COAS Biology 2 Teacher Resources Original material © Cambridge University Press 2009 1
9 Practical guidance
These practicals are included to give ideas for activities to support OCR A-level Biology
Units F215 [5.2.1: Cloning in plants and animals] and F216: Practical skills in Biology 2.
The practicals chosen relate closely to the learning outcomes, and may be used to develop
students’ practical skills in preparation for practical assessment.
However, they are not intended to form a complete practical course.
Safety
Although great care has been taken in checking the accuracy of the information provided,
Cambridge University Press shall not be responsible for any errors, omissions or inaccuracies.
Teachers and technicians should always follow their school and departmental safety policies.
You must ensure that you consult your employer’s model risk assessments and modify them as appropriate to meet local circumstances before starting any practical work. Risk assessments will depend on your own skills and experience, and the facilities available to you. Everyone is responsible for his or her own safety and for the safety of others.
The practicals should be carried out by teachers themselves before they are presented to students. Additional notes relating to each activity in this chapter are given below. These include, where appropriate, references to Hazcards and the CLEAPSS Laboratory Handbook, both of which provide model risk assessments and are available to CLEAPSS members.
The notes given below also contain some background information and advice, but in no way should they be regarded as risk assessments. Teachers and technicians are advised to read the relevant sections of the CLEAPSS Laboratory Handbook for further advice and guidance. The Handbook includes a great deal of useful background information and is an excellent source of references.
Practical: Cloning cauliflower
Hazcards: 40A, 89 Laboratory Handbook: 15.2, 15.14
This practical is a modified version of ‘Cloned cauliflower’ in Practical Biotechnology: a guide for schools and colleges published by the National Centre for Biotechnology Education (NCBE) (1993).
The growth medium contains Murashige and Skoog (M&S) medium, sucrose, kinetin and agar.
It is possible to make up the medium in situ, but the recipe is difficult and time-consuming.
(See the website below for the NCBE protocol.) It is easier to purchase the medium ready made; the ‘meristem culture medium’ available from Philip Harris Ltd is appropriate for cloning cauliflower.
Following the instructions supplied, heat the growth medium mixture in distilled water to about 95°C to dissolve the agar, cool to about 50–60 °C and dispense into test tubes, placing about 2–3 cm3 in each tube. Plug the tubes with non-absorbent cotton wool and cap them with aluminium foil. Autoclave at 121 °C for 15 minutes in a pressure cooker. When cool, the tubes may be refrigerated until they are needed.
The bleach solution used to surface-sterilise the explants is a 1% solution of sodium chlorate(I) with added detergent. See Table 15.16 in Section 15.14 of the CLEAPSS Laboratory Handbook.
This section also gives general guidance on tissue culture.
To avoid contamination, it is important to avoid all draughts during the investigation.
To sterilise the forceps, place them in a boiling tube, plug with cotton wool and then autoclave. Further information on aseptic techniques may be found in Section 15.2 of the Laboratory Handbook.
Growth of plantlets should be visible after 10 days. If contamination has occurred, this should also be visible by this time. Failure of anything to grow usually means that the bleach has not been rinsed from the plant tissue.
Website for NCBE protocol:
www.ncbe.reading.ac.uk/NCBE/PROTOCOLS/PRACBIOTECH/cauliflower.html
COAS Biology 2 Teacher Resources Original material © Cambridge University Press 2009 1