Energy For Biological Processes

Question 1

needs for energy

Answer 1

active transport
anabolic reactions
movement through organelles such as cilia and flagella

Question 2

photosynthesis

Answer 2

6CO2 + 6H20 ——-> C6H1206 + 6O2
light is trapped by chlorophyll
glucose produced is used in respiration oxygen is released

Question 3

what is the structure of chloroplasts

Answer 3

• thylakoids - provide large SA
• grana
• lamellae
• stroma

Question 4

what is chemiosmosis

Answer 4

diffusion of protons from a region of high conc. to low conc through a partially permeable membrane. protons release energy which attaches a inorganic phosphate to adp producing atp

Question 5

how are electrons ‘excited’

Answer 5

-electrons in chlorophyll are excited by absorbing light from the sun
-high energy electrons are released when chemical bonds are broken in respiratory substrate molecules

Question 6

electron transport chain

Answer 6

high energy electrons move from one carrier to another, energy is released. this is used to pump protons across a membrane creating a coc. difference across the membrane and therefore a proton gradient.

Question 7

photosynthesis

Answer 7

6CO2 + 6H20 ——-> C6H1206 + 6O2
light is trapped by chlorophyll
glucose produced is used in respiration oxygen is released

Question 8

what is the purpose of chlorophyll

Answer 8

to absorb red and blue but reflect green
provides pigment

Question 9

what is the reason for different shade and colors of leaves

Answer 9

different combinations of pigment

Question 10

where is chlorophyll located

Answer 10

in the light harvesting system- photosystems

Question 11

what are the two stages of photosynthesis

Answer 11

1. light dependent
2. light independent

Question 12

what occurs during the light dependent stage

Answer 12

energy from the sun is absorbed which forms ATP and hydrogen from the water will reduce coenzyme NADP into reduced NADP

Question 13

EXPLAIN THE LIGHT DEPENDENT STAGE

Answer 13

1. NON CYCLIC PHOSPHORYLATION
   light energy is absorbed by PSII which excites electrons and causes them to move to a higher energy state, these electrons are passed onto a series of electron carriers within electron transport chain to PSI ATP is again produced by chemiosmosis.
2. PHOTOLYSIS
   electrons lost from PSII needs to be replaced. water is split into hydrogen ions, electrons and oxygen molecules using energy provided by the sun. electrons released replace the electrons lost from the reaction Centre of PSII. oxygen released is a by product
3. CYCLIC PHOSPHORYLATION
   electrons leaving the electron transport chain after PSI can be returned to PSI instead of being used to form reduced NADP

Question 14

what is the light independent stage

Answer 14

hydrogen from the reduced NADP and co2 is used o build organic molecules such as o2, this is done by the process of the calvin cycle

Question 15

CALVIN CYCLE

Answer 15

The Calvin Cycle takes place in the stroma of the chloroplast and uses the products of the LDR (ATP and reduced NADP) to form glucose. The reactions which take place can be divided into three main stages: carbon fixation, reduction and regeneration.

Question 16

explain the process of the light independent stage ( CALVIN CYCLE)

Answer 16

1. FIXATION
   Carbon dioxide and RUBP ( ribulose bisphosphate ) combine
   RuBisCo ( ribulose bisphosphate carboxylase) catalyses’ the reaction and an unstable intermediate is formed.
   the unstable intermediate is broken down to form 2 GP molecules
2. REDUCTION
   Each GP molecule is converted into a TP molecule using hydrogen from reduced NADP and energy from ATP
3. REGENERATION
   Majority of the TP is recycled to regenerated the RUBP so hat the Calvin cycle can continue

Question 17

what is the use of TP

Answer 17

Five-sixths of the triose phosphate (TP) molecules are used to regenerate ribulose bisphosphate (RuBP). This process requires ATP

AMINO ACIDS
GLYCEROL
FATTY ACIDS

Question 18

LIMITING factors affecting photosynthesis

Answer 18

1. LIGHT INTENSITY
2. TEMPERATURE
3. CARBON DIOXIDE CONC

Question 19

effect of light intensity

Answer 19

as light intensity increases, ATP and reduced NADP is produced at a higher rate

Question 20

effect of carbon dioxide concentration

Answer 20

increasing co2 conc, increases rate of carbon fixation in the calvin cycle and the rate of TP production

Question 21

effect of temperature

Answer 21

in general, the higher the temperature the faster the rate of photosynthesis because the enzymes (e.g. Rubisco) and reacting molecules have more kinetic energy so they collide into each other more frequently. If the temperature becomes too high, the rate of photosynthesis decreases because the enzymes involved in photosynthesis are denatured.

Question 22

what is the effect of reducing light intensity on the calvin cycle

Answer 22

reducing light intensity will reduce the rate of the light dependent stage. this reduces atp and reduced NADP produced which is needed to convert GP into TP. The conc of GP would increase and conc of TP would decrease so less TP would be able to regenerate RUBP so conc of RUBP would decrease

Question 23

EFFECT OF CO2 AND TEMP ON CALVIN CYCLE

Answer 23

at lower temperature enzyme and substrate molecules have less kinetic energy which results in fewer successful collisions reducing the rate of reaction which results in low concentration of GP, TP, and RUBP
low concentration of co2 results in reduced concentration of GP and TP.