BRAINCAKEPlant structures and their functions
Revision notes for Plant structures and their functions in Edexcel Combined Science (1SC0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Photosynthetic organisms as producersPlants and algae can make their own food by photosynthesis, so they are called producers.
- The photosynthesis reactionPhotosynthesis happens in plants and algae.
- Limiting factors of photosynthesisThe rate of photosynthesis is how fast a plant makes glucose.
- Interactions between limiting factorsMore than one factor affects photosynthesis at the same time.
- Core practical: light intensity and photosynthesisThis practical investigates how light intensity affects the rate of photosynthesis, using an aquatic plant such as Canadian pondweed.
- Light intensity, distance and the inverse square lawWhen the rate of photosynthesis is limited by light, the rate is directly proportional to the light intensity.
- Root hair cells: adaptations for absorptionRoot hair cells are found near the tips of roots.
- Xylem and phloem: structure and functionXylem vessels carry water and mineral ions from the roots to the leaves.
- Transpiration and the stomataTranspiration is the loss of water vapour from the leaves of a plant.
- Translocation of sucroseTranslocation is the movement of sucrose around a plant.
- Environmental factors and water uptakeMost of the water a plant takes up is lost by transpiration, so anything that changes the rate of transpiration changes the rate of water uptake.
- Calculating the rate of transpirationThe rate of transpiration is the volume of water lost, or taken up, in a certain time.
- Displacement reactions of the halogensThe reactivity of the halogens decreases as you go down group 7.
- Why the noble gases are inertThe noble gases are the elements in group 0: helium, neon, argon, krypton, xenon and radon.
- Uses of the noble gasesThe uses of the noble gases depend on their properties.
- Patterns in the noble gasesThe physical properties of the noble gases change in a regular way down group 0.
- How the atomic model has changedScientists change a model when new evidence does not fit it.
- Beta-minus decaySome nuclei are unstable because they have too many neutrons.
- Beta plus decaySome unstable nuclei have too many protons for the number of neutrons they contain.
- Effects of radioactive decay on nucleiThe two numbers that describe a nucleus are its atomic (proton) number and its mass (nucleon) number.
- Gamma radiation and nuclear rearrangementAfter a nucleus has emitted an alpha or beta particle, the new nucleus often has more energy than it needs.
- Balancing nuclear equationsIn a nuclear equation, each particle is written with its mass number at the top and its atomic number at the bottom.
- How the activity of a source decreasesThe activity of a radioactive source is the number of nuclei that decay each second.
- The becquerel as the unit of activityActivity tells us how many nuclei in a radioactive source decay every second.
- Half-lifeThe nuclei of a radioactive isotope are unstable and decay.
- Random decay and predicting half-lifeRadioactive decay is random.
- Half-life calculations and graphsTo work out how the activity changes, first find the number of half-lives.
- Dangers of ionising radiationAlpha particles, beta particles and gamma rays are all ionising radiation.
- Safety precautions and medical exposureRadiation is used in medicine, for example in X-rays, scans with radioactive tracers and radiotherapy.
- Contamination and irradiationIrradiation is exposure to radiation from a source outside the body.