Photosynthesis

Question 1

what are chemoautotrophs

Answer 1

oxidation of inorganic compounds as energy source

Question 2

what are photoautotrophs

Answer 2

using light as energy source

Question 3

describe the structure of chloroplasts (3)

Answer 3

thylakoid
grana
stroma

Question 4

what is the thylakoid

Answer 4

flattened fluid filled sacs

Question 5

what is grana

Answer 5

thylakoids make up grana

Question 6

describe the grana

Answer 6

grana has high surface area, has pigment, enzymes and electron carrier
- lots of pigment + site of ATP synthase

Question 7

what is in the stroma (6)

Answer 7

enzymes 
sugars
organic acids 
small ribosomes
loop of DNA
lipids

Question 8

describe the location and overall reactions in light dependant reactions

Answer 8

thylakoid membrane

• photolysis of water
• photophosphorylation in synthesis of ATP
• carrier molecule NADP

Question 9

describe cyclic photophosphorylation (7)

Answer 9

PSI involved;
light energy absorbed;
electron excited;
emitted from chlorophyl;
chain of electron carriers;
ATP synthesis;
electron returns to PSI;

Question 10

how are photosystem arranged (4)

Answer 10

pigments in light harvesting clusters;
primary pigment;
accessory pigment;
photosystem located in thylakoid;

Question 11

describe non cylic photophosphorylation (5)

Answer 11

both photosystems involved;
photolysis of water;
H+ released from PSII;
e- released from PSI;
e- + H+ combine to NADP;

Question 12

purpose of reduced NADP (3)

Answer 12

reduced GP;
TP formed;
in stroma;

Question 13

purpose of accessory pigments (3)

Answer 13

pass energy to reaction centre;
absorb different wavelengths;
form light harvesting cluster;

Question 14

where is the location of light independant reactions

Answer 14

stroma

Question 15

describe the calvin’s cycle

Answer 15

RuBP + RuBisCo + co2 –> GP –> (rNADP - NADP) (ATP –> ADP + P) 2(TP) –> (ATP –> ADP) RuBP

Question 16

what is triose phosphate used for (3)

Answer 16

glucose
amino acids
lipids

Question 17

factors affecting photosynthesis (5)

Answer 17

supply of co2
water
light energy
photosynthetic pigment
temperature

Question 18

how does temperature affect rate of photosynthesis

Answer 18

photosynthesis increases due to enzymes more active

best combo = high light + high temp.

Question 19

adaptations of leaves able to consume more carbon dioxide

Answer 19

leaves able to consume more carbon dioxide

• thinner leaves
• more stomata
• more chloroplasts

Question 20

definition of limiting factors

Answer 20

a substance in shortest supply that affects the rate of photosynthesis

Question 21

how do you measure the rate of photosynthesis

Answer 21

using gas syringe to collect oxygen produced from plant

Question 22

describe bundle sheath cells in mesophyll

Answer 22

mesophyll cells surround bundle sheath cells

Question 23

what is present in bundle sheath cells (3)

Answer 23

carbon dioxide
RuBP
RuBisCo

Question 24

what takes place in bundle sheath cells

Answer 24

calvin cycle

Question 25

describe the process to avoid photorespiration (6)

Answer 25

RuBP and RuBisCo is kept away from oxygen in bundle sheath cells
carbon dioxide absorbed by mesophyll cells
mesophyll cells contain PEP carboxylase - high optimum temp.
PEP carboxylase catalyse carbon dioxide + PEP → oxaloacetate
converted to malate
malate decarboxylated and passed to RuBP by RuBisCo

Question 26

how do you find Rf value

Answer 26

distance travelled by substance/distance travelled by solvent

Question 27

describe the method for chromatography (10)

Answer 27

Grind leaf;
Use solvent (organic);
Leaf extract contains mixture of pigment;
Concentrate extract;
Pencil line drawn;
Paper places in jar of solvent;
Solvent rises up paper;
Each pigment travels in different speed;
Calculate Rf value;
Compare values;