5.6: Photosynthesis Flashcards
Describe two ways in which the structure of part C(granum/ grana/ granal stack) is adapted to its function. (2mks) [f214 june 15 q1aii]
1 contain, (named) pigment (molecules) / photosystems;
2 contain, (named) electron carriers/ ETC/ ATP synth(et)ase;
3 idea that has a large surface area (in a small volume)
for, light absorption / light dependent reaction (s)/ light dependent stage / electron transport;
[ ‘the membranes containing the pigments have a large
surface area for absorbing light’ = 2 mks;
‘there is a large surface area for electron transport
chain’ = 2 mks ]
explain why the theoretical rate of photosynthesis is not achieved at higher light intensities. (2mks) [f214 june 15 q1b]
1 at high light intensity other (temperature/ CO2 conc.) factor becomes a limiting factor; [light is no longer the limiting factor] 2 temperature becomes limiting as, Calvin cycle / light independent reaction, involves enzymes/ relies on kinetic energy of molecules; [ref to Rubisco being limited by temp (as a named enzyme being in the Calvin cycle)] 3 CO2 (concentration) becomes limiting as it is required for, Calvin cycle/ light independent reaction/ formation of (named) Calvin cycle compound/ reaction with RuBP/ fixation by Rubisco; [GP/ TP/ RuBP]
Using the information in Fig. 1.3, explain which of the two species, D or E, is better adapted to living in shady conditions. graph shows light intensity against rate of photosynthesis, E starts phtosynthesis earlier, reaches plateau quicker and remains lower levele. (2mks) [f214 june 15 q1ci]
species E because
1 E starts photosynthesising at low(er) light intensity;
2 E reaches its maximum rate at low(er) light intensity;
3 E steep(er) increase in rate of photosynthesis
(with small increase in light intensity);
4 E has a, higher/ greater / faster, rate of photosynthesis (than D) at low light intensities; [E has a faster increase in the rate of photosynthesis at low light intensities’ = 2 marks ]
The leaf of a plant that is adapted to living in shade will differ from the leaf of a plant that is adapted to living in sunlight.
Suggest one way in which the structure of these leaves will differ [f214 june 15 q1cii]
shade leaf will have
1 large(r) / more, chloroplast(s)/ (palisade) mesophyll; [more, chlorophyll/ photosystems]
2 more, grana/ thylakoids (in chloroplast);
3 large(r) surface area (of leaves);
Plants are autotrophs. Most other organisms are heterotrophs. Outline the ways in which heterotrophic organisms are dependent on plants (3mks) [f214 june 15 q1d]
1 animals / heterotrophs (need to), eat/ obtain organic material from, plants / autotrophs;
2 (plants / autotrophs) produce (named) organic molecules during, photosynthesis/ Calvin cycle/ light independent stage;
3(plants / autotrophs) produce oxygen during, photosynthesis/ photolysis/ light dependent stage;
4 glucose / carbohydrate / oxygen, (produced in photosynthesis) are used in respiration by, animals/ heterotrophs;
Name the primary photosynthetic pigment in photosystems I and II. [F214 June 14 q1ai]
chlorophyll, a/ A;
Name an accessory pigment. [F214 June 14 q1aii]
chlorophyll b/ xanthophyll(s)/ carotenoid(s)/ (/ beta-) carotene; [
State the advantage to the plant of having a range of accessory pigments in photosystems. [F214 June 14 q1aiii]
able to , absorb / use , a range of / different / more / other , (light) wavelengths;
Name the compound that is synthesised in the light-dependent stage as a result of the generation of an electrical and pH gradient across the thylakoid membrane. [F214 June 14 q1aiv]
ATP
Identify the enzyme that catalyses the fixation of carbon dioxide. [F214 June 14 q1bi]
rubisco / RuBP carboxylase / ribulose bisphosphate carboxylase; [ribulose biphosphate carboxylase]
Identify the first stable product of carbon dioxide fixation. [F214 June 14 q1bii]
GP / glycerate(3-)phosphate ;
Identify the compound that is regenerated in the Calvin cycle so that more carbon dioxide
can be fixed. [F214 June 14 q1biii]
RuBP / ribulose bisphosphate ;
Name two different polysaccharides that can be synthesised from the end products of the light-independent stage of photosynthesis. [F214 June 14 q1biv]
starch / amylose / amylopectin
and
cellulose ;
Respiration can be aerobic or anaerobic. Certain parasites live in the blood of mammals. Suggest why, even though blood carries oxygen, these parasites are adapted to respire anaerobically. (2mks) [F214 June 14 q5bi]
1 idea that parasites have little access to oxygen ;
2 (inaccessible because) little oxygen dissolved in plasma / oxygen not very soluble (in plasma) ;
3 (inaccessible because) idea that oxygen is , combined with haemoglobin / contained in red blood cells ; [in context of saturation]
4 idea that haemoglobin has greater affinity for oxygen than parasite (pigment) ; [‘because the oxygen is bound to haemoglobin, the parasite is unable to use it’ = 2 marks]
[F214 June 14 q6] The molecules listed below are all associated with photosynthesis. amino acid, reduced NADP, ATP, ribulose bisphosphate (RuBP), carbon dioxide, rubisco, glycerate-3-phosphate (GP), triose phosphate (TP), oxygen, water
From these molecules, identify:
(a) the enzyme.
(b) a product of the light-dependent reaction that is used in the light-independent reaction.
(c) a 3-carbon compound.
