CBSE Board Paper 2023 (Marking Scheme and Solutions) | Biology Class 12 - NEET PDF Download

 Page 1


XII_044_57/1/1 Biology # Page-1 
  
 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only) 
Senior School Certificate Examination, 2023 
SUBJECT NAME BIOLOGY (SUBJECT CODE 044) (PAPER CODE 57/1/1) 
General Instructions: - 
1  You are aware that evaluation is the most important process in the actual and correct 
assessment of the candidates. A small mistake in evaluation may lead to serious problems 
which may affect the future of the candidates, education system and teaching profession. 
To avoid mistakes, it is requested that before starting evaluation, you must read and 
understand the spot evaluation guidelines carefully. 
2  “Evaluation policy is a confidential policy as it is related to the confidentiality of the 
examinations conducted, Evaluation done and several other aspects. Its’ leakage to 
public in any manner could lead to derailment of the examination system and affect 
the life and future of millions of candidates. Sharing this policy/document to 
anyone, publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3  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. However, while 
evaluating, answers which are based on latest information or knowledge and/or are 
innovative, they may be assessed for their correctness otherwise and due marks be 
awarded to them. In class-X, while evaluating two competency-based questions, 
please try to understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks should be 
awarded.  
4  The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete answer. The 
students can have their own expression and if the expression is correct, the due marks 
should be awarded accordingly. 
5  The Head-Examiner must go through the first five answer books evaluated by each 
evaluator on the first day, to ensure that evaluation has been carried out as per the 
instructions given in the Marking Scheme. If there is any variation, the same should be 
zero after delibration and discussion. The remaining answer books meant for evaluation 
shall be given only after ensuring that there is no significant variation in the marking of 
individual evaluators. 
6  Evaluators will mark( v ) wherever answer is correct. For wrong answer CROSS ‘X” be 
marked. Evaluators will not put right ( ?)while evaluating which gives an impression that 
answer is correct and no marks are awarded. This is most common mistake which 
evaluators are committing. 
7  If a question has parts, please award marks on the right-hand side for each part. Marks 
awarded for different parts of the question should then be totaled up and written in the left-
hand margin and encircled. This may be followed strictly. 
Page 2


XII_044_57/1/1 Biology # Page-1 
  
 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only) 
Senior School Certificate Examination, 2023 
SUBJECT NAME BIOLOGY (SUBJECT CODE 044) (PAPER CODE 57/1/1) 
General Instructions: - 
1  You are aware that evaluation is the most important process in the actual and correct 
assessment of the candidates. A small mistake in evaluation may lead to serious problems 
which may affect the future of the candidates, education system and teaching profession. 
To avoid mistakes, it is requested that before starting evaluation, you must read and 
understand the spot evaluation guidelines carefully. 
2  “Evaluation policy is a confidential policy as it is related to the confidentiality of the 
examinations conducted, Evaluation done and several other aspects. Its’ leakage to 
public in any manner could lead to derailment of the examination system and affect 
the life and future of millions of candidates. Sharing this policy/document to 
anyone, publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3  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. However, while 
evaluating, answers which are based on latest information or knowledge and/or are 
innovative, they may be assessed for their correctness otherwise and due marks be 
awarded to them. In class-X, while evaluating two competency-based questions, 
please try to understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks should be 
awarded.  
4  The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete answer. The 
students can have their own expression and if the expression is correct, the due marks 
should be awarded accordingly. 
5  The Head-Examiner must go through the first five answer books evaluated by each 
evaluator on the first day, to ensure that evaluation has been carried out as per the 
instructions given in the Marking Scheme. If there is any variation, the same should be 
zero after delibration and discussion. The remaining answer books meant for evaluation 
shall be given only after ensuring that there is no significant variation in the marking of 
individual evaluators. 
6  Evaluators will mark( v ) wherever answer is correct. For wrong answer CROSS ‘X” be 
marked. Evaluators will not put right ( ?)while evaluating which gives an impression that 
answer is correct and no marks are awarded. This is most common mistake which 
evaluators are committing. 
7  If a question has parts, please award marks on the right-hand side for each part. Marks 
awarded for different parts of the question should then be totaled up and written in the left-
hand margin and encircled. This may be followed strictly. 
XII_044_57/1/1 Biology # Page-2 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8  If a question does not have any parts, marks must be awarded in the left-hand margin and 
encircled. This may also be followed strictly. 
9  If a student has attempted an extra question, answer of the question deserving more 
marks should be retained and the other answer scored out with a note “Extra Question”. 
10  No marks to be deducted for the cumulative effect of an error. It should be penalized only 
once. 
11  A full scale of marks 0-70 has to be used. Please do not hesitate to award full marks if the 
answer deserves it. 
12  Every examiner has to necessarily do evaluation work for full working hours i.e., 8 hours 
every day and evaluate 20 answer books per day in main subjects and 25 answer books 
per day in other subjects (Details are given in Spot Guidelines). 
13  Ensure that you do not make the following common types of errors committed by the 
Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right tick mark is 
correctly and clearly indicated. It should merely be a line. Same is with the X for 
incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no marks awarded.  
14  While evaluating the answer books if the answer is found to be totally incorrect, it should 
be marked as cross (X) and awarded zero (0)Marks. 
15  Any un assessed portion, non-carrying over of marks to the title page, or totalling error 
detected by the candidate shall damage the prestige of all the personnel engaged in the 
evaluation work as also of the Board. Hence, in order to uphold the prestige of all 
concerned, it is again reiterated that the instructions be followed meticulously and 
judiciously. 
16  The Examiners should acquaint themselves with the guidelines given in the “Guidelines 
for spot Evaluation” before starting the actual evaluation. 
17  Every Examiner shall also ensure that all the answers are evaluated, marks carried over to 
the title page, correctly totalled and written in figures and words. 
18  The candidates are entitled to obtain photocopy of the Answer Book on request on 
payment of the prescribed processing fee. All Examiners/Additional Head Examiners/Head 
Examiners are once again reminded that they must ensure that evaluation is carried out 
strictly as per value points for each answer as given in the Marking Scheme. 
Page 3


