CBSE Marking Scheme - Class XII Biology - CBSE 2012

Hi readers,  

Certain guidelines for CBSE marking scheme has been prescribed by CBSE Board. Students should have an idea of the marking scheme so that they can accordingly prepare and answer the questions. While preparation, student should examine a question in conjunction with the CBSE Marking Scheme and find out the proximity of the answer to that suggested in the CBSE Marking Scheme. The question paper will have no overall choice. However, there will be internal choice. The students shall get due credit for precise answers as per CBSEMarking Scheme.

CBSE Marking Scheme in Detail – Biology

The weightage of the distribution of marks over different dimensions of the question paper shall be as follows:

Weightage to content/subject units

Units Content	Marks
1. Reproduction	14
2. Genetics and evolution	18
3. Biology and Human Welfare	14
4. Biotechnology and its applications	10
5. Ecology and environment	14

CBSE Biology Question Paper Pattern

CBSE question paper for Biology shall consist of 8 very short answer questions of 1 mark each. There will be two types of short answer questions with 2 and 3 marks respectively. In addition to this, there will be 3 long answer questions which will require students to write answers in detail. The 5 long answer questions will carry 5 marks each. CBSE Biology question paper will be of 70 marks in total. CBSE paper will have no overall choice. However students will be given internal choice on any one question of 3 marks, any one question of 2 marks and all three long answer questions. In all, there will be internal choices on five questions.

Sample Question with CBSE Marking Scheme

The marking scheme for answer to sample question in Biology paper is given below:
Sample Question 1: Long Answer Question (5 Marks)
How is the “sixth episode of extinction” of species on earth, now currently in progress, different from the five earlier episodes? What is it due to? Explain the various causes that have brought about this difference.

Answer:
1. The difference is that 6th episode of extinction is taking place at a 100 to 1000 times faster than the earlier ones. (1/2 Mark)
2. It is largely due to human activities (1/2 Mark)
The various causes are:

A. Habitat loss and fragmentation (1 Mark)
B. Over exploitation (1 Mark)
C. Introduction / Invasion of alien species (1 Mark)
D. Co-extinctions (1 Mark)

It is suggested that students do not cross the word limit as no extra marks will be given for that. However, no marks shall be deducted for exceeding the word limit.

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