(d) a compound that can be made from TP but is not part of the Calvin cycle.
(e) a 5-carbon compound.
(f) a product of the light-dependent reaction that is not used in the light-independent reaction.
a) rubisco ;
b) ATP / reduced NADP ;
c) glycerate-3-phosphate / GP / triose phosphate / TP ;
d) amino acid ;
e) ribulose bisphosphate / RuBP ;
f) oxygen ;
Explain what is meant by the term autotroph [F214 Jan 13 q3a]
can make, organic molecule(s) / named organic molecule(s), from, inorganic molecule(s) / carbon dioxide ; [fixes carbon dioxide to produce (named)
carbohydrates / protein / lipid]
Explain what is meant by the term heterotroph [F214 Jan 13 q3a]
relies on / needs to use / has to obtain / feeds on and digests , (named) organic molecules (that have been made by another organism) ; [idea of need or taking in and breaking down is important; has to get its organic molecules from another organism’ = 1 mark]
The chloroplast contains fat droplets, as shown in Fig. 3.1. These act as a reserve of raw material for the chloroplast.
Suggest what this raw material might be used for in the chloroplast. [F214 Jan 13 q3bii]
for membrane formation or phospholipid / cholesterol / glycolipid , for membrane ;
fatty acid / (named) pigment , synthesis ; [ref to repair of membrane; ref to (chloroplast) envelope instead of membrane]
Fig. 3.2 represents the light harvesting system found on the surface of the internal membranes
of the chloroplast. Use the information in Fig. 3.2 to describe how light is harvested in the chloroplast membranes. [F214 Jan 13 q3c] {picture shows surface of internal membrane with light energy going into blobs and arrows jumping from blob to blob}
1 (primary and accessory) pigments , are in / form a(n), photosystem / complex / antenna complex; [if pigments are named, state that chlorophyll a and at least 1 named accessory pigment are in a photosystem]
2 photon / light energy , absorbed by pigment (molecule(s)) ; [idea of absorption required in the context of this Q]electron , excited / moves to higher energy level / delocalised , and returned to pigment ;
4 (energy / photon) passed from one pigment to another ;
5 (energy / photon) passed to , reaction centre / chlorophyll a / P680 / P700 / PSI / PSII / primary pigment ;
6 range of / accessory , pigments allow range of wavelengths to be absorbed ; [‘photon energy’ for ‘wavelengths’]
Triazine herbicide acts on the weeds by binding to a specific protein associated with photosystem II, blocking the movement of electrons between electron carriers.
Explain the effect that the herbicide binding to this protein will have on photosynthesis. (2mks) {table and questions} [F214 Jan 13 qdiii]
1 prevents non-cyclic photophosphorylation ;
2 no electron(s) available to form reduced NADP ;
3 idea that ATP production by cyclic
photophosphorylation is not prevented ;
4 no / less , ATP and no reduced NADP available for ,
Calvin cycle / light independent reaction /
conversion of GP to TP ;
Plants treated with triazine herbicide can, when illuminated under experimental conditions, be seen to fluoresce (emit light) and give off small quantities of heat.
Suggest how this experimental finding could be explained. {table and questions} [F214 Jan 13 qdiv]
idea that energy given off from , high energy / excited , electron (emitted by , chlorophyll / reaction centre) ;
State the precise location of the electron transport chain in the cell. [F214 June 12 3a]
crista(e) / inner mitochondrial membrane ; [thylakoid membrane / lamella(e) (of chloroplast)]
If oxygen is not present or is in short supply, respiration can take an anaerobic pathway after
glycolysis. In plant cells, this pathway is the same as the one used in yeast cells.
(i) Name the hydrogen acceptor in this pathway.
(ii) Name the intermediate compound in this pathway.
(iii) Name the products of this pathway.
(iv) Explain why this pathway is important for the plant cell. [F214 June 12 3c]
i) ethanal ; [acetaldehyde]
ii) ethanal ; [acetaldehyde]
iii) ethanol and carbon dioxide ; [formulae]
iv) 1 releases NAD , to accept more H / to be reduced again / so glycolysis can continue or allows (some) ATP to be generated (in glycolysis) ;
2 (some ATP available) for named cellular process ; [ active transport/ endocytosis/ exocytosis/ pinocytosis/ mitosis / meiosis/ protein synthesis DNA replication/ Calvin cycle / light-independent stage of photosynthesis]
3 [eg stated situation where oxygen is in short supply (e.g. waterlogging / compacted soil / roots situated very deep in soil)]
One way to determine the rate of photosynthesis is to measure the uptake of carbon dioxide.
(a) Discuss why measuring carbon dioxide uptake may or may not give a better indication of photosynthetic activity than measuring oxygen production. [F214 June 12 4a]
oxygen:
1 oxygen only produced in one (named) stage of photosynthesis ; [for O2 ‘only measures the rate of the light dependent stage / photolysis’]
2 oxygen produced might be used for respiration ;
carbon dioxide:
3 CO2 only used in one (named) stage of photosynthesis; [for CO2 ‘only measures the rate of the Calvin cycle’]
4 CO2 produced during respiration might be used for , photosynthesis / light independent reaction / Calvin cycle ;
5 O2 / CO2 / both , could be an underestimate or
represents net production (O2) or represents net use (CO2) ; [a description e.g. ‘measurement is less than expected because not all the oxygen produced can be measured’ (but not if expressed in terms of terms of experimental error – e.g. dissolves in the water)]