XII_044_57/1/1 Biology # Page-1 
  
 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only) 
Senior School Certificate Examination, 2023 
SUBJECT NAME BIOLOGY (SUBJECT CODE 044) (PAPER CODE 57/1/1) 
General Instructions: - 
1  You are aware that evaluation is the most important process in the actual and correct 
assessment of the candidates. A small mistake in evaluation may lead to serious problems 
which may affect the future of the candidates, education system and teaching profession. 
To avoid mistakes, it is requested that before starting evaluation, you must read and 
understand the spot evaluation guidelines carefully. 
2  “Evaluation policy is a confidential policy as it is related to the confidentiality of the 
examinations conducted, Evaluation done and several other aspects. Its’ leakage to 
public in any manner could lead to derailment of the examination system and affect 
the life and future of millions of candidates. Sharing this policy/document to 
anyone, publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3  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. However, while 
evaluating, answers which are based on latest information or knowledge and/or are 
innovative, they may be assessed for their correctness otherwise and due marks be 
awarded to them. In class-X, while evaluating two competency-based questions, 
please try to understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks should be 
awarded.  
4  The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete answer. The 
students can have their own expression and if the expression is correct, the due marks 
should be awarded accordingly. 
5  The Head-Examiner must go through the first five answer books evaluated by each 
evaluator on the first day, to ensure that evaluation has been carried out as per the 
instructions given in the Marking Scheme. If there is any variation, the same should be 
zero after delibration and discussion. The remaining answer books meant for evaluation 
shall be given only after ensuring that there is no significant variation in the marking of 
individual evaluators. 
6  Evaluators will mark( v ) wherever answer is correct. For wrong answer CROSS ‘X” be 
marked. Evaluators will not put right ( ?)while evaluating which gives an impression that 
answer is correct and no marks are awarded. This is most common mistake which 
evaluators are committing. 
7  If a question has parts, please award marks on the right-hand side for each part. Marks 
awarded for different parts of the question should then be totaled up and written in the left-
hand margin and encircled. This may be followed strictly. 
XII_044_57/1/1 Biology # Page-2 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8  If a question does not have any parts, marks must be awarded in the left-hand margin and 
encircled. This may also be followed strictly. 
9  If a student has attempted an extra question, answer of the question deserving more 
marks should be retained and the other answer scored out with a note “Extra Question”. 
10  No marks to be deducted for the cumulative effect of an error. It should be penalized only 
once. 
11  A full scale of marks 0-70 has to be used. Please do not hesitate to award full marks if the 
answer deserves it. 
12  Every examiner has to necessarily do evaluation work for full working hours i.e., 8 hours 
every day and evaluate 20 answer books per day in main subjects and 25 answer books 
per day in other subjects (Details are given in Spot Guidelines). 
13  Ensure that you do not make the following common types of errors committed by the 
Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right tick mark is 
correctly and clearly indicated. It should merely be a line. Same is with the X for 
incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no marks awarded.  
14  While evaluating the answer books if the answer is found to be totally incorrect, it should 
be marked as cross (X) and awarded zero (0)Marks. 
15  Any un assessed portion, non-carrying over of marks to the title page, or totalling error 
detected by the candidate shall damage the prestige of all the personnel engaged in the 
evaluation work as also of the Board. Hence, in order to uphold the prestige of all 
concerned, it is again reiterated that the instructions be followed meticulously and 
judiciously. 
16  The Examiners should acquaint themselves with the guidelines given in the “Guidelines 
for spot Evaluation” before starting the actual evaluation. 
17  Every Examiner shall also ensure that all the answers are evaluated, marks carried over to 
the title page, correctly totalled and written in figures and words. 
18  The candidates are entitled to obtain photocopy of the Answer Book on request on 
payment of the prescribed processing fee. All Examiners/Additional Head Examiners/Head 
Examiners are once again reminded that they must ensure that evaluation is carried out 
strictly as per value points for each answer as given in the Marking Scheme. 
XII_044_57/1/1 Biology # Page-3 
  
