Science Past Year Paper SA-2(Set -1) - 2015, Class 10, CBSE Class 10 Notes | EduRev

Past Year Papers For Class 10

Created by: Manju Sen

Class 10 : Science Past Year Paper SA-2(Set -1) - 2015, Class 10, CBSE Class 10 Notes | EduRev

 Page 1


Delhi – 31/1/1 Page 1 
 
Strictly Confidential- (For Internal and Restricted Use Only) Secondary School Examination 
SUMMATIVE ASSESSMENT - II 
March 2015 
 
Marking Scheme – Science (Delhi) 31/1/1 
 
 
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 on 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. 
 
 
 
 
Page 2


Delhi – 31/1/1 Page 1 
 
Strictly Confidential- (For Internal and Restricted Use Only) Secondary School Examination 
SUMMATIVE ASSESSMENT - II 
March 2015 
 
Marking Scheme – Science (Delhi) 31/1/1 
 
 
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 on 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. 
 
 
 
 
Delhi – 31/1/1 Page 2 
 
MARKING SCHEME 
CLASS X – DELHI 
Code No. 31/1/1 
 
 
 Expected Answer/ Value point Marks Total 
 SECTION – A   
    
Q 1. ? Propene ½    
 ? C
3
H
6
 ½  1 
    
Q2. a) To produce sperms 
b) To produce male sex hormone / testosterone 
½ 
½  1 
    
Q3. It shields the surface of the earth from ultraviolet rays from the Sun. 1 1 
    
Q4. i) Virtual 
ii) Erect 
iii) Same size as the object 
iv) As far behind the mirror as the object is in  front 
v) Laterally inverted 
(Any four) ½ × 4 2 
    
Q5. ? Because large number of life forms / range of life forms (such as bacteria, 
fungi, fern, nematodes, insects, birds, reptiles, mammals, gymnosperms 
and angiosperms) are found there / A region with large biodiversity of 
endangered species, many of them being highly endemic and such regions 
being subjected to large scale destruction are designated as “Hot spots” by 
ecologists. 
 
? Two ways –  
i) Not allowing cutting of trees 
ii) To promote / make people aware about the importance of forests and wild 
life. 
iii) Not using wild life products / fur coat or any other named product. 
(any two) 
1 
 
 
 
 
 
 
 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
2 
    
Q6. ? A type of management which encourages utilization of resources that meet 
current basic human needs while preserving the resources for the needs of 
future generations. 
? Reuse is better as it does not consume energy. 
 
1 
 
1 
 
 
 
2 
    
Q7. ? Example:  
 
½  
 ? Addition of hydrogen to the molecule of an unsaturated hydrocarbon 
/compounds is hydrogenation. ½  
Page 3


Delhi – 31/1/1 Page 1 
 
Strictly Confidential- (For Internal and Restricted Use Only) Secondary School Examination 
SUMMATIVE ASSESSMENT - II 
March 2015 
 
Marking Scheme – Science (Delhi) 31/1/1 
 
 
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 on 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. 
 
 
 
 
Delhi – 31/1/1 Page 2 
 
MARKING SCHEME 
CLASS X – DELHI 
Code No. 31/1/1 
 
 
 Expected Answer/ Value point Marks Total 
 SECTION – A   
    
Q 1. ? Propene ½    
 ? C
3
H
6
 ½  1 
    
Q2. a) To produce sperms 
b) To produce male sex hormone / testosterone 
½ 
½  1 
    
Q3. It shields the surface of the earth from ultraviolet rays from the Sun. 1 1 
    
Q4. i) Virtual 
ii) Erect 
iii) Same size as the object 
iv) As far behind the mirror as the object is in  front 
v) Laterally inverted 
(Any four) ½ × 4 2 
    
Q5. ? Because large number of life forms / range of life forms (such as bacteria, 
fungi, fern, nematodes, insects, birds, reptiles, mammals, gymnosperms 
and angiosperms) are found there / A region with large biodiversity of 
endangered species, many of them being highly endemic and such regions 
being subjected to large scale destruction are designated as “Hot spots” by 
ecologists. 
 
