Thursday, March 15, 2012

NEWLY ADDED NCERT BIOLOGY MATERIAL

CLASS XI
Unit I: Chapter 2, Pg. 17 along with 1st para after the sixth line
Three-domain of life
The three-domain system has also been proposed that divides the Kingdom Monera into two domains,
leaving the remaining eukaryotic kingdoms in the third domain and there by a six kingdom classification.
You will learn about this system in detail at higher classes.
Unit I: Chapter 3, Pg. 40, after eighth line
Classification of angiosperms upto class and their characteristic features
The dicotyledons are characterised by seeds having two cotyledons, reticulate venations in leaves, and
tetramerous or pentamerous flowers i.e having four or five members in each floral whorls. The monocotyledons
on the other hand are characterised by single cotyledonous seeds, parallel venation in leaves, and trimerous
flowers having three members in each floral whorls.
Unit IV: Chapter 13, Pg. 206 along with 1st para after the fourth line
Photosynthesis as a means of Autotrophic nutrition
The green plants make or rather synthesise the food they need by Photosynthesis and therefore called
autotrophs. You have already learnt that the autotrophic nutrition is found only in plants and all other
organisms that depend on the green plants for food are heterotrophs.
Unit IV: Chapter 15, Pg. 239 along with 1st para after the last line
Seed germination
The first step in the process of plant growth is seed germination. The seed germinates when favourable
conditions for growth exist in the environment. In absence of such favourable conditions the seeds do not
germinate and goes into a period of suspended growth or rest. Once favourable conditions return the
seeds resume metabolic activities and growth takes place.
Unit IV: Chapter 15, Pg. 252 as section 15.7
Seed dormancy
There are certain seeds which fail to germinate even when external conditions are favourable. Such
seeds are understood to be undergoing a period of dormancy which is controlled not by external
environment but are under endogenous control or conditions within the seed itself. Impermeable and
hard seed coat; presence of chemical inhibitors such as abscissic acids, phenolic acids, para-ascorbic
acid; and immature embryos are some of the reasons which causes seed dormancy. This dormancy
however can be overcome through natural means and various other men made measures. For.eg. the
seed coat barrier in some seeds can be broken by mechanical abrasions using knives, sandpaper etc. or
vigorous shaking. In nature, these abrasions are caused by microbial action, and passage through digestive
tract of animals. Effect of inhibitory substances can be removed by subjecting the seeds to chilling
conditions or by application of certain chemicals like gibberellic acid and nitrates. Changing the
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environmental conditions, such as light and temperature are other methods to overcome seed
dormancy.
Unit V: Chapter 16; 16.2 Pg. 264 (before 16.3 absorption of digested product)
Calorific value of Protein, Carbohydrate and Fat (Not for evaluation Box item)
The energy requirements of animals, and the energy content of food, are expressed in terms of measure of
heat energy because heat is the ultimate form of all energies. This is often measured to as calorie (cal) or
joule (J), which is the amount of heat energy required to raise the temperature of 1 g of water by 1° C.
Since this value is tiny amount of energy, physiologists commonly use kilocalorie (kcal) or kilojoule (kJ).
One kilocalorie is the amount of energy required to raise the temperature of 1 kg of water through 1° C.
Nutritionists, traditionally refer to kcal as the Calorie or Joule (always capitalised). The amount of heat
liberated from complete combustion of 1 g food in a bomb calorimeter (a closed metal chamber filled with
O2) is its gross calorific or gross energy value. The actual amount of energy combustion of 1 g of food is the
physiologic value of food. Gross calorific values of carbohydrates, proteins and fats are 4.1 kcal/g, 5.65
kcal/g and 9.45 kcal/g, respectively, whereas their physiologic values are 4.0 kcal/g, 4.0 kcal/g and 9.0
kcal/g, respectively.
Unit V: Chapter 16; 16.4 Pg. 266 after Indigestion
PEM
Dietary deficiencies of proteins and total food calories are widespread in many underdeveloped countries
of South and South-east Asia, South America, and West and Central Africa. Protein-energy malnutrition
(PEM) may affect large sections of the population during drought, famine and political turmoil. This happened
in Bangladesh during the liberation war and in Ethiopia during the severe drought in mid-eighties. PEM
affects infants and children to produce Marasmus and Kwashiorkar.
Marasmus is produced by a simultaneous deficiency of proteins and calories. It is found in infants less
than a year in age, if mother’s milk is replaced too early by other foods which are poor in both proteins and
caloric value. This often happens if the mother has second pregnancy or childbirth when the older infant is
still too young. In Marasmus, protein deficiency impairs growth and replacement of tissue proteins; extreme
emaciation of the body and thinning of limbs results, the skin becomes dry, thin and wrinkled. Growth rate
and body weight decline considerably. Even growth and development of brain and mental faculties are
impaired.
Kwashiorkar is produced by protein deficiency unaccompanied by calorie deficiency. It results from
the replacement of mother’s milk by a high calorie-low protein diet in a child more than one year in age.
Like marasmus, kwashiorkor shows wasting of muscles, thinning of limbs, failure of growth and brain
development. But unlike, marasmus, some fat is still left under the skin; moreover, extensive oedema and
swelling of body parts are seen.
Unit V: Chapter 18; 18.3.1 Pg. 284 (before 18.3.2 cardiac cycle)
The blood flows strictly by a fixed route through Blood Vessels, the arteries and veins. Basically, each
artery and veins consists of three layers: an inner lining of squamous endothelium, the tunica intima, a
middle layer of smooth muscle and elastic fibres, the tunica media, and an external layer of fibrous connective
tissue with collagen fibres, the tunica externa. The tunica media is comparatively thin in the veins (Figure
18.4).
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Unit V: Chapter 19; 19.8 Pg. 298 in 4th line
During the process of hemodialysis, the blood drained from a convenient artery is pumpud into a dialysing
unit called artificial kidney.
Unit V: Chapter 20; 20.1 Pg. 303 in the beginning of 2nd para
You have studied in chapter 8 that the cilia and flagella are the outgrowths of the cell membrane.
Flagellar movement helps in the swimming of spermatozoa, maintenance of water current in the canal
system of sponges and in locomotion of Protozoans like Euglena.
Unit V: Chapter 21; 21.2 Pg. 316 after parasympathetic neural system
Visceral nervous system is the part of the peripheral nervous system that comprises the whole
complex of nerves, fibers, ganglia, and plexuses by which impulses travel from the central nervous system
to the viscera and from the viscera to the central nervous system.
Unit V: Chapter 21; 21.6 Pg. 322 at the end
Sense Organs
We smell things by our nose, taste by tongue, hear by ear and see objects by eyes.
The nose contains mucus-coated receptors which are specialized for receiving the sense of smell and
called olfactory receptors. These are made up of olfactory epithelium that consists of three kinds of cells.
The neurons of the olfactory epithelium extend from the outside environment directly into a pair of broad
bean-sized organs, called olfactory bulb, which are extensions of the brain’s limbic system.
Both nose and tongue detect dissolved chemicals. The chemical senses of gustation (taste) and
olfactory (smell) are functionally similar and interrelated. The tongue detects tastes through taste buds,
containing gustatory receptors. With each taste of food or sip of drink, the brain integrates the differential
input from the taste buds and a complex flavour is perceived.
Unit V: Chapter 22; 22.2.2 Pg. 333 along with 1st para after (ADH)
An impairment affecting synthesis or release of ADH results in a diminished ability of the kidney to
conserve water leading to water loss and dehydration, this disease is known as Diabetes Insipidus.
Unit V: Chapter 22; 22.2.4 Pg. 333 at the end along with last line
Exopthalmic goitre is a form of hyperthyroidism, characterized by enlargement of the thyroid gland,
protrusion of the eyeballs, increased basal metabolic rate, and weight loss, also called Graves’ disease.
Unit V: Chapter 22; 22.2.7 Pg. 336 at the end of 1st para
Underproduction of hormones by the adrenal cortex alters carbohydrate metabolism causing acute
weakness and fatigue leading to a disease called Addison’s disease.