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
BIOLOGY (Subject Code – 044) 
[ Paper Code:57/1/1] 
                    Maximum Marks: 70 
Q. 
No. 
EXPECTED ANSWER / VALUE POINTS 
Marks Total 
Marks 
 SECTION A   
1. (b) / (ii) and (iv) 1 1 
2. (c) / X = Promoter, Y = Sigma factor,   Z = RNA polymerase. 1 1 
3. (a) / Declining population. 1 1 
4. (a) / Point (i) 1 1 
5. (d) / P - (iii), Q - (i), R- (ii), S- (iv) 1 1 
6. (c) / 1 and 3 1 1 
7. 
(c) / Directional selection as giraffes with longer neck lengths are selected 
// 
(d)/Stabilizing selection as giraffe with medium neck lengths are selected. 
1 
// 
1 
 
 
1 
8. (c) / 1300 1 1 
9. (a) /  P– (ii), Q – (iv), R – (iii), S – (i) 1 1 
10. (c) / Leydig cells – Androgen – Initiate the production of sperms. 1 1 
11. (b) / Salmonella typhimurium. 1 1 
12. (d) / Dr. R.A. Mashelkar. 1 1 
13. (c) / A is true, but R is false. 1 1 
14. (a) / A and R are true and R is  the correct explanation of A. 1 1 
15. (c) / A is true , but R is false. 1 1 
16. (a) / A and R are true and R is correct explanation of A. 1 1 
 SECTION B   
17. (a) Blastocyst   
(b)  Uterine wall/endometrium/innermost layer of uterine wall. 
(c) (Outer layer/trophoblast) ‘X’- helps in implantation in uterus/attachment to  
      endometrium. 
(Inner cell mass) ‘Y’- gets differentiated into embryo. 
½ 
½ 
½ 
 
½ 
 
 
 
 
 
2 
18. (a) From micropylar end, through the synergids (filiform apparatus)/filiform (within 
synergids) apparatus  guides the entry of pollen tube 
(b) One male nucleus fuses with two polar nuclei to form Primary endosperm nucleus  
and termed triple fusion, other male nucleus fuses with egg cell nucleus to form 
zygote i.e. undergoes Syngamy 
½×2 
 
 
½×2 
 
 
2 
19. (a)    
(i) ‘A; Circular DNA/Plasmid 
     ‘B’ Bacteriophage  
    (ii)(Plasmid)-Can carry foreign gene into the host cell/acts as cloning vector/has  
          selectable marker/   independent of the control of chromosomal DNA/ high 
copy number 
        (Bacteriophage) -Cloning vector have the ability to replicate in bacterial cells /    
     independent of the control of chromosomal DNA / high copy number per cell. 
                                                     OR 
(b) Treating bacteria with specific concentration of calcium (ions)which increases the  
 
