The correct option is (ii) hinge joint. Hinge joints allow movement mainly in one direction, like bending and straightening. Knees and ankles function similarly to door hinges, providing controlled movement and stability during walking, running and jumping.
Discussion Forum Latest Questions
Debarking damages the protective outer covering and may disturb food transport. The tree becomes vulnerable to water loss, infections and mechanical injury. If inner tissues are affected, movement of prepared food to roots and other parts decreases.
If tissues beneath the bark are severely damaged, transport of food throughout the plant would be hampered. Phloem damage prevents movement of sugars from leaves to roots and storage tissues, affecting growth, repair and survival of the tree.
Coconut husk fibres contain sclerenchyma with thick lignified walls, making them hard and brittle. Coriander leaf stalks contain collenchyma with unevenly thickened walls and pectin, providing softness, flexibility and support without breaking during bending or movement.
Different types of cells and tissues are present because organisms perform many specialised functions. Cells become structurally modified for particular tasks like protection, transport, support, movement and coordination, improving efficiency through division of labour in multicellular organisms.