Unit 2 : Life Process
TIPS
- All living things undergo life processes as follows: breathing, excretion, defecation, response to stimuli and reproduction.
- We use our lungs to breathe. When we inhale, the chest moves outwards and upwards causing the chest to expand; air flows in through the nose, down the windpipe and into the lungs.
- When we exhale, the chest moves inwards and downwards causing the chest to contract; air is pushed out of the lungs, up the windpipe and out through the nose.
- Excretion and defecation are two processes that get rid of waste materials from the body. Excretion means the removal of waste products from the human body. Defecation means the removal of faeces from the body.
- We excrete sweat through the skin; urine produced by the kidneys; water and carbon dioxide through the lungs in the form of exhaled air.
- We response to stimuli. This means that we react towards the changes around us.
- The reaction is called a response. Generally, humans respond to stimuli to protect ourselves from danger or for survival.
- All animals can reproduce and have young or offspring. We divide animals into two groups: animals that give birth and animals that lay eggs.
- Plants also respond to stimuli. However, their responses are usually slow and almost go unnoticed. Plants can respond to stimuli such as light, water, gravity and touch.
COMMON MISTAKES
Which of the following compares the contents of the inhaled air and exhaled air correctly?
- Inhaled air has oxygen only while exhaled air has carbon dioxide only.
- Inhaled air has more carbon dioxide than exhaled air.
- Both inhaled air and exhaled air have the same amount of oxygen and carbon dioxide.
- Inhaled air has more oxygen than exhaled air.
Χ Inhaled air has no carbon dioxide while exhaled air has no oxygen.
√ Inhaled air and exhaled air have both oxygen and carbon dioxide but of different amount.
