Irritability

What is irritability?

irritability is the ability to detect and respond to stimuli

What does animals have to do to ensure survival in an environment?

Be able to sense and respond to changes

What is a stimulus?

A change in the environment

What is a response?

A change in behavior or location of an organism resulting form a stimulus

What does animals use to detect stimuli?

Receptors ( these are specialized cells that organisms have)

What type of organs contain receptors in animals?

Sense organs

What acts as receptors in plants?

the very tips of roots and shoots

What are effectors?

Effectors are the parts of an organism that responds to stimuli.

What acts as effectors in animals?

muscles and glands

What does the regions just behind the tips of the roots and shoots, and the petioles of leaves act as in plants?

Effectors

How do plants respond to stimuli?

Plants respond to stimuli by making part movements or growth movements, which aid in survival

What is part movements cause by?

Part movement is caused by the change in turgidity of cells

Why do some plants respond to touch or strong winds by folding?

To protect themselves from damage ( eg: Mimosa)

Why do some flowers open in the morning and close at night?

Some flowers open in the morning to expose the stamens and carpels for pollination and close at night as a response to changing light intensities.

How do some leaves respond to changing light intensities

Some  leaves respond to changing light intensities by folding at night and opening in the morning to access light or for photosynthesis.

Why do growth movements occur in plants?

Growth movements occur as a result of a part of a plant growing in response to a stimulus. 

How do plants maximize the amount of light they have available for photosynthesis?

by growing shoots and bending towards unilateral light.

What do plants do when there is no light?

Soots grow upwards against gravity either “in search” of light, or to maximize the amount they receive.

What is the benefit for plants growing up?

Growing upwards ensures that flowers are in the best position for pollination; and fruits and seeds for seed dispersal. 

Which direction does roots grow?

Roots grow and bend downwards with the pull of gravity.

Why do roots grow downwards?

This enables roots to anchor the plant in the ground and to obtain water and minerals.

Why do roots grow and bend towards water?

Roots also grow and bend towards water to maximize the amount of water they can obtain for photosynthesis.

What moves their whole bodies towards or away from stimuli?

Invertebrates (millipedes, earthworms and woodlice)