Date of conduct: - 13-Oct-2014 Date of sub: - 16-Oct-2014 Class: - IX Science Answer Key 1. 2. 3. 4. Characteristics. On the basis of their body design in form and function. Whether organisms has eukaryotic cell or prokaryotic cell. Complete the following: Kingdom Type of organisms (a) Monera Bacteria and Cyanobacteria (b) Protista Unicellular organisms (c) Plantae All photosynthetic green plants (d) Fungi Lack chlorophyll and obtain food through absorption 5. Species Kingdom 6. (a) Complexity of cell structure (b) Body organization (c) Mode and source of nutrition (d) Phylogenetic relationships 7. (a) Both blue green algae and bacteria possess prokaryotic cells. (b) Like amphibians, the bryophytes require water to complete their life cycle. 8. (A) Protista (B) Monera (C) Algae 9. The characteristic which is dependent on the previous one and would decide the variety in the next level should be chosen for developing a hierarchy in classification. 10. Genus and species. 11. Pressure = 𝐓𝐡𝐫𝐮𝐬𝐭 𝐀𝐫𝐞𝐚 12. The weight of iron nail is greater than the up thrust of water on the iron nail, so iron nail sinks in water on the other hand, the upthrust on cork is more than the weight of the cork. Hence wooden cork floats on water. 13. The thrust of the train is spread over large area of sleepers. Therefore, the pressure acting on the ground under the sleepers is reduced. This prevents the sinking of the track under the weight of the train. 14. So that the weight of the building is spread over a large area and hence less pressure is exerted on the ground. Hence, the building is prevented to skin under its weight. 15. The weight of truck or motor bus spreads over larger area of their tyres and hence the ground under them does not skin. 16. Mass (m) = 600 gm = 0.6 kg Acc. Due to gravity (g) = 10 m/s2 There for thrust (f) = mg = 0.6X10=6N 17. Density: - The mass per unit volume of a substance is called density of substance. S.I unit of density is kg/m3. 18. Mass (m) = 2kg There for Thrust = weight = mg = 2X9.8kg m/s2 = 19.6 N 2 Side of cube = 2 cm = 100 m = 0.02 m There for Area of lower face of cube A = (side)2= (0.02)2 = 4X10-4 m2 𝐹 There for P = 𝐴 = 19.6 4x10-4 = 4.9X104 Pa. 19. Mass of person (m) = 60 kg Acc. Due to gravity (g) = 10 m/s2 There for thrust (f) = mg = 60 X 10 = 600 N Area (A) = 180 cm2 = 180 X 10-4 m2 𝐹 There for P = 𝐴 = 600 = 600 X 104 = 3.3 X 104 Pa. 180 X 10-4 20. We know pressure = 180 Thrust Area When we hold a heavy bag having strap made of a strong and thin string, then the area under the strap is small. Hence large pressure is exerted by the strap on our fingers on shoulder. Due to this large pressure, the strap tends to cut the skin and hence pain is caused.