All Correction In Biology NCERT ( NCERT Update CLASS 12th ) NEET Notes | EduRev

Created by: Krishna Chaudhary

NEET : All Correction In Biology NCERT ( NCERT Update CLASS 12th ) NEET Notes | EduRev

 Page 1


Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
1 16
1.Reproduction in 
Organism
Budding and gemmule formation are the common asexual methods 
seen in animals.
Budding and gemmule formation are the common asexual methods seen in lower 
animals.
2 51 3.Human Reproduction
3 58 4.Reproductive Health
Statutory ban on amniocentesis (a foetal sex determination test based 
on the chromosomal pattern in the amniotic fluid surrounding the 
developing embryo) for sex-determination to legally check increasing 
female foeticides, masssive child immunisation, etc., are some 
programmes that merit mention in this connection. 
Statutory ban on amniocentesis for sex-determination to legally check increasing 
menace female foeticides, masssive child immunisation, etc., are some programmes 
that merit mention in this connection. In aminocentesis some of the amniotic fluid 
of the developing foetus is taken to analyse the fetal cells and dissolved 
substances. This procedure is used to test for the presence of certain genetic 
disorders such as, down syndrome, haemoplilia, sickle-cell anemia, etc., 
determine the survivability of the foetus. 
4 59 4.Reproductive Health
The world population which was around 2 billion (2000 million) in 1900 
rocketed to about 6 billion by 2000. 
The world population which was around 2 billion (2000 million) in 1900 rocketed to 
about 6 billion by 2000 and 7.2 billion in 2011.
5 59 4.Reproductive Health
Out population which was approximately 350 million at the time of our 
independence reached close to the billion mark by 2000 and crossed 1 
billion in May 2000. 
Our population which was approximately 350 million at the time of our independence 
reached close to the billion mark by 2000 and crossed 1.2 billion in May 2011.  
6 59 4.Reproductive Health
According to the 2001 census report, the population growth rate was 
still around 1.7 percent, i.e. 17/1000/year,  a rate at which our 
population could double in 33 years.
According to the 2011 census report, the population growth rate was less than 2 
percent, i.e. 20/1000/year,  a rate at which our population could increase rapidly.
7 62 4.Reproductive Health
8 63 4.Reproductive Health
Sexually Transmitted Diseases (STDs)
Diseases or infections which are transmitted through sexual 
intercourse are collectively called sexually transmitted diseases (STD) 
or venereal diseases (VD) or reprodcutive tract infections (RTI). 
Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, 
trichomoniasis, hepatitis-B and of course , the most discussed infection 
in the recent years, HIV leading to AIDS are some of the common 
STDs. 
Sexually Transmitted Infections (STIs)
Diseases or infections which are transmitted through sexual intercourse are 
collectively called sexually transmitted Infections (STI) or venereal diseases (VD) 
or reprodcutive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, 
chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course , the most 
discussed infection in the recent years, HIV leading to AIDS are some of the common 
STIs.
9 96
6.Molecular Basis of 
Inheritance
A nitrogenous base is linked to the pentose sugar through a N-
glycosidic linkage to form a nucleoside
A nitrogenous base is linked to the OH of 1'C pentose sugar through a N-glycosidic 
linkage to form a nucleoside
NCERT UPDATE XII
Menstrual Hygiene
Maintenance of hygiene and sanitation during  menstruation is very important. Take bath and clean yourself regulary. 
Use sanitary napkins or clean homemade pads. Change sanitary napkins or homemade pads after every 4-5 hrs as 
per the requirement. Dispose of the used sanitary napkins properly wrapping it with a used paper.Do not throw the 
used napkins in the drainpipe of toilets or in the open area. After handling the napkin wash hands with soap.
The Medical Termination of Pregnancy (Amendment) Act, 2017 was enacted by the government of India with the 
intension of reducing the incidence of illegal abortion and consequent maternal mortality and morbidity. According to 
this Act, a pregnancy may be terminated on certain considered grounds within the first 12 weeks of pregnancy on the 
opinion of one registered medical practitioner. If the pregnancy has lasted more than  12 weeks, but fewer than 24 
weeks, two registered medical practitioners must be of the opinion, formed  in good faith, that the required  ground 
exist. The grounds for such termination of pregnancies are :
(i) The continuation of the pregnancy would involve a risk to the life of the pregnant woman or of grave injury physical 
or mental health : or 
(ii) There is a substantial risk that of the child were born, it would suffer from such physical or mental abnormalities  
as to be seriously handicapped.
Page 2


Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
1 16
1.Reproduction in 
Organism
Budding and gemmule formation are the common asexual methods 
seen in animals.
