Chapter 18: Coordination In Planes

Question 1

Flashcard 1
Q: What is coordination in plants?

Answer 1

A: The ability of an organism to detect and respond to internal and external stimuli.

Question 2

Flashcard 2
Q: What is a stimulus?

Answer 2

A: Any change in the environment that causes an organism to react or respond.

Question 3

Flashcard 3
Q: Why is responding to stimuli important for plants?

Answer 3

A: It allows organisms to survive and adapt to changing environmental conditions.

Question 4

Flashcard 4
Q: What controls coordination in plants?

Answer 4

A: Plant growth substances (plant hormones).

Question 5

Flashcard 5
Q: Define plant growth substances/hormones.

Answer 5

A: Chemical substances that affect the activities of particular cells and organs in plants.

Question 6

Flashcard 6
Q: Give examples of plant growth substances.

Answer 6

A: Auxins, Ethene, Abscisic acid, Gibberellin.

Question 7

Flashcard 7
Q: What is tropism?

Answer 7

A: A growth response of a part of a plant to stimuli such as light, water, gravity, chemicals, and touch.

Question 8

Flashcard 8
Q: What is positive tropism?

Answer 8

A: Growth towards a stimulus.

Question 9

Flashcard 9
Q: What is negative tropism?

Answer 9

A: Growth away from a stimulus.

Question 10

Flashcard 10
Q: Define gravitropism (geotropism).

Answer 10

A: A growth response in which parts of a plant grow towards or away from gravity.

Question 11

Flashcard 11
Q: What is positive gravitropism?

Answer 11

A: Roots grow downwards towards gravity.

Question 12

Flashcard 12
Q: What is negative gravitropism?

Answer 12

A: Shoots grow upwards away from gravity.

Question 13

Flashcard 13
Q: Define phototropism.

Answer 13

A: A growth response in which parts of a plant grow towards or away from the direction from which light is coming.

Question 14

Flashcard 14
Q: What is positive phototropism?

Answer 14

A: Shoots grow towards light.

Question 15

Flashcard 15
Q: What is negative phototropism?

Answer 15

A: Roots grow away from light.

Question 16

Flashcard 16
Q: What are auxins?

Answer 16

A: Plant growth substances that control responses in plants by causing differential growth.

Question 17

Flashcard 17
Q: Where are auxins produced?

Answer 17

A: In the tips of shoots (coleoptiles) and roots.

Question 18

Flashcard 18
Q: What is differential growth?

Answer 18

A: When one side of a plant grows at a different rate than the other side.

Question 19

Flashcard 19
Q: What role do auxins play in shoots?

Answer 19

A: Promote cell elongation in high concentration and slow down growth in low concentration.

Question 20

Flashcard 20
Q: What role do auxins play in roots?

Answer 20

A: Inhibit growth in high concentration and increase growth in low concentration.

Question 21

Flashcard 21
Q: How do auxins control gravitropism in roots?

Answer 21

A: Auxins accumulate on the lower side of the root, inhibiting elongation and causing the root to grow downward.

Question 22

Flashcard 22
Q: How do auxins control phototropism in shoots?

Answer 22

A: Auxins accumulate on the shaded side of the shoot, causing cells to grow faster and the shoot to bend towards light.

Question 23

Flashcard 23
Q: What are synthetic plant growth substances used for?

Answer 23

A: They are used as selective herbicides to kill weeds by causing rapid growth that leads to the weed’s death.

Question 24

Flashcard 24
Q: What is the purpose of a clinostat?

Answer 24

A: To study tropism in plants by rotating to equalize the effects of gravity.

Question 25

**Flashcard 25** **Q:** What happens when a clinostat is rotating?

Answer 25

**A:** Gravity acts equally on all sides, and there is no differential growth, so the plant grows straight.

Question 26

**Flashcard 26** **Q:** What happens when a clinostat is stationary?

Answer 26

**A:** Gravity affects one side, causing differential growth due to the uneven distribution of auxins.

Question 27

**Flashcard 27** **Q:** How do seedlings grown in different light conditions appear?

Answer 27

**A:** - Normal light: Green, strong growth. - Dark: Pale, elongated, and weak. - One-sided light: Bends towards light due to positive phototropism.

Question 28

**Flashcard 28** **Q:** Describe an experiment to investigate phototropism in shoots.

Answer 28

**A:** Using a cut tip, gelatin block, or mica to show how auxins affect growth direction.