Category: 12th Zoology

Bio Zoology Biology Higher Secondary Second Year Tamil Nadu State Board

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Post date December 10, 2018
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Bio Zoology Biology Higher Secondary Second Year Tamil Nadu State Board Syllabus

Human Physiology Content Zoology

Introduction – Carbohydrates – Proteins – Lipids – Vitamins – Minerals – Water – Balanced diet – Calorie values (ICMR standards) – Obesity – Hyperglycemia – hypoglycemia – Malnutritions. Digestion : Enzymes and enzyme action – Brief account of following – Dental caries – Root canal therapy – Peptic ulcer – Hernia – Appendicitis – Gall bladder stone – Liver cirrhosis – Hepatitis. Bones and Joints (Major types) : Fractures – Dislocations – Arthritis – Rickets and osteomalacia – Orthopaedics – Gout. Muscles : Muscle action – Muscle tone – Rigor mortis – Muscle pull (hernia) – Isometric and aerobic exercises (Body building) – Myasthenia gravis. Respiration : Process of pulmonary respiration – Inspiration – Expiration – Exchange of gases at alveolar level – Control of respiration – Pneumonia – Pleurisy – Tuberculosis – Bronchitis – Breathing exercises Circulation-Functioning of heart-Origin and conduction of heart beat. Artificial pacemaker-Coronary blood vessel and its significance-Myocardial infarction,Angina pectoris-Angiogram,angioplasty and coronary bipass surgery- Atherosclerosis-Heart attack-Heart block-ECG and Echo cardiograph-Heart valves Rheumatic Heart Disease (RHD)-ICCUArterial and venous systems-Blood pressure-pulse rate-Heart transplantation Resuscitation in Heart attack (First Aid)-Blood components Function-Plasma-Corpuscles -Blood clotting-Anticoagulants-Thrombosis- Embolism-blood related diseases like polycythemia Leukemia-Lymph fluid. Physiological-Co-ordination Systems-Brain-Functioning of different regions-Memory-Sleep-Stroke-Alzhemier’s disease-Meningitis/Brain fever Conditioned reflex-Electroencephalography-Right brain-left brain concept-Spinal cord- Functioning-Reflex action-CSF-Chemical co-ordination-Pituitary (Hormones of Adenohypophysis and their regulations)-Thyroid,Parathyroidal hormones-Insulin and Glucagon-Hormones of Adrenal cortex and Medulla-Reproductive Hormones-Problems related to Secretion Non secretion of Hormones. Receptor Organs-Eye-Focussing Mechanism & photo chemistry of retina-Short sightedness-Longsightedness-Optometry-Retinopathy-Cataract-Lens eplacement- Nyctalopia-Eye infection-Conjunctivitis-Glaucuoma-Eye care-EAR-Hearing mechanism- Organ of corti-Hearing impairments and aids-Noise pollution and its importance- SKIN-Melanin-functions-Effect of solar radiations/UV-Skin Grafting- Dematitis-TONGUE-Gustatory reception. Excretion-Ureotelism-Urea Biosynthesis(Ornithine Cycle)-Nephron ultrafiltration,tubular reabsorption and tubular secretion-Renal failure-Dialysis Kidney stone formation-Kidney Transplantation-Diabetes. Reproductive system-Brief account of speramtogenesis – Oogenesis Menstrual cycle-Invitro fertilization-Birthcontrol

Unit 1 – Human Physiology Topic List Zoology

Microbiology : Zoology

Introduction-History of Medical Microbiology-The influence of
Pasteur Koch, and Lister-Virology, Structure, Genetics, Culture and diseases-AIDS and its control-Bacteriology-Structure,Genetics and diseases-Protozoan microbiology- Disease oriented-Pathogenecity of Micro organism-Anti microbial resistance Chemotherapy.

Unit 2 – Microbiology Topic List Zoology

Immunology: Zoology

Innate(Non-specific) Immunity-Anatomical Barriers-Physiological Barriers-Phagocytic Barriers-Lymphoidal organs -Thymus-Bursa of Fabricius-Peripheral Lymphoid Organs-Lymph nodes-Spleen-Antibodies-Immunoglobulins-Regions of polypepetide chain-Transplantation immunology-Classification of grafts- Genetic basis of organ transplants-Immune system disorder.

