LIGHTENED TO LIGHT

  Chapter 10 Motion and Measurement of Distances 1. Give two examples each of modes of transport used on land, water, and air. Two examples of modes of transport used on land are buses and wheel carts. Two examples of modes of transport used on water are ships and boats. Two examples of modes of transport used in air are aeroplanes and helicopters. 2. Why can a pace or a footstep not be used as a standard unit of length? The size of the foot varies from person to person. If footsteps of two persons are used to measure the length respectively, then the two distances may not be equal. Thus, a footstep is not a constant quantity. Hence, it cannot be used as a standard unit of length. 3. Arrange the following lengths in their increasing magnitude: (1 metre, 1 centimetre, 1 kilometre, 1 millimetre) 1 cm = 10 mm 1 m = 100 cm = 1000 mm Again, 1 km = 1000 m = 100000 cm = 10000000 mm. Hence, 1 mm is smaller than 1 cm, 1 cm is smaller than 1 m, and 1 m is smaller than 1

  Chapter 10 Respiration in Animals and Plants   Q1. Why does an athlete breathe faster and deeper than usual after finishing the race? Answer: During the run, the demand of energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscle cells to fulfill the demand of energy. After finishing the race, an athlete breathe faster and deeper than usual so that more oxygen is supplied to the cells. Q2. List the similarities and differences between aerobic and anaerobic respiration. Answer: Similarity: (i) In both aerobic and anaerobic respiration, food is broken down to release energy. (ii) Both takes place inside cells. (iii) Both produces byproducts. Differences: Aerobic Respiration Anaerobic Respiration (i) It takes place in the presence of oxygen. (i) It takes place in the absence of oxygen. (ii) Energy is released in higher amount. (ii) Energ

  LESSON 10 THE RAILWAY JOURNEY   1.   Where were Sunil and Vikram going? Sunil and Vikram were going to spend a week with their friend Anil in Chennai.   2.   Who was going with the boys? Vikram’s dog, Moti was going with the boys to Chennai.   3.   What advice did Sunil’s sister give? Sunil’s young sister had some advice for the boys, Look after your money, she said and pointed to the small purse that Vikram had in his shirt pocket.   4.   Who shared the compartment with the boys? The two other passengers, a fat man and a fat woman shared the compartment with the boys.   5.   What did the boys see from the moving train?   The boys spread their sheets on the bunks, ate their food while enjoying the cool night air blowing through the open window, watched the lights of the cars in the distance, and then settled down for the night.   6.   What happened when the train stopped at a station? When the train stopped at the station, a man put his hand thro