Ch. 29 Plant Structure and Function

Question 1

define desiccation

Answer 1

excessive water loss

Question 2

what is the common ancestor to all land plants?

Answer 2

aquatic green algae

bryophytes

Question 3

which organisms are in the “bryophytes”?

Answer 3

mosses
liverworts
hornworts

Question 4

what are the 2 main groups that comprise all land plants?

Answer 4

vascular plants (monophyletic)
bryophytes (paraphyletic)

Question 5

what are the 4 subgroups of vascular plants?

Answer 5

1. ferns and horsetails
2. gymnosperms (pine trees, conifers)
3. angiosperms (flowering plants, oak trees, grasses, sunflowers)
4. lycophytes

Question 6

what is desiccation tolerance?

Answer 6

bryophytes can tolerate being without water for extended amounts of time, they can resume photosynthesis once water is available

Question 7

who can more easily adapt to varying environmental conditions: vascular plants or bryophytes?

Answer 7

vascular plants (bring water up from soil, and they don’t rely on surface moisture)

Question 8

what forms the “shoot” of vascular plants?

Answer 8

leaves
stem
reproductive organs

Question 9

what are the 4 main tissues in a leaf?

Answer 9

1. upper epidermis
2. palisade mesophyll
3. spongy mesophyll
4. lower epidermis

Question 10

where does most of the plant’s need for water come from?

Answer 10

plants’ need for water arises as a consequence of CO2 uptake in air (transpiration)

Question 11

how do guard cells of stomata open and close?

Answer 11

open = more H2O, more K+ and Cl- ions = swell
close = less H20, less K+ and Cl- ions = shrink

Question 12

what is the resting state of guard cells?

Answer 12

closed

closing doesn’t take any energy

Question 13

how long does it take for angiosperm stomata to completely close/open?

Answer 13

about 10 minutes

Question 14

what can cause stomata to open?

Answer 14

1. light

2. increase in temperature

Question 15

what can cause stomata to close?

Answer 15

1. darkness
2. increases in CO2
3. water deficit

Question 16

water loss and photosynthesis usually peak at the same time. what is one adaptation that allows plants to open their stomata and store CO2 during the nighttime?

Answer 16

CAM (crassulacean acid metabolism): CO2 fixed twice at two different times (temporal segregation)
opens stomata at night
greatly increases CO2 intake while minimizing water loss
-still go through C3 photosynthesis

Question 17

where is CAM most often found?

Answer 17

• habitats such as deserts

- among epiphytes (plants that do not contact the soil because they grow high in a canopy of other plants)

Question 18

all floral parts are modified leaves. true or false?

Answer 18

true!

Question 19

what are some of the functions of leaves?

Answer 19

1. capture insects (form of nitrogen)
2. protection against herbivores
3. protect juvenile leaves
4. capture water
5. store water/nutrients
6. attract pollinators

Question 20

what are C4 plants? what do they do?

Answer 20

C4: CO2 fixed twice in two different cell types

• spatial segregation
• these plants occur in dry environments
• still go through C3 photosynthesis

Question 21

define “bundle sheath”

Answer 21

a cylinder of cells that surrounds each vein

Question 22

what is xylem made up of? what is xylem’s main purpose?

Answer 22

to easily transport water throughout the plant

• tracheids (unicelular, narrow)
• vessel elements (multicellular, wider, unobstructed pipelines)
• water enters/exits through “pits”

Question 23

how is water moved through the plant?

Answer 23

• pulled from above by an evaporative pipeline
• evaporation of water from leaves causes water to flow up form the soil
• hydrogen bonds between water molecules allow water to be pulled up the xylem

Question 24

what are the two main threats to xylem?

Answer 24

• pipelines collapsing inward

- cavitation (caused by freezing, air leaks, or bubbles/ when water is abruptly replaced by water vapor)

Question 25

what does phloem do? what is is made up of?

Answer 25

phloem transports nutrients and sugars throughout the body (phloem sap)

• sieve elements (each one is accompanied by a companion cell which is alive and fully functional)
• moves nutrients from source (leaves) to sinks (roots, fruits, young leaves, anything that needs carbs)

Question 26

rhizosphere

Answer 26

phloem feeds this:
-the soil layer that surrounds actively growing
roots
• The rhizosphere is rich in microbial populations that aid in decomposition

Question 27

what are casparian strips?

Answer 27

hydrophobic material that surrounds each cell at the endodermis
-roots can be very selective as to what material enters the xylem

Question 28

how do plants benefit from fungi/fungal cells?

Answer 28

almost all plants do this! they form a symbiotic relationship with fungi
-mycorrhizae are fungi that form associations with plant roots, extend the surface area of the roots for plant, plant gives the fungi sugar in return

Question 29

how do plants benefit from bacteria?

Answer 29

symbiotic relaitonship! this is how they get nitrogen

• Some free living soil bacteria are capable of nitrogen fixation
• bacteria enter the root through a root hair or a break in the epidermis
• bacteria reside in a root nodule

Question 30

what are epiphytes?

Answer 30

• grow on trees

- absorb nutrients form rainwater that accumulates in leaves/on the bark of the host

Question 31

carnivorous plants

Answer 31

venus fly traps, pitcher plants

get nutrients by trapping insects