Topic 4

Question 1

3 advantages of multicellularity

Answer 1

• division of labour: cells can become specialized to carry out functions
• size: organisms can be larger bc many cells work tgt to transport materials
• interdependence: organism is unaffected if a cells dies

Question 2

shoot system

Answer 2

• stems, leaves, buds, fruits
• absorbs co2, releases o2

Question 3

root system

Answer 3

• root & root hairs
• absorbs water & minerals from soil

Question 4

meristems

Answer 4

• specialized cells, makes root & shoot tissue
• where mitosis occurs to increase size & repair damage

Question 5

dermal tissue (epidermis) 5 points

Answer 5

• outer layer of cells for non woody plants
• gas exchange in leaves & lenticels (pores in woody stems&roots)
• protects plant from disease
• cuticle in leaves & stem: prevents water loss & microorganisms
• root: takes water & minerals from soil

Question 6

ground tissue

Answer 6

• found in majority of plant, under epidermis
• leaves: location of photosynthesis
• stem: provides strength & support
• roots: food & water storage

Question 7

vascular tissue

Answer 7

• transport of materials through plant
• xylem tissue: movement of water/dissolved minerals from roots to leaves
• phloem tissue: movement of sucrose/dissolved sugars from leaves to roots

Question 8

guard cell

Answer 8

• specialized cells in dermal tissue
• controls shape of tiny pores (stomata) in leaves
• when guard cell is turgid (swollen): transpiration occurs & stomata opens to release o2 and absorb co2

Question 9

stomata

Answer 9

allows gas exchange by diffusion, found under epidermis

Question 10

what happens when plant is dehydrated

Answer 10

• turgor pressure decreases, guard cells shrink, stomata closes to save water
• slows down photosynthesis & may overheat

Question 11

mesophyll

Answer 11

specialized cells in ground tissue

Question 12

mesophyll type #1

Answer 12

palisade cells:
- long, rectangular cells tightly packed
- site of photosynthesis, has lots of chloroplasts

Question 13

xylem

Answer 13

• thick walled tubes w/ cellulose & lignin
• these support cells in xylem by transporting water up from roots

Question 13

mesophyll type #2

Answer 13

spongy mesophyll cells:
- irregular shape, loosely packed
- spaces allow gas exchange

Question 14

phloem

Answer 14

• has individual sieve tube cells w end walls & connected to companion cells
• companion cells: directs sieve tube cells, allows transport of sugar

Question 15

tropism

Answer 15

growth of plant in specific direction bc of a stimulus (causes an action)

Question 16

positive tropism

Answer 16

growth of plant towards stimulus

Question 17

negative tropism

Answer 17

growth of plant away from stimulus

Question 18

phototropism

Answer 18

growth of plant in response to light (stems = pos tropism, roots = neg)

Question 19

gravitropism

Answer 19

growth of plant in response to gravity (stems = neg, roots = pos)

Question 20

auxin

Answer 20

• hormone controlling phototropism
• found in shady side of stem, causes it to grow to light source

Question 21

transpiration

Answer 21

evaporation of water from plant

Question 22

cohesion

Answer 22

• attraction b/w molecules of same substance
• water molecules stick tgt, pulls on each one in evaporation

Question 23

adhesion

Answer 23

• attraction of 2 diff substances
• water sticks to xylem walls to keep gravity from pulling down

Question 24

transpiration pull

Answer 24

xylem uses cohesion&adhesion to pull water up from roots

Question 25

pressure-flow theory

Answer 25

describes how sucrose concentrations determines direction of flow