½ 
½ 
 
½ 
 
 
½ 
 
 
 
 
 
 
 
 
 
 
 
 
Page 4


XII_044_57/1/1 Biology # Page-1 
  
 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only) 
Senior School Certificate Examination, 2023 
SUBJECT NAME BIOLOGY (SUBJECT CODE 044) (PAPER CODE 57/1/1) 
General Instructions: - 
1  You are aware that evaluation is the most important process in the actual and correct 
assessment of the candidates. A small mistake in evaluation may lead to serious problems 
which may affect the future of the candidates, education system and teaching profession. 
To avoid mistakes, it is requested that before starting evaluation, you must read and 
understand the spot evaluation guidelines carefully. 
2  “Evaluation policy is a confidential policy as it is related to the confidentiality of the 
examinations conducted, Evaluation done and several other aspects. Its’ leakage to 
public in any manner could lead to derailment of the examination system and affect 
the life and future of millions of candidates. Sharing this policy/document to 
anyone, publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3  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. However, while 
evaluating, answers which are based on latest information or knowledge and/or are 
innovative, they may be assessed for their correctness otherwise and due marks be 
awarded to them. In class-X, while evaluating two competency-based questions, 
please try to understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks should be 
awarded.  
4  The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete answer. The 
students can have their own expression and if the expression is correct, the due marks 
should be awarded accordingly. 
5  The Head-Examiner must go through the first five answer books evaluated by each 
evaluator on the first day, to ensure that evaluation has been carried out as per the 
instructions given in the Marking Scheme. If there is any variation, the same should be 
zero after delibration and discussion. The remaining answer books meant for evaluation 
shall be given only after ensuring that there is no significant variation in the marking of 
individual evaluators. 
6  Evaluators will mark( v ) wherever answer is correct. For wrong answer CROSS ‘X” be 
marked. Evaluators will not put right ( ?)while evaluating which gives an impression that 
answer is correct and no marks are awarded. This is most common mistake which 
evaluators are committing. 
7  If a question has parts, please award marks on the right-hand side for each part. Marks 
awarded for different parts of the question should then be totaled up and written in the left-
hand margin and encircled. This may be followed strictly. 
XII_044_57/1/1 Biology # Page-2 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8  If a question does not have any parts, marks must be awarded in the left-hand margin and 
encircled. This may also be followed strictly. 
9  If a student has attempted an extra question, answer of the question deserving more 
marks should be retained and the other answer scored out with a note “Extra Question”. 
10  No marks to be deducted for the cumulative effect of an error. It should be penalized only 
once. 
11  A full scale of marks 0-70 has to be used. Please do not hesitate to award full marks if the 
answer deserves it. 
12  Every examiner has to necessarily do evaluation work for full working hours i.e., 8 hours 
every day and evaluate 20 answer books per day in main subjects and 25 answer books 
per day in other subjects (Details are given in Spot Guidelines). 
13  Ensure that you do not make the following common types of errors committed by the 
Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right tick mark is 
correctly and clearly indicated. It should merely be a line. Same is with the X for 
incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no marks awarded.  
14  While evaluating the answer books if the answer is found to be totally incorrect, it should 
be marked as cross (X) and awarded zero (0)Marks. 
15  Any un assessed portion, non-carrying over of marks to the title page, or totalling error 
detected by the candidate shall damage the prestige of all the personnel engaged in the 
evaluation work as also of the Board. Hence, in order to uphold the prestige of all 
concerned, it is again reiterated that the instructions be followed meticulously and 
judiciously. 
16  The Examiners should acquaint themselves with the guidelines given in the “Guidelines 
for spot Evaluation” before starting the actual evaluation. 
17  Every Examiner shall also ensure that all the answers are evaluated, marks carried over to 
the title page, correctly totalled and written in figures and words. 
18  The candidates are entitled to obtain photocopy of the Answer Book on request on 
payment of the prescribed processing fee. All Examiners/Additional Head Examiners/Head 
Examiners are once again reminded that they must ensure that evaluation is carried out 
strictly as per value points for each answer as given in the Marking Scheme. 
XII_044_57/1/1 Biology # Page-3 
  
