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
The Nervous System and the Identification and Consequences of Damage
Reflexes, reaction times and their investigation
- 3 things to know
- Components 01, 02 and 03
Overview
Recall questions on the reflex arc, reflexes and reactions, the blink, iris and plantar reflexes and the Babinski sign, measuring reaction time with a ruler drop test and its limits, and using Student's t-test with its degrees of freedom to compare groups.
What you need to know
Answer each one before you reveal it.
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Key term
List, in order, the five components of a reflex arc.
Key term
Give two ways in which a reaction differs from a reflex, other than speed.
Questions from this subtopic
Each one with the model answer underneath.
- 1
List, in order, the five components of a reflex arc.
Model answer
The components are the receptor, the sensory neurone, the relay neurone in the central nervous system, the motor neurone and the effector.
- 2
Give two ways in which a reaction differs from a reflex, other than speed.
Model answer
A reaction is voluntary and involves conscious processing in the cerebrum, and it can be improved with practice, whereas a reflex is involuntary and cannot be learned.
- 3
How is the blink reflex elicited, and what response is seen?
Model answer
Lightly touching the cornea, or a sudden bright light or loud noise, causes both eyelids to close rapidly.
- 4
Why is the blink reflex used when assessing an unconscious patient?
Model answer
The reflex pathway passes through the brainstem, so its absence indicates deep unconsciousness or damage to the brainstem.
- 5
Describe the normal iris reflex when a light is shone into one eye.
Model answer
The circular muscles of the iris contract and the radial muscles relax, so the pupil constricts, and the pupil of the other eye constricts as well.
- 6
What does a fixed, dilated pupil that does not respond to light suggest in a head injury patient?
Model answer
It suggests severe brain injury with raised pressure inside the skull compressing the nerve supply to the iris, and is a serious warning sign.
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