CHAPTER 3
EVOLUTION AND DIVERSITY OF GREEN AND LAND PLANTS
REVIEW QUESTIONS
GREEN PLANTS
1. What are two formal names for the green plants?
Viridiplantae or Chlorobionta
2. What are apomorphies for the green plants?
Cellulosic cell wall; specialized type of chloroplast.
3. The bulk of the primary cell wall of green plants is composed of what substance? (Give the common name and chemical
name.)
Cellulose - beta-1,4-glucopyranoside
4. Is the cell wall synthesized inside or outside the plasma membrane?
To the outside.
5. What are the unique features of green plant chloroplasts?
Chlorophyll b in addition to chlorophyll a, starch, and thylakoid membranes structured into grana.
6. How are chloroplasts thought to have originated (i.e., by what evolutionary process)?
Endosymbiosis.
7. What is a haplontic life cycle? Draw and label.
One in which adult individuals are haploid and produce egg and sperm, which fuse to form a diploid zygote, which
undergoes meiosis to produce haploid spores, which develop into new, haploid adults.
8. What is oogamy?
Evolution of the egg, a relatively large, non-motile gamete.
9. Describe and give the function of plasmodesmata.
These are holes in the primary cell wall and allow for cell-to-cell communication by transfer of larger molecules
between cells.
LAND PLANTS
10. What is the formal name for the land plants?
Embyrophyta.
11. Name the major apomorphies of the land plants.
Sporophyte/embryo (2n), with alternation of generations, cuticle, parenchyma, antheridia, archegonia.
12. Draw and label the basic haplodiplontic life cycle (alternation of generations) of all land plants, illustrating all structures,
processes, and ploidy levels.
13. What is an embryo?
An immature, diploid sporophyte.
14. What is a sporangium?
A reproductive structure produced by the sporophyte, cells of which (sporocytes) undergo meiosis, producing haploid
spores.
15. Name the possible adaptive features of the sporophyte.
a) A large increase in spore production.
b) A diploid ploidy level, with an increased fitness
--by potentially preventing the expression of recessive, deleterious alleles, or
-- by permitting increased genetic variability in the sporophyte generation (via genetic recombination from two
“parents”).
16. What are cutin and cuticle and what are their adaptive significance?
A cuticle is a protective layer that is secreted to the outside of the cells of the epidermis. Cutin is the substance,
composed of a polymer of fatty acids, that impregnates the cuticle and the outer, cellulosic cell wall of the epidermis,
functioning as a sealant, preventing excess water loss.
17. Define apical growth and parenchyma.
Apical growth is rapid cell divisions at the apex of the stem, shoot, and thallus or (in most vascular plants) of the root,
in the region called the apical meristem. Parenchyma is tissue consisting of cells that most resemble the unspecialized,
undifferentiated cells of actively dividing meristematic tissue, that are (a) are elongate to isodiametric; (b) have a
primary cell wall only (rarely a secondary wall); and (c) are living at maturity and potentially capable of continued
cell divisions. Parenchyma cells function in metabolic activities such as respiration, photosynthesis, lateral transport,
storage, and regeneration/wound healing.
18. In land plants what is the name of the pectic-rich layer between adjacent cell walls that functions to bind them together?
Middle lamella.
19. What is an antheridium? Draw and label the parts.
Gametangium that produces haploid sperm cells.
20. What is an archegonium? Draw and label the parts.
Gametangium that produces a haploid egg cell.
LIVERWORTS, MOSSES, AND HORNWORTS
21. Draw a phylogenetic tree denoting relationships of the liverworts, mosses, hornworts, and vascular plants.
22. What is the formal name of the liverworts?
Hepaticae.
23. Name two apomorphies of the liverworts.
Elaters; oil cells.
24. What is the function of elaters?
Spore dispersal, by hygroscopic movement.
25. What are the two major morphological forms of liverworts? Which is likely ancestral?
Thalloid and leafy. Thalloid is likely ancestral.
26. What are gemmae and gemma cups?
Vegetative propagules and the cup-like structure that contains them.
27. Describe the morphology of the leaves of leafy liverworts.
Very thin, in three rows. Most with two rows of larger leaves on dorsal side, one row of smaller leaves below.
28. What is an antheridiophore? An archegoniophore?
a) Stalked structure that produces antheridia on upper surface; b) Stalked structure that produces archegonia
beneath.
29. Describe the structural makeup and function of a stomate.
a) Made up of two, parallel cells, guard cells, which by expansion and contraction can control the size of the opening
between them (the stoma); b) to control gas (water vapor, oxygen, carbon dioxide) exchange.
30. What land plant groups possess stomates?
All land plants except for the liverworts.
31. What possible apomorphies may be shared by the mosses, hornworts, and vascular plants?
Stomates and an aerial sporophyte axis.
32. What is the formal name of the mosses?
Musci.
33. Name major apomorphies shared by the mosses alone.
Hydroids, leptoids, gametophytic leaves, perine in spore wall.
34. What is a calyptra, stipe, operculum, peristome tooth?
Calyptra - accrescent archegonial neck, lifted up by capsule during sporophyte development; stipe - stalk of
sporophyte; operculum - cap of capsule, which comes off during spore release; peristome tooth - one of several, teethlike structures at perimeter of capsule opening that control spore release by hygroscopic movement.
35. What is the scientific name of peat moss?
Sphagnum.
36. What feature of the leaf anatomy of peat moss enables the leaves to absorb and retain water?
Large, non-living, porous hyaline cells (surrounded by a network of chlorophyllous cells).
37. How is peat moss of economic importance?
Used as a fuel source and as a potting medium.
38. What is the formal name of hornworts?
Anthocerotae.
39. Describe the major features of hornworts, citing how they differ from the liverworts and mosses.
Sporophyte has a foot embedded in gametophyte (surrounded by protective collar), has centripetal growth, is
elongate/cylindrical, photosynthetic, splits into two valves, and contains a central columella and pseudo-elaters
surrounding spores.
40. What is the function of pseudo-elaters, and how do they differ structurally from the elaters of liverworts?
Spore dispersal, by hygroscopic movement. They differ in being composed of elongate, cohering cells.
41. What feature of the sporophyte might unite the hornworts with the vascular plants?
Sporophyte is chlorophyllous, somewhat long-lived, with an often lobed foot, resemling rhizoids.
42. What apomorphy links the Pan-Tracheophyta/polysporangiophytes with the vascular plants?
A branched sporophyte with multiple sporangia.