1. The Marking Scheme provides general guidelines to reduce subjectivity in the marking. It carries only suggested value points for the answer. These are only guidelines and do not constitute the complete answer. Any other individual response with suitable justification should also be accepted even if there is no reference to the text.
2. Evaluation is to be done as per instructions provided in the Marking Scheme. It should not be done according to one's own interpretation or any other consideration. Marking Scheme should be strictly adhered to and religiously followed.
3. If a question has parts, please award marks in the right hand side for each part. Marks awarded for different parts of the question should then be totalled up and written in the left hand margin.
4. If a question does not have any parts, marks be awarded in the left hand side margin.
5. If a candidate has attempted an extra question, marks obtained in the question attempted first should be retained and the other answer should be scored out.
6. Wherever only two/three of a 'given' number of examples/factors/points are expected only the first two/three or expected number should be read. The rest are irrelevant and should not be examined.
7. There should be no effort at 'moderation' of the marks by the evaluating teachers. The actual total marks obtained by the candidate may be of no concern of the evaluators.
8. All the Head Examiners / Examiners are instructed that while evaluating the answer scripts, if the answer is found to be totally incorrect, the (X) should be marked in the incorrect answer and awarded ‘0’ marks.

9. ½ mark may be deducted if a candidate either does not write units or writes wrong units in the final answer of a numerical problem.
10. A full scale of mark 0 to 100 has to be used. Please do not hesitate to award full marks if the answer deserves it.
11. As per orders of the Hon’ble Supreme Court the candidates would now be permitted to obtain photocopy of the Answer Book on request on payment of the prescribed fee. All Examiners/Head Examiners are once again reminded that they must ensure that evaluation is carried out strictly as per value points given in the marking scheme.

 

Code No. 531/1
Expected Answer/ Value point Marks Total
SECTION – A

Q1. By attaining Noble gas configuration / By completing its octet; covalent bond ½ + ½ 1
Q2. (i) Plasmodium (malarial parasite)
(ii) Amoeba / Leishmania/ (or any other example) ½ + ½ 1
Q3. Insects – second trophic level; Snake-Fourth trophic level ½ + ½ 1
Q4. Concave lens, ½

Q5. The problems caused by non-biodegradable waste are as follows:-
(i) Water pollution that makes water unfit for drinking ½
(ii) They cause land pollution leading to loss of fertility of soil ½
(iii) They cause stoppage of flow of water in drains/ may block drains. ½
(iv) They cause air pollution. ½ 2
Q6. Biodiversity is the existence of a wide variety of species of plants, animals and microorganisms in a natural habitat within a particular environment. 1

Advantages of conserving:

Q7. Note: Withdrawn, give full credit to each candidate. 3
Q8. (b) (i) C₄H₈ (ii) C₆H₁₀ 1 ½ +1 ½
Note: Part (a) withdrawn and mark adjusted in (b) part. 3
Q9. (i) Q has valency 3. Its electronic configuration is 2, 8, 3; It has 3 electrons
in valence shell/ outermost shell ½, ½
(ii) P and Q are metals as these can lose electrons. R and S are non-metals as these can gain electrons ½, ½
(iii) P will form the most basic oxide as it is most metallic. ½, ½ 3
Q10. a) Group 17, Period 3 ½, ½
b) 17, It is non-metallic because it has 7 valence electrons (it can gain one electron easily forming negative ion) ½, ½
c) Chlorine; Bromine or Iodine or Fluorine are chemically similar to chlorine. ½, ½ 3
Q11. a) Four reasons for adopting contraceptive methods are:
(i) To increase the gap between two children
(ii) To prevent unwanted pregnancy

 

(iii) To prevent transmission of STD
(iv) To control population growth 4 x ½
b) No, because it does not provide a physical barrier between the male and
female reproductive organs. ½, ½ 3
Q12. a) Fertilization is possible if sperm meets the ovum within one day of its release. 1
b) Sperm Ovum
(i) It is long It is oval or rounded
(ii) It is motile It is non-motile
(iii) Released in large numbers Only one is released per menstrual cycle (Any two) 1+1 3
( or any other point)
Q13. a) Multicellular organisms with simple body organisation break up into two or more small pieces or fragments. upon maturation these fragments grow into new individuals. e.g. Spirogyra. 1 + ½
b)

Q14. a) Analogous, different origin but same function ½, ½
b) Homologous, similar origin but different function ½, ½
c) Analogous, different origin but same function ½, ½ 3
Q15. To let rainwater recharge ground water by water harvesting is a better option. 1
Advantages are:

Q16. The ratio of the speed of light in the free space or vacuum (c) to the speed of light in the given medium (v) is called absolute refractive index of the medium.