Answer:
1.)HIV attacks the immune system, which also means your body cant defend if another bacteria/ virus is in the boidy (supressed immune system)
2.)physical defense: thorns, spines, trichomes etc
chemical defense: milky latex and volatile organic compounds
3.)When you pet a dog, your nerves send a signal to your brain of the soft, silky, warm fur of the dog. Your brain sends a signal back telling your arm to move up and down the dog. Your nerves feel the warmness and softness of his fur and send it to the brain. The brain relates this to other things and secretes hormones through glands which shows the pleasure.
Explanation: