Shoot And Leaf systems

Question 0

Describe buds. What kind of tissue is found in buds?

Answer 0

Mass of meristematic tissue.

-Cells divide and mature resulting in elongation, enlargement and maturation into stem/flowers/leaves

Question 1

What is the function of the stem?

Answer 1

Support of the crown

Conduct water and nutrients

Question 2

What is the terminal bud? What is its role?

Answer 2

Terminal bud is at the end of a shoot and is responsible for elongation.

Question 3

What is the lateral bud? what does it do?

Answer 3

Forms branches (external origin) forming outside stem.

Question 4

what is the difference between lateral stems and lateral roots?

Answer 4

Lateral stems arise from buds (outside) the stem.

lateral roots arise from periderm (inside root) internal origin

Question 5

What are lenticels?

Answer 5

Raised pores on bark that carry out radial gas exchange by connecting to ray cells

Question 6

What are leaf scars?

Answer 6

Places on the twig where leaves have senesced and the vascular tissue has been severed. The hole is filled by cork to prevent entry of pathogens.

Question 7

What are bud scars?

Answer 7

Rings of seasonal growth on a twig where bud scales fell away. Can be counted to gauge the age of the twig.

Question 8

How is bark formed?

Answer 8

Epidermis splits due to secondary growth. New cork cambium arises from cortex to fill the gap and produce new cork cells. The successive layers of cork along with the cork cambium and phelloderm compose the periderm. (Outer bark)

Question 9

What is cambium?

Answer 9

Continual cylinder of meristematic tissue that gives rise to secondary xylem and phloem.

Question 10

What is an annual ring?

Answer 10

layer of xylem formed by one years growth. Circumference of cambium increases as more xylem is pushed to the inside each year.

Question 11

What is cork cambium? What is its function?

Answer 11

Continual cylinder that develops from parenchyma in outer cortex

• produces suberized cork cells that are compacted between the phelloderm and the epidermis.
• Protects inner cells vs. evaporation and injury

Question 12

What are the differences between woody tissue in gymno/angiosperms?

Answer 12

In xylem angiosperms have Vessel elements and tracheary elements wheras gymnosperms only have tracheary elements.

In phloem angiosperms have seive tube elements with companion cells wheras gymnosperms have sieve cells with albuminous cells

p.s.-albuminous cells can be called companion cells

Question 13

What is heartwood?

Answer 13

Xylem that has become plugged with protrusions of cells .
Increase in tanins /resins/gums/pigments.

Protects against pathogens
Provides rigid structural support

Question 14

What is sapwood?

Answer 14

Exterior xylem that still conducts. Living cells.

Question 15

What are springwood and summerwood?

Answer 15

also referred as early and late wood.

Spring wood

• Inner band of annual xylem ring, lighter in color
• large thin walled cells

Summerwood

• smaller, thick walled cells
• Darker in color

Question 16

Outline conduction by xylem

Answer 16

• Upward transport of water and dissolved salts from roots to crown
• in early spring xylem will sometimes conduct stored food up from roots to leaves but this is an exception.

Question 17

Outline conduction by phloem

Answer 17

Downward conduction from leaves to roots

Question 18

Outline conduction by vascular rays

Answer 18

• extend radially through xylem and into phloem

- function in transverse conduction of water/gas by linking with lenticels

Question 19

Where Does food storage occur in plants?

Answer 19

Parenchyma of cortex, rays, pith, xylem and phloem. Roots store allot of food but generally food is stored throughout the plant in non green parenchyma.

Question 20

What are some methods of stems reproducing?

Answer 20

Runners

Rhizome branching - (Bracken fern!)

Formation of new bulbs from old ones

Question 21

Where do leaves arise and what is their function?

Answer 21

Arise at nodes on a twig and possess a bud at their axil. (lateral meristem)

Mainly function in photosynthesis. (manufacture of food)

Question 22

What are the two types of epidermal cells and their function?

Answer 22

Epidermis

• Ordinary epidermal cells
• -Protect from dessecration/evap./injury/pathogens
• -secrete cutin
• Guard cells (stomata)
• -occur in pairs and regulate gas exchange. Open in presence of light.

Question 23

What are the layers of a leaf?

Answer 23

Epidermis
Pallisade mesophyll
Vascular bundles
Spongy mesophyll

Question 24

What are the two types of mesophyll? how do they differ?

Answer 24

Pallisade mesophyll

• Vertically elongated
• High in chlorophyll
• Parenchyma

Spongy mesophyll
Irregularly spaced, loosely packed cells
also high in chlorophyll

Question 25

What are veins? What are their function?

Answer 25

Branched continuations of vascular bundles from petiole into mesophyll of leaf.

• Xylem above/Phloem below
• Transport water to leaf and products of photosynthesis down to roots
• Large veins are surrounded by thick walled strengthening cells.

Question 26

What is the layer that forms over leaf scars when they senesce

Answer 26

Abscission layer

-corky and waterproof (suberized)

Question 27

What triggers leaves to fall?

Answer 27

Senescence is a process by which a tree goes into dormancy to conserve energy. Triggered by seasonal changes and exposure to red and far red light. Photochrome is the pigment that keeps track of the light and triggers the dormancy response. Before dropping their leaves, trees suck out the remaining nutrients.