Unit 3 – Immunology Topic List Zoology

Modern genetics : Zoology

Introduction-Scope-Human Genetics karyotyping Chromosome gene mapping, Recombinant DNA technology and segmenting. Genetic diseases-Human Genome project-Cloning-Transgenic organisms Genetically Modified Organisms (GMO)-Genetherapy-Bio informatics application-DNA sequencing and protein structure.Biological database

UNIT 4. MODERN GENETICS Topic List Zoology

Environmental science : Zoology

Human population and explosion-Issue-Global warming Crisis Green House Effect-Ozone layer depletion Waste mangement-Biodiversiy conservation (Biosphere reserves) Government and Non Govermental organisations involved-Energy crisis and Environmental impact-Poverty and environment-Fresh water crisis and management.

UNIT 5. ENVIRONMENTAL SCIENCE Topic List Zoology

Applied biology : Zoology

Livestock and Management-Dairy-Breeds of cattle-Milch breed- Draught breed-Dual purpose-Common diseases and control-Exotic and cross breeds- Techniques adopted in cattle breeding. Poultry-Farming techniques-Breeds. Farming methods-Poultry diseases-Economic value. Pisciculture-Fish farming-Edible fishes of Tamilnadu. Medical Lab Techniques-Stethoscope-Sphygmomanometer-Heamocytometer-Urine- Sugar analysis-ECG-’PQRST’wave-CTScan-Endoscopic (Laproscopic) techniques-
Artificial pacemaker-Auto analyser

Unit 6. APPLIED BIOLOGY Topic List Zoology

Theories of evolution : Zoology

Lamarckism-Neolamarckism-Darwinism-NeoDarwinism / Modern concept of natural selection-Species concept-Origin of species and Isolating Mechanisms

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Modern concept of Natural Selection (or) Modern synthetic theory of Evolution

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Post date December 10, 2018
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Modern concept of Natural Selection (or) Modern synthetic theory of Evolution

Modern development in biological fields such as Cell biology,
Genetics and Populations genetics helped in the development of modern synthetic theory of evolution. It was caused due to contributions made by eminent scientists such as Th. Dobzhansky, S.Wright, H.J.Muller, J.S. Huxley, R.A.Fisher, Ernst Mayr, G.L.Stebbins and others.

The basic concept of modern synthetic theory was provided by Th.
Dobzhansky in his book titled “Genetics and the Origin of species” (1937) G.L.Stebbins in his book “Process of organic evolution” (1971) suggests five basic processes essential for evolution. They are gene mutations, chromosomal aberrations, genetic recombinations, natural selection and reproductive isolation. Contributions made by others provided additional factors such as Hardy-Weinberg equilibrium, Genetic drift and Polymorphism.

1. Gene Mutations

Since proteins perform several functions, they determine many of the
characteristics of organisms. The role played by a protein is largely
determined by its primary structure. The primary structure is due to the sequence of amino acids in its molecule. This structure in turn determines the three dimensional protein molecule. The conformation determines the protein function.

The basic sequence of amino acids in proteins is precisely regulated
by the genetic code. Any change in the code due to gene mutation will result in the production of abnormal proteins. The abnormal proteins thus formed may be either beneficial or harmful. A gene producing a beneficial protein confers an advantage on its possessor. Gradually its frequency increases in a population. Individuals having harmful mutations may not survive to reproductive age. So, such mutated genes are not passed to the next generation. (natural selection)

The mutations are considered as the ‘raw materials’ for evolution.
They help to create and provide variations in a population along with genetic recombinations. The collection of genes in a population is referred to as the ‘gene pool’. Mutations enrich the gene pool with new modified genes. A large scale accumulation of such genes will lead to evolutionary modifications.

2. Chromosomal aberrations

During the process of meiosis one or more chromosomes may break.
Such broken fragments of chromosomes may be subjected to several
modified organizations : (natural selection)

a) a small broken fragment may become lost (deletion)
b) the broken fragment may become attached to the end of another
chromosome (translocation)
c) the fragment may become turned around and rejoin the chromosome (inversion)
d) they may become inserted into another chromosome (duplication)
All the above mentioned changes may alter the genomes of gametes.

Sometimes a pair of homologous chromosomes may fail to separate
in meiosis. It will result in gametes with one chromosome less or one
chromosome more, than normal. The progeny formed from such gametes are called polysomics. They will have fewer or more chromosomes than normal.

In certain cases, whole set of homologous chromosomes do not
separate in meiosis. It results in diploid gametes. Fusion of such gametes with a normal haploid gamete gives rise to progeny with a triploid chromosome number. This condition is called polyploidy. It is commonly observed in plants. Polyploids are usually more vigorous. (natural selection)

Such forms can give rise to new species. While recombinations provide regular variations, mutations enrich such variations. Phenomena such as chromosomal abberrations, polysomics and
polyploidy while, found advantageous to the organisms, provide new
directions for speciation and further evolution. (natural selection)

3. Recombination

During meiosis, due to crossing over of chromosomes, genic
arrangements get altered. Such alterations cause reshuffling of gene
combinations. Such recombinations are regular events in gametogenesis. Due to such events new allelic formations happen and after fertilization variations result in the progeny. (natural selection)

4. Hardy-Weinberg equilibrium (Population genetics)

A population is defined as an assemblage of living beings showing a
closely interacting system. A population comprising of sexually interbreeding organisms is termed as the genetic population or Mendelian population.