Unit V: Chapter 22; 22.2.2 Pg. 332 2nd para in 3rd line after dwarfism
Excess secretion of growth hormone in adults especially in middle age can result in severe disfigurement
(especially of the face) called Acromegaly, this may leads to serious complicating conditions, and premature
death if unchecked. The disease is hard to diagnose in the early stages and is frequently missed for many
years, until changes in external features, become noticeable.
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Class XII
UNIT VI
Unit VI: Chapter 1; 1.
1 - Page 6 at the end of 1st Para
Under unfavourable condition the Amoeba withdraws its pseudopodia and secretes a three-layered hard
covering or cyst around itself. This phenomenon is termed as encystations. When favourable conditions
return, the encysted Amoeba divides by multiple fission and produces many minute amoebae or
pseudopodiospores; the cyst wall bursts out, and the spores are liberated in the surrounding medium to
grow up into many amoebae. This phenomenon is known as sporulation.
Unit VI: Chapter 1; 1.1 - Page 7 at the end of 2nd Para
In some organism, if the body breaks into distinct pieces (fragments) each fragment grows into an adult
capable of producing offspring (e.g., Hydra), this is also a mode of asexual reproduction called
fragmentation.
Unit VII: Chapter 5; Pg. 85 (to be given as section 5.4)
Polygenic Inheritance
Mendel’s studies mainly described those traits that have distinct alternate forms such as flower colour
which are either purple or white. But if you look around you will find that there are many traits which are
not so distinct in their occurrence and are spread across a gradient. For example in humans we don’t just
have tall or short people as two distinct alternatives but a whole range of possible heights. Such traits are
generally controlled by three or more genes and are thus called as polygenic traits. Besides the involvement
of multiple genes polygenic inheritance also takes into account the influence of environment. Human skin
colour is another classic example for this. In a polygenic trait the phenotype reflects the contribution of
each allele i.e the effect of each allele are additive. To understand this better let us assume that three genes
A, B, C control skin colour in human with the dominant forms A, B and C responsible for dark skin colour
and the recessive forms a, b and c for light skin colour. The genotype with all the dominant alleles (AABBCC)
will have the darkest skin colour and that with all the recessive alleles (aabbcc) will have the lightest skin
colour. As expected the genotype with three dominant alleles and three recessive alleles will have an
intermediate skin colour. In this manner the number of each type of alleles in the genotype would determine
the darkness or lightness of the skin in an individual.
Unit VII: Chapter 5; Pg. 85 (to be given as section 5.5)
Pleiotropy
We have so far seen the effect of a gene on a single phenotype or trait. There are however instances where
a single gene can exhibit multiple phenotypic expression. Such a gene is called a pleiotropic gene. The
underlying mechanism of pleitropy in most cases is the effect of a gene on metabolic pathways which
contributes towards different phenotypes. An example of this is the disease phenylketonuria, which occurs
in humans. The disease is caused by mutation in the gene that codes for the enzyme phenyl alanine
hydroxylase (single gene mutation). This manifests itself through phenotypic expression characterised
by mental retardation and a reduction in hair and skin pigmentation.
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Unit VII: Chapter 5; 5.4 - Page 86 after 2nd Para
The sex determination in Honey bee is based on the number of sets of chromosomes an individual receives.
An offspring formed from the union of a sperm and an egg develops as a female (queen or worker), and an
unfertilized egg develops as a male (drone) by means of parthenogenesis. This means that the males have
half the number of chromosomes than that of a female .The females are diploid having 32 chromosomes
and males are haploid i.e. 16 chromosomes. This is called as haplodiploid sex-determination system and
has special characteristic features such as the males produce sperms by mitosis (Figure 5.13), they do not
have father and thus cannot have sons, but have a grandfather and can have grandsons.
Parents Female
32
Meiosis
16 16
Male
Mitosis
18
Female
32
16
Male
16
F : 1
Gametes:
Fig.5.13. Sex Determination in honey bee.
Unit VII: Chapter 5; 5.6.2 - Page 89 after 1st Para
Colour Blindness: It is a sex-linked recessive disorder due to defect in either red or / and green cone of
eye resulting in failure to discriminate between red and green colour. This defect is due to mutation in
certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per
cent of females. This is because the genes that lead to red–green colour blindness are on the X chromosome.
