PHYSICS
PRESSURE
- Units
- atmosphere, technical atmosphere
- mm, cm, inches of mercury
- mm, cm, inch, foot of water
- kip, ton-force, pound-force
- pound per square inch
- bar, decibar, millibar
- barye, dyne
- sthene per square metre, pieze
- Pressure in everyday life
- Transpirational pull in plants (negative pressure caused by surface tension), used to suction water from the water to leaves
- Casimir effect: physical force betwen two uncharged metal plates in vaccuum. Used in nanotechnology
- Atmospheric pressure decreases with elevation. Due to this boiling point of water decreases with elevation
- Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels. For a healthy adult human the pressure should be 115 mm Hg (systolic) and 75 mm Hg (diastolic)
- A microphone works on the principle of sound pressure. A thin membrane converts sound pressure into an electrical signal
- Caisson Disease (aka The Bends or Decompression Sickness) occurs due to sudden change in atmospheric pressure. It happens when a person moves from a high pressure environment to a low pressure. Examples include divers returning from depth, workers in caissons during bridge construction, sudden drop in aircraft pressure etc. Can lead to paralysis and death.
- Vaccuum is a volume of space where pressure is less than atmospheric pressure. Examples include vaccuum cleaners, deep space, incandescent light bulb
GRAVITATION
- History of gravitational theory
- 4th century BCE: Aristotle proposed heavy bodies are attracted towards the center of the universe due to an inner gravitas
- 628 CE: Brahmagupta recognized a force of attraction. He followed the Heliocentric solar system and propsed gravitational attraction between the Sun and the Earth
- 1660s: Robert Hooke explains celestial gravity
- 1687: Isaac Newton proposes law of universal gravitation
- 1915: Albert Einstein proposes theory of general relativity
- Gravitation in everyday life
- Objects falling freely towards the earth’s surface have an acceleration due to gravity This is also known as g-force
- Escape velocity is the speed needed to break free from a gravitational field. On the surface of the Earth it is 11.2 km/s
- Weightlessness occurs in orbit when all gravitational forces acting on an object are uniformly distributed. Weightlessness does not occur due to an absence of gravity.
CHEMISTRY
CERTAIN COMMON SUBSTANCES
- Hydrogen
- Has same atomic number and atomic weight: 1
- Most abundant element in the universe
- Is the lightest element
- isotopes are Protium, Deutrium, Tritium
- Heavy water: water which has Deutirum instead of Hydrogen. Obtained by electrolysis of water. Used as moderator in nuclear reactors
- Used to prepare vanaspati by hydrogenation of vegetable oil
- Oxygen
- Most abundant element on earth’s crust (50% of all elements)
- Used for artificial respiration, and along with Nitrogen as an anesthetic
- Water
- About 70% of earth’s surface and 65% of body weight
- Hardness of water due to dissolved salts of Calcium and Magnesium
- Temporary hardness due to bicarbonates of Ca and Mg. Can be removed by boiling
- Permanent hardness due to chlorides and sulphates of Ca and Mg. Can not be removed by boiling
- Rain water is the purest form of water
- River water is hard water
- Spring water purer than river water
- Sea water is hard water. Contains Sodium Chloride in addition to salts of Ca and Mg
- Mineral water: spring water with minerals and having medicinal value
- Nitrogen
- Most abundant in atmosphere (78%)
- Occurs in animals and plants in the form of protein
- Used to manufacture fertilizers and explosives
- Liquid nitrogen used in refrigeration
- Phosphorus
- Found in bones, brain and urine
- Glows in dark
- Red phosphorus used to make matches
- White phosphorus used in smoke screens
- Carbon
- Second most abundant element in human body after Oxygen
- Occurs in free state as diamond, coal and graphite
- Diamond: purest form of carbon, hardest naturally occurring substance
- Graphite: only non-metal to act as a good conductor of electricity. Used to make lead pencils and lubricants
- Coal: formed by bacterial decomposition of plant material. Peat coal has lowest carbon content (60%), anthracite has highest (90%)
- Carbon gas: not a gas. Obtained by heating powdered coal and tar in absence of air. Good conductor of electricity
- Coke: obtained by heating coal in absence of air. Used as household fuel and in steel industry
- Wood charcoal: obtained by burning wood. Used to make gas masks, acts as bleaching agent
- Bone charcoal: obtained by destructive distillation of bones. Used as a decolouring agent in sugar industry
- Lamp Black: obtained by burning vegetable oil. Used to make printer’s ink and boot polish
- Sodium
- Does not occur in free state
- Highly reactive, always kept under kerosene
- Used to make sodium vapour lamps
- Removes traces of water in alchohol manufacturing
- Silver
- Best conductor of electricity
- Used to make jewellery, mirrors and hair dyes
- Gold
- Highly inert, does not react with water, air, alkalies or acids. Dissolves in aqua regia. Used to make electron microscope
- Aluminium
- Third most abundant on earth’s crust (8%)
- Used to make cooking utensils, transmission wires, paint
- Alloys Duralumin and Magnalumin used in aircraft building
HALOGENS
Halogen
|
Occurrence
|
Uses
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Fluorine
|
Gas
Found in soil, sea water
Found in tooth enamel
|
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Chlorine
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Gas
Found in common salt
|
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Bromine
|
Liquid
|
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Iodine
|
Solid
Found in sea water, sea weeds
Found in thyroid gland
