Chapter 4 - Tissues

Question 1

Meristematic tissues

Answer 1

Permanent regions of growth, areas of cell division

Question 2

Apical meristem

Answer 2

• Meristematic tissue
• Area of primary growth (in length).
• At tips of roots and shoots, also at base of leaves.

Question 3

Lateral meristems

Answer 3

• Meristematic tissue
• Area of secondary growth, produces tissues that increase the girth of roots and stems.
• Not in every plant (like impatiens).

Question 4

Vascular cambium

Answer 4

• One type of lateral meristem. Not in grasses.
• Function: Transport and support; make trees bigger in width (rings in trunk). Also just called “cambium”.
• Extends throughout the plant, roots to stems

Question 5

Cork cambium

Answer 5

• One type of lateral meristem. Not in grasses.
• Relates to bark, builds bark cells. Runs the length of the plant, roots to stems.
• Not in herbacious plants.

Question 6

Parenchyma

Answer 6

• A type of simple tissue
• The most abundant tissue, in every plant part: leaves, stems, fruits, roots, etc.
• Loosely packed in the cell, lots of space between cells for movement of materials like H2O, CO2, etc.
• Function: synthesize materials, some transport.
• Thin cell walls
• Living
• Live a long time; in some cactus plants, may live to over 100 years old.

Question 7

Chlorenchyma

Answer 7

• A type of parenchyma tissue, containing chlorophyll, for photosynthesis.

Question 8

Collenchyma

Answer 8

• A type of simple tissue
• Function: structure and strength; enables flexibility in such like palm trees to bend in the wind
• Thick cell walls, especially at corners (extra primary wall), thinner along sides; tightly packed together; ribs in celery, center rib in leaves are examples
• Living
• Can live a long time

Question 9

Sclereids

Answer 9

• A type of sclenenchyma
• “Stone cells”; thick cell walls, can be brittle; nut shells, peach pits, and gritty part of immature pears (protection from being eaten too soon)
• Dead

Question 10

Xylem

Answer 10

• A type of complex tissue
• Produced mostly by the vascular cambium (as opposed to the apical meristem)
• Made of: 1) vessel cells, 2) tracheids, 3) parenchyma, and 4) fibers (and 5) ray cells, a specialized type of parenchyma for lateral conduction of water and nutrients
• Function: transports water and nutrients from the roots to the above-ground parts of the plant (and sugars in the spring); some support - 90% of tree trunks are xylem-strength

Question 11

Sclerenchyma

Answer 11

• A type of simple tissue
• Two kinds: fiber and sclereids
• Function: support and strength
• Dead

Question 12

Fibers

Answer 12

• A type of sclerenchyma
• Long, tubular and pointed; thick cell walls
• Function: strength; source of twine, hemp, jute; keeps plants from breaking
• Dead

Question 13

Vessels

Answer 13

• Part of xylem tissue
• Tubular, stackable, and open-ended; largest-diameter transport cell; composed of vessel cells (elements)
• Function: transport water and nutrients; have some pores on sides to allow water to seep out along the way
• Dead cells

Question 14

Tracheids

Answer 14

• Part of xylem tissue
• Have thick secondary walls, tapered at each end. Where ends overlap with other tracheids, there are “pits” in cell wall where no secondary wall has formed, allowing the passage of water between them. Smaller of the 2 kinds of vessels
• Dead cells

Question 15

Phloem

Answer 15

• A type of complex tissue
• Made of 1) Sieve tube cells, 2) Companion cells, 3) Parenchyma, and 4) fibers (and 5) ray cells)
• Function: transports sugars and sometimes hormones from the above-ground plant parts to the roots and other parts of the plant

Question 16

Sieve tube members

Answer 16

• Part of phloem tissue
• Laid end-to-end like vessel elements. Hollow like vessels, but ends not open; have open pores in sieve plates that allow cytoplasm to flow from cell to cell. Have no nuclei.
• Function: Vessels to transport the sugars produced by the plant
• Living cells, but can’t regulate the transport (performed by the companion cells)

Question 17

Companion cells

Answer 17

• Part of phloem tissue
• Narrower, smaller than sieve tube cells, tapered.
• Function: Regulates the materials moving through the sieve tubes
• Living

Question 18

Epidermis/Epidermal tissue

Answer 18

• Outer layer of cells of all young plant organs, protective layer covering all plant organs
• Usually once cell thick, except in plants that produce aerial roots
• Made primarily of parenchyma cells, plus some other specialized cells
• Function: protection from water loss, fungi, insects; transport; produces (excretes) cutin for cuticle layer

Question 19

Cutin

Answer 19

• Waxy substance on outside surface of plants

* Excreted by the epidermis

Question 20

Cuticle

Answer 20

• Layer of wax (cutin) on the outside surface of leaves.

* Function: limits water evaporation through cell walls; resists bacteria and disease organisms

Question 21

Stomata

Answer 21

• Pores in the epidermis, composed of 2 guard cells which regulate it
• Function: Transport, allows passage of CO2 and O2 gases into and out of the leaves.
• Usually on the underside of leaves (to limit water loss through them), but can be on top or both (like corn leaves).
• When closed to drought, limits photosynthesis (last year’s fruits were smaller but sugars were more concentrated

Question 22

Glands

Answer 22

• Modified epidermal cells that excrete protective substances.

Question 22

Cork cells

Answer 22

A

Question 23

Guard cells

Answer 23

• 2 cells that regulate the stomates, opening and closing them
• Contain chloroplasts

Question 25

Periderm

Answer 25

• Part of epidermal tissue in woody plants: bark, cork cells, outer covering of trees and branches. In woody plants, the epidermis is sloughed off and replaced by periderm.
• Contains suberin, a type of lipid/wax
• Function: protection

Question 26

Lenticels

Answer 26

Pockets in the periderm to allow gas exchange with the stem and outside air. (At the base of fissures in bark.)

Question 26

Secretory cells

Answer 26

A

Question 27

Secretory tissues

Answer 27

• A derivative of parenchyma cells.
• Function: moves cell waste substances outside the plant, as well as nectar, oils, and hormones.
• Examples: nectar in flowers, oils in citrus and mint, latex, and pine resin.

Question 28

Simple tissues

Answer 28

• Groups of all the same type of cell, collectively performing a specific function
• 3 types: Parenchyma, Collenchyma, Sclerenchyma

Question 29

Complex tissues

Answer 29

• Groups of different types of cells, collectively performing a specific function
• Includes vascular tissues (xylem and phloem), epidermal tissues, and periderm (mostly cork, but contains some parenchyma)

Question 30

Tissues

Answer 30

Groups of cells that perform specific functions

Question 31

Trichome cells

Answer 31

• Extensions off the epidermal tissue, can take lots of different shapes
• Function: protection from water loss, animals, and diseases, some transport (root hairs, helps absorb water)

Question 32

Intercalary Meristems

Answer 32

Lateral meristematic tissue in grasses and related plants.