Topic 12-Sensitivity In Plants And Animals

Question 0

Sense organs in animals are a group of receptor cells, which respond to specific stimuli. Show some examples of these sense organs:

Answer 0

Eyes- sense light
Nose- sense chemicals (smell)
Ears-sense sound (and balance)
Tongue- sense chemicals (taste)
Skins- senses change in temperature, pressure, touch and pain

Question 1

How are all animals and plants sensitive?

Answer 1

They can detect changes in their environment. Any change ghost is detected is called stimulus. If necessary, they then respond to stimuli in various ways.

Question 2

What happens in the process called reaction time?

Answer 2

When the cells of a sense organs are simulated, they relay this information along nerve cells (neurons) to the central nervous system (the brain and spinal cord). Nerves contain large numbers of neurons, bundled together. The message travels in the form of an electrical impulse. The central nervous system can coordinate the information and send outgoing impulses to an effector, which can cause a response.

Question 3

What is the response to gravity called?

Answer 3

Gravitropism

Question 4

Roots are?

Answer 4

Positively Gravitropic

Question 5

Stems are?

Answer 5

Negatively Gravitropic

Question 6

What is the response to light called?

Answer 6

Phototropism

Question 7

Why is the stem called positively phototropic?

Answer 7

So they grow towards the light. This ensures they get maximum about of light.

Question 8

What are tropism a controlled by?

Answer 8

Tropisms are controlled by plant hormones. ( chemicals which can move around the plant and cause response)