chapter 25: plant tissue

What are some structural differences between the upper and lower epidermis of the leaf?

A leaf's upper epidermis, which receives the most direct sunlight, may secrete a thicker cuticle than the lower surface, which tends to be shaded. The lower surface usually has more stomata.

Four of the five answers listed below are functions of parenchymal tissue. Select the exception. a. conduct water b. wound healing c. food storage d. conduction of photosynthesis e. secretion

a. conduct water

Which tissue within a leaf has the most chloroplasts?

palisade mesophyll

Photosynthetic mesophyll tissue is a type of ____.

parenchyma

The bulk of a leaf consists of mesophyll, which is photosynthetic ____ with air spaces between cells.

parenchyma

This plant tissue is involved in photosynthesis and storage.

parenchyma

What is found in the center of eudicot roots?

vascular cylinder

Inside each leaf vein, ____ transports water and dissolved mineral ions to photosynthetic cells, while ____ transports products of photosynthesis (sugars) away from them.

xylem; phloem

How does primary growth occur at a terminal bud?

A mass of apical meristem lies just below the surface of the bud. Cells at the center of the mass are completely undifferentiated, and they divide continually during the growing season. The divisions push some of the cells toward the edge of the mass. Cells that are displaced away from the center of the meristem begin to differentiate. The shoot grows longer mainly because differentiating cells under the mass of meristem elongate as they take on their specialized functions. The apical meristem remains at the tip of the lengthening shoot, continually renewing itself and also producing cells that divide and differentiate below it.

In the accompanying figure, what does the relative thicknesses of a tree's rings tell us about the average annual rainfall? How does rainfall affect the size of rings? What were the likely conditions in 1587-1589?

In trees that are dormant in winter, vascular cambium gives rise to large-diameter, thin-walled xylem cells (early wood) during spring. Late wood, with small-diameter, thick-walled xylem cells, forms during summer. The thickness of a ring provides clues as to the average rainfall of the corresponding year. Rings are thicker in years where the tree's thrived and had favorable conditions, including rainfall. Narrower annual rings mark years of severe drought. The tree rings are very narrow for the years 1587-1589. This indicates that these were seasons of severe drought

What are the main differences between monocots and eudicots?

Monocots: one cotyledon, flower parts in threes, parallel veins in leaves, pollen grain with only one pore or furrow on surface, vascular bundles throughout ground tissue Eudicots: two cotyledons, flower parts in fours or fives, net-like veins in leaves, pollen grain with three pores or furrows, vascular bundles organized in a ring

Why are leaves usually so thin? When might you see thicker leaves?

Most leaves are quite flat to allow for a large surface-to-volume ratio. This in turn exposes more photopigments to the sun, which promotes more photosynthesis. In very dry climates, leaves are often thick or needle-like to help conserve water and limit evaporation.

What are the different meristems? What can each do?

Apical meristem, found in buds, allows primary growth (growth in length) of stems, shoots, and roots. Lateral meristems, also called cambiums, allow secondary growth (growth in girth) of roots and stems. There are two types of lateral meristems, cork cambium, which forms the bark of trees, and vascular cambium, which adds secondary xylem and phloem.

How does a woody plant widen during secondary growth?

As a woody plant matures, its inner core of xylem thickens and displaces the vascular cambium toward the outside of the stem or root. Displaced cells of the vascular cambium divide in a widening circle, so this meristem tissue keeps its cylindrical form. Another lateral meristem, cork cambium, forms outside the cylinder of vascular cambium. Cork cambium produces cork, a protective tissue that consists of densely packed dead cells with thick, waxy walls.

In the accompanying figure, the seeds are located inside the structure at letter ____.

B

In the accompanying figure, the absorption of water and minerals would occur at letter ____.

D

In the accompanying figure, vascular tissues of the plant are indicated by the letter ____.

E

Four of the five answers listed below are characteristic of xylem. Select the exception. a. Each vessel is one continuous cell. b. Cell walls contain lignin. c. Water and minerals are transported. d. Tracheids and vessel members are living. e. Cell walls contain pits.

a. Each vessel is one continuous cell.

Four of the five answers listed below are characteristics of phloem. Select the exception. a. Phloem contains dead cells when tissue is functional. b. Phloem is made of complex tissue. c. Phloem has sieve plates between some cells. d. Phloem includes accessory companion cells. e. Phloem transports sugar.

a. Phloem contains dead cells when tissue is functional.

