Key term
OCR A-Level Biology B H422
The Developing Cell: Cell Division and Cell Differentiation
The Developing Individual: Meiosis, Growth and Development
The Development of Species: Evolution and Classification
Cells and Microscopy
Topic overviewMicroscopy and the cell theoryBlood smears, staining and microscope drawingsBlood cells and their structureMagnification and measuring cellsHaemocytometer cell counts and dilutionsFlow cytometry in blood analysisUltrastructure of the animal cellPlant and prokaryotic cellsMembrane lipids and the fluid mosaic modelMovement of molecules across membranesThe roles of membranes and the secretion of proteins
Water and Its Importance in Plants and Animals
Proteins and Enzymes
Nucleic Acids
Patterns of Inheritance
Population Genetics and Epigenetics
Gene Technologies
The Principles and Importance of Homeostasis
The Hormonal Control of Blood Glucose and the Management of Diabetes
Kidney Functions and Malfunctions
Topic overviewExcretion and the gross structure of the kidneyThe nephron: ultrafiltration and selective reabsorptionInvestigating the composition of urine, plasma and filtrateOsmoregulation and the action of ADHThe kidney as an endocrine gland and kidney failureDialysis, transplantation and the future of transplant surgery
The Cellular Basis of Cancer and Treatment
Respiratory Diseases and Treatment
Cellular Respiration
Metabolism and Exercise
Topic overviewThe consequences of exercise on the bodyAerobic fitness and VO₂ maxTraining, F.I.T.T. factors and investigating fitnessEnhancing athletic performanceHaemoglobin and the transport of oxygenOxygen dissociation curves of different respiratory pigmentsOxygen deficit and oxygen debtThe structure of skeletal muscleThe sliding filament theory of muscle contraction
Pathogenic Microorganisms
The Immune System
Controlling Communicable Diseases
Photosynthesis, Food Production and Management of the Environment
Topic overviewChloroplast ultrastructure and photosynthetic pigmentsThe light-dependent stage of photosynthesisThe Calvin cycleInvestigating the factors affecting photosynthesisThe Hill reaction and DCPIPUsing TP and GP to build carbohydrates, lipids and amino acidsThe compensation point and crop productionMicroorganisms, the nitrogen cycle and biosensorsBiomass transfer and efficiency in food productionRuminants in the human food chainFarms as ecosystems and the conflict with conservationDeflected succession and measuring biodiversity
The Impact of Population Increase
Planning and Implementing Practical Work
Analysing and Evaluating Practical Results
Practical Skills, Apparatus and Techniques
Topic overviewInvestigative approaches and working safelyFollowing instructions, recording and presenting dataResearch, referencing and processing data with softwareMeasuring mass, volume, time, temperature, length and pHColorimeters and potometersLaboratory glassware and serial dilutionsLight microscopy, graticules and biological drawingQualitative reagents for biological moleculesChromatography and electrophoresisAseptic technique and dissectionWhole-organism responses, fieldwork sampling and data logging
Fertility and Assisted Reproduction
The Effects of Ageing on the Reproductive System
Plant Reproduction
The Nervous System and the Identification and Consequences of Damage
Topic overviewOrganisation of the nervous system and nervous tissueThe structure and function of the human brainThe structure of motor, sensory and relay neuronesResting potential and the action potentialSynapses and the integration of responsesReflexes, reaction times and their investigationBrain scans and the consequences of nervous system damageDrugs, brain function and dependency
Monitoring Visual Function
The Effect of Ageing on the Nervous System
The Heart and Monitoring Heart Function
Transport Systems in Mammals
Gas Exchange in Mammals and Plants
Photosynthesis, Food Production and Management of the Environment
The Hill reaction and DCPIP
- 3 things to know
- Components 01, 02 and 03
Overview
Recall questions on what isolated chloroplasts demonstrated, the dye's colour change, why the extraction medium is ice-cold, isotonic and buffered, and the controls a valid experiment needs.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Which naturally occurring molecule is DCPIP substituting for in the Hill reaction?
Key term
Describe how chloroplasts are extracted from leaf tissue for use in the Hill reaction.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What did the Hill reaction demonstrate about isolated chloroplasts?
Model answer
It showed that illuminated chloroplasts can reduce an added electron acceptor and release oxygen even when no carbon dioxide is present.
- 2
What does the abbreviation DCPIP stand for?
Model answer
DCPIP stands for 2,6-dichlorophenolindophenol.
- 3
What colour change does DCPIP show as it is reduced?
Model answer
It changes from blue to colourless.
- 4
Which naturally occurring molecule is DCPIP substituting for in the Hill reaction?
Model answer
DCPIP acts as an artificial electron acceptor in place of NADP.
- 5
Describe how chloroplasts are extracted from leaf tissue for use in the Hill reaction.
Model answer
Leaves are ground in an ice-cold buffered isotonic solution, the mixture is filtered through muslin to remove debris, and the filtrate is centrifuged to pellet the chloroplasts.
- 6
Why must the chloroplast extraction medium be ice-cold?
Model answer
The low temperature slows the enzymes released from damaged cells, so the chloroplasts are not broken down before they can be used.
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