Biology / IGCSE
Carbohydrates and lipids provide energy stores and structural materials; proteins have varied roles including transport and catalysis.
Carbohydrates and lipids provide energy stores and structural materials; proteins have varied roles including transport and catalysis. DNA carries inherited information, and water is a solvent for many reactions.
An enzyme’s active site binds suitable substrates and lowers activation energy. Temperature can increase reaction rate until structural changes reduce activity; a low rate does not by itself establish denaturation. Food-test results are chemical evidence, not dietary diagnoses.
An enzyme forms 24 mg of product in 6 minutes. Find mean rate.
Divide product formed by elapsed time: 24/6=4 mg per minute.
Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.
No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.
Biological catalyst
Enzymes accelerate reactions without being consumed in their overall catalytic cycle.
4 mg/min
Divide product formed by elapsed time: 24/6=4 mg per minute.
No
Cooling commonly slows reactions without destroying the active-site structure; denaturation is a different change.