? Two ways –  
i) Not allowing cutting of trees 
ii) To promote / make people aware about the importance of forests and wild 
life. 
iii) Not using wild life products / fur coat or any other named product. 
(any two) 
1 
 
 
 
 
 
 
 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
2 
    
Q6. ? A type of management which encourages utilization of resources that meet 
current basic human needs while preserving the resources for the needs of 
future generations. 
? Reuse is better as it does not consume energy. 
 
1 
 
1 
 
 
 
2 
    
Q7. ? Example:  
 
½  
 ? Addition of hydrogen to the molecule of an unsaturated hydrocarbon 
/compounds is hydrogenation. ½  
Delhi – 31/1/1 Page 3 
 
 ? Essential condition for hydrogenation is the presence of a catalyst like Ni 
/Pd / Pt. 1  
 ? Change observed in the physical property during hydrogenation is the 
change of the unsaturated compound from the liquid state to the 
corresponding saturated compound in the solid state / its boiling or melting 
point will increase. 1 3 
    
Q8. ? Soaps are sodium or potassium salts of long chain carboxylic acids.  ½   
 ? Detergents are ammonium or sulphonate salts. ½   
 ? Cleansing action of soap – One part of soap molecule is ionic / hydrophilic and 
dissolves in water. The other part is non-ionic / carbon chain / hydrophobic part 
which dissolves in oil. 
1 
 
 ? Thus soap molecules arrange themselves in the form of a micelle / diagram of a 
micelle. 
½  
 ? On rinsing with water, soap is washed off, lifting the oily dirt particles with it. 
½ 3 
    
Q9. 18 groups ½   
 7 periods ½   
 a) ? Atomic size increases. ½   
  ? Metallic character increases. ½   
 b) ? Atomic size decreases. ½   
  ? Metallic character decreases. ½  3 
    
Q10. (i) K / Potassium. 1  
 (ii) Be and Ca. 1  
 ? KX or KCl ½   
 ? Ionic / Electrovalent. ½  3  
    
Q11. ? A process where a DNA molecule produces two similar copies of itself in a 
reproducing cell. 
? Importance – 
(i) It makes possible the transmission of characters from parents to the 
next generation. 
(ii) It causes variation in the population. 
1 
 
 
1 
 
1 
 
 
 
 
 
3 
    
Q12. 
 
  
 Drawing 2  
 Two labeling – Bud, Tentacles ½, ½  3 
    
Page 4


Delhi – 31/1/1 Page 1 
 
Strictly Confidential- (For Internal and Restricted Use Only) Secondary School Examination 
SUMMATIVE ASSESSMENT - II 
March 2015 
 
Marking Scheme – Science (Delhi) 31/1/1 
 
 
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 on 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. 
 
 
 
 
Delhi – 31/1/1 Page 2 
 
MARKING SCHEME 
CLASS X – DELHI 
Code No. 31/1/1 
 
 
 Expected Answer/ Value point Marks Total 
 SECTION – A   
    
Q 1. ? Propene ½    
 ? C
3
H
6
 ½  1 
    
Q2. a) To produce sperms 
b) To produce male sex hormone / testosterone 
½ 
½  1 
    
Q3. It shields the surface of the earth from ultraviolet rays from the Sun. 1 1 
    
Q4. i) Virtual 
ii) Erect 
iii) Same size as the object 
iv) As far behind the mirror as the object is in  front 
v) Laterally inverted 
(Any four) ½ × 4 2 
    
Q5. ? Because large number of life forms / range of life forms (such as bacteria, 
fungi, fern, nematodes, insects, birds, reptiles, mammals, gymnosperms 
and angiosperms) are found there / A region with large biodiversity of 
endangered species, many of them being highly endemic and such regions 
being subjected to large scale destruction are designated as “Hot spots” by 
ecologists. 
 
? Two ways –  
i) Not allowing cutting of trees 
ii) To promote / make people aware about the importance of forests and wild 
life. 
iii) Not using wild life products / fur coat or any other named product. 
(any two) 
1 
 
 
 
 
 
 
 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
2 
    
Q6. ? A type of management which encourages utilization of resources that meet 
current basic human needs while preserving the resources for the needs of 
future generations. 
? Reuse is better as it does not consume energy. 
 
