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Fish breathe with the help of gills which are richly supplied with blood vessels. The gills help the fish to ______.
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Earthworms and frogs breathe through their skin because of which the skin of both the organisms is ______.
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Mark the following statement as True or False. Correct the false statement.
Frogs can breathe through their skin as well as lungs
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Cockroaches breathe with the help of air tubes called ______.
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On an average, an adult human being at rest breathes 15–18 times per minute. The breathing rate, however, may differ under different conditions. Arrange the following activities given in the box in order of increasing breathing rates and give reason for your answer.
| sleeping, cycling, brisk walk, watching T.V. |
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Match the names of organisms in Column I with their organs of breathing given in Column II.
| Column I | Column II | ||
| (a) | Butterfly | (i) | Lungs |
| (b) | Earthworms | (ii) | Gills |
| (c) | Sparrow | (iii) | Spiracles |
| (d) | Fish | (iv) | Skin |
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Observe figure and answer the given questions:
- Name the instrument.
- Label parts A, B and C.
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Match the parts of the heart in Column I with the direction of flow of blood in Column II.
| Column I | Column II | ||
| (i) | Right ventricle | (a) | Pushes blood into the pulmonary artery. |
| (ii) | Pulmonary veins | (b) | Take deoxygenated blood from the heart to the lungs. |
| (iii) | Left atrium | (c) | Receives blood from different parts of the body. |
| (iv) | Pulmonary arteries | (d) | Bring oxygenated blood from the lungs to the heart. |
| (v) | Left ventricle | (e) | Pushes blood into the aorta. |
| (vi) | Right auricle | (f) | Receives deoxygenated blood from the pulmonary veins. |
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The ovaries of different flowers may contain ______.
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Unscramble the following words:
HTRCO
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Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel at the night to get dim light. Has she taken the right step? Give one reason to justify your answer.
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Why do we cover plug pin holes which are within the reach of children with cellotape or a plastic cover when not in use?
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Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give reason.
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How does the magnetic effect of electric current help in the working of an electric bell? Explain with the help of a diagram.
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The amount of water recommended by the United Nations for drinking, washing, cooking and maintaining proper hygiene per person per day is a minimum of
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Fill in the blanks and complete the story by selecting words from the box given here.
| cold, demand, leaders, dry, hot, scarcity, workers, wet, oceans, harvesting, rivers |
Rajasthan is a ______ and dry place. The challenge of natural ______ of water was met by a successful experiment. A band of social ______ had transformed a ______ area into a green place. They have revived five dried-up ______ by constructing water ______ structures.
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Wrap a thin paper strip tightly around an iron rod. Try to burn the paper with candle while rotating the iron rod continuously. Does it burn? Explain your observation.
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Take a sheet of paper. Draw a spiral on it as shown in Figure. Cut out the paper along the line. Suspend the paper as shown in Figure above a lighted candle. Observe what happens. Think of an explanation.
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Take two similar transparent glass bottles having wide mouths. Put a few crystals of potassium permanganate or pour a few drops of ink in one bottle. Fill this bottle with hot water. Fill the other bottle with cold water. Cover the cold water bottle with a thick piece of paper such as a postcard. Press the postcard firmly with one hand and hold the bottle with the other hand. Invert the bottle and place it on top of the hot water bottle. Hold both the bottles firmly. Ask some other person to pull the postcard. Observe what happens. Explain.
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Using an electromagnet, you can make a working model of a railway signal as shown in figure.
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