bio12

 Notes " Evolution "  By :- Nagraj Sir ORIGIN OF LIFE: • Stellar distances are measured in light years. • The universe is very old – almost 20 billion years old. • The Big Bang theory attempts to explain to us the origin of universe. The Big Bang theory: • A singular huge explosion unimaginable in physical term. • The universe expanded and hence the temperature came down. • Hydrogen and Helium formed sometime later. • The gases condensed under gravitation and formed the galaxies of the present day universe. • In the solar system of the Milky Way galaxy, earth was supposed to have been formed about 4.5 billion years back. Condition of early earth: • Earth formed 4.5 billion years back. • There was no atmosphere on early earth. • Water vapor, methane, carbon dioxide and ammonia released from molten mass covered the surface. • The UV rays from the sun broke up water into Hydrogen and oxygen and lighter H2 escaped. • Oxygen combined with ammonia and methane to form water, CO2 and...

 Notes "HUMAN HEALTH AND DISEASE" By:- Nagraj Sir   HUMAN HEALTH AND DISEASE • Improper functioning of one or more organs or systems of the body is adversely affected, gives rise to various signs and symptoms i.e we have disease. • Diseases which can easily transmit from one person to other by any means are called infectious or communicable diseases. • Diseases which can not be transmitted from one person to another are called non-infectious or non-communicable diseases. • Disease causing organisms are said to be pathogen. TYPHOID: Pathogen: Salmonella typhi (bacterium) Organs affected: small intestine, migrate to other organs through blood. Method of transmission: contamination of food and water. Symptoms: • Sustained high fever (39o to 40o C) • Weakness, stomach pain, constipation, headache and loss of appetite. • Intestinal perforation and death may occur. Test: Typhoid fever could be confirmed by Widal test. PNEUMONIA: Pathogen: Streptococcus pneumoniae and Haemophilu...

  Notes :- MOLECULAR BASIS OF INHERITANCE By Nagraj Sir  THE DNA: • DNA is a long polymer of deoxyribonucleotides. • The length of the DNA depends on, number of nucleotide pair present in it. • Characteristics of the organism depend on the length of the DNA. • Bacteriophage ø174 has 5386 nucleotides. • Bacteriophage lambda has 48502 base pairs. • Escherichia coli have 4.6 X 106 base pairs. • Human genome (haploid) is 3.3 X 109 bp. Structure of polynucleotide chain: • A nucleotide has three component:-          o A nitrogen base          o A pentose sugar ( ribose in RNA and deoxyribose in DNA)          o A phosphoric acid. • There are two types of nitrogen bases:          o Purines ( Adenine and Guanine)          o Pyrimidines ( Cytosine, Uracil and Thymine) • Adenine, Guanine and Cytosine is common in RNA and DNA. • Uracil is present in RNA and Thymine ...