Chapter 2 Solutions — The Invisible Living World: Beyond Our Naked Eye

Keep the Curiosity Alive

1. 1.
   Various parts of a cell are given below. Write them in the appropriate places in the following diagram (a Venn diagram with three overlapping circles for Animal Cell, Plant Cell, and Bacterial Cell). Nucleus Cytoplasm Cell wall Chloroplast Cell membrane Nucleoid
2. 2.
   Aanandi took two test tubes and marked them A and B. She put two spoonfuls of sugar solution in each of the test tubes. In test tube B, she added a spoonful of yeast. Then she attached two incompletely inflated balloons to the mouth of each test tube. She kept the set-up in a warm place, away from sunlight. (i) What do you predict will happen after 3–4 hours? She observed that the balloon…
3. 3.
   A farmer was planting wheat crops in his field. He added nitrogen-rich fertiliser to the soil to get a good yield of crops. In the neighbouring field, another farmer was growing bean crops, but she preferred not to add nitrogen fertiliser to get healthy crops. Can you think of the reasons?
4. 4.
   Snehal dug two pits, A and B, in her garden. In pit A, she put fruit and vegetable peels and mixed it with dried leaves. In pit B, she dumped the same kind of waste without mixing it with dried leaves. She covered both the pits with soil and observed after 3 weeks. What is she trying to test?
5. 5.
   Identify the following microorganisms:

   • (i) I live in every kind of environment, and inside your gut.
   • (ii) I make bread and cakes soft and fluffy.
   • (iii) I live in the roots of pulse crops and provide nutrients for their growth.
6. 6.
   Design an experiment to test that microorganisms need optimal temperature, air, and moisture for their growth.
7. 7.
   Take 2 slices of bread. Place one slice in a plate near the sink. Place the other slice in the refrigerator. Compare after three days. Note your observations. Give reasons for your observations.
8. 8.
   A student observes that when curd is left out for a day, it becomes more sour. What can be two possible explanations for this observation?
9. 9.
   Observe the set-up given in Fig. 2.15 and answer the following questions. The set-up shows: Flask A containing warm sugar solution + Yeast, connected by a delivery tube to Test tube B containing Lime water.

   • (i) What happens to the sugar solution in flask A?
   • (ii) What do you observe in test tube B after four hours? Why do you think this happened?
   • (iii) What would happen if yeast was not added in…