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
BIOLOGY (Subject Code – 044) 
[ Paper Code:57/1/1] 
                    Maximum Marks: 70 
Q. 
No. 
EXPECTED ANSWER / VALUE POINTS 
Marks Total 
Marks 
 SECTION A   
1. (b) / (ii) and (iv) 1 1 
2. (c) / X = Promoter, Y = Sigma factor,   Z = RNA polymerase. 1 1 
3. (a) / Declining population. 1 1 
4. (a) / Point (i) 1 1 
5. (d) / P - (iii), Q - (i), R- (ii), S- (iv) 1 1 
6. (c) / 1 and 3 1 1 
7. 
(c) / Directional selection as giraffes with longer neck lengths are selected 
// 
(d)/Stabilizing selection as giraffe with medium neck lengths are selected. 
1 
// 
1 
 
 
1 
8. (c) / 1300 1 1 
9. (a) /  P– (ii), Q – (iv), R – (iii), S – (i) 1 1 
10. (c) / Leydig cells – Androgen – Initiate the production of sperms. 1 1 
11. (b) / Salmonella typhimurium. 1 1 
12. (d) / Dr. R.A. Mashelkar. 1 1 
13. (c) / A is true, but R is false. 1 1 
14. (a) / A and R are true and R is  the correct explanation of A. 1 1 
15. (c) / A is true , but R is false. 1 1 
16. (a) / A and R are true and R is correct explanation of A. 1 1 
 SECTION B   
17. (a) Blastocyst   
(b)  Uterine wall/endometrium/innermost layer of uterine wall. 
(c) (Outer layer/trophoblast) ‘X’- helps in implantation in uterus/attachment to  
      endometrium. 
(Inner cell mass) ‘Y’- gets differentiated into embryo. 
½ 
½ 
½ 
 
½ 
 
 
 
 
 
2 
18. (a) From micropylar end, through the synergids (filiform apparatus)/filiform (within 
synergids) apparatus  guides the entry of pollen tube 
(b) One male nucleus fuses with two polar nuclei to form Primary endosperm nucleus  
and termed triple fusion, other male nucleus fuses with egg cell nucleus to form 
zygote i.e. undergoes Syngamy 
½×2 
 
 
½×2 
 
 
2 
19. (a)    
(i) ‘A; Circular DNA/Plasmid 
     ‘B’ Bacteriophage  
    (ii)(Plasmid)-Can carry foreign gene into the host cell/acts as cloning vector/has  
          selectable marker/   independent of the control of chromosomal DNA/ high 
copy number 
        (Bacteriophage) -Cloning vector have the ability to replicate in bacterial cells /    
     independent of the control of chromosomal DNA / high copy number per cell. 
                                                     OR 
(b) Treating bacteria with specific concentration of calcium (ions)which increases the  
 
½ 
½ 
 
½ 
 
 
½ 
 
 
 
 
 
 
 
 
 
 
 
 
XII_044_57/1/1 Biology # Page-4 
  
 
 efficiency with which DNA enters the bacteria through pores in its cell  
 wall ,recombinant DNA can then be forced into such cells by incubating the cells 
with recombinant DNA on ice, followed by placing them briefly at 42
0
C (heat shock), 
then putting them back on ice. 
 
 
½×4 
 
 
2 
20. •  Doesn’t take into account same species belonging to two or more trophic levels. 
 
• Assumes a simple food chain which never exists in nature/does not accommodate a  
       food web. 
• Saprophytes are not given any place though they play an important ecological role. 
                            
                                                                                                     (Any two points) 
 
 
 
1 × 2 
 
 
 
 
 
 
 
2 
21. 2·4 percent 
 
8·1 percent share of the global species diversity                 
1 
 
1 
 
 
2 
 SECTION C   
22.     
  
 
 
 
 
 
 
½×6 
 
 
 
 
 
 
 
 
 
 
 
3 
 
23. (a) Recessive trait, both the parents in generation I do not express the trait yet it 
appears in the progeny.   
 
(b) Autosomal trait, both male and females have equal chances of getting the trait. 
  
 
(c) Child ‘1’ : Aa/AA ,  Child ‘3’ : Aa      
                                                               //    
(a) Recessive trait, both the parents in generation I do not express the trait, yet it 
appears in the progeny.   
                   
(b) Sex linked trait, comparatively more male are getting affected.  
 