A genetic population may be defined as “a community of similar individuals living within a limited circumscribed area at a given time and capable of interbreeding”. The genes of all the individuals of such a Mendelian population will constitute the gene pool. A gene pool comprises a diverse forms of a gene combining and recombining by the process of sexual reproduction. The frequency of genes and genotypes in a population had been worked out by mathematical formulations.

The gene frequency refers to the proportion of an allele in the
gene pool as compared with other alleles at the same locus. Hence the gene frequency can be calculated by substracting the number of a particular gene in question from the total number of genes present on that locus in the population.

If the frequency of gene ‘A’ is represented by ‘P’ and that of gene a
by ‘q’ and at gene equilibrium condition their total frequency is represented by 1, then at equilibrium (natural selection)
P+q = 1
or p = 1-q
or q = 1-p

A mathematical interpretation for the distribution of gene and
genotype frequencies in the population was developed by R.A. Fisher
(England) and Sewall Wright (United States). A fundamental idea in the form of a law to understand population genetics was provided by G.H. Hardy of England and W.Weinberg of Germany in 1908. The law proposed by them is known as Hardy-Weinberg’s law. It is the foundation of population genetics and of modern evolutionary theory. (natural selection)

According to this law ‘the relative frequencies of various kinds of genes in a large and randomly mating sexual population tend to remain constant from generation to generation in the absence of mutation, selection and gene flow or migration.

This law concerns a theoretical situation for a population not undergoing any evolutionary change. Thus according to the law the normal mendelian genic frequencies are maintained under certain conditions only. If such conditions are not followed, the gene frequency will change leading to deviations and cause variations, such variation will be the sources for future evolution. (natural selection)

5. Genetic drift or Sewal Wright effect

This theory was developed by Sewall Wright in 1930. It is concerned with the gene frequency of a reproducing small population. In a small population not all the alleles which are representatives of that species may be present. Thus the process of inheritance is in violation of Hardy-Weinberg law. In such a small population a chance event may increase the frequency of a character that has little adaptive value. Thus the genetic drift may remain a significant factor in the origin of new species on islands and other isolated populations. (natural selection)

Due to loss of alleles having low frequency, amount of genetic variation may get reduced in small populations. Further, continual mating within such populations may cause decrease in the proportion of heterozygotes and increase in the number of homozygotes. However the small population as a whole may develop characters different from that found in the main population. (natural selection)

Such deviations may even lead to speciation or formation of a new
species. When a small group of individuals due to genetic drift become founders of a new population the phenomenon is termed as ‘founder principle’. The new population often has genotype frequencies different from the parent population.

Sometimes genotypic frequencies may get changed in a small population isolated temporarily due to natural calamities. When the population regains its original size the members of the small population may have diverged genetically from the original parental population. Hence interbreeding between members of small and larger populations may not be possible. The small population might have evolved into a new species. This type of genetic drift is referred to as bottleneck effect. (natural selection)

6. Natural Selection

In the modern or synthetic theory of evolution natural selection is
considered as a population related genetic phenomenon. It leads to changes in allele frequencies and favours or promotes adaptation as a product of evolution.

When the population size of animals or plants in specific locality
increases certain environmental factors such as availability of food may become limiting factors. Those organisms exhibiting characteristics which give them a competitive advantage may survive.

Thus population size and environmental limiting factor operate together to produce a selective pressure. The selection pressure may increase or decrease the spreading of an allele in a gene pool depending on its adaptive value. This inturn will lead
to evolutionary changes.

There are three types of selection processes in operation. They are
stabilizing, directional and disruptive selections. In stabilizing selection competition in nature is not severe. The phenotypic features coincide with normal environmental situations. However this selection may eliminate characters that are abnormal and harmful and it tends to maintain the phenotypic stability within population for successive generations.

The directional selection operates in response to gradual changes
in the environment. It operates within the phenotypic range available within the population. The selection gradually changes the phenotypic character towards a possible extreme condition found suitable for the changed environmental situation.

This selection will increase the frequency of desirable
phenotypic character within the population. Thus it results in gradual
evolutionary change.

