T5 energy transfers

Question 1

adaptations of chloroplasts for the LDR

Answer 1

-thylakoid membranes provide large SA to increase no of LDRs that occur
-network of proteins in grana that hold chlorophyll for max light absorption
-grana membranes have ATP synthase channels (for production of ATP) and are selectively permeable (proton gradient established)
-chloroplasts contain DNA and ribosomes so can quickly make proteins needed

Question 2

adaptations of chloroplasts for LIDR

Answer 2

-stroma contains all enzymes needed for LIDR
-stroma fluid is membrane bound, allowing high conc of enzymes to be maintained
-stroma fluid surrounds grana so products of LDR can readily diffuse into stroma
-chloroplasts contain DNA and ribosomes so can quickly make proteins needed

Question 3

process of light dependent reaction (LDR)

Answer 3

1. photoionisation
2. electron carriers & transport chain
3. chemiosmosis
4. NADP to reduced NADP
5. photolysis of light replace electrons

Question 4

process of light independent reaction (LIDR)

Answer 4

1. CO2 diffuses into leaf
2. CO2 reacts w ribulose bisphosphate (RUBP), catalysed by rubisco enzyme, to make 2 mols of glycerate-3-phosphate (GP)
3. reduced NADP used to reduce GP to 2 mols of triose phosphate (TP) using ATP
4. NADP reformed and goes back to LDR
5. 1/6 TP mols used to produce organic mols eg. starch, amino acids, cellulose, lipids
6. 5/6 TP mols used to reform RUBP, using ATP

Question 5

process of phosphorus cycle

Answer 5

-p ions in rocks released into soils by weathering
-p ions taken up by plants and transferred to consumers during feeding
-p ions in waste products and dead organisms released into soil during decomposition by saprobionts
-p ions can be taken up and used again by producers or trapped in sediments that turn into sedimentary rock over long periods of time

Question 6

4 stages of nitrogen cycle (brief)

Answer 6

1. nitrogen fixation
2. ammonification
3. nitrification
4. denitrification

Question 7

what happens during nitrogen fixation

Answer 7

-nitrogen fixing bacteria convert n gas into ammonia, which forms ammonium ions that can be used in plants

Question 8

what happens during ammonification

Answer 8

-organic material in waste products and dead organisms is broken down by saprobionts to release ammonium ions into soil

Question 9

what happens during nitrification

Answer 9

-ammonium ions in soil are converted into NITRITES (by nitrifying bacteria) and then into NITRATES that can be used by plants
-nitrifying bacteria need oxygen

Question 10

what happens during denitrification

Answer 10

-when soils become waterlogged and have low oxygen conc, there is an increase in anaerobic denitrifying bacteria
-denitrifying bacteria convert soil nitrates into gaseous nitrogen

Question 11

what are saprobionts

Answer 11

-organisms (such as bacteria and fungi) that decompose organic matter to release nutrients that would otherwise be locked up as complex molecules that cannot be recycled

Question 12

what is mycorrhizae

Answer 12

-fungi that form a network of filaments around plant roots that increase the SA of plant roots for absorption of water and minerals
-can also form connections between different plants to transport minerals from an area of surplus to an area of deficit.
-type of mutualistic fungi

Question 13

what is biomass

Answer 13

-total mass of living material in a specific area at a given time