(c)   Child ‘1’  :   XY,                      Child ‘3’:  X ’ X(carrier) 
 ½×2 
 
 
½ × 2 
 
 
½ × 2 
   // 
 
½ × 2 
 
½ × 2 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3 
24. (a) They have the ability of self-renewal / to divide, and differentiate into any  
      kind of cell/tissue/organ.  
 
(b) – Inner cell mass of blastocyst / umbilical cord / Bone marrow  
                                                                                        (or any other correct source)  
 
½ × 2 
 
 
 
1 
 
 
 
 
 
 
 
Page 5


XII_044_57/1/1 Biology # Page-1 
  
 
Marking Scheme 
Strictly Confidential 
(For Internal and Restricted use only) 
Senior School Certificate Examination, 2023 
SUBJECT NAME BIOLOGY (SUBJECT CODE 044) (PAPER CODE 57/1/1) 
General Instructions: - 
1  You are aware that evaluation is the most important process in the actual and correct 
assessment of the candidates. A small mistake in evaluation may lead to serious problems 
which may affect the future of the candidates, education system and teaching profession. 
To avoid mistakes, it is requested that before starting evaluation, you must read and 
understand the spot evaluation guidelines carefully. 
2  “Evaluation policy is a confidential policy as it is related to the confidentiality of the 
examinations conducted, Evaluation done and several other aspects. Its’ leakage to 
public in any manner could lead to derailment of the examination system and affect 
the life and future of millions of candidates. Sharing this policy/document to 
anyone, publishing in any magazine and printing in News Paper/Website etc may 
invite action under various rules of the Board and IPC.” 
3  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. However, while 
evaluating, answers which are based on latest information or knowledge and/or are 
innovative, they may be assessed for their correctness otherwise and due marks be 
awarded to them. In class-X, while evaluating two competency-based questions, 
please try to understand given answer and even if reply is not from marking scheme 
but correct competency is enumerated by the candidate, due marks should be 
awarded.  
4  The Marking scheme carries only suggested value points for the answers 
These are in the nature of Guidelines only and do not constitute the complete answer. The 
students can have their own expression and if the expression is correct, the due marks 
should be awarded accordingly. 
5  The Head-Examiner must go through the first five answer books evaluated by each 
evaluator on the first day, to ensure that evaluation has been carried out as per the 
instructions given in the Marking Scheme. If there is any variation, the same should be 
zero after delibration and discussion. The remaining answer books meant for evaluation 
shall be given only after ensuring that there is no significant variation in the marking of 
individual evaluators. 
6  Evaluators will mark( v ) wherever answer is correct. For wrong answer CROSS ‘X” be 
marked. Evaluators will not put right ( ?)while evaluating which gives an impression that 
answer is correct and no marks are awarded. This is most common mistake which 
evaluators are committing. 
7  If a question has parts, please award marks on the right-hand side for each part. Marks 
awarded for different parts of the question should then be totaled up and written in the left-
hand margin and encircled. This may be followed strictly. 
XII_044_57/1/1 Biology # Page-2 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8  If a question does not have any parts, marks must be awarded in the left-hand margin and 
encircled. This may also be followed strictly. 
9  If a student has attempted an extra question, answer of the question deserving more 
marks should be retained and the other answer scored out with a note “Extra Question”. 
10  No marks to be deducted for the cumulative effect of an error. It should be penalized only 
once. 
11  A full scale of marks 0-70 has to be used. Please do not hesitate to award full marks if the 
answer deserves it. 
12  Every examiner has to necessarily do evaluation work for full working hours i.e., 8 hours 
every day and evaluate 20 answer books per day in main subjects and 25 answer books 
per day in other subjects (Details are given in Spot Guidelines). 
13  Ensure that you do not make the following common types of errors committed by the 
Examiner in the past:- 
? Leaving answer or part thereof unassessed in an answer book. 
? Giving more marks for an answer than assigned to it. 
? Wrong totaling of marks awarded on an answer. 
? Wrong transfer of marks from the inside pages of the answer book to the title page. 
? Wrong question wise totaling on the title page. 
? Wrong totaling of marks of the two columns on the title page. 
? Wrong grand total. 
? Marks in words and figures not tallying/not same. 
? Wrong transfer of marks from the answer book to online award list. 
? Answers marked as correct, but marks not awarded. (Ensure that the right tick mark is 
correctly and clearly indicated. It should merely be a line. Same is with the X for 
incorrect answer.) 
? Half or a part of answer marked correct and the rest as wrong, but no marks awarded.  
14  While evaluating the answer books if the answer is found to be totally incorrect, it should 
be marked as cross (X) and awarded zero (0)Marks. 
15  Any un assessed portion, non-carrying over of marks to the title page, or totalling error 
detected by the candidate shall damage the prestige of all the personnel engaged in the 
evaluation work as also of the Board. Hence, in order to uphold the prestige of all 
concerned, it is again reiterated that the instructions be followed meticulously and 
judiciously. 
16  The Examiners should acquaint themselves with the guidelines given in the “Guidelines 
for spot Evaluation” before starting the actual evaluation. 
17  Every Examiner shall also ensure that all the answers are evaluated, marks carried over to 
the title page, correctly totalled and written in figures and words. 
18  The candidates are entitled to obtain photocopy of the Answer Book on request on 
payment of the prescribed processing fee. All Examiners/Additional Head Examiners/Head 
Examiners are once again reminded that they must ensure that evaluation is carried out 
strictly as per value points for each answer as given in the Marking Scheme. 
XII_044_57/1/1 Biology # Page-3 
  
