Pack 24 - Survival and Response

Question 1

what is a stimulus?

Answer 1

detectable change in the internal and external environment of an organism that provides a response

Question 2

what are the stimulus in plants?

Answer 2

light
gravity
water

Question 3

what are the stimulus in animals?

Answer 3

light
sound
chemicals
pressure

Question 4

what is a tropism?

Answer 4

plant growth in response to an external, directional stimulus

Question 5

role of IAA in plant shoots?

Answer 5

• produced in cells by root tips and transported down growing region
• IAA transported evenly
• light from one side causes IAA to go from light to shaded side
• shaded side grows faster

Question 6

role of IAA in roots?

Answer 6

• unilateral light shone on root so IAA moves to shaded side
• IAA accumulates on shaded side which inhibits growth on that side (root cells react differently then the shoot cells)
• root now bends away from light (negative phototropsim)

Question 7

Role of IAA in controlling gravitropisms?

Answer 7

• growth of plants roots and shoots respond to gravity
• seeds placed horizontally make the roots grow down and the shoot grow up
• IAA redistributed in both directions on lower side

Question 8

what is taxis?

Answer 8

• simple directional response to a stimulus
• positive is towards stimulus
• negative is away from stimulus

Question 9

what is kinesis?

Answer 9

• non directional response to a stimulus
• rate of movement/rate of change of direction
• related to intensity of stimulus
• random movement patterns

Question 10

what is a reflex?

Answer 10

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

Question 11

examples of a reflex? (5 points)

Answer 11

• knee jerk
• blinking
• swallowing
• pain withdrawal
• pupil dilation

Question 12

what is a reflex arc?

Answer 12

-shortest pathway taken by an impulse in a simple reflex

Question 13

what is a simple reflex?

Answer 13

• very fast
• involve electrical impulses
• very short neurone pathway