Chapter 30

Explain the role of the cork cambium in woody plants

In woody plants, the cork cambium is the outermost lateral meristem; it produces new cells towards the interior, which enables the plant to increase in girth. The cork cambium also produces cork cells towards the exterior, which protect the plant from physical damage while reducing water loss.

What is the function of lenticels?

In woody stems, lenticels allow internal cells to exchange gases with the outside atmosphere.

Cork cambium

Is the outermost lateral meristem. Produces cork cells (bark) containing a waxy substance known as suberin that can repel water. Produces a layer of cells known as phelloderm, which grows inward from the cambium.

What type of meristem is found only in monocots, such as lawn grasses? Explain how this type of meristematic tissue is beneficial in lawn grasses that are mowed each week.

Lawn grasses and other monocots have an intercalary meristem, which is a region of meristematic tissue at the base of the leaf blade. This is beneficial to the plant because it can continue to grow even when the tip of the plant is removed by grazing or mowing.

Tracheids, vessel elements, sieve-tube cells, and companion cells are components of ________. a. vascular tissue b. meristematic tissue c. ground tissue d. dermal tissue

a. vascular tissue

Apical bud

bud formed at the tip of the shoot

Fibers Cells

long, slender cells making fibers that have been used to make linen and rope

parenchyma cell

most common type of plant cell; found in the stem, root, leaf, and in fruit pulp; site of photosynthesis and starch storage

Parenchyma

most common type of plant cell; found in the stem, root, leaf, and in fruit pulp; site of photosynthesis and starch storage. Help repair and heal wounds.

Vessel elements

xylem cell that is shorter than a tracheid and has thinner walls. Conduct water.

Which layers of the stem are made of parenchyma cells? a. cortex and pith b. epidermis c. sclerenchyma d. cortex and epidermis

A and B. The cortex, pith, and epidermis are made of parenchyma cells.

Which layers of the stem are made of parenchyma cells? a. cortex and pith b. epidermis sclerenchyma epidermis and cortex.

A and B. The cortex, pith, and epidermis are made of parenchyma cells.

Plant tissues

A plant is composed of two main types of tissue: meristematic tissue and permanent tissue

Epidermis

A single layer of cells covering and protecting the underlying tissue.

Besides the age of a tree, what additional information can annual rings reveal?

Annual rings can also indicate the climate conditions that prevailed during each growing season.

Give two examples of modified stems and explain how each example benefits the plant.

Answers will vary. Rhizomes, stolons, and runners can give rise to new plants. Corms, tubers, and bulbs can also produce new plants and can store food. Tendrils help a plant to climb, while thorns discourage herbivores.

Simple tissues (cell types)

Made up of similar cell types; examples include dermal tissue and ground tissue. Dermal tissue provides the outer covering of the plant. Ground tissue is responsible for photosynthesis; it also supports vascular tissue and may store water and sugars.

Ground tissue is mostly made up of ____________ but may also contain collenchyma and sclerenchyma cells that help support the stem.

Parenchyma

Three cell types of stem simple tissues

Parenchyma, Collenchyma, and Sclerenchyma cells

Stems

Part of the shoot system. Their main function is to provide support to the plant, holding leaves, flowers and buds; in some cases, stems also store food for the plant. Plant stems, whether above or below ground, are characterized by the presence of nodes and internodes

Phloem conducting cells are alive at _____________.

Phloem conducting cells are alive at maturity.

Describe the roles played by stomata and guard cells. What would happen to a plant if these cells did not function correctly?

Stomata allow gases to enter and exit the plant. Guard cells regulate the opening and closing of stomata. If these cells did not function correctly, a plant could not get the carbon dioxide needed for photosynthesis, nor could it release the oxygen produced by photosynthesis

Which of the following is the major site of photosynthesis? a. apical meristem b. ground tissue c. xylem cells d. phloem cells

B. ground tissue.

Complex tissue (cell types)

Complex tissues are made up of different cell types. Vascular tissue, for example, is made up of xylem and phloem cells.

Meristematic tissue

Consists of actively dividing cells found in root and shoot tips. As growth occurs, meristematic tissue differentiates into permanent tissue, which is categorized as either simple or complex.

Meristem cell types

Dermal, vascular, and ground tissue

Types of Root Systems

Dicots have a tap root system, while monocots have fibrous root system.

Secondary Vascular Tissue

Either simple (composed of similar cell types) or complex (composed of different cell types). Dermal tissue, for example, is a simple tissue that covers the outer surface of the plant and controls gas exchange.

Which plant part is responsible for transporting water, minerals, and sugars to different parts of the plant? Name the two types of tissue that make up this overall tissue, and explain the role of each.

Vascular tissue transports water, minerals, and sugars throughout the plant. Vascular tissue is made up of xylem tissue and phloem tissue. Xylem tissue transports water and nutrients from the roots upward. Phloem tissue carries sugars from the sites of photosynthesis to the rest of the plant.

Compare the structure and function of xylem to that of phloem.

Xylem is made up tracheids and vessel elements, which are cells that transport water and dissolved minerals and that are dead at maturity. Phloem is made up of sieve-tube cells and companion cells, which transport carbohydrates and are alive at maturity.

Sclereids

a reduced form of sclerenchyma cells. Have thick, lignified walls that form durable layers of tissue such as the cores of apples and the gritty texture of pears.

Shoot system

above ground portion of the plant; consists of non-reproductive plant parts, such as leaves and stems, and reproductive parts, such as flowers and fruits

Secondary Growth

allows the plant stem to increase in thickness or girth. Secondary vascular tissue is added as the plant grows.

