Thursday, 12 February 2015

Circulation Notes

Circulation (Notes)
Portal System:
A vein carrying deoxygenated blood from a system of capillaries divides again to form a second capillary system in tissues before returning to the heart. Such a vein is called a portal vein.
Portal vein + Capillary System -----à Portal System.
Eg: Hepatic Portal Vein returns blood from the intestine and breaks into a portal system of capillaries in the liver (hepatic portal system). This allows the liver cells to take up the nutrients from the portal blood brought from the small intestine.
The recording of electric potential generated by the spread of Cardiac Impulse is called ECG. It is the graphic record of the electric current produced by the excitation of the cardiac muscles. A normal ECG consists of a P wave, a QRS complex and a T wave.
P Wave : Small upward wave that indicates the depolarization of atria. (Spread of impulse from sinus node throughout the atria).
QRS Complex: Ventricular depolarization.
T Wave : Return of ventricles from excited to normal state. (repolarisation).
Importance of Hepatic Portal Circulation :
Blood which comes from alimentary canal contains absorbed food like glucose and amino acids. Excess of glucose is converted into glycogen which is stored in the liver for later use.
When an individual feels the deficiency of food, the glycogen is converted into glucose and transferred to blood stream via hepatic veins.
Also, liver produces proteins which are put into blood circulation.       
Rh (Rhesus) Blood Group:
A protein named Rhesus Antigen is present on the surface of the RBCs in many persons. It was first discovered in the blood of the Rhesus Monkey.
People who have this antigen --à Rh+
Those who do not have -à Rh-
Formation of Rh protein is controlled by a dominant gene, called R.
Incompatibility during blood Transfusion:
Q: First blood transfusion of Rh+ blood to Rh- person causes no harm. Why?
A: Rh- person develops anti Rh factors or antibodies in his/her blood. In the second transfusion, anti Rh factors of Rh- person attacks and destroys the RBCs of the donor.
Incompatibility during Pregnancy
If the father’s blood is Rh+ and the mother’s blood is Rh-, the foetus’s blood will be Rh+. If the Rh- blood of the mother has not earlier come in contact with the Rh+ blood through transfusion, her first child does not suffer. But, the Rh+ blood of the foetus stimulates the formation of anti Rh factors (enough anti Rh factors are not produced in the mother’s blood to harm the foetus).
But, in the subsequent Rh+ fetuses, anti Rh factors of the mother may destroy the foetal RBCs.
This results in the Haemolytic Disease of the Newborn (HDN)- Erythroblastosis foetalis

Wednesday, 28 January 2015

Important viva questions

Q. What are enzymes? Give two most important characteristics of enzymes.
A: Enzymes are biocatalysts that are involved in various metabolic reactions in a living system. All enzymes are proteins chemically, and they remain unchanged at the end of a reaction.
Q. Name the glands from which saliva is produced.
A. 3 pairs of salivary glands: parotid, submaxillary and sublingual.
Q. What is achromic point?
A: It is the time required to digest starch completely by salivary amylase.
Q: What happens to enzyme activity at very high or very low temperature?
A: Enzymes get denatured at high temperature and deactivated at low temperature, as they are proteins in nature.
Q: How are enzymes different from hormones?
A: (i) All enzymes exceptionally are proteins in nature while hormones can either be proteins or amies or lipids.
(ii) Hormones always have a target organ to act while the enzymes don’t.
Q: What are conjugated enzymes?
A: When along with the protein, some other non-protein moiety is also attached to the enzyme, it is known as conjugated enzyme.
Q:  Can a haploid cell divide meiotically?
A: No, since meiosis reduces the chromosome number to half.
Q: What is the significance of crossing over in meiosis?
A: During crossing over in meiosis, exchange of genetic material between non-sister chromatids occurs; as a result, the genotype of the cells is altered. So it results in genetic recombination and finally helps in introducing variations in populations.
Q: What do you mean by the term karyokinesis?
A: Karyokinesis means the division of the nucleus.
Q: What is a meiocyte cell?
A: A cell that is to divide by meiosis is called a meiocyte.
Q: How do you differentiate the chromosomes of mitosis and meiosis?
A: Meiotic chromosomes are comparatively longer and thiner. They show a characteristic beaded appearance by the presence of chromomeres.
Q: From one parent cell, how many daughter cells will be produced after meiosis and mitosis respectively?
A: two cells after mitosis and four cells after meiosis.
Q: At what stage of cell division does nuclear membrane reappear?
A: Telophase
Q: In which stage of cell division chromosomes are seen best?
A: metaphase stage
Q: Name the chemical that can arrest the process of cell division at metaphase stage.
A: Colchicine
Q: What do you mean by cytokinesis?
A: division of the cytoplasm
Q: Why is mitosis termed as equational division and meiosis as reductional division?
A: Mitosis is equational division because the daughter cells formed are identical to the parent cell in all respects. Meiosis is termed as reduction division because the daughter cells formed have half the number of chromosomes as the parent cell.

