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Solved Everyday Science Subjective Paper 2011

Q. 5.

a)     Basically how many forms of energy are there? Also name these. (1+1)
b)     Enlist different types of energy. (4)
c)     Why are trying to find alternate energy sources? (2)
d)    What is renewable energy source? Quote three examples of renewable energy source. (2)

Forms of energy
Energy exists in various forms, including kinetic, potential, elastic potential,  mechanical, thermal, chemical, electrical, radiant sound and atomic.  All forms of energy are inter-convertible by appropriate processes.

Types of energy
Solar energy, Wind energy, Nuclear energy, Chemical energy, Tidal energy, Geothermal energy, Hydel energy, Thermal energy, Wood energy, Fossil fuels, etc.

Why alternate energy
Fossil fuels account for more than 90 per cent of global energy production but are considered problematic resources. They are non-renewable, they can be depleted and it is said that world reserves will end in 50’s or 60’s. Their use causes air pollution. In particular, coal plants have been one of the worst industrial polluters. Moreover, mining or drilling for fossil fuels has caused extensive environmental damage.

Renewable energy source
Renewable energy source is such a source which can be used again and again to produce energy and source doesn’t dissipate in this process. Water (Hydel power), wind (wind energy), tides (tidal energy), sun (solar energy), and wood (forest) are renewable energy sources.

Q. 6. Is plastic a natural or an artificial polymer? Describe various types of plastics and their uses. (10)
Plastic

Materials that are made up of long, chainlike molecules are called polymers and plastic is an artificial polymer. Materials made up of large, organic (carbon-containing) molecules can be formed into a variety of products. The molecules that compose plastics are long carbon chains that give plastics many of their useful properties. More than 50 families of plastics have been produced, and new types are currently under development.

Major plastic materials
Plastic molecules are made of long chains of repeating units called monomers. The atoms that make up a plastic’s monomers and the arrangement of the monomers within the molecule both determine many of the plastics properties. This table lists the monomers for several major plastics and uses of each type of plastic.

Polyethylene
Film, bags, pipe and tubing, insulating sleeves, bottle stoppers, lids, plastic wrap, toys.

Polypropylene
Household items, plastic wrap, automobile parts, batteries, bumpers, garden furniture, syringes, bottles, appliances.

Polystyrene
Plastic wrap, kitchen utensils, furniture covers, thermal insulation, toys, office supplies, disposable razors.

Polyvinyl Chloride (PVC)
Household items, electric wire insulation, water pipes, floor coverings, window and door coverings, bag gage, vinyl, sport and camping gear, items for chemical and automobile industries.

Polytetrafluoroethylene (PTFE) or Teflon
Orthopedic and prosthetic appliances, hearing aids, joints, upholstery, corrosion-resistant mechanical parts, electrical insulation, frying pan coatings.

Polymethyl Methacrylates
Glass substitute, neon signs, windows, portholes, optical fibers, dentistry, appliances, contact lenses.

Polyamides (example: Nylon)
Food wrap, counters, gas, electricity, fuel pipes, shoes, ski bindings, bicycle seats.

Silicone
Fluid for electrical transformers, putty, molding, anti-adhesive coverings, varnish, wax, burn treatments, cosmetic surgery.

Polyesters
Textiles, plastic wrap, bottles, switches, electric sockets and fuses, appliances.

Q. 7. (a) What do the following abbreviations stand for? (5)
a)    LAN: Local area network
b)    HTTP: Hyper text transfer protocol
c)    HTML: Hyper text markup language
d)    PDF: Portable document format
e)    URL: Universal resource locator

(b) Differentiate between natural and artificial satellite. For what purpose artificial satellites are used? (4)
Natural Satellite

In astronomy, a celestial body that orbits a larger celestial body. The larger body is referred to as the satellite’s primary. Natural satellites that orbit planets are often called moons. The best-known natural satellite is Earth’s Moon. The Moon is unusually large relative to the size of its primary (Earth). According to Encarta encyclo-paedia Jupiter has more than 30 natural satellites, four of which are quite large: Io, Ganymede, Callisto, and Europa. Ganymede is even larger than the planet Mercury. Saturn has more than 20 natural satellites, the largest of which is Titan. Titan is even bigger than Mercury. The motion of most of the solar system’s natural satellites about their planets is direct: west to east, in the same direction as the rotation of their planets.

Artificial Satellite
Any object purposely placed into orbit around Earth, other planets, or the Sun. Since the launching of the first artificial satellite in 1957, thousands of these “man-made moons” have been rocketed into Earth orbit. An artificial satellite is launched through a rocket. As satellite is to operate in a very harsh environment so it needs very durable technology. A satellite provides its own power for the duration of its mission, which can extend to 10 years or more. The most common source of power for Earth-orbiting satellites is a combination of solar cells. The first artificial satellite to orbit Earth was Sputnik 1. Built by former Soviet Union and launched on October 4, 1957.

Role of Artificial Satellite
Today, artificial satellites play key role in the communications industry, in military intelligence, and in the scientific study of both Earth and outer space. Engineers have developed many kinds of satellites, each designed to serve a specific purpose or mission. For instance the telecommunications and broadcasting industries use communications satellites to carry radio, television, and telephone signals over long distances without the need for cables or microwave relays. Navigational satellites pinpoint the location of objects on the Earth, while weather satellites help meteorologists forecast the weather. The United States government uses surveillance satellites to monitor military activities. Scientific satellites serve as space-based platforms for observation of Earth, the other planets, the Sun, comets, and galaxies, and are useful in a wide variety of other applications.

Q. 8. (a) What is the main function of the following? (5)
Ribosome
Ribosome, cell structure that uses genetic instructions transported in ribonucleic acid (RNA) to link a specific sequence of amino acids into chains to form proteins.

Mitochondria
The chief function of the mitochondria is to create energy for cellular activity by the process of aerobic respiration.

Lysosomes
Lysosomes, membrane-bound sac found in nucleated cells that contains digestive enzymes that break down complex molecules in the body. Lysosomes are numerous in disease-fighting cells, such as white blood cells, that destroy harmful invaders or cell debris.

Chloroplasts
Chloroplasts are organelles present in the plant cell these are of green colour which have chlorophyll in their body and are responsible for photosynthesis. Plants have green colour due to chloroplasts.

Golgi apparatus
Proteins and lipids manufactured in the endoplasmic reticulum bud off in tiny, hollow structures, or vesicles. They are enclosed in the golgi apparatus. They may be modified by the attachment of lipids or carbohydrates and then sorted out.

(b) Give habitats of the following. (5)
(i)    Rattle snake; United States of America
(ii)    Ostrich; Africa
(iii)     Platypus; Tasmania and Australia
(iv)     Rhinoceros; Asia and Africa
(v)     Chimpanzee; Africa

Q.9. Write short notes on the following:
Nucleic acids

Nucleic acids, extremely complex molecules, are produced by living cells and viruses. Their name comes from their initial isolation from the nuclei of living cells. Certain nucleic acids, however, are found not in the cell nucleus but in cell cytoplasm. Nucleic acids have at least two functions: to pass on hereditary characteristics from one generation to the next, and to trigger the manufacture of specific proteins. The two classes of nucleic acids are the deoxyribonucleic acids (DNA) and the ribonucleic acids (RNA). While all living cells contain the genetic material DNA in the nucleus or cytoplasm. On the other hand, Ribonucleic Acid (RNA), genetic material of certain viruses (RNA viruses) and, in cellular organisms, the molecule that directs the middle steps of protein production.

Fertilizer
Fertilizer, natural or synthetic chemical substance or mixture is used to enrich soil so as to promote plant growth. Virgin soil usually contains adequate amounts of all the elements required for proper plant nutrition. When a particular crop is grown on the same parcel of land year after year, however, the land may become exhausted of one or more specific nutrients. If such exhaustion occurs, nutrients in the form of fertilizers must be added to the soil.

The three elements that most commonly must be supplied in fertilizers are nitrogen, phosphorus, and potassium. Certain other elements, such as boron, copper, and manganese, sometimes need to be included in small quantities.

Semiconductor
Semiconductor, solid or liquid material, is able to conduct electricity at room temperature more readily than an insulator, but less easily than a metal. At low temperatures, pure semiconductors behave like insulators. Under higher temperatures or light or with the addition of impurities, however, the conductivity of semiconductors can be increased dramatically, reaching levels that may approach those of metals. The common semiconductors include chemical elements and compounds such as silicon, germanium; selenium, gallium arsenide, zinc selenide, and lead telluride.

Microwave Oven
Microwave Oven, appliance that uses electromagnetic energy to heat and cook foods. A microwave oven uses microwaves, very short radio waves commonly employed in radar and satellite communications. When concentrated within a small space, these waves efficiently heat water and other substances within foods. In a microwave oven, an electronic vacuum tube known as a magnetron produces an oscillating beam of microwaves.

Internet

Internet is computer-based global information system. The Internet is composed of many interconnected computer networks. Each network may link tens, hundreds, or even thousands of computers, enabling them to share information with one another and to share computational resources such as powerful supercomputers and databases of information. The Internet has made it possible for people all over the world to communicate with one another effectively and inexpensively.

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