@vindeez1811

A:
At C, T rises beyond optimum T of the enzyme.
Enzymes will start to denature (irreversibly) and lose the shape of its active site.
Active site of enzymes will no longer me complementary to the substrate.
Hence unable to form enzyme-substrate complexes to produce products.
Leading to decrease in rate of reaction. (hence the shape of the graph is sloping downwards)

@LiamKIPROP-x8f

At area C the temperature rises beyond the optimum temperature needed so the enzyme starts to denature. The enzyme is not able to bind to the substrate at this point leading to the drop in the rate of reaction

@Silly_LouLou

The shape of the graph at area C shows that the reactions have stopped due to the temperature rising above the optimum level at which the enzyme catalyses reactions faster, and as a result, the active site changes shape, and will no longer bond with other substrates, therefore being called "denatured."

@gnyani555

The rate of reaction decreases as enzymes above the optimum the temperature are denatured so the substrate can no longer bind to the active site

@zaina-i6x

At area C, the rate of reaction decreases. the temperature rises above optimum temperature of the enzyme, therefore the enzyme becomes denatured meaning its active site has lost its specific shape and wont be complementary to the substrate, this means that there will no longer be a temporary enzyme-substrate complex and the enzyme wont be able to catalyse the reaction anymore.

@Issssshhhhh

You’re life saver! TYSMMM

@MaxcellTV_YT

My answer is when the temperature is increasing until 37C, the enzyme-catalysed reaction will increase. When the temperature is increasing more than 37C, the enzyme-catalysed reaction will decrease due to the high temperature.

@anabmohamud9600

Thanks a lot for this

@Aviationworld-yx7by

Thank you. I have my cambridge igcse biology exam in 2 months

@vendaval682

The shape of the graph at area C will decrease as enzymes will denature at a high temperature, and as a result, substrate molecules will no longer be able to bind to active sites of enzymes.

@denzelsetiawan7168

this is amazing also you look exactly like my biology teacher

@xpoint849

Only the shape of the graph at area c is asked. Sir, why do u want to say about the binding of the substrate molecule? 
Just say it reduce sharply as the enzyme denature as the temperature increases thus, reducing the rate of reaction. 

Pls correct me if I am wrong sir🙏🏻

@osazuwaesther-ku8uk

Thanks 😊

@Rzs.247

Your answer is out of bound so it won’t really register on the igcse checking page. So your answer would be incomplete

@adisalian

Is it also true that whatver is written beyond the lines will not be scanned by the examiner,  thus making us lose a mark?

@roronoazoro8626

will i get a mark for mentioning the optimum temperature?