Secondary growth in stems is usually seen in ________. a. monocots b. dicots c. both monocots and dicots d. neither monocots nor dicots

b. dicots

Which of the following is an example of secondary growth? a. increase in length b. increase in thickness or girth c. increase in root hairs d. increase in leaf number

b. increase in thickness or girth

Root system

below ground portion of the plant that supports the plant and absorbs water and minerals

Axillary bud

bud located in the axil: the stem area where the petiole connects to the stem

The primary growth of a plant is due to the action of the ________. a. lateral meristem b. vascular cambium c. apical meristem d. cork cambium

c. apical meristem

Plant regions of continuous growth are made up of ________. a. dermal tissue b. vascular tissue c. meristematic tissue d. permanent tissue

c. meristematic tissue

Which of the following cell types forms most of the inside of a plant? a. meristem cells b. collenchyma cells c. sclerenchyma cells d. parenchyma cells

d. parenchyma cells

collenchyma cell

elongated plant cell with unevenly thickened walls; provides structural support to the stem and leaves

Collenchyma

elongated plant cell with unevenly thickened walls; provides structural support to the stem and leaves. Alive at maturity.

The dermal tissue of the stem consists primarily of __________

epidermis

Cortex

ground tissue found between the vascular tissue and the epidermis in a stem or root

Pith

ground tissue found towards the interior of the vascular tissue in a stem or root

Determinate growth

growth ceases when a plant part such as leaves and flowers, reaches a particular size.

Indeterminate growth

growth occurs throughout the plants life. It is evident in certain plant parts such as stems and roots.

Primary Growth

growth resulting in an increase in length of the stem and the root; caused by cell division in the shoot or root apical meristem

Secondary Growth

growth resulting in an increase in thickness or girth; caused by the lateral meristem and cork cambium

Trichomes

hair-like structure on the epidermal surface

Root hairs

hair-like structure that is an extension of epidermal cells; increases the root surface area and aids in absorption of water and minerals

Stele

inner portion of the root containing the vascular tissue; surrounded by the endodermis

Primary Growth

is growth in length such as the growth in height of a stem or lengthening of roots.

Intercalary meristems

meristematic tissue located at nodes and the bases of leaf blades; found only in monocots

Apical meristems

meristematic tissue located at the tips of stems and roots; enables a plant to extend in length

Lateral meristems

meristematic tissue that enables a plant to increase in thickness or girth

Thorns

modified stem branch appearing as a sharp outgrowth that protects the plant

Tendrils

modified stem consisting of slender, twining strands used for support or climbing

Stolons

modified stem that runs parallel to the ground and can give rise to new plants at the nodes

Tubers

modified underground stem adapted for starch storage; has many adventitious buds

Bulb

modified underground stem that consists of a large bud surrounded by numerous leaf scales

rhizome

modified underground stem that grows horizontally to the soil surface and has nodes and internodes

The root tip can be divided into three zones:

o A zone of cell division that is closest to the root tip and made up of the actively dividing cells of the root meristem o A zone of elongation is where newly formed cells increase in length to lengthen the root o A zone of maturation and differentiation, where the root cells begin to differentiate into special cell types. o All three zones are in the first centimeter or so of the root tip.

Plant cells have structures not found in animal cells:

o Cell walls o Plastids o A large central vacuole: structures that are not found in animal cells.

Internode

opening on the surface of mature woody stems that facilitates gas exchange

lenticels

opening on the surface of mature woody stems that facilitates gas exchange

periderm

outermost covering of woody stems; consists of the cork cambium, cork cells, and the phelloderm

Guard cells

paired cells on either side of a stoma that control stomatal opening and thereby regulate the movement of gases and water vapor

sieve-tube cells

phloem cell arranged end to end to form a sieve tube that transports organic substances such as sugars and amino acids

Companion cells

phloem cell that is connected to sieve-tube cells; has large amounts of ribosomes and mitochondrion

sclerenchyma cell

plant cell that has thick secondary walls and provides structural support; usually dead at maturity

Sclerenchyma

plant cell that has thick secondary walls and provides structural support; usually dead at maturity. There are two types of sclerenchyma cells, fiber and sclereids.

Meristem

plant region of continuous growth

Ground tissue

plant tissue involved in photosynthesis; provides support, and stores water and sugars intercalary meristem

Nodes

point along the stem at which leaves, flowers, or aerial roots originate

Root cap

protective cells covering the tip of the growing root

Dermal tissue

protective plant tissue covering the outermost part of the plant; controls gas exchange

Corms

rounded, fleshy underground stem that contains stored food

Plant Organ Systems

shoot system and root system

Phloem tissue is composed of:

sieve-tube cells, companion cells, phloem parenchyma, and phloem fibers.

Runners

stolon that runs above the ground and produces new clone plants at nodes

Vascular stele or vascular cylinder

strands of root tissue made up of xylem and phloem

Vascular bundle

strands of stem tissue made up of xylem and phloem

Apex

tip of the shoot. It contains the apical meristem within the apical bud.

Vascular tissue

tissue made up of xylem and phloem that transports food and water throughout the plant

Bark

tough, waterproof, outer epidermal layer of cork cells

Fibrous root system

type of root system in which the roots arise from the base of the stem in a cluster, forming a dense network of roots; found in monocots

Tap root system

type of root system with a main root that grows vertically with few lateral roots; found in dicots

Tracheids

xylem cell with thick secondary walls that helps transport water. Conduct water.

Xylem tissue has three types of cells:

xylem parenchyma, tracheids, and vessel elements