Tuesday, 2 December 2014


             Allele : Various or slightly different forms of a gene, having same position on chromosomes.
Phenotype : The observable or external characteristics of an organism
Genotype : The genetic constitution of an organism.
Monohybrid cross : A cross between two individuals of species, considering the inheritance of single pair of contrasting character e.g., a cross between pure tall (TT) and Dwarf (tt).
Dihybrid cross : A cross between two individuals of a species, considering the inheritance of two pairs of contrasting traits/characters e.g., a cross between Round and Yellow (RRYY) and wrinkled and green (rryy) pea seeds
Co-dominance : When two alleles of a gene are equally dominant and express themselves even when they are together.
Multiple allelism : When a gene exists in more than two allelic forms e.g., gene for blood group exist in three allelic forms, IA, IB and i.
Aneuploidy : The phenomenon of gain or loss of one or more chromosome(s), that results due to failure of separation of homologous pair of chromosomes during meiosis.
Trisomy : The condition in which a particular chromosome is present in three copies in a diploid cell/ nucleus.
Male heterogamety : When male produces two different types of gametes/ sperms e.g., In human beings X and Y.
Mutation : The sudden heritable change in the base sequence of DNA, or structure of chromosome or a change in the number of chromosomes.
Pedigree Analysis : The analysis of the distribution and movement of trait in a series of generations of a family.
Female heterogamety : When female produces two different types of gametes/ova e.g., female bird produces Z and W gametes.
Law of Dominance : When two individuals of a species differing in a pair of contrasting characters/traits are crossed, the trait that appears in the F1 hybrid is dominant and the alternate from that remain hidden, is called recessive.
Law of Segregation : The members of allelic pair that remained together in the parent, segregate/separate during gamete formation and only one of the factors enters a gamete.
Law of Independent Assortment : In the inheritance of two pairs of contrasting characters, the factors of each pair of characters segregate independently of the factors of the other pair of characters.
Test Cross : When offspring or individual with dominant phenotype, whose genotype is not known, is crossed with an individual who is homozygous recessive for the trait.

The progeny of monohybrid test cross ratio is 1 : 1 while the dihybrid test cross ratio is 1 : 1 : 1 : 1.

