Plant Control Systems

Question 1

environmental factor organism responds to

Answer 1

stimulus

Question 2

reaction to stimulus

Answer 2

response

Question 3

plant response to stimulus

Answer 3

tropism

Question 4

types of tropism

Answer 4

phototropism
gravitropism
nastic

Question 5

phototropism def

Answer 5

responding to light

Question 6

gravitropism def

Answer 6

responding to gravity

Question 7

nastic def

Answer 7

responding to touch

Question 8

positive tropism

Answer 8

plant moves toward stimulus

Question 9

positive phototropism? gravitropism?

Answer 9

PP - plant moves toward light

PG - plant moves down

Question 10

negative tropism

Answer 10

plant moves away from stimulus

Question 11

negative phototropism? gravitropism?

Answer 11

NP -plant moves away from light

NG - plant moves up

Question 12

stems/phototropism

Answer 12

positively phototropic

Question 13

roots/phototropism

Answer 13

negatively phototropic

Question 14

stems/gravitropism

Answer 14

negatively gravitropic

Question 15

roots/gravitropism

Answer 15

positively gravitropic

Question 16

hydrotropism

Answer 16

growth of plant roots toward/away from moisture

Question 17

controlled by turgor pressure

Answer 17

nastic response

Question 18

why phototropism occurs

Answer 18

stem bends toward light 
leaf gets more sunlight
increased photosynthesis 
more glucose produced
plant grows bigger faster

Question 19

why gravitropism occurs

Answer 19

healthier plant (grows bigger faster)
water + nutrients found deep in soil
roots grow down

Question 20

how phototropism occurs

Answer 20

cells grow more elongated on shaded side

cells grow smaller on light side

Question 21

who’s involved in discovery of phototropism

Answer 21

Charles Darwin
Boysen-Johnsen
Went

Question 22

Charles Darwin

Answer 22

cut off top of stem

found top of stem controls phototropism

Question 23

Boysen-Johnsen

Answer 23

found signal produced by tips of seedlings could pass through gelatin but not mica
suggested some type of growth chemical

Question 24

Went

Answer 24

cut off top, put agar between top and stem
found top of stem uses chemical to control phototropism
discovered “Auxin”

Question 25

"Auxin"

Answer 25

growth hormone | used to make shaded side grow larger cells

Question 26

Auxin experiment?

Answer 26

light straight on top - Auxin diffuses down shoot stimulating growth light to side - Auxin diffuses away from light causing that side to grow larger cells

Question 27

causes cells to grow larger | produced only on shaded side

Answer 27

Auxin

Question 28

roots reaction to water

Answer 28

positive hydrotropism (toward water)