BY 124- Ch 35 Gibbons

• Underground (typically)

• Fibrous roots

• Tap roots

• Secondary roots/lateral roots

• Root hairs

• rely on sugars from shoot

Root System Characteristics

• Above ground (typically)

• Leaves

• Stems

• Lateral and apical buds

• Flowers

• rely on water and minerals from roots

Shoot system characteristics

Shoot system parts

Root system parts

• Anchor

  • Taproot

  • Fibrous root

• Absorb

  • Occurs at lateral roots

  • Root hairs

• Store

  • Some can store more in taproot

Functions of the root system

• an alternating system of nodes, the points at which leaves are attached

• internodes, the stem segments between nodes

• Function to grow tall, maximize light exposure

A stem is a plant organ that consists of…

• Rhizome: horizontal shoot below the surface

• Stolon: horizontal shoot above the surface, asexual reproduction

• Tuber: storage in the end of rhizomes or stolons

Examples of modified stems

• The leaf is the main photosynthetic organ of most

  vascular plants

• Leaves intercept light, exchange gases, dissipate

  heat, and defend the plant from herbivores and

  pathogens

• Leaves generally consist of a flattened blade and a

  stalk called the petiole, which joins the leaf to a

  node of the stem

Role of leaves

Simple Leaves: A single, undivided blade (though it may be lobed).

Compound Leaves: A leaf that is divided into multiple segments, called leaflet

Simple vs compound leaf

Modified leafs examples

What are the three plant organs?

A. Roots, shoots, and stems

B. Roots, stems, and leaves

C. Flowers, shoots, and roots

D. Stolons, tubers, and pneumatophores

B. Roots, stems, and leaves

What are the 3 types of plant tissue?

1. Dermal

2. Vascular

3. Ground

1. Epidermis or epidermal/dermal cells (do not

have chloroplasts)

2. Specialized dermal cells

• Guard cells: gas exchange, have chloroplasts

• Trichomes: reduce water loss, reflect light, defense

• Root hair: helps with water absorption

3. Non cellular structures:

• Cuticle: waxy coating prevents water loss, covering dermal cells

• Stomata: openings for gas exchange, surrounded by guard cells

Dermal Tissue is comprised of …

Replaces epidermis on old growth of woody plants

Periderm

• facilitates the transport of materials and provides mechanical support

• Xylem conducts water and dissolved minerals upward from roots into the shoots

• Phloem transports sugars from where they are made (primarily

  leaves) to storage structures or sites of growth

Vascular tissue

• Tissues that are neither dermal nor vascular

• Ground tissue internal to the vascular tissue is pith

• Ground tissue external to the vascular tissue is cortex

• Ground tissue includes cells specialized for storage, photosynthesis, support, and transport

Ground Tissue

Plant Cell diagram

• Mature parenchyma cells

• Have thin and flexible primary walls

• Have a large central vacuole

• Perform the most metabolic functions

• (Photosynthesis, cellular respiration, storage, etc)

• Retain the ability to divide and differentiate

Parenchyma Cells

• Collenchyma cells are grouped in strands and help support young parts of the plant shoot

• They are living at maturity

• These cells provide flexible support without restraining growth

• Celery strings

Collenchyma Cells

• Sclerenchyma cells function in rigid support are due to thick secondary walls containing lignin, a strengthening polymer

• They are dead at functional maturity

• There are two types:

  • Sclereids are short and irregular in shape and have thick, lignified secondary walls (give pears their

    texture)

  • Fibers are long and slender and arranged in threads (used for textiles)

Schlerenchyma Cells

• Dead and lignified at maturity

• Tracheids - long, thin cells; tapered ends

• Water moves between tracheids through pits, thin regions lacking secondary cell wall

• Vessel elements – align end to end, form long pipes called vessels; end walls contain perforated plates

Water-conducting cells of the xylem

• Alive at maturity, but lack organelles

• Sieve-tube elements – form chains of cells (sieve-tubes) for sugar transport

• Sieve plates: porous end walls between sieve-tube elements allow fluid flow between cells

• Each connected to a companion cell (parenchyma) by plasmodesmata

• Companion cell’s nucleus and ribosomes serve sieve-tube element

Sugar-conducting cells of the Xylem

Which of the following cells functions in flexible support of plants?

A. Collenchyma

B. Companion cells

C. Sclerenchyma

D. Parenchyma

E. Sieve tubes

A. Collenchyma

• Indeterminate growth: grow throughout life with no set limit

  • Plant growth at meristems

  • Indeterminate growth is NOT immortality

• Most animals have determinate growth: growth stops at a point

Plant growth types

• Annuals: one season to complete life cycle

• Biennials: two seasons

• Perennials: multiple seasons

Plants lifespan

Unspecialized tissues composed of dividing cells (i.e., stem cells)

Meristems

tips of roots and stems; growth in height/length of shoots and roots

• Primary growth

Apical meristem

lateral surface; growth in girth of stem

• Secondary growth

Lateral meristem

Meristematic Growth Chart

Embryonic tissue

Eudicot cross-section

Monocot cross-section

The growth of a lateral root is an example of

A. Primary growth

B. Secondary growth

C. Lateral meristem

D. All of these are correct

B. Secondary growth

Primary Growth Chart

Apical meristem picture

Eudicot stem cross section

Monocot stem cross section

Based on what I’ve learned about primary growth in shoots, If I put up a basketball hoop on a tree trunk and the tree is allowed to grow, 10 years later, the hoop will be higher up.

