Zadanie 6, Paper 2, maj 2022, TZ2, Biologia IB HL

(a) The process is translocation OR compounds move from sources to sinks OR the overall transport system can operate in both directions. ✔

Organic compounds such as sucrose are produced in leaves. ✔

Loading can involve active transport or an apoplastic route. ✔

Compounds enter companion cells and/or phloem sieve tubes. ✔

High solute concentration at the source draws in water by osmosis. ✔

This produces pressure that drives sap towards a sink. ✔

Compounds are unloaded, stored or used at the sink. ✔

Lower pressure at the sink maintains a pressure difference OR water returns to xylem. ✔

(b) Both use membrane-bound organelles with specialized structures. ✔

Both use membrane electron transport chains. ✔

Both generate proton gradients OR use chemiosmosis OR use ATP synthase. ✔

Both generate ATP. ✔

Photosynthesis converts light energy into chemical energy; respiration makes energy in organic substrates available through ATP formation. ✔

Photosynthesis occurs in chloroplasts, whereas aerobic respiratory stages occur in mitochondria; glycolysis occurs in cytosol, not the mitochondrial matrix. ✔

Photosynthetic electron transfer reduces NADP, whereas respiratory substrate oxidation reduces NAD or FAD. ✔

Photosynthesis fixes carbon dioxide OR produces carbon compounds; respiration releases carbon dioxide OR breaks down carbon compounds. Give a paired contrast. ✔

Photosynthesis releases oxygen OR splits water; aerobic respiration uses oxygen OR has oxygen as terminal electron acceptor. Mechanistic elaboration is optional. ✔

Quality: the response is clear on first reading, concise and contains little repetition or irrelevant material. ✔

Part (a):any 4,maximum 4. Part (b):any 7 valid paired comparisons,maximum 7; include both similarities and differences to answer the command. The source error placing glycolysis in the matrix is corrected. Award 1 independent communication-quality mark. Total 12. Original6(c), integrated starch digestion, omitted.