Chapter 3 Solutions — Tissues in Action

Revise, Reflect, Refine

1. 1.
   Meristematic tissues divide repeatedly. Which property of their cells allows them to do this?

   • (i) They have thick walls for protection.
   • (ii) They contain large vacuoles that store nutrients.
   • (iii) They have thin walls, dense cytoplasm and large prominent nucleus.
   • (iv) They are functionally differentiated cells.
2. 2.
   If a plant is unable to transport food from leaves to roots which tissue is malfunctioning?

   • (i) Xylem
   • (ii) Phloem
   • (iii) Epidermis
   • (iv) Sclerenchyma
3. 3.
   Why are the epithelial tissues that line an animal's internal organs usually only one or a few cells thick?

   • (i) To store food efficiently.
   • (ii) To provide maximum strength.
   • (iii) To allow quick exchange of materials across them.
   • (iv) To reduce friction.
4. 4.
   You can perform these two jumps (Fig. 3.21): Straight-leg jump — keep knees and ankles stiff. Normal jump — bend knees and ankles naturally. How did your ankle, knee and hip positions differ between the two jumps?
5. 5.
   Which type of joint is involved when you bend your knees and ankles?

   • (i) Ball and socket
   • (ii) Hinge
   • (iii) Pivot
6. 6.
   In each of the following cases (A, B, C and D), choose the correct option:

   • (i) Both (A) and (R) are true, and (R) is the correct explanation of (A).
   • (ii) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
   • (iii) (A) is true, but (R) is false.
   • (iv) (A) is false, but (R) is true. A. Assertion: Epithelium is well-suited for gas exchange in the lungs. Reason: It consists of…
7. 7.
   Plot a graph between the age of a tree (in years) on the x-axis and the diameter of the tree (in cm) along with the number of annual rings formed over time on the y-axis, using the data given in Table 3.7. Table 3.7: S.No. | Age (Years) | DBH (cm) | Annual rings 1 | 5 | 4 | 5 2 | 10 | 8 | 10 3 | 20 | 24 | 20 4 | 25 | 28 | 25 5 | 30 | 32 | 30 6 | 40 | 40 | 40 (i) Analyse the graph in terms of the…
8. 8.
   In a forest, it was observed that one of the trees was severely debarked by an elephant to meet its food requirements, as the bark is a rich source of nutrients (Fig. 3.22). Based on your learning, answer the following:

   • (i) Which function(s) of the tree is/are hampered by debarking?
   • (ii) Which plant tissue would be affected by further damage to the tree trunk even after debarking?
   • (iii) Which…
9. 9.
   Aamrapali observed that a young mango sapling's stem bends flexibly during monsoon winds and does not break. Which tissue is responsible for this flexibility? Predict and provide your explanation of the impact if the existing tissue was replaced by sclerenchyma.
10. 10.
    Sohan designed an experiment for the regeneration of sugarcane, where he used cuttings to grow sugarcane. He used two types of cuttings, type 'A' and type 'B' (Fig. 3.23). After a few weeks, type 'B' cuttings sprouted and developed into sugarcane plants, whereas the type 'A' cuttings did not sprout.

    • (i) Why were the type 'B' cuttings able to grow as sugarcane but type 'A' could not?
    • (ii) What…
11. 11.
    During the discussion in class, Rohan gives a statement that, "A tissue is a group of similar cells performing similar functions". But Rajiv counter argues that, "this is true in case of simple tissues but little different in case of complex tissues". Provide your explanation in view of the discussion in class.
12. 12.
    Coconut husk fibres are used for mats which are tough and fibrous. Which tissue has structural features suitable for providing this strength? Explain why living parenchyma couldn't serve the same purpose.
13. 13.
    Vibha claims to her friend Neha that, "Meristematic cells are located only at the root and shoot apices". What do you think about this statement? What question can Neha ask Vibha to help her understand further if the statement is incorrect?
14. 14.
    A plant cell and an animal cell are of the same size.

    • (i) Which cell will have a larger vacuole? Give reasons.
    • (ii) What assumptions are you making to answer the question above?
15. 15.
    A textbook states, "Each plant tissue performs only one specific function". What questions would you ask to critically examine the correctness of this statement? What examples of tissues would you take to find out the answers to these questions?