Help in an Alevel bio question on the effects of global warming ?Please?

Here's a link to the paper https://pmt.physicsandmathstutor.com/download/Biology/A-level/Past-Papers/Edexcel-IAL/Unit-4/June%202015%20QP%20-%20Unit%204%20Edexcel%20Biology%20A-level.pdf
And here's a link to the Marking scheme
https://pmt.physicsandmathstutor.com/download/Biology/A-level/Past-Papers/Edexcel-IAL/Unit-4/June%202015%20MS%20-%20Unit%204%20Edexcel%20Biology%20A-level.pdf

Q7bi and bii

I'm not sure I understand why the pH of the oceans would .
and for 7bii I don't understand marking points 4 and 5

b i) - rising CO2 levels in the atmosphere are causing the oceans to absorb more CO2. This results in a fall in the pH, and is having major impacts on marine ecosystems, including coral bleaching, and changes in marine plants and algae populations

b ii) climate warming is affecting the geographic range, survival and phenology (timing of flowering, leafburst etc) of plants, and this will have a knock on effect on the animals that depend on them. Examples include the desertification of some habitats, as they become warmer and drier, meaning green plants with higher water needs die off, leaving less plant cover for animals to forage and find food in. Similarly they might be left with less vegetation to shelter from high or low temperatures, or hide/escape from predators, nest in etc. Overall result = higher mortality, higher predation, and lower breeding success = falling numbers

Hello , can I ask a question please ? https://pmt.physicsandmathstutor.com/download/Biology/A-level/Past-Papers/Edexcel-IAL/Unit-4/January%202016%20(IAL)%20QP%20-%20Unit%204%20Edexcel%20Biology%20A-level.pdf
What is the difference between parts (a) and c(ii) ? Here's a link to the mark scheme
https://pmt.physicsandmathstutor.com/download/Biology/A-level/Past-Papers/Edexcel-IAL/Unit-4/January%202016%20(IAL)%20MS%20-%20Unit%204%20Edexcel%20Biology%20A-level.pdf

Which question number?

Ah sorry , Q4

The way I interpret this question is that in a), you are being asked simply to describe what you see on the graph (so eg- rapid rise in temp due to decomp up to day 10, followed by gradual fall etc). Part c ii) comes after you've been asked to intepret the graph by adding in some knowledge of the biological process concerned, so here they want you to suggest the mechanism that results in the shape of the graph you have described. Does that make sense?