Budding and gemmule formation are the common asexual methods seen in lower 
animals.
2 51 3.Human Reproduction
3 58 4.Reproductive Health
Statutory ban on amniocentesis (a foetal sex determination test based 
on the chromosomal pattern in the amniotic fluid surrounding the 
developing embryo) for sex-determination to legally check increasing 
female foeticides, masssive child immunisation, etc., are some 
programmes that merit mention in this connection. 
Statutory ban on amniocentesis for sex-determination to legally check increasing 
menace female foeticides, masssive child immunisation, etc., are some programmes 
that merit mention in this connection. In aminocentesis some of the amniotic fluid 
of the developing foetus is taken to analyse the fetal cells and dissolved 
substances. This procedure is used to test for the presence of certain genetic 
disorders such as, down syndrome, haemoplilia, sickle-cell anemia, etc., 
determine the survivability of the foetus. 
4 59 4.Reproductive Health
The world population which was around 2 billion (2000 million) in 1900 
rocketed to about 6 billion by 2000. 
The world population which was around 2 billion (2000 million) in 1900 rocketed to 
about 6 billion by 2000 and 7.2 billion in 2011.
5 59 4.Reproductive Health
Out population which was approximately 350 million at the time of our 
independence reached close to the billion mark by 2000 and crossed 1 
billion in May 2000. 
Our population which was approximately 350 million at the time of our independence 
reached close to the billion mark by 2000 and crossed 1.2 billion in May 2011.  
6 59 4.Reproductive Health
According to the 2001 census report, the population growth rate was 
still around 1.7 percent, i.e. 17/1000/year,  a rate at which our 
population could double in 33 years.
According to the 2011 census report, the population growth rate was less than 2 
percent, i.e. 20/1000/year,  a rate at which our population could increase rapidly.
7 62 4.Reproductive Health
8 63 4.Reproductive Health
Sexually Transmitted Diseases (STDs)
Diseases or infections which are transmitted through sexual 
intercourse are collectively called sexually transmitted diseases (STD) 
or venereal diseases (VD) or reprodcutive tract infections (RTI). 
Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, 
trichomoniasis, hepatitis-B and of course , the most discussed infection 
in the recent years, HIV leading to AIDS are some of the common 
STDs. 
Sexually Transmitted Infections (STIs)
Diseases or infections which are transmitted through sexual intercourse are 
collectively called sexually transmitted Infections (STI) or venereal diseases (VD) 
or reprodcutive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, 
chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course , the most 
discussed infection in the recent years, HIV leading to AIDS are some of the common 
STIs.
9 96
6.Molecular Basis of 
Inheritance
A nitrogenous base is linked to the pentose sugar through a N-
glycosidic linkage to form a nucleoside
A nitrogenous base is linked to the OH of 1'C pentose sugar through a N-glycosidic 
linkage to form a nucleoside
NCERT UPDATE XII
Menstrual Hygiene
Maintenance of hygiene and sanitation during  menstruation is very important. Take bath and clean yourself regulary. 
Use sanitary napkins or clean homemade pads. Change sanitary napkins or homemade pads after every 4-5 hrs as 
per the requirement. Dispose of the used sanitary napkins properly wrapping it with a used paper.Do not throw the 
used napkins in the drainpipe of toilets or in the open area. After handling the napkin wash hands with soap.
The Medical Termination of Pregnancy (Amendment) Act, 2017 was enacted by the government of India with the 
intension of reducing the incidence of illegal abortion and consequent maternal mortality and morbidity. According to 
this Act, a pregnancy may be terminated on certain considered grounds within the first 12 weeks of pregnancy on the 
opinion of one registered medical practitioner. If the pregnancy has lasted more than  12 weeks, but fewer than 24 
weeks, two registered medical practitioners must be of the opinion, formed  in good faith, that the required  ground 
exist. The grounds for such termination of pregnancies are :
(i) The continuation of the pregnancy would involve a risk to the life of the pregnant woman or of grave injury physical 
or mental health : or 
(ii) There is a substantial risk that of the child were born, it would suffer from such physical or mental abnormalities  
as to be seriously handicapped.
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
10 96
6.Molecular Basis of 
Inheritance
When a phosphate group is linked to 5' -OH of a nucleoside through 
phosphoester linkage,
When a phosphate group is linked to OH of 5'C of a nucleoside through 
phosphoester linkage,
11 97
6.Molecular Basis of 
Inheritance
Similarly, at the other end of the polymer the ribose has a free 3' -OH 
group which is referred to as 3'- end of the polynucleotide chain.