Males have only one X chromosome and females have two. The son of a woman who carries the gene has
a 50 per cent chance of being colour blind. The mother is not herself colour blind because the gene is
recessive. That means that its effect is suppressed by her matching dominant normal gene. A daughter will
not normally be colour blind, unless her mother is a carrier and her father is colour blind. Colour blindness
is most commonly inherited from mutations on the X chromosomes.
Unit VII: Chapter 5; 5.6.2 - Page 90 after 2nd Para
Thalassemia: This is also an autosome linked recessive blood disease transmitted from parents to the
offspring when both the partners are unaffected carrier for the gene (or heterozygous). The defect could be
due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globins
chains (á and â chains) that make up haemoglobin. This causes the formation of abnormal haemoglobin
molecules resulting into anaemia which is characteristic of the disease. Thalassemia can be classified according
to which chain of the haemoglobin molecule is affected. In á Thalassemia production of á globin chain is
affected while in â Thalassemia production of â globin chain is affected. á Thalassemia is controlled by two
closely linked genes HBA1 and HBA2 on chromosome 16 of each parent and it is observed due to
mutation or deletion of one or more of the four genes. The more genes affected, the less alpha globin
molecules produced. While â Thalassemia is controlled by a single gene HBB on chromosome 11 of each
parent and occurs due to mutation of one or both the genes. Thalassemia differs from sickle-cell anaemia
in that the former is a quantitative problem of synthesizing too few globin molecules while the latter is a
qualitative problem of synthesizing an incorrectly functioning globin.
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Unit VII: Chapter 7; 7.3- Page 129 after 2ndnd Para
Embryological support for evolution was also proposed by Ernst Heckel based upon the observation of
certain features during embryonic stage common to all vertebrates that are absent in adult. For example,
the embryos of all vertebrates including human develop a row of vestigial gill slit just behind head but it is
a functional organ only in fishes and not found in any other adult vertebrates. However, this proposal was
disapproved on careful study preformed by Von Bear, he noted that embryos never pass through the adult
stages of other animals.
Unit X: Chapter 13; 13.1-Page 221 at the end of 1st Para
Each organism has an invariably defined range of conditions that it can tolerate, diversity in the resources
it utilizes and a distinct functional role in the ecological system, all these together comprises its niche.
Unit X: Chapter 15; 15.2.2- Page 266 in 3rd Para, 22nd line after the word thretened
(organisms facing a very high risk of extinction in the wild in the near future)
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Deletions, Changes in the name of Chapter/Theme, Shifting of text matters
Biology Text Book Class XI and XII
CLASS XI
To Delete
Unit II: STRUCTURAL ORGANISATION IN ANIMALS AND PLANTS
Chapter 7 STRUCTURAL ORGANISATION IN ANIMALS
– To be Deleted 7.3 Earthworm from page 106 up to page 111 1st Para and 7.5 FROGS from
page 116 up to page 120 1st Para
Unit III: CELL STRUCTURE AND FUNCTION
Chapter 9 BIOMOLECULES
– To be Deleted inhibition on page 158 2nd and 3rd Para
To Change Chapter/Theme Title
– Chapter title Photosynthesis in Higher Plants to be changed as Photosynthesis
– Chapter title Chemical coordination and integration to be changed as Chemical Coordination
and Regulation
– Name of the Theme 16.4 on page 265 to be changed as Nutritional and Digestive Disorders
To Shift
– In Chapter 12 MINERAL NUTRITION, Theme 12.1 from page 194 up to page 195 1st
Para will be deleted and shifted on page 200 just before Theme 12.6 and then Theme
numbering will be accordingly rearranged.
CLASS XII
To Change Chapter/Theme Title
– Chapter title Principles of Inheritance and Variation to be changed as Heredity and Variation
– Chapter title Human health and disease to be changed as Health and disease
– Chapter title Organism and population to be changed as Organism and Environment
– Chapter title Biodiversity and Conservation to be changed as Biodiversity and its
conservation
To Shift
Delete last Para from page 152 In Chapter 8 under Theme 8.2.4 and shift to page 212 In Chapter 12
under Theme 12.2 as Sub Theme 12.2.4 Vaccine production

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