A. True

B. False

B. False

• Leaves develop from leaf primordia

• Stomata, pores that allow CO2 and O2 exchange

  • Also site of evaporative water loss

• Guard cells flank stomatal opening and regulate opening and closing

• Ground tissue called mesophyll

  • Palisade mesophyll – upper part of leaf

  • Spongy mesophyll – lower part of leaf; loose arrangement

Leaf Growth and Anatomy

Pattern of Cell Division

• Two lateral meristems:

  • Vascular Cambium – vascular tissue; secondary xylem

    (wood) and secondary phloem

  • Cork Cambium – epidermis to periderm

Secondary Growth

Cambium Growth

Includes both vascular and cork cambium

Choose the incorrect statement

A. Cork cambium makes new cork

B. There are two types of lateral meristem, vascular

cambium and cork cambium

C. Vascular cambium creates both new xylem and

new phloem cells

D. Vascular cambium remains close to the center of

the stem, no matter how old the tree becomes

Vascular cambium remains close to the center of the stem, no matter how old the tree becomes

A region of dividing cells in a plant is called a __________.

• ground tissue

• cortex

• cotyledon

• meristem

• mycorrhizal zone

meristem

Why does pinching off the top of a plant make it bushier?

• Removal of a node stimulates the internodes to grow and make the plant bushier.

• Removing the apical meristem stimulates growth in the lateral meristem, thus making the plant bushier.

• Removing the apical meristem causes the plant to change from its vegetative phase to its reproductive phase. The reproductive phase is bushier.

• Removing the apical meristem stimulates growth in the axillary buds, thus making the plant bushier.

• Removing plant stems always leads to the plant producing more leaves.

Removing the apical meristem stimulates growth in the axillary buds, thus making the plant bushier.

Annual rings in wood are evidence that in climates with a single annual growing season, the __________ divides actively when water is plentiful and temperatures are suitable for growth, and ceases to divide when water is scarce and the weather is cold.

• lateral meristem

• cork cambium

• vascular cambium

• apical meristem

• marginal meristem

Vascular cambium

Water-conducting cells of plants are called ___________.

• parenchyma cells

• collenchyma cells

• sclerenchyma cells

• sieve-tube elements

• tracheids and vessel elements

Tracheids and vessel elements

In woody plants, the vascular cambium initial is ________.

• meiotically active and divides to form an inner layer of secondary xylem and an outer layer of secondary phloem

• mitotically active and divides to form an inner layer of primary xylem and an outer layer of primary phloem

• mitotically active and divides to form an inner layer of secondary xylem and an outer layer of primary phloem

• meiotically active and divides to form an inner layer of primary xylem and an outer layer of primary phloem

• mitotically active and divides to form an inner layer of secondary xylem and an outer layer of secondary phloem

mitotically active and divides to form an inner layer of secondary xylem and an outer layer of secondary phloem

Root hair formation is regulated by __________.

• the ABC model

• MADS-box

• KNOTTED-1

• Ubx

• GLABRA-2

GLABRA-2

Sugar-conducting structures of plants are called ___________.

• tracheids and vessel elements

• collenchyma cells

• parenchyma cells

• sieve-tube elements

• sclerenchyma cells

sieve-tube elements

A Hox gene homolog in plants is called __________ and is important in __________.

• GLABRA-2; leaf morphology

• ABC model; flowers

• MADS-box; root hairs

• KNOTTED-1; leaf morphology

• Ubx; flowers

KNOTTED-1; leaf morphology

Phase changes are __________.

• morphological changes that arise from transitions in shoot lateral meristem activity

• morphological changes that arise from seasonal transitions

• changes that occur only in adult plants

• morphological changes that arise from transitions in shoot apical meristem activity

• None of the listed responses is correct.

Morphological changes that arise from transitions in shoot apical meristem activity

The main difference between a primary root and a lateral root is that ________.

• None of the listed responses is correct.

• primary roots are the most important roots because they are the only roots that form in most plants

• lateral roots enhance the ability of the root system to anchor the plant and acquire resources from the soil

• there is no functional difference between primary and lateral roots

• lateral roots are the most important roots because they form in the absence of primary roots

Lateral roots enhance the ability of the root system to anchor the plant and acquire resources from the soil

Preprophase bands __________.

