPP used

A

-it is the energy left over that is available to the plant to create new biomass and therefore available to the next trophic level in a food web

33
Q

how to work out the net production of consumers

A

N=I-(F+R)
I= the chemical energy store in ingested food
F= the chemical energy lost to the environment in faeces and urine
R= respiratory losses

34
Q

what units are rate of production measured in

A

kJ/ha/year

35
Q

which biological molecules contain nitrogen

A

proteins, atp, nucleic acids

36
Q

what are the steps of the nitrogen cycle

A

nitrgoen fixation
ammonification
nitrification
denitrification

37
Q

describe nitrogen fixation

A

the process of converting N2 gas into nitrogen-containing compounds
can be done by:
-nitrogen-fixing bacteria reduce N2 gas into ammonia. when they die and decay, nitrogen-rich compounds are released.
-humans use the haber process to make nitrogenous fertilisers
-nitrogen is oxidised naturally to nitrate by lightning

38
Q

what is mutualistic nitrogen-fixing bacteria

A

mutualistic nitrogen-fixing bacteria is found inside root nodules of leguminous plants (peas, clover, beans). The plant produces carbohydrates, the bacteria provides N-containing compounds.

39
Q

describe ammonification

A

-microbial saprobionts (organisms that feed on dead organic matter) break down proteins in detritus and dead organic matter to form ammonia

40
Q

describe nitrification

A

involves the conversion of ammonium ions (NH4+) into nitrites (NO2-) and nitrates (NO3-)
oxidation reaction occur caused by nitrifying bacteria
2 stages:
ammonium to nitrites
nitrites to nitrates
requires O2 so soil needs to be kept well aerated by ploughing

41
Q

describe denitrification

A

-converts nitrates into N2 gas and nitrogen oxides by denitrifying bacteria
-occurs under anaerobic conditions e.g. compacted or waterlogged soils

42
Q

describe assimilation

A

-the proteins made by plants enter and pass through food webs when consumers eat the plants. nitrogen is incorporated into biological molecules e.g. DNA, ATP, proteins

43
Q

describe decomposition

A

-N is added to the soil when waster materials and dead organic matter is broken down

44
Q

what is phosphorous used for in organisms

A

-DNA/RNA
-ATP
-phospholipid bilayer

45
Q

what are mycorrhizae

A

-associations between plants roots and beneficial fungi
-they increase SA for mineral and water absorption
-they hold water and minerals around the roots
-they make plants more drought resistant and able to take up more inorganic ions
-this is a mutualistic relationship as it improves the uptake of relatively scarce ions such phosphorous

46
Q

describe the phosphorous cycle

A

-phosphate ions in rocks are released into soil by weathering
-the ions are taken into plants through roots. mycorrhizae increase the rate of assimilation
-the ions are transferred through the food chain as animals eat the plants and are in turn eaten by other animals
-phosphate ions are lost from animals through waste product
-when plants and animals die, saprobionts break down the organic compounds, releasing phosphate ions for assimilation by plants
-waste produced by seabirds (guano) contains a high proportion of phosphate ions which are returned to soils often in coastal areas
-weathering of rocks releases phosphate ions into lakes, seas and rivers

47
Q

why are fertilisers added to soil

A

to replace the nitrate and phoshpate ions lost when plants are harvested and removed from nutrient cycles as crops

48
Q

advantages and disadvantages of natural fertilisers

A

-cheaper and often free if the farmer owns animals
-exact minerals and proportions can’t be controlled

49
Q

advantages and disadvantages of artificial fertilisers

A

-can control exact proportions of minerals
-the inorganic ions have high solubility so large quantities are washed away which has a greater impact on the environment

50
Q

what is leaching

A

when water soluble compounds are washed away into rivers or ponds
if nitrogen fertilisers leach into water, it causes eutrohpication

51
Q

what is eutrophication

A

-when nitrates from fertilised fields stimulate growth of algae in ponds
-this blocks out sunlight so plants cant photosynthesis and die
-bacteria in the water redd and respire on dead plant matter causing an increase in bacteria which use up oxygen in the water
-eventually fish die due to lack of dissolved oxygen

Biology (9 decks)

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