exam Q's

Question 1

suggests why it is important that the leaf extract was dried thoroughly before mixing with the organic solvent

Answer 1

-may alter the Rf value

Question 2

discuss the fate of triose phosphate TP in the calvin cycle

Answer 2

-regenerates RuBP
-so cycle can continue for further CO2 fixation
-formation of glucose, sucrose, starch, cellulose
-formation of amino acids, fatty acids, nucelotides
-most used to produce RuBP and the rest for production

Question 3

describe why measuring CO2 uptake may or may not give a better indication of photosynthetic activity than measuring oxygen production

Answer 3

-oxygen only produced in one stage of photosynthesis
-oxygen produced might be used for respiration

-co2 only used in one stage
-might be used for photosynthesis

Question 4

explain the change observed in the tube exposed to green light

Answer 4

-can’t absorb the green light/ green pigment reflects it
-light cant be used in photosynthesis
-no carbon fixation in the carbon cycle= co2 builds up in creasing acidity and decreasing the pH

Question 5

outline the importance of photosynthetic pigments in photosynthesis

Answer 5

-absorb light/photons
-electrons excited to higher energy level
-accessory pigments pass energy to primary pigments
-primary pigments pass electrons to ETC
-for light dependent reaction

Question 6

suggest why chromista -live in deep sea- need pigments that are different from those of other photosynthetic organisms

Answer 6

-some wavelenghts dont reach depth/ them as they are in deep water

Question 7

suggest two ways in which the ultrastructure of the chloroplast can be altered by high temperatures

Answer 7

-damage to membranes in chloroplast = will reduce photophosphorylation/ ATP production in the light dependent stage

-damage to chlorophyl= reduce light dependent stage

-damage to membrane around chloroplast/ release enzymes = reduce light independent stage/ calvin cycle

Question 8

explain what is meant by a limiting factor

Answer 8

the factor that will determine/ limit the rate
-when at lower level

Question 9

suggest the role of DNA and ribosomes in chloroplast

Answer 9

• (DNA) coding for , gene(s) / protein / enzyme ;
• (ribosome) protein / enzyme , synthesis ;
• (protein for) electron , acceptor(s) / carrier(s) ;
• ATP synthase ;
• (enzyme / PSII) for , photolysis / splitting of water ;
• (enzymes for) Calvin cycle / light independent reaction ;

Question 10

describe 2 ways the structure of grana is adapted for its function

Answer 10

-contain (named) pigment/ photosystems
-contain electron carriers/ ETC/ ATP synthase
-have large surface area for light absorption

Question 11

with reference to the biochemistry of photosynthesis, explain why the theoretical rate of photosynthesis is not achieved at higher light intensities

Answer 11

-At high light intensity, other factor becomes a limiting factor
-CO2 becomes limiting as it is required for Calvin cycle/ light independent reaction
-temperature becomes limiting as calvin cycle involves enzymes/ relies on kinetic energy of molecules

Question 12

outline the ways in which heterotrophic organisms are dependent on plants

Answer 12

-heterotrophs eat/ obtain organic material from plants
-plants produce organic material during photosynthesis
-plants produce oxygen during light dependent stage
-glucose/ carbohydrate/ oxygen are used in respiration by animals and produced by plants

Question 13

explain what is meant by the term autotroph and heterotroph

Answer 13

autotroph-can make organic molecules from inorganic molecules/ carbon dioxide

heterotrophs- rely on, feed/ obtain organic molecules that have been made by another organism

Question 14

the chloroplast contains fat droplets that act as reserves of raw material for the chloroplast
suggest what this might be used for in the chloroplast

Answer 14

-for membrane formation/ phospholipids for membrane

Question 15

explain how light is harvested in the chloroplast membranes

Answer 15

1 (primary & accessory) pigments , are in / form a(n)
photosystem / complex / antenna complex ;

2 photon / light energy , absorbed by
pigment (molecule(s)) ;

3 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 ;