|
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COMPOUNDS OF SODIUM AND THEIR USES
Compound
|
Uses
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Sodium peroxide
|
|
Sodium hydroxide (caustic soda)
|
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Sodium carbonate
|
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Sodium bicarbonate (baking soda)
|
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Sodium chloride (common salt)
|
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Sodium nitrate (Chile saltpetre)
|
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Sodium sulphate (Glauber’s salt)
|
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Sodium thiosulphate (hypo)
|
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COMPOUNDS OF POTASSIUM AND THEIR USES
Compound
|
Uses
|
Potassium hydroxide (caustic potash)
|
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Potassium bromide
|
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Potassium nitrite (nitre)
|
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Potassium chlorate
|
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Potassium carbonate (potash)
|
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ALLOYS OF COPPER AND THEIR USES
Alloy
|
Components
|
Uses
|
Bell metal
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Copper, Tin
|
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Brass
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Copper, Zinc
|
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Bronze
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Copper, Tin, Zinc
|
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German silver
|
Copper, Zinc, Nickel
|
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Gun metal
|
Copper, Tin, Zinc
|
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BIOLOGY
HISTORY OF CELL STUDIES
- 1665: Robert Hooke discovers cells in cork
- 1839: Theodor Schwan and Matthias Jakob Schleiden found cell theory
- 1931: Ernst Ruska builds first Transmission Electron Microscope at the University of Berlin
- 1953: Watson and Crick discover double helix structure of DNA. They, along with Maurice Wilkins, won the Nobel Prize in Physiology or Medicine in 1962
GENETIC MATERIAL IN A CELL
- DNA used mainly for storing genetic information
- RNA used mainly for information transport. Sometimes used for genetic storage in certain viruses
- Human cell encodes genetic information in DNA
- Human genetic material found in nuclear genome and mitochondrial genome
- Nuclear genome divided into 23 pairs of DNA molecules called chromosomes
- Mitochondrial genome codes for 13 proteins used in mitochondrial energy production
COMPONENTS OF A CELL
- Cell Membrane
- Separates interior of a cell from outside environment
- Semi-permeable
- Made of proteins and lipids
- Protein receptors are found on the cell membrane
- Cytoplasm
- Part of a cell enclosed withing cell membrane
- Contains three major elements: cytosol, inclusions, organelles
- Cytosol
- Translucent fluid made of water, salts and organic molecules
- Makes up 70% of cell volume
- Contains protein filaments (that make up the cytoskeleton) and vault complexes
- Inclusions
- Small insoluble particles suspended in cytosol
- Include energy storage materials such as starch and glycogen
- Organelles
- Compartments withing the cell that have specific functions. Eg: mitochondria, golgi apparatus, lysosomes etc
- Mitochondria and Chloroplasts
- Both generate energy in the cell
- Mitochondria uses Oxygen to generate ATP
- Chloroplasts generate carbohydrates and Oxygen from carbon dioxide and water
- Mitochondria found in plants and animals. Chloroplasts found only in plants
- Ribosomes
- Large complex of RNA and protein molecules
- Nucleus
- Contains chromosomes
- Site of DNA replication and RNA synthesis
- Golgi Apparatus
- Found in eukaryotes only
- Process and package proteins and lipids synthesised by a cell
- Lysosomes and Peroxisomes
- Lysosomes have digestive enzymes
- Digest excess or worn-out organelles, food particles, virus/bacteria
- Peroxisomes have enzymes that rid the cell of toxic peroxides
- Vacuoles
- Store food and waste
FUNCTIONS OF A CELL
- Cell metabolism
- Cell metabolism required for cell growth
- Metabolism is the process by which cells process nutrient molecules
- Catabolism: cell produces energy by breaking down complex molecules
- Anabolism: cell uses energy to construct complex molecules and perform other functions
- Cell division
- Required for building tissue and procreation
- Prokaryotic cells divide by binary fission
- Eukaryotic cells divide by mitosis or meiosis
- Mitosis produces two identical daughter cells, meiosis produces two daughter cells each with half the number of chromosomes
- DNA replication is required every time a cell divides
- Protein synthesis
- New proteins formed from amino acids
- Consists of two steps: transcription and translation
ASK AND TELL…
- Prokaryotes are
- animals without developed nervous systems
- organisms lacking nucleus
- primitive plants without vascular systems
- plants that do not produce flowers and fruits
- Honey that has high concentration of sugar does not decay because
- it contains natural anti oxidants that prevents bacterial attack
- bacteria can’t survive in active state in a solution of high osmotic strength as water is drawn out
- bacteria can’t survive in active state as it is deprived of oxygen
- none of these
- The number of chromosomes in a bacterium is
- 1
- 2
- 4
- varies with species
- Granum is a component of
- chloroplasts
- golgi apparatus
- ribosomes
- starch grains
- In a plant cell, DNA is found in
- chloroplasts
- mitochondria
- nucleus
- all these
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