Similarly, at the other end of the polymer the sugar has a free 3' -OH group which is 
referred to as 3'- end of the polynucleotide chain.
12 107
6.Molecular Basis of 
Inheritance
Except the adenosine now forms base pair with uracil instead of 
thymine. 
Except the adenosine complements now forms base pair with uracil instead of 
thymine. 
13 111
6.Molecular Basis of 
Inheritance
The process of translation requires transfer of genetic information from 
a polymer of nucleotides to a polymer of amino acids.
The process of translation requires transfer of genetic information from a polymer of 
nucleotides to from a polymer of amino acids.
14 112
6.Molecular Basis of 
Inheritance
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons 
do not code for any amino acids, hence they function as stop codons.
(ii)	 One codon codes for only one amino acid, hence, it is 
unambiguous and specific.
(iii)	 Some amino acids are coded by more than one codon, hence the 
code is degenerate.
(iv)	 The codon is read in mRNA in a contiguous fashion. There are no 
punctuations.
(v)	 The code is nearly universal: for example, from bacteria to human 
UUU would code for Phenylalanine (phe). Some exceptions to this rule 
have been found in mitochondrial codons, and in some protozoans.
(vi)	 AUG has dual functions. It codes for Methionine (met) , and it also 
act as initiator codon.
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons do not code 
for any amino acids, hence they function as stop codons.
(ii)	 Some amino acids are coded by more than one codon, hence the code is 
degenerate.
(iii)	 The codon is read in mRNA in a contiguous fashion. There are no punctuations.
(iv)	 The code is nearly universal: for example, from bacteria to human UUU would 
code for Phenylalanine (phe). Some exceptions to this rule have been found in 
mitochondrial codons, and in some protozoans.
(v)	 AUG has dual functions. It codes for Methionine (met) , and it also act as initiator 
codon.
(vi) UAA, UAG, UGA are stop terminator codons.
15 114
6.Molecular Basis of 
Inheritance
16 141 7.Evolution
Pre-historic cave art developed about 18,000 years ago. Agriculture 
came around 10,000 years back and human settlements started.
Pre-historic cave art developed about 18,000 years ago One such cave paintings 
by Pre-historic humans can be seen at Bhimbetka rock shelter in Raisen district 
of Madhya Pradesh. Agriculture came around 10,000 years back and human 
settlements started.
17 158
8.Human Health and 
Disease
Page 3


Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
1 16
1.Reproduction in 
Organism
Budding and gemmule formation are the common asexual methods 
seen in animals.
Budding and gemmule formation are the common asexual methods seen in lower 
animals.
2 51 3.Human Reproduction
3 58 4.Reproductive Health
Statutory ban on amniocentesis (a foetal sex determination test based 
on the chromosomal pattern in the amniotic fluid surrounding the 
developing embryo) for sex-determination to legally check increasing 
female foeticides, masssive child immunisation, etc., are some 
programmes that merit mention in this connection. 
Statutory ban on amniocentesis for sex-determination to legally check increasing 
menace female foeticides, masssive child immunisation, etc., are some programmes 
that merit mention in this connection. In aminocentesis some of the amniotic fluid 
of the developing foetus is taken to analyse the fetal cells and dissolved 
substances. This procedure is used to test for the presence of certain genetic 
disorders such as, down syndrome, haemoplilia, sickle-cell anemia, etc., 
determine the survivability of the foetus. 
4 59 4.Reproductive Health
The world population which was around 2 billion (2000 million) in 1900 
rocketed to about 6 billion by 2000. 
The world population which was around 2 billion (2000 million) in 1900 rocketed to 
about 6 billion by 2000 and 7.2 billion in 2011.
5 59 4.Reproductive Health
Out population which was approximately 350 million at the time of our 
independence reached close to the billion mark by 2000 and crossed 1 
billion in May 2000. 
Our population which was approximately 350 million at the time of our independence 
reached close to the billion mark by 2000 and crossed 1.2 billion in May 2011.  
6 59 4.Reproductive Health
According to the 2001 census report, the population growth rate was 
still around 1.7 percent, i.e. 17/1000/year,  a rate at which our 
population could double in 33 years.
According to the 2011 census report, the population growth rate was less than 2 
percent, i.e. 20/1000/year,  a rate at which our population could increase rapidly.
7 62 4.Reproductive Health
8 63 4.Reproductive Health
Sexually Transmitted Diseases (STDs)
Diseases or infections which are transmitted through sexual 
intercourse are collectively called sexually transmitted diseases (STD) 
or venereal diseases (VD) or reprodcutive tract infections (RTI). 
Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, 
trichomoniasis, hepatitis-B and of course , the most discussed infection 
in the recent years, HIV leading to AIDS are some of the common 
STDs. 
Sexually Transmitted Infections (STIs)
Diseases or infections which are transmitted through sexual intercourse are 
collectively called sexually transmitted Infections (STI) or venereal diseases (VD) 
or reprodcutive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, 
chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course , the most 
discussed infection in the recent years, HIV leading to AIDS are some of the common 
STIs.
9 96
6.Molecular Basis of 
Inheritance
A nitrogenous base is linked to the pentose sugar through a N-
glycosidic linkage to form a nucleoside
A nitrogenous base is linked to the OH of 1'C pentose sugar through a N-glycosidic 
linkage to form a nucleoside
NCERT UPDATE XII
Menstrual Hygiene
Maintenance of hygiene and sanitation during  menstruation is very important. Take bath and clean yourself regulary. 
Use sanitary napkins or clean homemade pads. Change sanitary napkins or homemade pads after every 4-5 hrs as 
per the requirement. Dispose of the used sanitary napkins properly wrapping it with a used paper.Do not throw the 
used napkins in the drainpipe of toilets or in the open area. After handling the napkin wash hands with soap.
The Medical Termination of Pregnancy (Amendment) Act, 2017 was enacted by the government of India with the 
intension of reducing the incidence of illegal abortion and consequent maternal mortality and morbidity. According to 
this Act, a pregnancy may be terminated on certain considered grounds within the first 12 weeks of pregnancy on the 
opinion of one registered medical practitioner. If the pregnancy has lasted more than  12 weeks, but fewer than 24 
weeks, two registered medical practitioners must be of the opinion, formed  in good faith, that the required  ground 
exist. The grounds for such termination of pregnancies are :
(i) The continuation of the pregnancy would involve a risk to the life of the pregnant woman or of grave injury physical 
or mental health : or 
(ii) There is a substantial risk that of the child were born, it would suffer from such physical or mental abnormalities  
as to be seriously handicapped.
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
10 96
6.Molecular Basis of 
Inheritance
When a phosphate group is linked to 5' -OH of a nucleoside through 
phosphoester linkage,
When a phosphate group is linked to OH of 5'C of a nucleoside through 
phosphoester linkage,
11 97
6.Molecular Basis of 
Inheritance
Similarly, at the other end of the polymer the ribose has a free 3' -OH 
group which is referred to as 3'- end of the polynucleotide chain.
Similarly, at the other end of the polymer the sugar has a free 3' -OH group which is 
referred to as 3'- end of the polynucleotide chain.
12 107
6.Molecular Basis of 
Inheritance
Except the adenosine now forms base pair with uracil instead of 
thymine. 
Except the adenosine complements now forms base pair with uracil instead of 
thymine. 
13 111
6.Molecular Basis of 
Inheritance
The process of translation requires transfer of genetic information from 
a polymer of nucleotides to a polymer of amino acids.
The process of translation requires transfer of genetic information from a polymer of 
nucleotides to from a polymer of amino acids.
14 112
6.Molecular Basis of 
Inheritance
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons 
do not code for any amino acids, hence they function as stop codons.
(ii)	 One codon codes for only one amino acid, hence, it is 
unambiguous and specific.
(iii)	 Some amino acids are coded by more than one codon, hence the 
code is degenerate.
(iv)	 The codon is read in mRNA in a contiguous fashion. There are no 
punctuations.
(v)	 The code is nearly universal: for example, from bacteria to human 
UUU would code for Phenylalanine (phe). Some exceptions to this rule 
have been found in mitochondrial codons, and in some protozoans.
(vi)	 AUG has dual functions. It codes for Methionine (met) , and it also 
act as initiator codon.
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons do not code 
for any amino acids, hence they function as stop codons.
(ii)	 Some amino acids are coded by more than one codon, hence the code is 
degenerate.
(iii)	 The codon is read in mRNA in a contiguous fashion. There are no punctuations.
(iv)	 The code is nearly universal: for example, from bacteria to human UUU would 
code for Phenylalanine (phe). Some exceptions to this rule have been found in 
mitochondrial codons, and in some protozoans.
(v)	 AUG has dual functions. It codes for Methionine (met) , and it also act as initiator 
codon.
(vi) UAA, UAG, UGA are stop terminator codons.
15 114
6.Molecular Basis of 
Inheritance
16 141 7.Evolution
Pre-historic cave art developed about 18,000 years ago. Agriculture 
came around 10,000 years back and human settlements started.