• run parallel to the direction of elongation as a cell matures

• are present throughout the cell cycle

• determine the location where the cell plate will form during cell division

• constrict the cell and "pinch" it in two during cell division

• run perpendicular to the cellulose microfibrils in a dividing cell

determine the location where the cell plate will form during cell division

Which example below is the site of primary growth that results in the plant increasing in height?

• Nodes

• Bud scales

• Axillary buds

• Apical meristems

• Lateral meristems

Apical meristems

If you pound a nail into a tree one meter off the ground and come back to find it in 20 years, it will be __________.

• None of the listed responses is correct.

• more than one meter off the ground and the same depth in the tree

• more than one meter off the ground and more deeply embedded in the tree

• one meter off the ground and more deeply embedded in the tree

• one meter off the ground and the same depth in the tree
  

one meter off the ground and more deeply embedded in the tree

In most leaves, chloroplast-containing cells are most closely compacted in the __________.

• upper epidermis

• guard cells

• palisade mesophyll

• vein (vascular bundle)

• lower epidermis

palisade mesophyll

The ________ of a root or a stem is called the ________.

• vascular tissue; stele

• ground tissue; stele

• dermal tissue; cuticle

• dermal tissue; pith

• ground tissue; pith

vascular tissue; stele

The layer that covers the apical meristem of a root is called the __________.

• root cap

• root hair

• taproot

• primordium

• pericycle

root cap

Evolutionary adaptations of roots include all of the following root structures except __________.

• buttress roots

• prop roots

• pneumatophores

• stolons

• aerial roots

stolons

Which of the following correctly describes a feature unique to monocot stems?

• Vascular bundles are scattered throughout.

• Ground tissue consists mainly of parenchyma.

• Vascular tissue is located all in the center.

• Lateral shoots cannot originate near the surface.

• Vascular bundles are arranged in a ring.

Vascular bundles are scattered throughout.

What accounts for about 90% of a plant cell's expansion?

• Water stored in the nucleus

• Water uptake stored in a large central vacuole

• Additional organic material in a plant's cytoplasm

• Mineral uptake by the roots

• Additional organic material stored in vacuoles

Water uptake stored in a large central vacuole

Root tips are pushed farther into the soil mainly by __________.

• differentiation (specialization) of root cells

• elongation of cells

• cell division in the meristem

• cell division in the vascular cambium

• pulling by root hairs

elongation of cells

Leaves occur at intervals along the plant stem. The region where a leaf is attached to the stem is the __________.

• internode

• petiole

• shoot apex

• None of the listed responses is correct.

• node

node

The three types of tissue systems that are found in all plant organs are __________.

• root hairs, trichomes, and spines

• epidermal, dermal, and ground tissue systems

• dermal, vascular, and ground tissue systems

• epidermal, dermal, and vascular systems

• epidermal, vascular, and ground tissue systems

dermal, vascular, and ground tissue systems

Leaves consist of __________.

• a node and an internode

• a bud and a node

• an axillary bud and a terminal bud

• a leaflet and a blade

• a blade and a petiole

a blade and a petiole

The difference between primary growth and secondary growth is that ________.

• primary growth occurs only during seed germination and secondary growth occurs throughout the life of the plant

• None of the listed responses is correct.

• primary growth increases the length and the diameter of roots and shoots and secondary growth increases only the diameter of stems and roots in woody plants

• primary growth lengthens roots and shoots and secondary growth increases the diameter of stems and roots in woody plants

• primary growth lengthens roots and shoots and secondary growth increases the diameter of stems and roots in herbaceous and woody plants
  

primary growth lengthens roots and shoots and secondary growth increases the diameter of stems and roots in woody plants

Most of the photosynthesis in plants takes place in specialized __________ cells called the __________.

• parenchyma; pith

• sclerenchyma; palisades

• dermal; mesophyll

• vascular; collenchyma

• parenchyma; mesophyll

parenchyma; mesophyll

Repetitive patterns in plant growth are __________.

• kaleidoscopes

• eternal patterns

• fractals

• circadian patterns

• None of the listed responses is correct.

fractals

_________ are the three basic plant organs.

• Flowers, stems, and leaves

• Roots, stems, and leaves

• Roots, stems, and flowers

• Stems, tissues, and cells

• Roots, root hairs, and stems

Roots, stems, and leaves

Artichoke hearts are tender and have a strong taste. The leaves have a strong taste too, but most of an artichoke leaf is fibrous and too difficult to chew. The leaves must contain lots of __________.

• sclerenchyma cells

• phloem

• epidermal cells

• meristematic tissue

• collenchyma cells

sclerenchyma cells

Evolutionary adaptations of leaves include all of the following except _________.

• adventitious plantlets

• spines

• bulbs

• tendrils

• rhizomes

rhizomes

Evolutionary adaptations of stems include __________.

• aerial stems

• buttress and prop roots

• pneumatophores

• stolons and tubers

• flowers

stolons and tubers