 
MARKING SCHEME 
Senior Secondary School Examination, 2023 
BIOLOGY (Subject Code – 044) 
[ Paper Code:57/1/1] 
                    Maximum Marks: 70 
Q. 
No. 
EXPECTED ANSWER / VALUE POINTS 
Marks Total 
Marks 
 SECTION A   
1. (b) / (ii) and (iv) 1 1 
2. (c) / X = Promoter, Y = Sigma factor,   Z = RNA polymerase. 1 1 
3. (a) / Declining population. 1 1 
4. (a) / Point (i) 1 1 
5. (d) / P - (iii), Q - (i), R- (ii), S- (iv) 1 1 
6. (c) / 1 and 3 1 1 
7. 
(c) / Directional selection as giraffes with longer neck lengths are selected 
// 
(d)/Stabilizing selection as giraffe with medium neck lengths are selected. 
1 
// 
1 
 
 
1 
8. (c) / 1300 1 1 
9. (a) /  P– (ii), Q – (iv), R – (iii), S – (i) 1 1 
10. (c) / Leydig cells – Androgen – Initiate the production of sperms. 1 1 
11. (b) / Salmonella typhimurium. 1 1 
12. (d) / Dr. R.A. Mashelkar. 1 1 
13. (c) / A is true, but R is false. 1 1 
14. (a) / A and R are true and R is  the correct explanation of A. 1 1 
15. (c) / A is true , but R is false. 1 1 
16. (a) / A and R are true and R is correct explanation of A. 1 1 
 SECTION B   
17. (a) Blastocyst   
(b)  Uterine wall/endometrium/innermost layer of uterine wall. 
(c) (Outer layer/trophoblast) ‘X’- helps in implantation in uterus/attachment to  
      endometrium. 
(Inner cell mass) ‘Y’- gets differentiated into embryo. 
½ 
½ 
½ 
 
½ 
 
 
 
 
 
2 
18. (a) From micropylar end, through the synergids (filiform apparatus)/filiform (within 
synergids) apparatus  guides the entry of pollen tube 
(b) One male nucleus fuses with two polar nuclei to form Primary endosperm nucleus  
and termed triple fusion, other male nucleus fuses with egg cell nucleus to form 
zygote i.e. undergoes Syngamy 
½×2 
 
 
½×2 
 
 
2 
19. (a)    
(i) ‘A; Circular DNA/Plasmid 
     ‘B’ Bacteriophage  
    (ii)(Plasmid)-Can carry foreign gene into the host cell/acts as cloning vector/has  
          selectable marker/   independent of the control of chromosomal DNA/ high 
copy number 
        (Bacteriophage) -Cloning vector have the ability to replicate in bacterial cells /    
     independent of the control of chromosomal DNA / high copy number per cell. 
                                                     OR 
(b) Treating bacteria with specific concentration of calcium (ions)which increases the  
 
½ 
½ 
 
½ 
 
 
½ 
 
 
 
 
 
 
 
 
 
 
 
 
XII_044_57/1/1 Biology # Page-4 
  
 
 efficiency with which DNA enters the bacteria through pores in its cell  
 wall ,recombinant DNA can then be forced into such cells by incubating the cells 
with recombinant DNA on ice, followed by placing them briefly at 42
0
C (heat shock), 
then putting them back on ice. 
 
