GCSE Biology: Practicals
Biology is clearly a practical science, students confirm understanding and apply knowledge through practical activity.
Practicals are by their very nature active, they stimulate interest and motivate students.
In GCSE Biology from September 2016 there are required practical activities that students must complete and whilst these will not contribute marks to a final grade, schools will be required to confirm that they have provided opportunities for students to undertake these practical activities. Teachers should consult their Awarding Body specifications to confirm the exact practicals that are required.
Ideas for protocols and investigations that will meet the requirements of some of these specified practicals are provided in the following resouce list, along with other investigations that will support the development of practical skills.
A-level set practicals: dissection and microscopy of a plant stem
As the title suggests this practical is at the level of KS5 , however it would be possible to use it for GCSE Biology with some slight modifications and with teacher and technician support.
The questions that accompany the practical do not need to be used.
The practical provides a quick and eye-catching way to teach about the vascular tissue in plants and the structure of plant stems. It provides students with the opportunity to develop (and demonstrate) their scientific drawing skills as well as their use of a light microscope and eye-piece graticule (not essential for GCSE students).
The viewed specimen clearly shows the location of vascular bundles and the xylem, phloem and sclerenchyma or collenchyma. The use of the stain toluidine blue provides a colour difference between lignified and non-lignified cell walls, clearly highlighting specialised cells and one adaptation they have.
The other possible use of this resource would be to use the protocol for a teacher led demonstration with images displayed onto the whiteboard
Ecological Survey
This resource describes a series of investigations to measure the distribution of plants and animals, including a range of sampling techniques and the measurement of abiotic factors such as soil conditions, temperature and light intensity.
These activities are generally suitable for surveying in the school grounds but they can also be applied to other locations.
There are two protocols provided-one for Key Stage Five and one for Key Stage Four. These are provided as 'for teachers'. The relevant sections for students just need to be cut and pasted to the particular investigation that is being undertaken.
The protocols do provide clear, easy to follow instructions for the various sampling techniques and investigations into abiotic factors
Designing Investigations
This PowerPoint presentation is aimed at teachers but could easily be adapted for students. It gives a range of possible ideas for ecological investigations on heathland.
Students could be shown the possible investigation titles (slides four and five). Then working in pairs, they could be asked to come up with a protocol for carrying out a particular investigation. they would need to include a step by step procedure, an equipment list, risk assessment and any important notes/considerations.
Pairs could then swap protocols and be taken to an appropriate location to undertake a particular investigation. Students would be able to come up with results and conclusions, but would also be able to comment on the clarity/suitability/reliability/accuracy of the protocol they were provided with by their peers.
investigating the effect of "pH" on amylase activity
This is a standard protocol for this investigation, which is a required practical activity for GCSE Biology students. The Nuffield Foundation link here provides a student sheet with questions and answers (remember to remove the answer sheet before handing out to students.
Having completed the practical in class, the questions would provide a useful homework for students.
Observation of cells in a sample of blood
There are two investigations noted here-staining blood to observe the variety of cells and investigating the osmotic balance of red blood cells, both investigations can be carried out seperately, however the suggestion is that carrying out both in the same session will make it easier to deal with contaminated lancets and slides.
These investigations do involve taking samples of students' blood . Any work with blood is safer if students are handling their own blood, schools may have policies relating to the use of student samples, for example requirement to obtain parental permission.
It is the responsibility of the school to inform teachers about requirements or forbidden procedures, remember to complete a full risk asssessment and ensure appropriate procedures are in place for safe disposal of contaminated items.
Biology experiments
This is a collection of standard biology experiments, many of which are suitable for GCSE Biology. Each experiment contains: a protocol which can be downloaded as a word file, there is then a discussion document (set of student questions), a word document containing the answers to these questions and a set of teachers notes about the experiment, including equipment requirements and set up procedures.
Assessing skin sensitivity-touch discrimination
This procedure provides students with the opportunity to explore the subtlety of information that receptors in the skin can detect. It is a good investigation with class results collected onto a provided spreadsheet that will support students maths skills.
The investigation also includes some useful web links related to this practical activity.
As with all such investigations, where students are in effect "test subjects" it is important that health and safety is of paramount importance and that all ethical considerations are taken into account. Not all students will be comfortable with the idea of being touched by another student with a cocktail stick. An alternative approach would be to have only appropriate adults-teachers, assisstant, technician etc.. as the testers with cocktail sticks, with students as test subjects and recorders of information.
The protocol for this investgation includes a consent form for students to sign which states that they understand the procedure they have agreed to be involved in.
Assessing skin sensitivity-temperature receptors
The purpose of this practical is to find out about the temperature receptors in human skin. The investigation requires students to put their hands in water of different temperatures and describe how it feels. It is a quick and simple practical, but one which can generate a good discussion in relation to how receptors work and why differences are seen between individuals.
