Grade XII Practical will be conducted according to the practical syllabus prescribed by CBSE for Class XII Biology Practical Examination in its website. The complete practical session will be of three hours long, which will be divided into following three parts:
- Written work
- Lab Work
- Viva Voce
CBSE Class XII Biology (044) Practical Examination Scheme (30 Marks). Marks Distribution
| Headings | Marks |
| One Major Experiment (Exp. 5) | 5 |
| One Minor Experiment (Exp. 2 & 3) | 4 |
| Slide Preparation (Exp. 1 & 4) | 5 |
| Spotting | 7 |
| Practical Record + Viva Voce | 4 |
| Investigatory Project + Project Record + Viva | 5 |
| Total | 30 |
Written Work
In Written work a candidate has to write
- One major experiment allotted to him/her on the day of the practical examination.
- One minor experiment allotted to him/her on the day of the practical examination.
- One slide preparation allotted to him/her on the day of the practical examination.
- Five points upon seven different spots of laboratory museum specimens given on the day of the practical examination.
The following points should be kept in mind while writing a practical in board practical examination.
- Diagram must be drawn (with pencil only) with required labelling.
- Procedure for any experiment will not be written.
- The observation table and calculations are to be drawn/done with the help of a pencil only.
- Avoid cutting owing to the limited number of pages in the practical examination copy supplied from the board.
Standard way of writing practical in CBSE Class XII Board Practical Examination
Thumb Rule: The heading must be written with a black pen, and content will be written with a blue pen.
- Aim: The aim will always start with ‘To..’ For example: To prepare a temporary mount on an onion root tip for studying mitotis.
- Materials Required: It will include all apparatus, instruments, and equipment required for the conduction of the experiment.
- Theory: Four to five lines upon the topic of which/from which/related to which the experiment will be conducted.
- Procedure: The procedure is to be written only in the practical copy or lab manual of the school. It is not allowed to write procedure in the board practical examination. Each step of the experiment will be each point of procedure for the experiment.
The procedure is to be written in such a way that a layman can conduct the experiment after reading it. Every step is to be written clearly, indicating the proper use of every of equipment, apparatus & instrument required.
- Observation: Record observations of the experiment carefully.
Or
- Observation Table
- Calculation: to be done only in the case of an observation table or if required.
- Result/Conclusion: It will begin with, ‘Upon observation it was concluded that….’
- Sources of Error and Precautions: Mention all sources of errors and precautions faced during the experiment. It should be a minimum of three & a maximum of five.
Lab Work.
The lab work will be conducted under two headings
- Experiment & Slide Preparation
- Spotting
Experiments Prescribed by CBSE for Class XII Biology Board Practical Examination.
Major Experiment:
DNA Isolation from Plant Material
Minor Experiment
Plant Population Density by Quadrat Method
Formula:
Density = Total number of individuals ÷ Total number of quadrats studied
Plant Population Frequency by Quadrat Method
Formula:
Frequency (%) = Number of quadrats in which species occurs ÷ Total quadrats studied × 100
Slide Preparation
Temporary mount of pollen grain to observe pollination
Temporary mount of onion root tip to observe mitosis
Important Spotting (7 Marks)
Reproduction
Wind-pollinated flowers
Insect-pollinated flowers
Bird-pollinated flowers
Pollen germination slide
Human Reproduction
T.S. of Testis
T.S. of Ovary
Cell Division
Meiosis slide
Blastula slide
Genetics
Mendelian seed inheritance
Pedigree charts of following
Tongue rolling
Blood groups
Ear lobes
Widow’s peak
Colour blindness
Pollination Techniques
Emasculation, Bagging & Tagging
Health and Disease
Identification and indicating symptoms of :
Ascariasis
Amoebiasis
Malaria
Ringworm
Ecology
Lichens (symbiosis)
Root nodules of legumes
Cuscuta (parasitic nutrition)
Evolution
Homologous organs
Analogous organs
Viva voice
For Vaiva voice a candidate has to prepare
- Lab manual/practical copy which should be maintained with all major experiments, minor experiments, slide preparations and spotting along with well-labelled and presentable diagrams of each experiment slide preparation and spotting. The lab manual should be checked by the subject teacher and countersigned by the principal of the school.
- Investigatory project upon any topic related to the syllabus of NCERT Class XII Bio.
The Project file should consist of following pages:
- Cover Page (Should include the name of the school, the name of the topic, the submitter, and the submittee)
- Certificate
- Acknowledgement
- Index
- Content
- References
In general, Viva can also be conducted from the theoretical topics practically prescribed in the syllabus of Class XII Bio Practical Examination.