PACK 24: SURVIVAL AND RESPONSE

Question 1

What is a Stimulus?

Answer 1

A detectable change in the internal or external environment of an organism, that produces a response.

Question 2

Give 3 examples of stimuli in plants.

Answer 2

• Light
• Gravity
• Water

Question 3

Give 3 examples of stimuli in animals.

Answer 3

• Light
• Sound
• Chemicals
• Pressure

Question 4

What is a tropism?

Answer 4

A plant’s growth response to an external, directional stimulus.

Question 5

What is a positive response/tropism?

Answer 5

Growth towards the stimulus.

Question 6

What is a negative response/tropism?

Answer 6

Growth away from the stimulus.

Question 7

Define positive phototropism.

Answer 7

Plant shoots grow towards light.

Question 8

Define negative phototropism.

Answer 8

Plant roots grow away from light.

Question 9

What is positive gravitropism?

Answer 9

Young roots of seedlings grow towards gravity.

Question 10

What is negative gravitropism?

Answer 10

Young stems of seedlings grow away from gravity.

Question 11

What is positive hydrotropism?

Answer 11

Plant roots grow towards water.

Question 12

What are plant growth factors?

Answer 12

Substances produced in the growing regions of the plant that can stimulate or inhibit growth.

Question 13

What is IAA?

Answer 13

Indoleacetic acid, a main auxin that controls directional growth in flowering plants.

Question 14

Where is IAA produced?

Answer 14

In the tip of the shoot (or root).

Question 15

How does IAA affect shoots?

Answer 15

Causes cell elongation.

Question 16

How does IAA affect roots?

Answer 16

Inhibits growth.

Question 17

What is a gravitropism?

Answer 17

The growth of plant roots and shoots in response to gravity.

Question 18

What is a taxis?

Answer 18

A simple, directional response to a stimulus carried out by the whole organism.

Question 19

What is positive phototaxis?

Answer 19

Movement towards light, enhancing survival chances for photosynthesis.

Question 20

What is negative phototaxis?

Answer 20

Movement away from light, helping to conserve water and avoid predation.

Question 21

What is positive chemotaxis?

Answer 21

Movement towards chemicals, increasing the chance of finding a mate.

Question 22

What is a kinesis?

Answer 22

A non-directional response to a stimulus where the rate of movement relates to stimulus intensity.

Question 23

How do woodlice respond in dry conditions?

Answer 23

They move faster and change direction less often to avoid drier air.

Question 24

What are the two sections of the nervous system?

Answer 24

• Central NS: brain and spinal cord
• Peripheral NS: sensory and motor nerves

Question 25

What is a reflex action?

Answer 25

A rapid, short-lived, involuntary response to a specific stimulus.

Question 26

What is the reflex arc?

Answer 26

The shortest pathway taken by impulses in a simple reflex.

Question 27

What is the function of a sensory neurone?

Answer 27

Carries impulses from receptors to CNS (brain/spinal cord).

Question 28

What is the function of a motor neurone?

Answer 28

Carries impulses from CNS to effectors (muscle/gland).

Question 29

What is an example of a simple reflex?

Answer 29

Knee jerk, blinking, swallowing, pain withdrawal, pupil dilation.

Question 30

Describe the pathway of a withdrawal reflex.

Answer 30

Sensory neurone → relay neurone → motor neurone → effector.

Question 31

What happens when you touch a hot pan?

Answer 31

Temperature and pain receptors generate impulses in the sensory neurone.