As with all such investigations, where students are in effect "test subjects" it is important that health and safety is of paramount importance and that all ethical considerations are taken into account
Water Potential During Ripening and Storage
This practical sees cylinders of a vegetable (potato is the easiest to use) placed in different sucrose solutions. Depending on the concentration of the solution, the potato cylinder either gains or losses weight due to the movement of water in or out of the potato cells.
It is best to calculate the % change in weight for each potato cylinder. Plot this data on a graph. Loss in weight (negative change) is below the x-axis and a gain in weight above it.
Similar results can be obtained by measuring the change in length of the potato cylinder. This is then related to the cells either shrinking or expanding depending on water movements.
tudents may need to be prompted to realise that any change in weight is due to the movement of water in or out of cells.
Looking at the graph, challenge students to think about the overall direction of water movement in relation to the concentration of the sugar solution. Notes can be added to the graph.
What would they suggest is happening when there is overall no change in weight (where the line crosses the x-axis)?
Using these observations, it is possible to challenge students to come up with a definition of osmosis. You may need to prompt them into including that osmosis requires the presence of a differentially permeable membrane.
Measuring Photosynthesis with Cabomba
One of a series of resources from Science & Plants for Schools (SAPS) investigating key topics in plant biology.
A reliable way to demonstrate photosynthesis in the classroom. When the pond-weed Cabomba is placed in a solution of sodium hydrogen carbonate in the presence of light of appropriate intensity, it will begin to produce bubbles of oxygen-containing gas. These bubbles can be counted and the rate of bubbling can serve as an indication of the rate of photosynthesis.
Cabomba is highly reliable, especially compared to Elodea, which is often used to demonstrate this process.
Silver Award: Squeaky Clean
This set of resources was designed for students to undertake a STEM project as part of their CREST award.
The materials provided however would be useful to provide a context for experiments to investigate the effect of antiseptics and antibiotics on bacterial growth.
It is the practical project where students investigate if hand washing makes hands cleaner and compare the effectiveness of using soap and water with the an alcohol hand gel, that would be the most useful section of this resource pack.
Fungal Inhibition
In this experiment students grow yeast on agar plates and look at the effect on growth of some common anti-fungal treatments, which are available to treat conditions such athlete's foot and thrush.
Antifungal products may be bought from a local pharmacist, for example, Canistan, Daktarin, Diflucan. Several different yeast preparations can be used: Saccharomyces cerevisiae can be taken from a block of fresh yeast or grown up on a slope or agar plate. Phaffia rhodozyma or candida utilis can be grown up on a slope or agar plate.
Investigating Antimicrobials
In this protocol from Science & Plants for Schools (SAPS), students use disc diffusion tests to investigate antibacterial or anti-yeast properties.
A wide range of products, both synthetic and natural, claim to have microbicidal properties. Students can test these claims.
Although designed with post 16 students in mind it would still be possible to use this protocol with GCSE Biology students with some slight modifications, for example some initial steps of the protocol could be performed by a technician
Suggested test substancesin the protocol include:
• disinfectants
• hand washes
• surface cleaners
• garlic or other herbs
• T-tree oil
Tackling Tropisms: Gravitropism and Phototropism
This set of demonstrations into the effects of tropisms on seedlings is both simple and extendable, making it useful across key stages, including for GCSE Biology students.
In this investigation seeds are sown on damp cotton wool in (plastic) Petri dishes which are either flat or stuck vertically to a wall. Students enjoy the dramatic effect of sticking Petri dishes to the wall, and they will have well-grown seedlings within a week, showing the different effects of gravitropism and phototropism
Nuffield practical: Observing effects of exercise on the human body
This is a classic school biology experiment; measuring the effect of exercise on heart rate and recovery time.
Full experimental details are included on the Nuffield website.
This type of activity is useful, but can also be quite personal. Some students may feel uncomfortable taking exercise in front of their peers, especially if they are perceived to be unfit. Similarly, some students may suffer from conditions such as asthma and be sensitive about exercise.
A risk assessment relevant to the class (not just a generic one) is clearly warranted.
The materials include a useful students briefing and consent form. It is wise to issue this the lesson before and have students show it to their parents / guardians and get it signed before the lesson. This does also serve as a good example of how scientists work, in that permission is necessary from participants before any such investigation.
A possible alternative approach would be to use willing volunteers to carry out the exercise and be measured.
The experiment can be enhanced by the use of ICT. If possible, use a data logger with a heart rate monitor and a pulse oximeter. Blood pressure measurements can be taken with inexpensive monitors available from pharmacists or even some supermarkets.
It is useful to take reliable measurements of resting levels before the exercise begins. It is worth taking measurements for 10 to 15 minutes after exercise has stopped. Sometimes it is possible to see a temporary dip below resting levels as the body ‘overshoots’ due to negative feedback.