Pre-historic cave art developed about 18,000 years ago One such cave paintings 
by Pre-historic humans can be seen at Bhimbetka rock shelter in Raisen district 
of Madhya Pradesh. Agriculture came around 10,000 years back and human 
settlements started.
17 158
8.Human Health and 
Disease
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
18 159
8.Human Health and 
Disease
Drugs like barbiturates, amphetamines, benzodiazepines, lysergic acid 
diethyl amides (LSD), and other similar drugs, that are normally used 
as medicines to help patients cope with mental illnesses like 
depression and insomnia, are often abused.
Drugs like barbiturates, amphetamines, benzodiazepines, and other similar drugs, 
that are normally used as medicines to help patients cope with mental illnesses like 
depression and insomnia, are often abused.
19 176
9.Strategies for 
Enhancement in Food 
Production
Microbes are being grown on an industrial scale as source of good 
protein. Microbes like Spirulina can be grown easily on materials like 
waste water from potato processing plants (containing starch), straw, 
molasses, animal manure and even sewage, to produce large 
quantities and can serve as food rich in protein, minerals, fats, 
carbohydrate and vitamins. Incidentally such utilisation also reduces 
environmental pollution.
Microbes are being grown on an industrial scale as source of good protein. (Blue-
green algae) Microbes like Spirulina can be grown easily on materials like waste 
water from potato processing plants (containing starch), straw, molasses, animal 
manure and even sewage, to produce large quantities and can serve as food rich in 
protein, minerals, fats, carbohydrate and vitamins. Incidentally such utilisation also 
reduces environmental pollution.
20 176
9.Strategies for 
Enhancement in Food 
Production
It has been calculated that a 250 Kg cow produces 200 g of protein per 
day. In the same period, 250g of a micro-organism like Methylophilus 
methylotrophus, because of its high rate of biomass production and 
growth, can be expected to produce 25 tonnes of protein.
Certain bacterial species like Methylophilus methylotrophus, because of its high 
rate of biomass production and growth, can be expected to produce 25 tonnes of 
protein.
21 179
10.Microbes in Human 
Welfare
Microbes are diverse– protozoa, bacteria, fungi and microscopic plants 
viruses, viroids and also prions that are proteinacious infectious 
agents.
Microbes are diverse– protozoa, bacteria, fungi and microscopic animal and plant 
viruses, viroids and also prions that are proteinacious infectious agents.
22 194
11.Biotechnology: 
Principles and 
Processes
(ii)	 Maintenance of sterile (microbial contamination-free) ambience in 
chemical engineering processes to enable growth of only the desired 
microbe/eukaryotic cell in large quantities for the manufacture of 
biotechnological products like antibiotics, vaccines, enzymes, etc.
(ii)Bioprocess engineering
Maintenance of sterile (microbial contamination-free) ambience in chemical 
engineering processes to enable growth of only the desired microbe/eukaryotic cell in 
large quantities for the manufacture of biotechnological products like antibiotics, 
vaccines, enzymes, etc.
23 197
11.Biotechnology: 
Principles and 
Processes
24 199
11.Biotechnology: 
Principles and 
Processes
The recombinant plasmids will lose tetracycline resistance due to 
insertion of foreign DNA but can still be selected out from non-
recombinant ones by plating the transformants on ampicillin 
containing medium. 
The recombinant plasmids will lose tetracycline resistance due to insertion of foreign 
DNA but can still be selected out from non-recombinant ones by plating the 
transformants on tetracycline containing medium. 
25 200
11.Biotechnology: 
Principles and 
Processes
This results into inactivation of the enzyme, which is referred to as 
insertional inactivation.
This results into inactivation of the gene for synthesis of this enzyme, which is 
referred to as insertional inactivation.
26 208
12.Biotechnology and 
its Applications
(v)	 enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice. (v)	 enhanced nutritional value  food , e.g. golden rice i.e., Vitamin ‘A’ enriched rice.
27 209
12.Biotechnology and 
its Applications
The toxin is coded by a gene named cry. The toxin is coded by a gene crylAc named cry.
Page 4


Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
1 16
1.Reproduction in 
Organism
Budding and gemmule formation are the common asexual methods 
seen in animals.
Budding and gemmule formation are the common asexual methods seen in lower 
animals.
2 51 3.Human Reproduction
3 58 4.Reproductive Health
Statutory ban on amniocentesis (a foetal sex determination test based 
on the chromosomal pattern in the amniotic fluid surrounding the 
developing embryo) for sex-determination to legally check increasing 
female foeticides, masssive child immunisation, etc., are some 
programmes that merit mention in this connection. 
