Lab 4

Question 1

How have leaves evolved

Answer 1

As lateral appendages of the stem

Question 2

Microphylls

Answer 2

-most ancestral
-1 strand of vascular tissue
-small leaves
Lycophytes and equisetales

Question 3

Megaphylls

Answer 3

-more derived
-more than one vascular bundle (vein)

Question 4

Enations

Answer 4

Tissue extension that lack vascular bundles and are not true leaves
eg. bryophytes

Question 5

Blade

Answer 5

Expanded portion for photosynthesis

Question 6

Petiole

Answer 6

The “stem” of the leaf

Question 7

Stipules

Answer 7

Outgrowths at the base of the petiole
-appear as leaflike, scales, hairs, spines

Question 8

Axillary bud

Answer 8

Found at base of leaf
-precursor for branch or lateral shoot

This will not be found at base of leaflet or compound leaf

Question 9

Monocot leaves

Answer 9

Leaf base usually extends into a sheath surrounding the stem
-lack petioles

Question 10

Sessile leaves

Answer 10

Leaves without petioles

Question 11

Transpiration

Answer 11

Evaporative cooling
-prevents plant from over heating
-driving force for pulling water through xylem

Question 12

Simple leaves

Answer 12

Blades are not divided
-look for axillary bud

Question 13

Compound leaves

Answer 13

Blade divided into leaflets with petiolules.

Question 14

Types of compound leaves

Answer 14

Pinnately -leaflets attach to either side of rachis
Palmately -all leaflets emerge from tip of petiole, no rachis

Question 15

Rachis

Answer 15

Main axis of compound leaf structure

Question 16

Leaf arrangement

Answer 16

Alternate - 1 leaf per node (distichous)
Opposite -2 leave per node (distichous or decussate)
Whorled -3 or more at node
Distichous
Decussate (90 degree alternate)

Question 17

Leaf venation

Answer 17

Dichotomous -the veins branch off from one another like the branches of a tree
Parallel (monocots) -parallel veins
Netted (eudicots)
-net pinnate- veins come off midrib
-net palmate- veins emerge from one point

Question 18

Dermal system of leaf consists of

Answer 18

Upper and lower epidermis

Question 19

Cuticle

Answer 19

Waxy layer that covers the epidermis

Question 20

Stomata

Answer 20

Leaf openings
-usually located in the lower dermis
-gas exchange, water movement

Question 21

Divisions of ground system

Answer 21

Palisade mesophyll- parallel, densely arranged
Spongy mesophyll- loosely arranged

Question 22

Bundle sheath extensions

Answer 22

Supporting tissues
-extending away from vascular bundles

Question 23

Bundle sheath

Answer 23

Large specialized parenchyma cells that control movement of water and food material in/out of veins

Question 24

What tissue contains the most chloroplast?

Answer 24

Palisade mesophyll

Question 25

What has no clear differentiation between palisade and spongey parenchyma

Answer 25

Grass leaves

Question 26

Bulliform cells

Answer 26

-large cells in epidermis
-play a role in folding/unfolding leaves via changes in turgor pressure

Question 27

What are associated with subsidiary cells

Answer 27

Guard cells

Question 28

What adaptation allows conifers to live in dry environments?

Answer 28

They have sunken stomata to prevent water loss
-waxy cuticle

Question 29

What is the function of a guard cell?

Answer 29

They control the size of the leaf’s pores (stomata) and regulate water loss and CO2 gain

Question 30

Function of waxy cuticle

Answer 30

Protects against water vapour loss

Question 31

Trichomes

Answer 31

Found on the outer surface of many leaves
-help reduce water loss by reflecting solar radiation and trapping humid air at the surface
-some used for defence (chemical, physical) depends on shape/secretions

Question 32

What happens with excessive transpiration in hot dry environments?

Answer 32

-means of cooling but wastes too much water
-plant leaves are adapted to prevent excessive transpiration
-some need more transpiration
eg. where stomata is placed, how many

Question 33

Xeromorphic plants + features

Answer 33

Adapted to dry environments with ability to prevent water loss
-low SA:V
-large vascular bundles
-stomata in crypts
-thick epidermis/cuticle

Question 34

Hydromorphic plants + features

Answer 34

Adapted to wet environments
-ability to grow wholly or partially submerged in water
-stomata on surface only
-large air spaces
-reduced vascular tissue

Question 35

Sun vs shade leaves

Answer 35

Sun
-lower SA:V
-thicker plant

Shade
-thinner plant
-larger SA:V