Plant Structure and Systems

Question 1

What is the shoot system?

Answer 1

adapted to the need for acquiring resources from above the ground, in the atmosphere
made up from the
leaves: broad surface to maximize photosynthesis and gas exchange
stems: elevate leaves to assist with photosynthesis and reproduction
depends on water/minerals acquired from the root system

Question 2

What is the root system?

Answer 2

adapted to the need to acquire nutrients from below the ground, in the soil
made up from the
tap root: central root that anchors the plant, providing support
lateral roots: branched roots that absorb both water/nutrients
depends on the sugars made in the shoot system

Question 3

What are the three primary organs in the shoot and root systems?

Answer 3

Roots
Stems
Leaves (including flowers)

Question 4

What are the three tissue types?

Answer 4

Dermal
Ground
Vascular

Question 5

What is the dermal tissue?

Answer 5

outer protectie layer

epidermis: in non-woody plants
periderm: in wooded plants

Question 6

What is the vascular tissue?

Answer 6

conduct fluid movement

xylem: water/dissolved minerals move up
phloem: sugars move down (or to the fruits)

Question 7

What is the ground tissue?

Answer 7

all other functions
photosynthesis
storage
physical support

Question 8

What does the xylem do?

Answer 8

conveys water and dissolved mineral upward from roots into the shoots, for photosynthesis
made of dead cells
fortified with lignin

Question 9

What does the phloem do?

Answer 9

moves photosynthetic sugar from stem and leaves to roots and other growth sites
made of living cells

Question 10

What are tracheids?

Answer 10

exist in all vascular plants while vessel elements are in most angiosperms
part of the xylem

Question 11

What are pits?

Answer 11

part of tracheids (of xylem) that allow bulk movement of fluid through cells vertically and laterally

Question 12

What are perforation plates?

Answer 12

part of tracheids (of xylem) in vessel elements to assist fluid movement

Question 13

What are sieve-tube elements?

Answer 13

special cells that have lost nucleus, ribosomes, vacuoles, and cytoskeleton to assist in nutrient movement

Question 14

What are companion cells?

Answer 14

neighbor cell with nucleus and ribosomes to make the proteins for sieve-tube element.

Question 15

What did the vascular system allow for?

Answer 15

the development of true roots, stems, and leaves
movement of nutrients over greater distances
structural support for heavier organisms

Question 16

What are the primary roles of the root system?

Answer 16

anchoring (support)
absorbing water/minerals
storing organic nutrients

Question 17

What do primary roots develop into?

Answer 17

taproot system: one main vertical root that gives rise to lateral roots, which branch outward for absorption
fibrous root system: monocots and seedless vascular plants lose the primary root and develop network of lateral roots from the stem

Question 18

What are root hairs?

Answer 18

they conduct most of the absorption
finger like extensions that grow from elongating roots
increase surface area of branching roots
most absorption occurs through cells of the root hairs
most mycorrhizal interactions occur here

Question 19

What modifications have roots undergone?

Answer 19

prop roots: support tall, top-heavy plants
storage roots: taproot has evolved to store tons of sugar
air roots: some is above the ground, to acquire oxygen
buttress roots: shallow root systems

Question 20

How does vascular bundles differ in monocots and eudicots?

Answer 20

monocots: vascular bundles are more dispersed
eudicots: central star-like stele of vascular tissue

Question 21

What is the primary role of the stem?

Answer 21

to bear the buds and leaves of the root system, in order to position them such that they can maximize photosynthesis
raise reproductive structures to help pollination/seed dispersal

Question 22

What do stems consist of?

Answer 22

alternating systems of nodes

Question 23

What is a node?

Answer 23

points where the leaves are attached, by growing from buds

Question 24

What is the apical bud?

Answer 24

terminal bud: located at the shoot tip, and elongates the main, central stem

Question 25

What is the axillary bud?

Answer 25

buds that can form lateral stalks, which attach to leaves, thorns, flowers or even entirely new branches

Question 26

What modifications have stems undergone?

Answer 26

rhizomes: horizontal stem just below the surface which gives rise to shoots
bulbs: underground shoots that give rise to enlarged storage leaves
stolons: horizontal shoots along soil surface, allows asexual reproduction
tubers: enlarged ends of rhizomes or stolon stems used for food storage

Question 27

What is the primary role of leaves?

Answer 27

to conduct the process of photosynthesis

Question 28

What are the secondary roles of leaves?

Answer 28

to conduct:
gas exchange
heat dissipation
herbivore defense
cone, flower, fruit development

Question 29

How does the vascular tissue form assist photosynthesis?

Answer 29

vascular tissue of the leaf connects with the vascular tissue of the stem to move materials both need and produced by photosynthesis
called veins in the leaves, which also act as structural support

Question 30

How does the dermal tissue form assist photosynthesis?

Answer 30

the epidermis reduces water loss by forming tight layer that makes the cuticle
the waxy cuticle also protects against pathogens from entering
ground tissue in a leaf is called mesophyll

Question 31

What is the purpose of stomata?

Answer 31

allow CO2 exchange between the air and the photosynthetic cells
pores are flanked by guard cells which regulate opening and closing

Question 32

How does the ground tissue form assist photosynthesis?

Answer 32

called the mesophyll has two layers:
palisade mesophyll: photosynthetic cells that are tightly packed
spongy mesophyll: photosynthetic cells that are arranged loosely, such that gas exchange can occur within the leaf

Question 33

What the three morphologies of leaves?

Answer 33

simple
compound
doubly compound

Question 34

What is a simple leaf?

Answer 34

single, broad, undivided blade (can be lobed)

Question 35

What is a compound leaf?

Answer 35

many “leaflets” come from petiole; no axillary bud at base

Question 36

What is a doubly compound leaf?

Answer 36

the “leaflets” are divided again into smaller leaflets

Question 37

What are the three heavily modified forms of leaves?

Answer 37

tendrils: provide support
spines and thorns: protection
storage leaves: house both water and food

Question 38

What are parenchyma cells?

Answer 38

when mature:
they have thin flexible primary walls
generally lack secondary walls
have a large central vacuole
perform the most metabolic functions
retain the ability to divide and differentiate
Examples: phloem cells, photosynthetic cells, some storage tissues

Question 39

What are collenchyma cells?

Answer 39

grouped in strands and help support young parts of the plant shoot
they have thicker and uneven cell walls
these cells provide flexible support without restraining growth
often serve as mechanical support (especially for young or growing parts of the plant)

Question 40

What are sclerenchyma cells?

Answer 40

highly specialized for mechanical rigidity
thick secondary walls, often strengthened with lignin for rigidity
usually elongated when mature; resistant to bending, cannot grow
often dead at maturity (no active biochem need for function)
examples: xylem cells, fibers, and sclerids