In disruptive selection the selection pressure may favour the
existence of more than one phenotype in a population. It may even split a population into two sub-populations. If gene flow between such sub-populations is prevented a new species or a sub specie may evolve. When a disruptive selection produces more than one phenotype within a population the phenomenon is known as polymorphism.

7. Polymorphism

It is the “the existence in a natural population of two or more alleles
in frequencies too large to be explained by recurrent mutation”.
Thus a polymorphic population will have several alleles of a gene as
a permanent feature of the species. The varied alleles are favoured and maintained in the population by genetical mechanisms.

A classical example for such a polymorphism could be the existence
of a genetic disorder in humans, namely sickle-cell anaemia. This disease reduces the oxygen-carrying capacity of the blood and affects blood supply to various organs. This disorder is inherited as a Mendelian recessive. It is more frequent among American blacks than American whites. In spite of its harmful nature the allelic gene responsible for the disorder is maintained in the black population.

According to the work of Allison (1955, 61) it was shown that in Africa the same allelic gene conferred an advantage, that is it protected the inheritors of such gene from malaria. Thus the connection between sickle-cell anaemia and malaria was estabilished. Hence selection has encouraged the existence of such a polymorphic allele in the population. (natural selection)

8. Isolating mechanisms

A species may be defined as “a group of organisms that are
reproductively isolated from other such groups”. Thus the maintenance of a species as a dintinct group is due to several isolating mechanisms. They are

1. Geographical isolation

It is a common type of isolation. The isolation between populations is
caused due to geographical barriers such as mountains, rivers, oceans, forests or deserts. These natural barriers prevent interbreeding between them. Thus mutations formed in one population will lead to the formation of new species. The existence of closely related species of frogs in Southern India and Srilanka is a classical example. These fresh water animals are prevented from interbreeding due to a narrow sea namely Gulf of Mannar. Because of isolation for a fairly long time they have evolved into distinct species.

2. Premating isolations

such mechanisms prevent interspecific crosses.
a) Ecological isolation – Members of the populations occur in different
habitates in the same general region.
b) Seasonal or Temporal isolation – Mating or flowering periods
occur at different seasons.
c) Sexual, Psychological or Ethological isolation – It is a behavioural
isolation where males and females of the same species get attracted to each other.
d) Mechanical isolation – Physical non-correspondence of the genitalia or floral parts.
e) Gametic isolation – Spermatozoa, or pollen tubes of one species are not attracted to the eggs or ovules of another species.

3. Postmating or postzygotic isolations – These isolating mechanisms while allowing fertilization may prevent the hybrid zygote from further
development.
a) Hybrid inviability – The hybrid zyotes are inviable.
b) Hybrid sterility – The hybrids develop but they remain sterile. They are incapable of producing a normal complement of functional sex cells.
c) Hybrid breakdown – F1 hybrids are normal and fertile, but F2 contains many weak or sterile individuals. (natural selection)

Speciation :-

A species is a natural, biological unit. Among the various taxa, a
species is not man made. It is a natural reality. The process of evolution operates at the species level only. It is because of these reasons, in evolution much importance is given to the ‘Origin of Species’. There are several types of species.

Allopatric species – Species occupying different geographical areas.
Ex : species of frogs in India and Srilanka. The two land areas are separated by the Gulf of Mannar. Sympatric species – closely related species living together in one common locality, yet maintain their species identity Ex: Rana hexadactyla, R.tigrina and R.cyanophlictis living together in a pond.

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Objections to Darwinism

While the ideas of Darwin, related to reproductive capability,
prevalence of variations, concept of struggle and survival of suitable forms
are all commonly accepted, there are certain drawbacks in his original theory.

1. Darwin could not explain, the origin and cause for variations while insisting
their importance in progressive evolution.

2. He overemphasized the importance of the ‘fittest’ organisms. During later
periods it has been suggested that ‘fit’ and fitter forms can also exist along
with the fittest.

3. As the principle of inheritance as explained in the later years were not
available during Darwin’s time. Hence he believed in the theory of
‘pangenesis’. According to this concept from every organ in the body very
minute such replicate structures will orginate. Later they are transferred to
the gonads for transmission to future generations.

4. ‘Over-specialization’ as in Irish deer and its consequent harmful effect on
animals had not been accounted for by Darwin.

Neo-Darwinism

A modified form of Darwinism is known as neo-Darwinism. It was
developed due to acceptance of Darwinism and provision of several
evidences in support of Natural Selection concept. The early
neo-Darwinians were T.H. Huxley of England, Asa Gray of United States
and E.Haeckel of Germany.

