Key term
OCR GCSE Biology A J247
Cell Level Systems
Topic overviewMicroscopy, and sub-cellular structuresDNA structure: polymer, double helix and nucleotidesEnzyme action, and investigating enzymesCellular respiration as an exothermic processAerobic and anaerobic respiration comparedSynthesis and breakdown of carbohydrates, proteins and lipidsPhotosynthesis: producers and the processPhotosynthesis as endothermic, and investigating itLimiting factors in photosynthesis
Community Level Systems
Genes, Inheritance and Selection
Topic overviewGenetic terms, and the genomeGenome, environment and mutationsAsexual and sexual reproduction comparedHaploid, diploid and meiosisSingle gene inheritance and Punnett squaresSex determination, multiple genes and Mendel's workVariation within a population, and classificationNatural selection and evolutionEvidence for evolution, and the work of Darwin and Wallace
Global Challenges
Topic overviewField investigations, and human impact on ecosystemsMaintaining biodiversity, monitoring conservation and ecotourismFood security, agricultural and biotechnological solutionsSelective breeding and genetic engineeringHealth, disease, and types of diseaseInteractions between diseases, and how they spreadReducing the spread of disease, and named examplesPhysical and chemical plant defencesWhite blood cells, antibodies and plateletsNon-specific defences and the immune systemVaccines, medicines and aseptic techniqueDeveloping new medicines, and non-communicable diseaseTreating cardiovascular disease, and lifestyle factorsCancer, and the use of stem cells in medicineGene technology in medicine, and the human genome
Organism Level Systems
Topic overviewThe nervous system and coordinated responsesThe reflex arcThe eye and its common defectsThe structure and function of the brainHormones and the endocrine glandsHormones in reproduction and the menstrual cycleMethods of contraceptionTropisms, auxin and the roles of plant hormonesHomeostasis, and the skin in temperature controlInsulin and the control of blood glucoseType 1 and type 2 diabetesOsmotic changes in body fluids, and the kidneysKidney structure and the parts of the tubule
Scaling Up
Topic overviewDiffusion, osmosis and active transportMitosis, the cell cycle and cell differentiationStem cells in animals and meristems in plantsSurface area to volume ratio and exchange surfacesThe circulatory system, the heart and blood vesselsRed blood cells and plasmaRoot hair cells, transpiration and translocationXylem and phloemFactors affecting water uptake, and the potometer
Cell Level Systems
Limiting factors in photosynthesis
- 3 things to know
- Paper 1
Overview
How light intensity, carbon dioxide concentration and temperature each change the rate of photosynthesis, why the rate stops rising in very bright light and falls when too hot, why growers heat, light and burn fuel in greenhouses, and slow photosynthesis on a cold bright day.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why does the rate of photosynthesis stop rising at very high light intensity?
Key term
What is the effect of increasing carbon dioxide concentration on the rate of photosynthesis?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What happens to the rate of photosynthesis as light intensity is increased from darkness?
Model answer
The rate increases, because more light energy is available to drive the reaction.
- 2
Why does the rate of photosynthesis stop rising at very high light intensity?
Model answer
Something else, such as the temperature or the carbon dioxide supply, is then holding the rate back.
- 3
What is the effect of increasing carbon dioxide concentration on the rate of photosynthesis?
Model answer
The rate rises, because more carbon dioxide is available as a reactant, until another factor holds it back.
- 4
Why does raising the temperature towards the optimum increase the rate of photosynthesis?
Model answer
The enzymes controlling the reaction work faster as the molecules move more quickly.
- 5
Why does the rate of photosynthesis fall sharply at very high temperatures?
Model answer
The enzymes controlling the reaction are denatured, so it slows down and stops.
- 6
Why is a greenhouse often heated and lit in winter?
Model answer
Raising both temperature and light intensity increases the rate of photosynthesis, so the crop grows faster.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
Every question in Cell Level Systems, 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.
Or £46 a year, about £3.83 a month. Cancel anytime.