Statutory ban on amniocentesis for sex-determination to legally check increasing 
menace female foeticides, masssive child immunisation, etc., are some programmes 
that merit mention in this connection. In aminocentesis some of the amniotic fluid 
of the developing foetus is taken to analyse the fetal cells and dissolved 
substances. This procedure is used to test for the presence of certain genetic 
disorders such as, down syndrome, haemoplilia, sickle-cell anemia, etc., 
determine the survivability of the foetus. 
4 59 4.Reproductive Health
The world population which was around 2 billion (2000 million) in 1900 
rocketed to about 6 billion by 2000. 
The world population which was around 2 billion (2000 million) in 1900 rocketed to 
about 6 billion by 2000 and 7.2 billion in 2011.
5 59 4.Reproductive Health
Out population which was approximately 350 million at the time of our 
independence reached close to the billion mark by 2000 and crossed 1 
billion in May 2000. 
Our population which was approximately 350 million at the time of our independence 
reached close to the billion mark by 2000 and crossed 1.2 billion in May 2011.  
6 59 4.Reproductive Health
According to the 2001 census report, the population growth rate was 
still around 1.7 percent, i.e. 17/1000/year,  a rate at which our 
population could double in 33 years.
According to the 2011 census report, the population growth rate was less than 2 
percent, i.e. 20/1000/year,  a rate at which our population could increase rapidly.
7 62 4.Reproductive Health
8 63 4.Reproductive Health
Sexually Transmitted Diseases (STDs)
Diseases or infections which are transmitted through sexual 
intercourse are collectively called sexually transmitted diseases (STD) 
or venereal diseases (VD) or reprodcutive tract infections (RTI). 
Gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, 
trichomoniasis, hepatitis-B and of course , the most discussed infection 
in the recent years, HIV leading to AIDS are some of the common 
STDs. 
Sexually Transmitted Infections (STIs)
Diseases or infections which are transmitted through sexual intercourse are 
collectively called sexually transmitted Infections (STI) or venereal diseases (VD) 
or reprodcutive tract infections (RTI). Gonorrhoea, syphilis, genital herpes, 
chlamydiasis, genital warts, trichomoniasis, hepatitis-B and of course , the most 
discussed infection in the recent years, HIV leading to AIDS are some of the common 
STIs.
9 96
6.Molecular Basis of 
Inheritance
A nitrogenous base is linked to the pentose sugar through a N-
glycosidic linkage to form a nucleoside
A nitrogenous base is linked to the OH of 1'C pentose sugar through a N-glycosidic 
linkage to form a nucleoside
NCERT UPDATE XII
Menstrual Hygiene
Maintenance of hygiene and sanitation during  menstruation is very important. Take bath and clean yourself regulary. 
Use sanitary napkins or clean homemade pads. Change sanitary napkins or homemade pads after every 4-5 hrs as 
per the requirement. Dispose of the used sanitary napkins properly wrapping it with a used paper.Do not throw the 
used napkins in the drainpipe of toilets or in the open area. After handling the napkin wash hands with soap.
The Medical Termination of Pregnancy (Amendment) Act, 2017 was enacted by the government of India with the 
intension of reducing the incidence of illegal abortion and consequent maternal mortality and morbidity. According to 
this Act, a pregnancy may be terminated on certain considered grounds within the first 12 weeks of pregnancy on the 
opinion of one registered medical practitioner. If the pregnancy has lasted more than  12 weeks, but fewer than 24 
weeks, two registered medical practitioners must be of the opinion, formed  in good faith, that the required  ground 
exist. The grounds for such termination of pregnancies are :
(i) The continuation of the pregnancy would involve a risk to the life of the pregnant woman or of grave injury physical 
or mental health : or 
(ii) There is a substantial risk that of the child were born, it would suffer from such physical or mental abnormalities  
as to be seriously handicapped.
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
10 96
6.Molecular Basis of 
Inheritance
When a phosphate group is linked to 5' -OH of a nucleoside through 
phosphoester linkage,
When a phosphate group is linked to OH of 5'C of a nucleoside through 
phosphoester linkage,
11 97
6.Molecular Basis of 
Inheritance
Similarly, at the other end of the polymer the ribose has a free 3' -OH 
group which is referred to as 3'- end of the polynucleotide chain.
Similarly, at the other end of the polymer the sugar has a free 3' -OH group which is 
referred to as 3'- end of the polynucleotide chain.
12 107
6.Molecular Basis of 
Inheritance
Except the adenosine now forms base pair with uracil instead of 
thymine. 
Except the adenosine complements now forms base pair with uracil instead of 
thymine. 