 
½×4 
 
 
2 
20. •  Doesn’t take into account same species belonging to two or more trophic levels. 
 
• Assumes a simple food chain which never exists in nature/does not accommodate a  
       food web. 
• Saprophytes are not given any place though they play an important ecological role. 
                            
                                                                                                     (Any two points) 
 
 
 
1 × 2 
 
 
 
 
 
 
 
2 
21. 2·4 percent 
 
8·1 percent share of the global species diversity                 
1 
 
1 
 
 
2 
 SECTION C   
22.     
  
 
 
 
 
 
 
½×6 
 
 
 
 
 
 
 
 
 
 
 
3 
 
23. (a) Recessive trait, both the parents in generation I do not express the trait yet it 
appears in the progeny.   
 
(b) Autosomal trait, both male and females have equal chances of getting the trait. 
  
 
(c) Child ‘1’ : Aa/AA ,  Child ‘3’ : Aa      
                                                               //    
(a) Recessive trait, both the parents in generation I do not express the trait, yet it 
appears in the progeny.   
                   
(b) Sex linked trait, comparatively more male are getting affected.  
 
(c)   Child ‘1’  :   XY,                      Child ‘3’:  X ’ X(carrier) 
 ½×2 
 
 
½ × 2 
 
 
½ × 2 
   // 
 
½ × 2 
 
½ × 2 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3 
24. (a) They have the ability of self-renewal / to divide, and differentiate into any  
      kind of cell/tissue/organ.  
 
(b) – Inner cell mass of blastocyst / umbilical cord / Bone marrow  
                                                                                        (or any other correct source)  
 
½ × 2 
 
 
 
1 
 
 
 
 
 
 
 
XII_044_57/1/1 Biology # Page-5 
  
 
                                                                                                 (Any one) 
(c)  Diabetes treatment via forming islets of Langerhans, 
      Restoration of vision by injecting stem cells, to treat rheumatoid arthritis, reduces 
pancreatic cancer, to treat genetic disorder like cystic fibrosis, spinal cord injurie, 
heart disease, any other correct application 
                                                                                                (Any two) 
 
 
½ × 2 
 
 
 
 
3 
25. (a)   
  
S. 
No. 
Malignant tumor Benign tumor 
1 Cells grow very rapidly and 
invade and damage the  
      surrounding normal tissue. 
Comparatively slow growth and remain 
confined to their original location and do 
not spread to other parts of the body 
2 Show metastasis   Do not show metastasis 
(Any one difference) 
 
 
(b)• Metastasis 
 
   • Cells from these tumors slough off and reach distant sites through blood,     
      wherever they get lodged in the body they start a new tumor there.                                                                  
 
 
 
1 
 
 
 
 
 
 
 
 
1 
 
½ × 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3 
26. (a)  Primary Sludge: All the solids that settle down, during the primary treatment of 
sewage water.  
 
(b) Activated Sludge: Produced during the secondary treatment or biological  
      treatment of sewage, primary effluent + aerobic microbes flocs (bacteria and  
      fungus) – get converted to a sediment whose BOD has reduced significantly.  
 
(c) Anaerobic sludge digesters: Large tanks where activated sludge is treated with 
anaerobic bacteria which digest the bacteria and fungi, and produce a mixture of CH4, 
H2S and CO2/ Biogas         
½ × 2 
 
 
½ × 2 
 
 
½ × 2 
 
 
 
 
 
 
 
 
3 
27. (a) Dryopithecus, Ramapithecus  
 
(b) Time period : 2 million years ago  
      Place : East African grasslands   
 
(c) 
        
Homo habilis Homo erectus 
Brain capacity 
between 650 – 800 cc 
Brain capacity 900 cc 
probably did not eat 
meat. 
probably ate meat 
 
½+½ 
 
½ 
½ 
 
 
 
 
 
½ 
 
½ 
 
 
 
 
 
 
 
 
 
 
 
 
3 
28. (a) (i) (1) ZIFT : Zygote intrafallopian transfer.  
          (2) ICSI : Intracytoplasmic sperm injection. 
          (3) IUT : Intra uterine transfer.   
          (4) GIFT : Gamete intrafallopian transfer.   
      
 
 
 
½ × 4