Lecture 21 Plant Structure

Question 1

How do plants grow

Answer 1

they grow according to a genetically determined, repetitive program (under genetic control)

Question 2

developmental plasticity

Answer 2

ability to alter form in response to its environment

Question 3

In addition to plasticity, plant species by natural selection accumlated adaptations in

Answer 3

morphology

Question 4

water retention features

Answer 4

spines, water storage organs, shape

Question 5

Three basic plant organs are:

Answer 5

roots, stems, and leaves

Question 6

plants have what type of system

Answer 6

root & shoot system

Question 7

Root & shoot system

Answer 7

• roots rely on sugar produced by photosynthesis in the shoot system
• shoots rely on water & minerals

Question 8

3 functions of roots

Answer 8

1. anchoring the plant
2. absorbing minerals & water
3. storing organic nutrients

Question 9

taproot system

Answer 9

one main vertical root that gives rise to lateral roots, or branch roots

Question 10

adventitious roots

Answer 10

arise from stems or leaves

Question 11

taproot system

Answer 11

consists of one main vertical root that gives rise to lateral roots, or branch roots

Question 12

adventitious roots

Answer 12

arise from stems or leaves

Question 13

what root system do seedless vascular plants & monocots have? explain it

Answer 13

fibrous root system; thin lateral roots with no main root (no main tap)

Question 14

in most plants, absorption of water & minerals occurs where and why?

Answer 14

root hairs; increase surface area of water & nutrient uptake

Question 15

Explain root modifications

Answer 15

1. prop roots: support tall, top heavy plants
2. storage roots (carrot, beets)
3. air roots = help get O2, common in swamps
4. buttress roots (rainforest trees)
5. strangling roots : cover a tree & kill it

Question 16

A stem is an ______ consisting of ________

Answer 16

organ; nodes

Question 17

nodes and internodes

Answer 17

• nodes: points at which leaves are attached to stem
• internodes: stem segments between nodes

Question 18

axillary bud

Answer 18

potential to form a lateral shoot or banch

Question 19

apical bud

Answer 19

• terminal bud, near shoot tip and causes elongation of young shoot

Question 20

what is apical dominance?

Answer 20

helps maintain dormancy in most non-apical buds

Question 21

stem modifications

Answer 21

1. rhizomes
2. bulbs
3. stolons
4. tubers

Question 22

rhizomes

Answer 22

• horizontal stem just below ground

Question 23

bulbs

Answer 23

vertical underground shoots consisting of enlarged bases of storage leaves (onion)

Question 24

stolons

Answer 24

horizontal shoots along soil surface; allows asexual reproduction

Question 25

tubers

Answer 25

enlarged ends of rhizomes or stolons for food storage

Question 26

leaves

Answer 26

leaf is main photosynthetic organ of most vascular plants

Question 27

leaf structure

Answer 27

- flattened blade - stalk called **petiole**, which joins leaf to a node of the stem

Question 28

where the petiole & stem interact is called

Answer 28

the axillary bud

Question 29

Leaf Modifications

Answer 29

1. Simple Leaf: single undivided blade, sometimes deeply lobed 2. Compound Leaf: multiple leaflets arising from petiole; no axillary bud at base 3. Doubly Compound Leaf: leaflets divided again into smaller leaflets

Question 30

leaf tendrils

Answer 30

provide support like a vine

Question 31

leaf spines

Answer 31

protection; reduced surface area; spiky-like

Question 32

storage leaves

Answer 32

water, food

Question 33

reproductive leaves:

Answer 33

adventitious plantlets - fall & root

Question 34

leaf bracts

Answer 34

surround flowers that attract pollinators

Question 35

tissue systems

Answer 35

1. dermal (protective skin): tough epidermal cells w/wax 2. vascular (fluid movement): xylem & phloem move things through the plant 3. ground (all othet function like photosynthesis, storage)

Question 36

the vascular tissue system consists of ? and does what

Answer 36

- carries out long-distance transport of materials between roots & shoots - xylem takes water & dissolved minerals upward from roots --> shoots - phloem transports organic nutrients & carbohydrates down into the plant

Question 37

xylem has two types of water-conducting cells

Answer 37

tracheids & vessel elements; both dead at maturity

Question 38

xylem vessel elements align end to end to form micro-pipes called

Answer 38

vessels

Question 39

phloem conducts

Answer 39

sugars primarily

Question 40

what are the porous end walls that allow fluid to flow between cells along the ______________

Answer 40

sieve plates; sieve tube

Question 41

each sieve-tube element has a

Answer 41

companion cell whose nucleus & ribosomes serve both cells

Question 42

Major types of plant cells that make up dermal & ground tissues

Answer 42

1. parenchyma 2. collenchyma 3. sclerenchyma

Question 43

Parenchyma cells

Answer 43

1. thin & flexible primary walls 2. initial undifferentiated cell type for all plant cells (default) 3. least specialized 4. retain ability to divide & differentiate 5. perform most metabolic functions

Question 44

Collenchyma cells

Answer 44

1. grouped in strands and support cells; support young parts of the plant shoot 2. thicker & uneven cell walls 3. provide flexible support (rigid) 4. mechanical support

Question 45

Sclerenchyma cells

Answer 45

- highly specialized for mechanical rigidity - thick secondary walls; often strengthened with lignin for rigidity - lignin makes cell walls tough - resistant to bending, cannot grow - often dead at maturity