13 111
6.Molecular Basis of 
Inheritance
The process of translation requires transfer of genetic information from 
a polymer of nucleotides to a polymer of amino acids.
The process of translation requires transfer of genetic information from a polymer of 
nucleotides to from a polymer of amino acids.
14 112
6.Molecular Basis of 
Inheritance
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons 
do not code for any amino acids, hence they function as stop codons.
(ii)	 One codon codes for only one amino acid, hence, it is 
unambiguous and specific.
(iii)	 Some amino acids are coded by more than one codon, hence the 
code is degenerate.
(iv)	 The codon is read in mRNA in a contiguous fashion. There are no 
punctuations.
(v)	 The code is nearly universal: for example, from bacteria to human 
UUU would code for Phenylalanine (phe). Some exceptions to this rule 
have been found in mitochondrial codons, and in some protozoans.
(vi)	 AUG has dual functions. It codes for Methionine (met) , and it also 
act as initiator codon.
The salient features of genetic code are as follows:
(i)	 The codon is triplet. 61 codons code for amino acids and 3 codons do not code 
for any amino acids, hence they function as stop codons.
(ii)	 Some amino acids are coded by more than one codon, hence the code is 
degenerate.
(iii)	 The codon is read in mRNA in a contiguous fashion. There are no punctuations.
(iv)	 The code is nearly universal: for example, from bacteria to human UUU would 
code for Phenylalanine (phe). Some exceptions to this rule have been found in 
mitochondrial codons, and in some protozoans.
(v)	 AUG has dual functions. It codes for Methionine (met) , and it also act as initiator 
codon.
(vi) UAA, UAG, UGA are stop terminator codons.
15 114
6.Molecular Basis of 
Inheritance
16 141 7.Evolution
Pre-historic cave art developed about 18,000 years ago. Agriculture 
came around 10,000 years back and human settlements started.
Pre-historic cave art developed about 18,000 years ago One such cave paintings 
by Pre-historic humans can be seen at Bhimbetka rock shelter in Raisen district 
of Madhya Pradesh. Agriculture came around 10,000 years back and human 
settlements started.
17 158
8.Human Health and 
Disease
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
18 159
8.Human Health and 
Disease
Drugs like barbiturates, amphetamines, benzodiazepines, lysergic acid 
diethyl amides (LSD), and other similar drugs, that are normally used 
as medicines to help patients cope with mental illnesses like 
depression and insomnia, are often abused.
Drugs like barbiturates, amphetamines, benzodiazepines, and other similar drugs, 
that are normally used as medicines to help patients cope with mental illnesses like 
depression and insomnia, are often abused.
19 176
9.Strategies for 
Enhancement in Food 
Production
Microbes are being grown on an industrial scale as source of good 
protein. Microbes like Spirulina can be grown easily on materials like 
waste water from potato processing plants (containing starch), straw, 
molasses, animal manure and even sewage, to produce large 
quantities and can serve as food rich in protein, minerals, fats, 
carbohydrate and vitamins. Incidentally such utilisation also reduces 
environmental pollution.
Microbes are being grown on an industrial scale as source of good protein. (Blue-
green algae) Microbes like Spirulina can be grown easily on materials like waste 
water from potato processing plants (containing starch), straw, molasses, animal 
manure and even sewage, to produce large quantities and can serve as food rich in 
protein, minerals, fats, carbohydrate and vitamins. Incidentally such utilisation also 
reduces environmental pollution.
20 176
9.Strategies for 
Enhancement in Food 
Production
It has been calculated that a 250 Kg cow produces 200 g of protein per 
day. In the same period, 250g of a micro-organism like Methylophilus 
methylotrophus, because of its high rate of biomass production and 
growth, can be expected to produce 25 tonnes of protein.
Certain bacterial species like Methylophilus methylotrophus, because of its high 
rate of biomass production and growth, can be expected to produce 25 tonnes of 
protein.
21 179
10.Microbes in Human 
Welfare
Microbes are diverse– protozoa, bacteria, fungi and microscopic plants 
viruses, viroids and also prions that are proteinacious infectious 
agents.
Microbes are diverse– protozoa, bacteria, fungi and microscopic animal and plant 
viruses, viroids and also prions that are proteinacious infectious agents.
22 194
11.Biotechnology: 
Principles and 
Processes
(ii)	 Maintenance of sterile (microbial contamination-free) ambience in 
chemical engineering processes to enable growth of only the desired 
microbe/eukaryotic cell in large quantities for the manufacture of 
biotechnological products like antibiotics, vaccines, enzymes, etc.