Most monocots have numerous ____ roots arising from the stem.

adventitious

Primary growth occurs at ____ and secondary growth occurs at ____.

apical meristems; lateral meristems

Four of the five answers listed below are components of roots. Select the exception. a. root hairs b. bulb c. pericycle d. vascular cylinder e. endodermis

b. bulb

short underground stem with overlapping thick leaves called scales

bulb

What is the term for a short section of an underground stem that is encased by overlapping layers of thickened, modified leaves (scales)?

bulbs

Which specialized stem structure does not have nodes?

bulbs

Four of the five answers listed below are characteristic of sclerenchyma cells. Select the exception. a. sclereid b. found in seed coats c. retain the ability to divide at maturity d. have the gritty texture of pear cells e. used in the manufacturing of paper, textiles, and rope

c. retain the ability to divide at maturity

Four of the five answers listed below possess chloroplasts. Select the exception. a. mesophyll cells b. guard cells c. sclereid cells d. palisade cells e. spongy cells

c. sclereid cells

flattened photosynthetic stem that stores water; succulents

cladode

What is a photosynthetic stem that stores water and is found in succulent plants in the desert?

cladodes

This tissue gives rise to periderm

cork cambium

This tissue gives rise to the protective covering that forms the bark of a tree.

cork cambium

thick underground stem that stores nutrients; has nodes off of which shoots arise

corm

Four of the five answers listed below are types of complex tissue. Select the exception. a. phloem b. xylem c. epidermis d. parenchyma e. periderm

d. parenchyma

Four of the five answers listed below are features of the pericycle. Select the exception. a. can continue to differentiate b. origins of lateral roots c. found in the root, but not in the stem d. site for food storage e. located inside the endodermis

d. site for food storage

Four of the five answers listed below are characteristic of monocots. Select the exception. a. flower parts in threes or multiples of three b. pollen grains with one pore c. one cotyledon in the seed d. vascular tissue in the stems arranged in a ring e. parallel veins in the leaf

d. vascular tissue in the stems arranged in a ring

Veins in leaves are composed of:

dermal tissue

Four of the five answers listed below are characteristic of dicots. Select the exception. a. vascular bundles organized in a ring b. veins form a net-like array c. flower parts in fours or fives d. two cotyledons e. pollen grains with one pore or furrow

e. pollen grains with one pore or furrow

Which structure is in direct contact with the soil into which it is growing?

epidermis

The vascular bundles in eudicot stems separate the ground tissue into two zones. Which sequence correctly describes the arrangement of those zones from the outside to the center?

epidermis → cortex → vascular bundle → pith

What is the most common type of tissue in plants?

ground

This tissue makes up the bulk of the plant body.

ground tissue

The only possible photosynthetic cells or structures in a leaf's epidermis are:

guard cells

Stolons are stems that branch from the main stem of the plant and grow along the ground. Stolons may look like roots, but they:

have nodes

Secondary xylem is formed in association with the ____.

inner face of the vascular cambium

How do primary and secondary growth differ? In primary growth, plants _______________. In secondary growth, stems and roots ______________ and become woody.

lengthen; thicken

Photosynthesis takes place in the ____.

mesophyll tissue

_______ is a type of simple plant tissue that is known for photosynthesis, storage, and secretion.

parenchyma

This tissue gives rise to lateral roots

pericycle

Which layer of cells in a root retain the capacity to divide, differentiate, and produce lateral roots?

pericycle

What is the short stalk that attaches the eudicot leaf to the stem?

petiole

This is a vascular tissue that conducts and distributes food to plant cells.

phloem

Which term or terms best describe a plant that is growing taller with growth of its stems, leaves, and roots?

primary, apical meristem

fleshy main stem that grows horizontally underground

rhizome

What tiny structures increase the root's surface area available for taking up soil water along with dissolved oxygen and mineral ions?

root hairs

If a mutation prevented the formation of lignin, what tissue would be most affected?

sclerenchyma

This is a ground tissue of plants that forms hardened cells often found in nut shells.

sclerenchyma

This tissue gives pear flesh a gritty texture and makes seed coats hard:

sclerenchyma

What is wood?

secondary xylem

. In the accompanying figure, the plant parts ABOVE the line at "C" represent the:

shoots

The cells that function in phloem are:

sieve elements

"runners"; horizontal branches from main stem; contain nodes

stolon

Which specialized stem structure does not store nutrients?

stolon

Gaseous exchange occurs in plants through which structures in the epidermis?

stomata

In terms of structure, most leaves are _______________, with a high _______________ to _______________ ratio.

thin; surface; volume

Xylem consists of which cells?

tracheids and vessel elements

Which environment would be most likely to produce trees without annual rings?

tropical rain forest

thickened areas of underground stolons used for food storage

tuber

Annual growth rings are formed in woody stems principally through the activities of the ____.

vascular cambium

This tissue gives rise to secondary phloem and xylem.

vascular cambium

This tissue gives rise to the xylem and phloem of an older tree.

vascular cambium

Which of these is/are considered lateral meristem(s)?

vascular cambium and cork cambium

What are vascular bundles that are strengthened with sclerenchyma fibers called in leaves?

veins

The outward-facing cell walls of epidermal cells contain which substance to reduce water loss?

wax

This is a vascular tissue that conducts water and dissolved salts throughout a plant.

xylem

This tissue supports rapidly growing plant parts; its pectin offers flexibility.

xylem

Vascular tissues distribute water and solutes through ground tissue. In ____, water and ions flow through tubes of dead tracheids and vessel elements.

xylem

What are tree rings? How can they be used to map changes in weather?

Tree rings represent seasonal growth of xylem in temperate regions. In spring, when rain is plentiful, vascular cambium produces large xylem cells with thin walls. In drier summers, they produce smaller cells with thicker walls. Each alternating band of spring and summer growth is a tree ring. The width of annual tree rings can be used as an indicator of past weather patterns.