Chapter 2 Solutions — Cell: The Building Block of Life

Revise, Reflect, Refine

1. 1.
   Differentiate between the following pairs of terms based on the clues given in parentheses:

   • (i) Cell membrane and cell wall (permeability)
   • (ii) RER and SER (structure)
   • (iii) Chloroplasts and chromoplasts (pigments)
2. 2.
   Two similar animal cells are placed in two different solutions: - Cell X is placed in pure water. - Cell Y is placed in a concentrated salt solution. Cells are observed after some time. Cell X swells, and Cell Y shrinks. Which statement provides the correct explanation for the above observations?

   • (i) Salt molecules moved into Cell Y, causing it to shrink.
   • (ii) Water moved into Cell X and more…
3. 3.
   Look at the diagram of a cell in Fig. 2.20. Identify the parts labelled from

   • (a) to
   • (g) and correctly match them with their functions given below:
   • (i) Controlling all the activities of a cell.
   • (ii) Site of cellular respiration.
   • (iii) Storage organelle that also provides rigidity to the cell.
   • (iv) Separates the cell contents from surroundings.
   • (v) Provides structural rigidity to the cell. (vi)…
4. 4.
   Which of the following option(s) of the pairs of cell organelles are correctly placed under the given categories? Option | Present in the plant cells | Absent in the animal cells

   • (i) | Leucoplast | Cell wall
   • (ii) | Mitochondria | Ribosome
   • (iii) | Cell wall | Golgi apparatus
   • (iv) | Lysosome | Endoplasmic reticulum
5. 5.
   Two students, Renu and Rohit, were having a discussion on the plastids. Renu emphasised that all parts of the plants, even roots, contain plastids. However, Rohit did not agree with the statement and told her that plastids are absent in plant roots since the roots are underground and do not need to perform photosynthesis. Who is correct? Justify your answer.
6. 6.
   Mitochondria and chloroplasts are two important organelles in a plant cell. Discuss how these two organelles are structurally and functionally similar to each other, and different from each other.
7. 7.
   Which of the following pairs of cell organelles contains DNA?

   • (i) Chloroplasts, Ribosomes
   • (ii) Mitochondria, Nucleus
   • (iii) Golgi bodies, Ribosomes
   • (iv) Nucleus, Lysosomes
8. 8.
   A researcher carried out an experiment in which she took two carrots of similar size. She placed one carrot in plain water (A) and the other carrot in concentrated salt solution (B) (Fig. 2.21). After 24 hours she recorded her observations.

   • (i) What hypothesis does she want to test through this experiment?
   • (ii) What would you suggest for the improvement of this experiment?
   • (iii) Why does the…
9. 9.
   Indicate the presence or absence of following structures in bacterial and animal cells: Structures in a cell | Bacterial cell | Animal cell Chromosome | | Nucleus | | Mitochondria | | Golgi complex | | Chromoplasts | |
10. 10.
    Carry out the following experiment: Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Place each of the potato cups in a beaker containing water (Fig. 2.22). Set up as follows:

    • (a) Keep Cup A empty.
    • (b) Add one teaspoon sugar in Cup B.
    • (c) Add one teaspoon salt in Cup C.
    • (d) Add one teaspoon sugar in the…
11. 11.
    Identify the pair that incorrectly matches the cell organelle with its function.

    • (i) Ribosome — Protein synthesis
    • (ii) SER — Lipid and cellulose synthesis
    • (iii) Lysosome — Digestion of foreign agents
12. 12.
    What outcome do you expect, if all the mitochondria are removed from a eukaryotic cell?
13. 13.
    Which phenomenon inhibits the formation of tumors in the human body? Can plants also develop tumors? Explain.
14. 14.
    The cell membrane of a cell is made up of proteins and lipids. Which cell organelles help in the synthesis of cell membrane? Write the path of these compounds from their site of synthesis to the cell membrane and show this through a labelled diagram.
15. 15.
    What would happen if gametes are formed by mitotic divisions?
16. 16.
    A farmer, Deepa, was very happy with the harvest of amla (Indian Gooseberry) and lemons on her farm. However, she could sell only one-fourth of the produce in the local market. She employed a traditional yet scientifically sound method to extend the shelf life of amla and lemons. She turned perishable produce into profitable products, such as pickles and sharbat, by adding appropriate amounts of…