(ii)Bioprocess engineering
Maintenance of sterile (microbial contamination-free) ambience in chemical 
engineering processes to enable growth of only the desired microbe/eukaryotic cell in 
large quantities for the manufacture of biotechnological products like antibiotics, 
vaccines, enzymes, etc.
23 197
11.Biotechnology: 
Principles and 
Processes
24 199
11.Biotechnology: 
Principles and 
Processes
The recombinant plasmids will lose tetracycline resistance due to 
insertion of foreign DNA but can still be selected out from non-
recombinant ones by plating the transformants on ampicillin 
containing medium. 
The recombinant plasmids will lose tetracycline resistance due to insertion of foreign 
DNA but can still be selected out from non-recombinant ones by plating the 
transformants on tetracycline containing medium. 
25 200
11.Biotechnology: 
Principles and 
Processes
This results into inactivation of the enzyme, which is referred to as 
insertional inactivation.
This results into inactivation of the gene for synthesis of this enzyme, which is 
referred to as insertional inactivation.
26 208
12.Biotechnology and 
its Applications
(v)	 enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice. (v)	 enhanced nutritional value  food , e.g. golden rice i.e., Vitamin ‘A’ enriched rice.
27 209
12.Biotechnology and 
its Applications
The toxin is coded by a gene named cry. The toxin is coded by a gene crylAc named cry.
Sno.
Page 
No.
Topic Previous Content Content Added Updated Content
28 220
13.Organisms and 
Populations
perpetually rain-soaked Meghalaya forests, deep ocean trenches, 
torrential streams, permafrost polar regions, high mountain tops, boiling 
thermal springs, and stinking compost pits, to name a few. Even our 
intestine is a unique habitat for hundreds of species of microbes.
rain-soaked Meghalaya forests, deep ocean trenches, torrential streams, 
permafrost(snow laden) polar regions, high mountain tops, boiling thermal springs, 
and stinking compost pits, to name a few. Even our intestine is a unique habitat for 
hundreds of species of microbes.
29 222
13.Organisms and 
Populations
Water: Next to temperature, water is the most important factor 
influencing the life of organisms. In fact, life on earth originated in water 
and is unsustainable without water. Its availability is so limited in 
deserts that only special adaptations make it possible to live there
Water:  Water is another the most important factor influencing the life of organisms. 
In fact, life on earth originated in water and is unsustainable without water. Its 
availability is so limited in deserts that only special adaptations make it possible for 
organism to live there
30 224
13.Organisms and 
Populations
the organism has two other alternatives. the organism has two other alternatives for survival.
31 225
13.Organisms and 
Populations
their stomata arranged in deep pits to minimise water loss through 
transpiration. 
their stomata arranged in deep pits (sunken) to minimise water loss through 
transpiration. 
32 226
13.Organisms and 
Populations
If you had ever been to any high altitude place (>3,500m Rohtang Pass 
near Manali and Mansarovar,
If you had ever been to any high altitude place (>3,500m Rohtang Pass near Manali 
and Leh,
33 226
13.Organisms and 
Populations
How do they live under such crushing pressures and do they have any 
special enzymes? 
How do they live under such high pressures and do they have any special enzymes?
34 236
13.Organisms and 
Populations
as they move, stir up and flush out from the vegetation insects that 
otherwise might be difficult for the egrets to find and catch.
as they move, stir up and flush out insects from the vegetation that otherwise might 
be difficult for the egrets to find and catch.
35 250 14.Ecosystem
During succession some species colonise an area and their 
populations become more numerous, whereas populations of other 
species decline and even disappear.
During succession some species colonise an area and whereas populations of other 
species decline and even disappear.
36 250 14.Ecosystem
Succession is hence a process that starts where no living organisms 
are there
Succession is hence a process that starts in an area where no living organisms are 
there
37 253 14.Ecosystem
What is important is to appreciate that nutrients which are never lost 
from the ecosystems, they are recycled time and again indefinitely. 
What is important is to appreciate that nutrients which are never lost from the 
ecosystems, rather they are recycled time and again indefinitely. 
38 256 14.Ecosystem
SUMMARY
An ecosystem is a functional unit of nature and comprises abiotic and 
biotic components.
SUMMARY
An ecosystem is a structural and functional unit of nature and comprises abiotic and 
biotic components.
39 278
16.Environmental 
Issues
Burning reduces the volume of the wastes, although it is generally not 
burnt to completion and open dumps often serve as the breeding 
ground for rats and flies.
Burning reduces the volume of the wastes, although it is generally not completely 
burnt to completion and open dumps often serve as the breeding ground for rats and 
flies.
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