The neo-Darwinians differentiated the germplasm from somatoplasm
and proposed the ‘germplasm concept’. They also belived that characters
are due to certain factors called the determinants that control the
development. The neo-Darwinism concept was incomplete and erroneous.
It lacked in an understanding of genetics as it is known in later periods.

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

The Theory of Natural Selection

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Post date December 5, 2018
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The Theory of Natural Selection

During his period of study Darwin has made several observations
and collected facts. Through these facts he arrived at certain conclusions.
These conclusions constitute Darwinism. Thus Darwinism or the theory of
Natural selection includes the following elements.

1. Overproduction or Prodigality of nature

All living beings have an innate desire to reproduce and form their
own progeny. In this attempt they have the capacity to multiply in a
geometrical manner. Such an enormous reproductive potentiality can be
observed in all species of organisms. For example a single female salmon fish
can produce 28,000,000 eggs in a season. A common oyster of the Atlantic
coast may release as many as 80 million eggs in one season. At the time of
breeding the ovaries of a cod fish may contain 10 million eggs. (theory of natural selection)

If natural processes of reproduction are allowed without any check a single pair of
English sparrows can produce 275 billion descendents in 10 years. The
elephants are the slowest breeders. An elephant begins to breed at 30 years
of age. It goes on breeding till it is 90 years old. A female elephant can give
birth to 6 young ones during its life time. Under these conditions, a pair of
male and female elephants can cause the production of 19 million elephants
in 750 years. Thus, the reproductive capacity is an innate nature of living
organisms.(theory of natural selection)

2. Struggle for existence

According to Darwin while the population increases in geometric
ratio there is no corresponding increase in food production. This causes an
intensive struggle for living. The struggle happens for food, space for
living and for coping with environmental conditions. The struggle may be
intraspecific or interspecific. In an intraspecific struggle there is a
competition among the individuals of the same species. Such a struggle is
severe because the needs of the competing organisms are identical. Struggle
might happen with environment too. Conditions like heat, cold, drought,
storms, floods and other natural changes can affect organisms resulting in
struggle for existence. (theory of natural selection)

3. The universal occurrence of variations

The occurrence of variations is a characteristic feature of all groups
of animals and plants. The variations may be morphological , anatomical,
physiological or behavioral. (However during Darwin’s time the actual cause
and nature of variations were not known).

As a result of variations, no two animals would look alike. Even the
progeny of the same parents are not exactly alike in all respects. Eventhough
variations are universal all such variations need not be significant from an
evolutionary point of view. Certain variations that get established in the
population and get inherited continually are termed, heritable variations.
Such variations form the raw material for evolution.(theory of natural selection)

4. Survival of the fittest

While all living organisms face the struggle for existence, certain
organisms possessing adequate modifications are able to escape and survive. Such modifications are due to inherent variations. Hence favourable
variations make an animal or a plant to be successful in life. They survive as
fittest organisms in an environment which gets altered frequently. (theory of natural selection)

5. Natural Selection

According to Darwin ‘the fittest’ forms that are allowed to survive
are chosen by ‘Natural Selection’ (an imaginative concept which includes all
real aspects of the natural environment that supports the life of
organisms).

The forces of natural selection will encourage only those that have
suitable variations as adaptive features, to survive. Darwin designated them
as ‘fittest’ forms. All other organisms having non adaptive or deleterious
modifications shall be disqualified. Natural selection will eliminate such
organisms from the populations. The selected group of modified
individuals will occupy the next level in the evolutionary ladder.
Darwin strongly believed that using the natural selection concept, all
evolutionary processes in the living world can be explained. As an
example he differed from the explanation provided by Lamarck while
explaining the lengthening of neck in giraffe. According to Darwin the
population of giraffes had individuals having varying neck lengths. Those that
had longer necks had more survival value, since they had more food and
remained healthy. Gradually natural selection encouraged them to
survive. Thus in course of time the average length of the neck increased. (theory of natural selection)

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Darwinism

Darwinism comprises the natural selection concept as advanced by
Charles Robert Darwin in 1859. His theory provided the correct idea to
explain all processes and intricate mechanisms of evolution. The theory of
natural selection is considered on par with Newton’s law of gravitation and
Einstein’s theory of relativity. The monumental work of Darwin was titled as
“The Origin of species” (the original full title of the book was ‘On the Origin of species by means of Natural Selection, or the Preservation of favoured
Races in the struggle for life’).