Wednesday, 26 November 2014

                                                                                SUPPORT MATERIAL
Clone : A group of organism derived from a single individual and hence morphologically and genetically similar.
Embryogenesis : The process of development of embryo from zygote.
Juvenile Phase : It is the period of growth before maturity when sex organs are not functional.
Meiocytes : These are specialized cells of diploid organisms which undergo meiosis.
Pericarp : It is the protective covering of fruit, may be divided into epicarp, mesocarp and endocarp.
Parthenogenesis : Development of an egg into an embryo without fertilisation.
Gamete Transfer
1. In Algae, Bryophytes and Pteridophytes : The male and female gametes are flagellated and motile, need a medium (water) to reach the egg.
2. In seed Plants : Pollen grains are transferred to stigma of flower of same species by various agents.
3. In animals :
(a) By Copulation . e.g., Reptiles, Birds and Mammals.
(b) By External medium . e.g., Fishes and Amphibians.
Sporulation :- During unfavorable conditions organisms like Amoeba surrounded by resistant coat (three layered - hard covering ) or cyst. This is called encystation . Within cyst a number of spores are formed . On returning favourable conditions, the cyst burt and spores are liberated and gradually grows into adults. This process is known as sporulation.
Fragmentation : It is a type of asexual reproduction where an organism splits into fragments. There fragments develops into fully grown individual. eg. spirogyra, fungi and some annelids.
Regeneration: It is a process of renewal, restoration and growth. It can occur at the level of the cell tissue and organ . It is common in Hydra , Planaria and echinoderms .ŸIn human, liver has power of regeneration, if it is partially damaged.ŸDuring danger a lizard discard a part of tail which can regenerate latter.
Autogamy : When pollen grains of a flower are transferred from anther to stigma of the same flower.
Coleorhiza : Aprotective sheath of radicle in monocot seed.
Endothecium : A fibrous layer in the anther next to epidermis.
Geitonogamy : Self pollination between flowers of the same plant.
Micropyle : Asmall pore in the ovule through which the pollen tube enters.
Nucellus : Multicellular tissue in the centre of ovule where embryo sac is present.
Tapetum : Inner most layer of cells in pollen sac which provide nutrition to developing pollen grains
Viability of Seed : Ability of seed to retain the power of germination.
1. Microsporangium (Pollen sac) : Outermost layer = Epidermis
Second layer = Endothecium
Middle layer = 2 - 4 layers of cells
Innermost layer = Tapetum [Nourishes the developing pollen grains(Microspores)]
2. Microsporogenesis : Process of formation of microspores from a pollen mother cell.
Megasporangium (Ovule) :
ŸThe ovule is a small structure attached to the placenta by means of a stalk called funicle.
ŸThe point of attachment of the body of the ovule to the funicle is known as hilum. The main body of the ovule is composed of paranchymatous cells known as nucellus.
ŸEach ovule has one or two protective integument, which encircle the ovule except at the tip having small opening called micropyle.
ŸOpposite to micropylar end, is chalaza. Generally a single embryosac or female gametophyte located in
ŸCells of nucellus have abundant reserve food material and provide nourishment to the developing embryo.
 Female gametophyte (Embryo sac) : In a majority of flowering plant one of the megaspore is functional while other three degenerate.
The functional megaspore develops in embryo sac.
The nucleus of the functional megaspore (n) undergoes three successive mitotic cell division which results the formation of eight nucleate stage of embryo sac (free nuclear division).The cell wall formation starts at eight nuclear stages. Three cells are grouped together at micropylar end to form the egg apparatus.(2 synergids + 1 egg cell).
Dicot Embryo : A typical dicot embryo consist of an embryonal axis and two cotyledons.The portion of embryonal axis above the level of cotyledons is the epicotyle which terminates with the plumule or stem tip.
The portion below the level of cotyledons is hypocotyl that terminates at its lower end in the radicle or root tip.
Monocot Embryo : Monocot (Rice, Maize etc.) has one cotyledon called Scutellum.The embryonal axis has the radicle and root cap enclosed by a sheath called Coleorrhiza.
The upper end (epicotyle) has plumule which is covered by hollow folder sturcture, the coleoptile.
Apomixis : Apomixis is a form of asexual reproduction that mimics sexual reproduction where seed are formed without fertilisation.
Polyembryony : Occurance of more than one embryo in a seed. e.g. Orange, lemon, onion, mango, ground nut.
Reasons of polyembryony : More than one egg may be formed in the embryo sac.More than one embryo sac may be formed in an ovule.

Ramsar Sites Notes

Ramsar sites are wetlands considered to be of international importance. The international convention which forms the basis for their identification is commonly referred to as the "Ramsar Convention" after the city in Iran where the convention was signed in 1971. The Convention is an international treaty for the conservation and wise use of wetlands. All joining Parties of the Ramsar Convention commit themselves to work towards the “three pillars” of the Convention.
Ensuring the conservation and wise use of wetlands it has designated as Wetlands of International Importance,
Including as far as possible the wise use of all wetlands in national environmental planning, and
Consulting with other Parties about implementation of the Convention, especially in regard to transboundary wetlands, shared water systems, and shared species.

Sites are selected by the Contracting Parties for designation under the Convention by reference to the Criteria for the Identification of Wetlands of International Importance. Sites must meet one or more of the following nine criteria:
·         Contains a representative, rare or unique example of a natural or near-natural wetland type found within the appropriate biogeographic region.
·         Supports vulnerable, endangered, or critically endangered species or threatened ecological communities.
·         Supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.
·         Supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.
·         Regularly supports 20,000 or more waterbirds.
·         Regularly supports 1% of the individuals in a population of one species or subspecies of water birds.
·         Supports a significant proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity.
·         Is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend.
·         Regularly supports 1% of the individuals in a population of one species or subspecies of wetland-dependent non-avian animal species.