1 
 
1 
 
 
 
2 
    
Q7. ? Example:  
 
½  
 ? Addition of hydrogen to the molecule of an unsaturated hydrocarbon 
/compounds is hydrogenation. ½  
Delhi – 31/1/1 Page 3 
 
 ? Essential condition for hydrogenation is the presence of a catalyst like Ni 
/Pd / Pt. 1  
 ? Change observed in the physical property during hydrogenation is the 
change of the unsaturated compound from the liquid state to the 
corresponding saturated compound in the solid state / its boiling or melting 
point will increase. 1 3 
    
Q8. ? Soaps are sodium or potassium salts of long chain carboxylic acids.  ½   
 ? Detergents are ammonium or sulphonate salts. ½   
 ? Cleansing action of soap – One part of soap molecule is ionic / hydrophilic and 
dissolves in water. The other part is non-ionic / carbon chain / hydrophobic part 
which dissolves in oil. 
1 
 
 ? Thus soap molecules arrange themselves in the form of a micelle / diagram of a 
micelle. 
½  
 ? On rinsing with water, soap is washed off, lifting the oily dirt particles with it. 
½ 3 
    
Q9. 18 groups ½   
 7 periods ½   
 a) ? Atomic size increases. ½   
  ? Metallic character increases. ½   
 b) ? Atomic size decreases. ½   
  ? Metallic character decreases. ½  3 
    
Q10. (i) K / Potassium. 1  
 (ii) Be and Ca. 1  
 ? KX or KCl ½   
 ? Ionic / Electrovalent. ½  3  
    
Q11. ? A process where a DNA molecule produces two similar copies of itself in a 
reproducing cell. 
? Importance – 
(i) It makes possible the transmission of characters from parents to the 
next generation. 
(ii) It causes variation in the population. 
1 
 
 
1 
 
1 
 
 
 
 
 
3 
    
Q12. 
 
  
 Drawing 2  
 Two labeling – Bud, Tentacles ½, ½  3 
    
Delhi – 31/1/1 Page 4 
 
Q13 ? Four methods –  
(i)       Mechanical or barrier method  OR  Male or female condoms 
(ii) Use of hormonal preparations  OR  Oral Pills / i-pill / Saheli 
(iii) Use of loop or copper T  OR  IUCD 
(iv) Surgical method  OR  tubectomy / vasectomy 
 
? Effect on health & prosperity:  
(i)       Health of women is maintained 
(ii)       Parents can give more attention to children 
(iii) More resources can be made available. 
                                                                            (any two) 
 
 
 
 
 
½ x 4 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
3 
    
Q14. ? Acquiring knowledge / skill in one’s lifetime such as learning dance, 
music, physical fitness or any other suitable example. 
                                                                                        (any two) 
? Reason : 
(i) Such characters / experiences acquired during one’s lifetime do 
 not bring any change in the DNA of the reproducing cell  / germ cell. 
(ii) Only germ cells are responsible for passing on the characters from the 
parents to the progeny. 
 
 
½, ½ 
 
1 
 
1 
 
 
 
 
 
 
3 
    
Q15. (i) No, the structure of the eye in each of the organisms is different. 
(ii) ? Fossils of certain dinosaurs / reptiles show imprints of feathers along   
   with their bones but they could not fly presumably using the feathers  
   for insulation; 
? Later they developed / evolved and adapted feathers for flight, thus 
becoming the ancestors of present day birds. (OR any other suitable 
evidence/example) 
½, ½ 
1 
 
 
1 
 
 
 
 
3 
    
Q16. The candidate may choose any two of the following rays:   
 i) A ray parallel to the principal axis, after reflection, will pass through the 
principal focus of a concave mirror. 
ii) A ray passing through the principal focus of a concave mirror after 
reflection will emerge parallel to the principal axis. 
iii) A ray passing through the centre of curvature of a concave mirror after 
reflection is reflected back along the same path. 
iv) A ray incident obliquely to the principal axis towards the pole of a concave 
mirror is reflected obliquely, making equal angles with the principal axis. 
(any two) 1 × 2  
 
 or a similar representation  1 3 
 Note: The candidate must draw the ray diagram as per the two rays chosen by 
him/her. In the diagram shown above first two rays have been chosen/used. 
  
