Stimuli And Responses In Plants

Question 1

Phototropism (Explanation)

Answer 1

• Growth of plants on response to light stimuli
• Shoots of plants show positive phototropism
• Roots of plants show negative phototropism

Question 2

Geotropism (Explanation)

Answer 2

• Growth of plants in response to gravity stimuli
• Roots of plants show positive geotropism
• Shoots of plants show negative geotropism

Question 3

Hydrotropism (Explanation)

Answer 3

□ Response of plant towards water
□ Roots of plants show positive hydrotropism
□ Shoots of plants show negative hydrotropism

Question 4

Thigmotropism (Explanation)

Answer 4

▪︎ Response of plants towards touch stimuli
▪︎ Tendrils or twining stems show positive thigmotropism
▪︎ Roots of plants show negative thigmotropism

Question 5

Nastic movement (Explanation)

Answer 5

▪︎ Response towards a stimuli such as touch but does not depend on direction of stimulus.
▪︎ Occurs more rapidly than tropism
▪︎ Protects the plant from enemies and strong wind

Question 6

Stereoscopic vision (Explanation)

Answer 6

◇ Both eyes located in front of head
◇ Narrow field of vision
◇ Fields of vision overlap and produce 3D vision
◇ 3D image allow distance, size and depth of object estimated accurately
◇ Helps animals to hunt
◇ Humans and most predators has this vision