26. 1 µm is (a) 10–6 m (b) 10–9 m (c) 10–10 m (d) 10–3 m 27. Lysosome arises from (a) endoplasmic reticulum (b) golgi apparatus (c) nucleus (d) mitochondria 28. Living cells were discovered by (a) Robert Hooke (b) Purkinje (c) Leeuwenhoek (d) Robert Brown 29. Select the odd one out (a) The movement of water across a semi permeable membrane is affected by the amount of substances dissolved in it. (b) Membranes are made of organic molecules like proteins and lipids (c) Molecules soluble in organic solvents can easily pass through the membrane. (d) Plasma membranes contain chitin sugar in plants Short Answer Questions 30. Why are lysosomes known as ‘suicide-bags’ of a cell? 31. Do you agree that “A cell is a building unit of an organism”. If yes, explain why? 32. Why does the skin of your finger shrink when you wash clothes for a long time? 33. Why is endocytosis found in animals only? 34. A person takes concentrated solution of salt, after sometime, he starts vomiting. What is the phenomenon responsible for such situation? Explain. 35. Name any cell organelle which is non membranous. 36. We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, aminoacids, fatty acids, glycerol etc. What mechanisms are involved in absorption of digested food and water? THE FUNDAMENTAL UNIT OF L IFE 37

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