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
Transport Systems in Mammals
- 4 subtopics
- 12 things to know
- Components 01, 02 and 03
What Transport Systems in Mammals covers
Transport Systems in Mammals is examined in all three written papers — the specification states that Components 01, 02 and 03 can each assess content from any of the five modules, so nothing is confined to one paper. It covers the closed double circulatory system, blood vessels and their microscopic structure, tissue fluid and capillary exchange and measuring and interpreting blood pressure.
Where it is assessed
Components 01, 02 and 03
Every module can be assessed on any of the three papers.
Check the OCR specification ↗The 4 subtopics
Each one has its own page.
- The closed double circulatory systemRecall questions on closed and double circulatory systems, the pulmonary and systemic circuits, why pulmonary blood pressure is lower and its typical values, and why a double circulation supports the high metabolic rate of a mammal.Open →
- Blood vessels and their microscopic structureRecall questions on the tunica intima, media and externa of arteries, elastic tissue and smooth muscle in arteries and arterioles, how capillaries suit exchange and why flow through them is slow, venules and veins with their valves, and telling vessels apart in stained transverse sections.Open →
- Tissue fluid and capillary exchangeRecall questions on tissue fluid and what it lacks, hydrostatic and oncotic pressure at the arteriolar and venule ends of a capillary bed, why each changes or stays constant, the lymphatic system, and oedema caused by protein deficiency or high blood pressure.Open →
- Measuring and interpreting blood pressureRecall questions on systolic and diastolic pressure in mmHg, measuring blood pressure with manual and electronic sphygmomanometers and their advantages, reliable readings, hypertension and its consequences for the arteries and heart, hypotension, and calculating pulse pressure.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Name the three layers of an artery wall, describe the innermost layer, and say which vessel controls blood distribution.
Evaluation
Why can a single blood pressure reading mislead, what can untreated hypertension lead to, and what is the pulse pressure for a reading of 118/76 mmHg?
Key term
Name two components of the blood in a capillary that are absent from tissue fluid.
Key term
What is meant by a closed circulatory system?
Key term
What are the three layers found in the wall of an artery?
Key term
Why does hydrostatic pressure fall along the length of a capillary?
Key term
State the unit in which blood pressure is conventionally recorded.
Key term
Name the two circuits of the mammalian circulation and state what each supplies.
Key term
What is the tunica intima made of?
Key term
Which system returns excess tissue fluid to the blood?
Key term
What is heard when the cuff pressure of a manual sphygmomanometer first falls below the systolic pressure?
Take Transport Systems in Mammals further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Hydrostatic pressure vs Oncotic pressure
Hydrostatic pressure: the outward force the blood exerts against the capillary wall, generated by the pumping of the heart, which drives fluid out. Oncotic pressure: the inward force produced by the plasma proteins lowering the water potential of the blood, which draws water back in by osmosis.
Tissue fluid vs Plasma
Tissue fluid: the liquid bathing the cells of the body, formed from what has been forced out through the capillary wall and holding no cells or large proteins. Plasma: the liquid part of the blood, which carries the dissolved substances and also the proteins too large to leave a capillary.
Systolic pressure vs Diastolic pressure
Systolic pressure: the highest arterial reading, reached as the left ventricle contracts and forces blood into the aorta. Diastolic pressure: the lowest arterial reading, reached while the ventricles are relaxed and refilling.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by a closed circulatory system?
Model answer
The blood is held within blood vessels at all times and does not flow freely through the body cavity.
- 2
What is meant by a double circulatory system?
Model answer
Blood passes through the heart twice for each complete circuit of the body, once on the pulmonary circuit and once on the systemic circuit.
- 3
Name the two circuits of the mammalian circulation and state what each supplies.
Model answer
The pulmonary circuit carries blood to and from the lungs, and the systemic circuit carries blood to and from the rest of the body.
- 4
Why is blood pressure in the pulmonary circulation much lower than in the systemic circulation?
Model answer
High pressure would damage the very thin alveolar capillaries and force fluid into the alveoli, so the right ventricle generates only a fraction of the pressure produced by the left.
- 5
Give a typical value for systemic arterial blood pressure and for pulmonary arterial blood pressure in a healthy adult.
Model answer
Systemic arterial pressure is about 120/80 mmHg and pulmonary arterial pressure is about 25/10 mmHg.
- 6
Apart from protecting the capillaries, give one advantage of the low pressure in the pulmonary circulation.
Model answer
Blood moves more slowly through the lung capillaries, so there is more time for gas exchange to go to completion.
What is inside Levo
Six ways to work the same material.
Transport Systems in Mammals revision questions
- What does Transport Systems in Mammals cover in OCR A-Level Biology B?
- 4 subtopics: the closed double circulatory system, blood vessels and their microscopic structure, tissue fluid and capillary exchange and measuring and interpreting blood pressure. Each one has its own page with questions and model answers.
- How is Transport Systems in Mammals organised?
- By the OCR H422 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Transport Systems in Mammals, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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