Describe changes in arterioles during thermoregulation. 16. State the class of bean plants and bats, giving a reason for each.

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15. During thermoregulation, the changes that occur in arterioles in the human skin are:

• Vasodilation: When the body is hot, arterioles widen to increase blood flow to the skin surface, allowing more heat to be lost by radiation and convection.
• Vasoconstriction: When the body is cold, arterioles narrow to reduce blood flow to the skin surface, thereby conserving heat.

16. Giving a reason in each case, the class to which each of the following organisms belong:

• Bean plant -
  • Class: Dicotyledoneae (or Magnoliopsida)
  • Reason: It has two cotyledons in its seed, net-veined leaves, and a taproot system.
• Bat -
  • Class: Mammalia
  • Reason: It possesses mammary glands (produces milk), has hair or fur, is warm-blooded, and gives live birth.