    
Page 5


Delhi – 31/1/1 Page 1 
 
Strictly Confidential- (For Internal and Restricted Use Only) Secondary School Examination 
SUMMATIVE ASSESSMENT - II 
March 2015 
 
Marking Scheme – Science (Delhi) 31/1/1 
 
 
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 on 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. 
 
 
 
 
Delhi – 31/1/1 Page 2 
 
MARKING SCHEME 
CLASS X – DELHI 
Code No. 31/1/1 
 
 
 Expected Answer/ Value point Marks Total 
 SECTION – A   
    
Q 1. ? Propene ½    
 ? C
3
H
6
 ½  1 
    
Q2. a) To produce sperms 
b) To produce male sex hormone / testosterone 
½ 
½  1 
    
Q3. It shields the surface of the earth from ultraviolet rays from the Sun. 1 1 
    
Q4. i) Virtual 
ii) Erect 
iii) Same size as the object 
iv) As far behind the mirror as the object is in  front 
v) Laterally inverted 
(Any four) ½ × 4 2 
    
Q5. ? Because large number of life forms / range of life forms (such as bacteria, 
fungi, fern, nematodes, insects, birds, reptiles, mammals, gymnosperms 
and angiosperms) are found there / A region with large biodiversity of 
endangered species, many of them being highly endemic and such regions 
being subjected to large scale destruction are designated as “Hot spots” by 
ecologists. 
 
? Two ways –  
i) Not allowing cutting of trees 
ii) To promote / make people aware about the importance of forests and wild 
life. 
iii) Not using wild life products / fur coat or any other named product. 
(any two) 
1 
 
 
 
 
 
 
 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
2 
    
Q6. ? A type of management which encourages utilization of resources that meet 
current basic human needs while preserving the resources for the needs of 
future generations. 
? Reuse is better as it does not consume energy. 
 
1 
 
1 
 
 
 
2 
    
Q7. ? Example:  
 
½  
 ? Addition of hydrogen to the molecule of an unsaturated hydrocarbon 
/compounds is hydrogenation. ½  
Delhi – 31/1/1 Page 3 
 
 ? Essential condition for hydrogenation is the presence of a catalyst like Ni 
/Pd / Pt. 1  
 ? Change observed in the physical property during hydrogenation is the 
change of the unsaturated compound from the liquid state to the 
corresponding saturated compound in the solid state / its boiling or melting 
point will increase. 1 3 
    
Q8. ? Soaps are sodium or potassium salts of long chain carboxylic acids.  ½   
 ? Detergents are ammonium or sulphonate salts. ½   
 ? Cleansing action of soap – One part of soap molecule is ionic / hydrophilic and 
dissolves in water. The other part is non-ionic / carbon chain / hydrophobic part 
which dissolves in oil. 
1 
 
 ? Thus soap molecules arrange themselves in the form of a micelle / diagram of a 
micelle. 
½  
 ? On rinsing with water, soap is washed off, lifting the oily dirt particles with it. 
½ 3 
    
Q9. 18 groups ½   
 7 periods ½   
 a) ? Atomic size increases. ½   
  ? Metallic character increases. ½   
 b) ? Atomic size decreases. ½   
  ? Metallic character decreases. ½  3 
    
Q10. (i) K / Potassium. 1  
 (ii) Be and Ca. 1  
 ? KX or KCl ½   
 ? Ionic / Electrovalent. ½  3  
    
Q11. ? A process where a DNA molecule produces two similar copies of itself in a 
reproducing cell. 
? Importance – 
(i) It makes possible the transmission of characters from parents to the 
next generation. 
(ii) It causes variation in the population. 
1 
 
 
1 
 
1 
 
 
 
 
 
3 
    
Q12. 
 
