Survival and Response

Question 1

How can organisms increase their chance of survival?

Answer 1

By responding to stimuli

Question 2

What is a stimulus?

Answer 2

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

Question 3

Define tropism

Answer 3

A plants growth response to an external, directional stimulus

Question 4

What is positive phototropism and its survival value?

Answer 4

Plant shoots grow towards light
Leaves able to absorb more light for photosynthesis

Question 5

What is negative phototropism and its survival value?

Answer 5

Plant roots grow away from light
Increases probability that roots grow into soil- increases chance of absorbing water and ions

Question 6

What is positive gravitropism and its survival value?

Answer 6

Young roots grow towards gravity
Increases probability that roots grow into soil- increases chance of absorbing water and ions

Question 7

What is negative gravitropism and its survival value?

Answer 7

Young stems grow away from gravity
Grows out of soil- leaves exposed to sunlight

Question 8

What is positive hydrotropism and its survival value?

Answer 8

Plant roots grow towards water
Root systems grow and spread in soil where more water

Question 9

What are the plant growth regulators?

Answer 9

Auxins

Answer 10

IAA is produced in the TIP of the shoot
It is moved to other parts of the plant by diffusion
Tropisms in shoot and root due to an uneven distribution of IAA = uneven growth of different parts of the plants