The book of Darwin convincingly demonstrates the fact of
evolution. Further, it elaborates on the theory of natural selection as a
convincing mechanism for providing evolutionary transformations.
Charles Darwin was born in Shrewsbury, England on February 12,
1809. While studying in college at England through his friendship with
Professor J.S. Henslow, Darwin became familiar with Botany. Later he
accepted the job of a naturalist aboard the ship H.M.S Beagle. The ship was
to spend five years, in exploration around South America (1829 – 34).
During the period of five years, Darwin visited pacific islands and
many parts of the world. He returned to England in 1836. Later he worked
for a further period of 20 years to develop his theory of natural selection.
While Darwin prepared his work for publication, a similar idea to explain
evolution was proposed by another naturalist, Alfred Russel Wallace
(1823-1913) from Malay archipelago. Charles Darwin gracefully accepted
for the publication of his theory as a joint paper with Wallace. Thus the theory
of natural selection is actually titled as ‘Darwin-Wallace theory of
evolution’.

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Neo lamarckism

Lamarck’s ‘theory of inhertitance’ was further studied by a group of
scientists. Their ideas supporting Lamarck’s opinion collectively constitute
neo Lamarckism.

The neo Lamarckians were of the opinion that ‘adaptions’ are
universal in nature. An adaptation happens through causal relationship of
structure, function and environment. Due to changes in the environment, habits
and life style of organism gets altered. Thus gradually the organism acquires
new structures. The newly obtained character gradually becomes an
inheritable trait. This opinion and argument is a modified form of
Lamarckism. These ideas stressed direct action of environment on organisms.
Support to neo-Lamarckian concept – Experiments (Neo lamarckism)

Neo Lamarckism

1. McDougall (1938) tried to prove that learning is an acquired character
that can be inherited. He did his experiments on rats.

He deviced a ‘T’ shaped tank. The tank had two exits. One exit was
well lighted. However at the terminal region of the exit he deviced an
arrangement for giving electrical shock. The pathway to the other exit was
kept dark. At the terminal exit point a small piece of cheese was kept as a
reward. McDougall dropped several rats into the tank. Many of the rats
preferred lighted pathway to escape and at the exit they received electric
shock. Those rats, that preferred dark pathway received the cheese. He
repeated the trial several times. Gradually many rats learnt the correct route
for escape. Subsequently the rats were allowed to breed and the next
generation developed.
The same experiment was repeated in the second generation. (Neo lamarckism)

According to Mc Dougall, it was claimed that the number of mistakes
committed, gradually got reduced. The speed of learning increased from generation to generation. Thus he concluded that learning is an acquired
character.

However later workers found some technical mistakes in the work
of Mc Dougall. The same experiment while repeated in other laboratories
failed to give similar results. (Neo lamarckism)

2. Temperature related changes in the body of mice was noted by F.B.Sumner
(1910). He reared one set of white mice in warmer temperature (20 – 300c)
and another set in cold conditions. He found that in warmer conditions the
mice developed larger ears and longer tails. He further claimed that these
characters were inherited.

Through similar works claim for inheritance of acquired characters
were made by Lindsey, Guyer and Smith and Kammerer. In all these works
while repeating, critics have found technical mistakes and rejected them
outright.

However, the controversy over ‘inheritance’ of acquired characters
still continues. This theory of Lamarck while has not been disproved totally,
it remains to be proved correct. (Neo lamarckism)

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Lamarck Laws

Lamarck Evolution Laws

Jean Baptiste de Lamarck (1744 – 1829) is well known for his theory
of evolution. In 1809 he published his book titled ‘Philosophie Zoologique’.
This book contains his views on evolutionary mechanisms. Eventhough the
views of Lamarck are not fully accepted, he occupies a very important place
in the history of evolutionary thought.

The theory of evolution as proposed by Lamarck is popularly known
as the ‘theory of inheritance of acquired characters’. According to this theory
modifications or changes acquired during the life time of an organism can
automatically be transmitted to succeeding generations. While elaborating
this theory, Lamarck advanced four laws or propositions.

I Law (or) Proposition

‘In evolution, during course of time, organisms or their
component parts gradually tend to increase in size.
Lamarck cited the evolution of horses as an example to
explain this law. The modern horses, namely, Equus evolved from very small
ancestral forms called Hyracotherium or Eohippus. Such small forms
survived years ago. They gradually evolved into larger modern Equus.

Lamarck’s opinion was based on fossils of several intermediate ancestors of
horses. Whose fossils had already been discovered. However during recent
years various other fossils had been obtained. Of these fossils, some of them
are much smaller than their immediate ancestors. This finding is against the
view already expresed by Lamarck. Thus the first law of Lamarck lost its
significance.

II Law or Proposition

‘If an organism is ‘in need’ of an organ, sooner or later it will
arise.