  
 Drawing 2  
 Two labeling – Bud, Tentacles ½, ½  3 
    
Delhi – 31/1/1 Page 4 
 
Q13 ? Four methods –  
(i)       Mechanical or barrier method  OR  Male or female condoms 
(ii) Use of hormonal preparations  OR  Oral Pills / i-pill / Saheli 
(iii) Use of loop or copper T  OR  IUCD 
(iv) Surgical method  OR  tubectomy / vasectomy 
 
? Effect on health & prosperity:  
(i)       Health of women is maintained 
(ii)       Parents can give more attention to children 
(iii) More resources can be made available. 
                                                                            (any two) 
 
 
 
 
 
½ x 4 
 
 
 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
3 
    
Q14. ? Acquiring knowledge / skill in one’s lifetime such as learning dance, 
music, physical fitness or any other suitable example. 
                                                                                        (any two) 
? Reason : 
(i) Such characters / experiences acquired during one’s lifetime do 
 not bring any change in the DNA of the reproducing cell  / germ cell. 
(ii) Only germ cells are responsible for passing on the characters from the 
parents to the progeny. 
 
 
½, ½ 
 
1 
 
1 
 
 
 
 
 
 
3 
    
Q15. (i) No, the structure of the eye in each of the organisms is different. 
(ii) ? Fossils of certain dinosaurs / reptiles show imprints of feathers along   
   with their bones but they could not fly presumably using the feathers  
   for insulation; 
? Later they developed / evolved and adapted feathers for flight, thus 
becoming the ancestors of present day birds. (OR any other suitable 
evidence/example) 
½, ½ 
1 
 
 
1 
 
 
 
 
3 
    
Q16. The candidate may choose any two of the following rays:   
 i) A ray parallel to the principal axis, after reflection, will pass through the 
principal focus of a concave mirror. 
ii) A ray passing through the principal focus of a concave mirror after 
reflection will emerge parallel to the principal axis. 
iii) A ray passing through the centre of curvature of a concave mirror after 
reflection is reflected back along the same path. 
iv) A ray incident obliquely to the principal axis towards the pole of a concave 
mirror is reflected obliquely, making equal angles with the principal axis. 
(any two) 1 × 2  
 
 or a similar representation  1 3 
 Note: The candidate must draw the ray diagram as per the two rays chosen by 
him/her. In the diagram shown above first two rays have been chosen/used. 
  
    
Delhi – 31/1/1 Page 5 
 
Q17. 
 
1  
 ? Light from the Sun near the horizon passes through thicker layers of air 
and longer distance 1  
 ? Most of the blue light and shorter wavelengths of sunlight are scattered 
away by the particles. Light of larger wavelength reaches us giving the 
reddish appearance  1 3 
    
Q18.  (a) No, it pollutes air. 
 
Advantage:  
Segregation of wastes into biodegradable and non biodegradable wastes at the 
initial stage of disposal saves time and energy. 
 
(b) By putting wastes in proper dustbins 
                                                                                   Or any other 
½, ½ 
 
 
1 
 
 
1 
 
 
 
 
 
 
3 
    
Q19. ? Carbon has 4 electrons in its outermost shell, and needs to gain or lose 4 
electrons to attain noble gas configuration. 1  
 ? Losing or gaining 4 electrons is not possible due to energy considerations; 
hence it shares electrons to form covalent bonds. 1  
 Two reasons for large number of carbon compounds :   
 ? Catenation: The unique ability of carbon to form bonds with other atoms of 
carbon giving rise to long chains of different types of compounds. 1  
 ? Tetravalency : Since carbon has a valency of 4, it is capable of bonding 
with four other atoms of carbon or atoms of elements like  oxygen, 
hydrogen, nitrogen, sulphur, chlorine, etc. 1  
 The reason for the formation of strong bonds by carbon is its small size which 
enables the nucleus to hold on to the shared pairs of electrons strongly. 1 5 
    
Q20. ? Functions: - 
Ovary:  (i) Production of female hormone / oestrogen and   progesterone. 
(ii) Production of female gamete / egg /germ cell. 
    Oviduct :     (i) Transfer of female gamete from the ovary. 
                         (ii) Site of fertilization. 
    Uterus:         (i) Implantation of Zygote / embryo. 
                         (ii) Nourishment of developing embryo. 
 
½  
½  
½ 
½ 
½ 
½  
 
 ? Placenta is a special disc like tissue embedded in the mother’s uterine wall 
and connected to the foetus / embryo. 1  
 ? Placenta provides a large surface area for glucose and oxygen/ nutrients to 
pass from the mother’s blood to the embryo/ foetus. 1 5 
    
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