11.1 Sensing the environment

Do you remember the seven common characteristics of living things learnt in Unit 2?

- One of the common characteristic is that living things can detect stimuli and react to them. - To do this, living things must be able to detect changes in the environment.

What are the sense organs that detect different stimuli?

(Sight) (Hearing) (Taste) (Smell) (Touch) 5 sense organs in humans EyeEye TongueTongue EarEar SkinSkin NoseNose

Which sense organ helps Mrs Wong to hear the phone call? Why can Lily detect the burning smell? Which sense organ does Jimmy use to detect the taste of the banana? How Grandfather knows the tea is hot? Look at the following diagram and see how important our senses are. p.64

1 1 Helps us avoid danger. Lily can smell smoke from a fire. E.g. Lily can smell smoke from a fire. Grandfather can sense that the tea is hot. Importance of sensing the environment 2 2 Helps us detect messages and communicate. Mrs Wong can hear people talk. E.g. Mrs Wong can hear people talk. 3 3 Offers us feelings. Jimmy can taste and smell the food and watch TV. E.g. Jimmy can taste and smell the food and watch TV. Mr Wong can see obstacles in front of him.

For other animals, sense organs ( 感覺器官 ) help them avoid danger, find food and shelters... p.65

- Each kind of sense organ has its own sensory cells ( 感覺細胞 ). Different kinds of sensory cells detect different kinds of stimuli. p.66 detects sound EarEar detects light EyeEye detects taste tonguetongue detects temperature, touch, pressure and painSkinSkin detects smell NoseNose

- When a sense organ detects a stimulus, a message will be sent to the brain. - The brain interprets and analyzes the message and a sense will be produced.

Special methods used by other animals to sense the environment p.66 How do other animals like snakes, honey bees, mosquitoes and fish sense the environment? Find this out from the library or the internet.

How would you distinguish between the following pairs of objects? Check-point 1 p.67 1 Soy sauce and vinegar Eye Ear Tongue Nose Skin

Eye Ear Tongue Nose Skin 2 Flute and tambourine Eye Ear Tongue Nose Skin 3 Iced lemon tea and hot lemon tea

4 $5 coin and $2 coin Eye Ear Tongue Nose Skin 5 Grey sock and white sock Eye Ear Tongue Nose Skin