This view of Lamarck emphasized the significance of mind and its
thinking being related to needs in an environment. Thus, according to Lamarck
a continuous thinking for several generations can lead to the origin of an
adaptive character. Lamarck elaborated his view citing the lengthening of
neck in giraffee over the years.

It is known through fossil records that the ancestors of modern
giraffe were small and they had short neck and forelimbs. They lived in the
grasslands of Africa. These ancestral animals were feeding on grasses and
the leaves of small trees nearby. Gradually, as the grasslands were
transformed into deserts, the animals became dependent on trees for food.
Due to competition for food they had to stretch their neck for more leaves.
They strained their neck for several generations with a very strong inner
feeling to have longer neck. This strong desire, in course of time, led to gradual
increase in the length of neck and forelimbs.

In this explanation Lamarck considered that mere ‘want’ or ‘inner
feeling’ to possess a particular character can lead to the
origin of such a character. This view of Lamarck is not accepted by modern
evolutionists.

III Law (or) Proposition – Law of use and disuse

According to this law, constant use of an organ changes its
efficiency and makes that organ to increase in size with better development.
Similarly if an organ is not used for a long time, it might lead to reduction in
efficiency and size of that organ. The development of hand muscles of a
blacksmith and thigh muscles in the legs of an experienced runner were
quoted as examples. Eventhough this view of Lamarck is correct and
acceptable, it is not relevant to evolution due to lack of inheritance.

IV Law (or) Proposition. Inheritance of Acquired Characters

‘Bodily changes or new charateristics obtained by an
organism during its life time will automatically get transferred to the
next generation’.

While proposing this law, Lamarck did not provide any
specific example. He simply believed that due to conditions prevalent in an
environment, an organism can use an organ extensively and such an usage
can lead to more efficient and perfect nature of that organ. Similarly, an organ
not used for a longer period would degenerate. These perfect or degenerate
characteristics will be inherited by subsequent generations resulting in new
types.

The IV Law of Lamarck had been subjected to severe
criticisms. Several experiments had been carried out, either to prove or
disprove this concept.

In 1890, the German Scientist, August Weismann performed some
experiments with the rats. He selected a set of healthy male and female rats.
He started cutting their tails continually for more than twenty generations.
This experiment was performed to verify inheritance of the acquired
character, namely the tailless condition. Interestingly such a condition was
never observed in any of the young rats born. This finding led to the
proposition of the theory, that any change to the body regions (somatoplasm) will not have influence over the reproductive cells (Germplasm). Thus
Weismann, for the first time segregated germplasm from the somatoplasm.

This lead to the formulation of the ‘Germplasm theory’ which states
that ‘any change to the somatoplam will not have an influence over
the germplasm’.

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

THEORIES OF EVOLUTION

Introduction

Several opinions had been made available to explain the origin and
existence of various forms of life. The existing living beings show characteristic
resemblances in form and functions.

There are evidences for succession of several types of living organisms occupying earth. Populations of animals and Plants tend to undergo predictable changes in their population intensities.

An explanation to all these interesting natural happenings had been
attempted through various modern theories of evolution. An initiation for such
evolutionary thought process was well provided by Lamarck.

This evolutionary theorizing culminates in the modern synthetic theory of
evolution afforded by different fields in biology. (THEORIES OF EVOLUTION)

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Autoanalyser

To assist in the diagnaosis of diseases and disorders and to
monitor therapy, a wide range of clinical tests has been developed. The
demand for investigations is growing with the growing population and
diseases.

To get fast results on a large number of specimens, it is becoming
inevitable to replace manual methods. This could be done by autoanalysers.
With help of autoanalysers an increased work load can be processed rapidly
and with reproducible results. To maintain the quailty of results, standards
(samples of Known values) will be run along with every batch of test samples.

Advantages of an autoanalyser :

1. Accuracy is more when compared with manual method.
2. Large number of samples may be processed in minimal time.
3. Two or more assays may be performed simultaneously.
4. Calculations are not required.

Disadvantages of an autoanalyser :

1. It is impractical for small number of specimens.
2. Instruments may fail occasionally.
3. Additional training of the staff about the working, maintenance and
potential problems of the machine is needed.
4. They are expensive.

Parameters to be analysed by an autoanalyser

Autoanalyser can be used to estimate parameters such as glucose,
protein, albumin, creatinine, blood urea nitrogen (BUN), sodium, potassium,
chlorine, transaminase, lactic dehydrogenase, bilirubin, inorganic phosphate,
calcium, cholesterol, uric acid, phosphatases and bicarbonate.

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

12th Zoology

Endoscopy (Laproscopy) techniques

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Post date December 3, 2018
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Endoscopy (Laproscopy) techniques

Endoscopy is a method of examining the interior of a body cavity or
hollow organ (e.g., oesophagus, stomach) using an endoscope, a narrow,
flexible fiber optic instrument that conducts light. Until recently, surgery was
the most traditional of medical practices, employing techniques and
instruments developed more than a century ago, but now patients have a
new choice.

Endoscopy is a minimally invasive approach to sugery of various parts
It accomplishes traditional surgical goals while delivering less pain, faster
recovery, and happier patients.The procedure does not require hospital
admission and acute care and observation may be performed outside the
premises of a hospital. Outpatient procedures performed at hospitals or
ambulatory centers allow the patient to go home or return to work within a
short period after endoscopic diagnosis.

Types of Endoscopy

1. Bronchoscopy: (trachea and lung’s bronchial trees)
2. Colonoscopy: (colon and large intestine)
3. Colpscopy: (vagina and cervix)

4. Cystoscopy: (bladder,urethra, urinary tract, uteral orifices, and
prostate (men)
5. Gastroscopy: (Oesophagus, stomach,and intestine)
6. Laryngoscopy: (larynx or voice box)
7. Proctoscopy: (rectum and sigmoid colon)
8. Thoracoscopy: (pleura, pleural spaces, mediastinum, and
pericardium).
9. Laparoscopy: (stomach, liver and other abdominal organs
including the female reproductive organs, for example, the fallopian
tubes.)
10. Arthroscopy: (joints such as knee)

Artificial Pacemaker

A pacemaker is a small, battery-operated electronic device, which is
inserted under the skin to help the heart to beat regularly and at an appropriate
rate. The purpose of an artificial pacemaker is to stimulate the heart when
either the heart’s natural pacemaker is not fast enough or if there are blocks
in the heart’s electrical conduction system, preventing the propagation of
electrical impulses from the natural pacemaker to the ventricles.

Natural Pacemaker of heart

The sinus node (sinoatrial node), (1.5 cm long, 3mm wide muscle),
situated on the right wall of the right atrium (auricle) where cadiac impulse is
initiated. It is known as the natural pacemaker of mammalian heart,

Componets of an Artificial Pacemaker

A pacemaker generally has two parts, the generator and the leads.
The generator contains the battery and the information to regulate the
heartbeat. The leads are wires that go from the generator through a large
vein to the heart, where the wires are anchored. The leads send the electrical
impulse to the heart to tell it to beat. Most pacemakers run on lithium
batteries. The battery can last for 7-8 years. It will be routinely monitored by health care professional and replaced when necessary. The generators
have become smaller over the years and often weigh less than 30
grams.

Bio Zoology Biology Higher Secondary Second Year Tamil Nadu State Board Syllabus

Human Physiology Content Zoology

Unit 1 – Human Physiology Topic List Zoology

Microbiology : Zoology

Unit 2 – Microbiology Topic List Zoology

Immunology: Zoology

Unit 3 – Immunology Topic List Zoology

Modern genetics : Zoology

UNIT 4. MODERN GENETICS Topic List Zoology

Environmental science : Zoology

UNIT 5. ENVIRONMENTAL SCIENCE Topic List Zoology

Applied biology : Zoology

Unit 6. APPLIED BIOLOGY Topic List Zoology

Theories of evolution : Zoology

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Modern concept of Natural Selection (or) Modern synthetic theory of Evolution

1. Gene Mutations

2. Chromosomal aberrations

3. Recombination

4. Hardy-Weinberg equilibrium (Population genetics)

5. Genetic drift or Sewal Wright effect

6. Natural Selection

7. Polymorphism

8. Isolating mechanisms

1. Geographical isolation

2. Premating isolations

Speciation :-

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Objections to Darwinism

Neo-Darwinism

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

The Theory of Natural Selection

1. Overproduction or Prodigality of nature

2. Struggle for existence

3. The universal occurrence of variations

4. Survival of the fittest

5. Natural Selection

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Darwinism

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Neo lamarckism

Neo Lamarckism

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Lamarck Evolution Laws

I Law (or) Proposition

II Law or Proposition

III Law (or) Proposition – Law of use and disuse

IV Law (or) Proposition. Inheritance of Acquired Characters

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

THEORIES OF EVOLUTION

Introduction

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Autoanalyser

Advantages of an autoanalyser :

Disadvantages of an autoanalyser :

Parameters to be analysed by an autoanalyser

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

Endoscopy (Laproscopy) techniques

Types of Endoscopy

Artificial Pacemaker

Natural Pacemaker of heart

Componets of an Artificial Pacemaker

Related Topics in Zoology:

Unit 7. THEORIES OF EVOLUTION Topic List Zoology