lecture 9 part 2

Question 1

What is the ancestral stelar type in the vascular plants and what is its structural anatomy?

Answer 1

Protostele: ancestral, solid cylinder of xylem and
phloem

Question 2

What is the general morphology and function of leaves?

Answer 2

• To the sides of the apical
  meristem region, certain
  regions of the outermost
  cell layers of a shoot
  undergo cell division and
  elongation
• Further growth and
  differentiation in these
  regions result in the
  formation of a leaf
• Sporophytic leaf: dorsiventrally flattened,
  primary organ of photosynthesis
• Major adaptive innovation: greatly increases
  photosynthetic tissue
• Evolution of a variety of ecological adaptive
  strategies
• Modified for other functions

Question 3

What are the internal, chlorophyllous cells of a leaf called? Into what two layers are these cells
typically formed?

Answer 3

Mesophyll can be
specialized into
upper (palisade) and
lower (spongy)

Question 4

What is a vein?

Answer 4

a vascular bundle

Question 5

What is a shoot?

Answer 5

• Sporophytic leaves
  originate as part of an
  integral association: shoot
• The tip of a shoot contains
  actively dividing cells of the
  apical meristem –
  continuous mitosis
• Cell elongation pushes the
  meristem upward of
  forward
• Cells later differentiate into
  the mature form

Question 6

What is the name of the region of actively dividing cells in the shoot?

Answer 6

apical meristem

Question 7

What is the name of the region of actively dividing cells in the root?

Answer 7

apical meristem

Question 8

What is the function of: (a) rootcap; (b) root hairs; (c) endodermis/Casparian strips?

Answer 8

cap- protection of the apical meristem
hairs- increase SA to increase absorption
endodermis/casparian strip- In roots and underground
stems – sheath of cells
* Each endodermis cells with
lignin and suberin:
Casparian strip
* Bound to the plasma
membrane
* Water impermeable
* Differentially controls solute
transfer – toxic or unneeded
minerals may be
differentially excluded

Question 9

What is the most basal (earliest diverging) lineage of the vascular plants, now extinct? Name the two
most important fossil species representing the lineage.

Answer 9

rhyniophyta
- cooksonia
- rhynia

Question 10

What fossil lycophyte was a large tree in the Carboniferous and now makes up a large percentage of coal deposits?

Answer 10

Lepidodendron, Sigillaria, and relatives

Question 11

What is a lycophyll (microphyll)? an enation?

Answer 11

theorized that microphylls evolved through the vascularization of leaf-like enations

Question 12

What is the position of the sporangia in lycophytes?

Answer 12

Sporangia develops on the axils of specialized leaves

Question 13

What is a sporophyll? a strobilus?

Answer 13

sporophyll- sporangia in lycophytes (on the axils of specialized leaves)
strobilus- sporangia aggregated into a terminal determinate shoot system

Question 14

What is a ligule?

Answer 14

Ligule: small appendage on
the upper side of the leaf

Question 15

What is homospory? Name one familiy of lycophytes that have this condition.

Answer 15

only one type of diploid germ cells in capsules or sporangia enters meiosis and produces morphologically indistinguishable spores
club mosses

Question 16

Are all lycophytes homosporous?

Answer 16

no

Question 17

Name and define the two types of leaf morphology in Selaginella species.

Answer 17

Isomorphic leaves- morphologically similar
heteromorphic leaves- morphologically different

Question 18

Name two genera of extant lycophytes that are heterosporous. What structure is associated with
their leaves?

Answer 18

isoetes, sellaginella
* Selaginella: strobili with
specialized sporophylls
* Isoetes: sporangia located on
the upper side of the
sheathing leaf bas

Question 19

Define the terms heterospory and endosporic.

Answer 19

• Heterospory: microsporangia and macrosporangia
  producing two types of spores
• Endosporic: gametophytes develop entirely within the
  original spore wall

Question 20

What is a macrosporangium? And a microsporangium?

Answer 20

macro produce large spores, micro produce small

Question 21

What distinguishes a microspore from a megaspore?

Answer 21

• Megaspore: produced in low numbers (typically four) per sporangium
• Microspore: relatively small and produced in large
  numbers