Bone and muscle mass differ because of age, gender, nutrition, genetics and physical activity. Bones provide support and protection, while muscles help movement and posture. Together, they contribute significantly to total body weight and body strength.
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The correct option is (iii). Epithelial tissues are thin to allow rapid exchange of gases, nutrients and wastes across them. Their thin structure supports efficient absorption, secretion and diffusion in organs like lungs, intestines and blood vessels.
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.
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.