Key term
Edexcel GCSE Combined Science Biology 1SC0
Key Concepts in Biology
Topic overviewEukaryotic and prokaryotic cellsSpecialised cells and their adaptationsMicroscopes and magnification calculationsSize, scale and units in cell biologyEnzyme action and denaturationFactors affecting enzyme activityEnzymes in synthesis and digestion, and rate calculationsDiffusion, osmosis and active transportOsmosis in potatoes and percentage change in mass
Cells and Control
Genetics
Topic overviewMeiosis and the formation of gametesDNA structure, genes and the genomeExtracting DNA from fruitAlleles, genotype and phenotypeMonohybrid crosses and sex determinationProbability and ratios from genetic crossesCauses of variation: genes and environmentThe Human Genome ProjectGenetic variation and the effects of mutation
Natural Selection and Genetic Modification
Health, Disease and the Development of Medicines
Topic overviewHealth, disease and susceptibilityPathogens and common infectionsHow pathogens spread, and the virus life cycleSexually transmitted infectionsPhysical barriers and chemical defencesThe immune system, immunisation and herd immunityAntibiotics and developing new medicinesLifestyle factors and non-communicable diseaseTreatments for cardiovascular disease
Plant Structures and Their Functions
Animal Coordination, Control and Homeostasis
Exchange and Transport in Animals
Topic overviewWhy multicellular organisms need exchange surfacesAlveoli and gas exchangeThe blood and its componentsArteries, veins and capillariesThe heart and the circulatory systemCellular respiration as an exothermic reactionAerobic and anaerobic respiration comparedInvestigating the rate of respirationCardiac output, stroke volume and heart rate
Ecosystems and Material Cycles
Key Concepts in Biology
Enzyme action and denaturation
- 3 things to know
- Papers 1 and 2
Overview
Enzymes as biological catalysts, the active site and substrate, specificity and the lock and key model, lowering the energy needed to start a reaction, and how high temperature and extreme pH permanently denature an enzyme so its substrate no longer fits.
What you need to know
Answer each one before you reveal it.
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Key term
What is meant by the substrate of an enzyme?
Key term
Explain why each enzyme will only work on one type of substrate.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is an enzyme?
Model answer
An enzyme is a protein that acts as a biological catalyst, speeding up a reaction in a living organism without being used up.
- 2
What is the active site of an enzyme?
Model answer
It is the small pocket on the enzyme's surface where the substrate binds and the reaction takes place.
- 3
What is meant by the substrate of an enzyme?
Model answer
The substrate is the molecule that the enzyme acts on and changes into products.
- 4
Explain why each enzyme will only work on one type of substrate.
Model answer
The shape of the active site is complementary to only one substrate shape, so no other molecule can fit into it.
- 5
Why is the mechanism of enzyme action described as a lock and key model?
Model answer
Only one substrate fits the active site, in the same way that only one key fits a particular lock.
- 6
Explain how an enzyme speeds up a reaction.
Model answer
It lowers the amount of energy needed for the reaction to start, so the reaction proceeds quickly at the low temperatures found in living things.
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