Topic 5 - Energy Transfers Between And In Organisms

Question 1

Where does the LPD take place, and what products are needed for the LIR

Answer 1

Takes place in the thylakoid membrane and produces ATP and NADPH for LIR

Question 2

Where does the LIR take place and what is needed

Answer 2

Takes place in the stoma and it needs ATP, NADPH, CO2
RuBP and Rubisco are also needed

Question 3

Explain 4 stages of LDR

Answer 3

.Photolysis - Light energy splits water into oxygen (used in respiration or diffuses out stomata), H ions (picked up by NADP to make NADPH for LIR) and electrons (used in ETC)

.Photoionisation - light energy absorbed by chlorophyll, causing electrons to be excited, raising their energy level and they leave the chlorophyll. Chlorophyll is now ionised (positively charged)

.Chemiosmisis - Electrons from chlorophyll enter ETC, releasing energy used to pump protons across membrane (from stoma to thylakoid lumen). High conc of H ions in thylakoid (H ions from photolysis aswell) causes an electrochemical gradient, so protons move through ATP synthase, producing ATP

.Production or ATP and NADPH - some protons in the stoma after chemiosmosis , and electrons at the end of the ETC are picked up by NADP to produce NADPH

Question 4

Describe the LIR

Answer 4

.CO2 reacts with ribulose biphosphate (RuBp) to for 2 molecules of GP, catalysed by rubisco
.ATP and reduced NADP from LDR are used to reduce GP into triose phosphate
.Some triose phosphate is used to regenerate RuBP in Calvin cycle
.Some triose phosphate tee to useful organic substances (glucose/simple sugars)

Question 5

How is energy produced in anaerobic respiration

Answer 5

Pyruvate is reduced into Ethanol (releasing CO2 in plants) or into lactose using NADH. NAD is oxidised and used in further glycolysis.

Question 6

Where does pyruvate go after glycolysis

Answer 6

Enters the mitochondrial matrix via active transport

Question 7

Describe krebs cycle

Answer 7

.Acetylcoenzyme A reacts with a 4 carbon molecule, releasing coenzyme A and producing a 6 carbon molecule which enters the Krebs cycle
.In a series of oxidation reduction reactions, NADH and FADH2 produced, ATP made via substrate level phosphorylation and CO2 is lost
.Lipids and amino acids can enter Krebs cycle (amino acids must have amino group removed)

Question 8

What is biomass

Answer 8

Mass of carbon/ dry mass of tissue per given area. (GPP is the chemical energy site plant biomass per given area/volume)

Question 9

2 ways in which farming practices increase efficiency of energy transfer

Answer 9

.Simplifying food webs to reduce energy losses to non-human food chains
.Reducing respiratory losses within a human food chain