Chapter 29: Plant Diversity I

Question 1

What did land plants evolve from

Answer 1

Green algae (charophytes)

Question 2

Morphological/molecular evidence of evolution

Answer 2

• Rings of cellulose-synthesizing proteins
• Structure of flagellated sperm
• Formation of phragmoplast

Question 3

Sporopollenin

Answer 3

• Layer of durable polymer that prevents exposed zygotes from drying out; probably enabled plants to live on land

Question 4

Derived Traits of Land Plants

Answer 4

• Alternation of generations
• Multicellular, dependent embryos
• Walled spores in sporangia
• Multicellular gametangia (female are archegonia, male are antheridia)
• Apical meristems (localize regions of cell division at tips of roots/shoots)

Question 5

Alternation of Generations in Plants–Gametophyte

Answer 5

• Multicellular haploid gametophyte produces haploid gametes that fuse during fertilization

Question 6

Alternation of Generations in Plants–Sporophyte

Answer 6

• Mitotic division of zygote produces multicellular diploid sporophyte
• Meiosis in mature sporophyte produces haploid spores, reproductive cells that can develop into new haploid organism without fusing with another cell
• Cycle begins again

Question 7

Stomata

Answer 7

• Specialized pores that support photosynthesis by allowing exchange of CO2 and O2 between outside air and plant; main avenues for evaporation

Question 8

Vascular tissue

Answer 8

• Cells joined into tubes that transport water and nutrients throughout the plant body; most plants have complex vascular tissue system (vascular plants)

Question 9

Bryophytes

Answer 9

• Nonvascular plants; do not form monophyletic group

- Liverworts, mosses, hornworts

Question 10

Lycophytes

Answer 10

• Type of vascular plant

- Club mosses and their relatives

Question 11

Monilophytes

Answer 11

• Type of vascular plant

- Ferns and their relatives

Question 12

Seedless Vascular Plants

Answer 12

• Include lycophytes and monilophytes

Question 13

Seed

Answer 13

Embryo packaged with supply of nutrients inside a protective coat

Question 14

Seed Plant Groups

Answer 14

• Gymnosperms: Naked seed plants

- Angiosperms: (90%) Huge clade of flowering plants; seeds develop inside chambers

Question 15

Mosses + Nonvascular plant life cycles dominated by?

Answer 15

Gametophytes

Question 16

Bryophyte Gametophytes

Answer 16

• Spores develop into protonemata
• Haploid protonemata produce “buds” that divide by mitosis and grow into gametophores
• Sperm swims through film of moisture to reach egg
• Fertilization
• Zygote develops into sporophyte embryo
• Sporophyte grows long stalk that emerges from archegonium
• Attached by foot, sporophyte remain nutritionally dependent n gametophyte
• Meiosis occurs and haploid spores develop in capsule; spores released

Question 17

Protonema

Answer 17

mass of green, branched, one-cell-thick filaments

Question 18

Gametophyte

Answer 18

Gamete-producing structure

Question 19

Rhizoids

Answer 19

Long, tubular single cells (in liverworts and hornworts) or filaments of cells (in mosses) that anchor gametophytes

Question 20

Typical Bryophyte structure

Answer 20

• Foot: Absorbes nutrients from gametophyte
• Seta: Stalk conducts materials to sporangium
• Capsule: Uses nutrients to produce spores by meiosis

Question 21

Ecological importance of mosses

Answer 21

• Colonize bare, sandy soil where they help retain nitrogen
• In coniferous forests, harbor nitrogen-fixing cyanobacteria that increase availability of nitrogen in the ecosystem
• Inhabit extreme environments
• Phenolic compounds absorb dangerous UV radiation present in deserts at high altitudes
• Peat moss serves as fuel

Question 22

First plants to grow tall

Answer 22

• likely to have been ferns and other seedless vascular plants

Question 23

Xylem

Answer 23

• Conducts most of water and minerals; include tracheids (tube shaped cells that carry water and minerals up from the roots)

Question 24

Lignin

Answer 24

• Cell walls of plant are strengthened by this polymer

- Allowed plants to grow taller

Question 25

Phloem

Answer 25

• Tissue that has cells arranged into tubes that distribute sugars, amino acids, and other organic products

Question 26

Roots

Answer 26

• Organs that absorb water and nutrients from the soil; anchor vascular plants and allow shoot system to grow taller

Question 27

Leaves

Answer 27

• Increase surface area of plant body and serve as primary photosynthetic organ of vascular plants

Question 28

Microphylls

Answer 28

• Small, often spine-shaped leaves supported by single strand of vascular tissue

Question 29

Megaphylls

Answer 29

• Leaves with highly branched vascular system; few species have reduced leaves that appear to have evolved from megaphylls

Question 30

Sporophylls and Spore Variations

Answer 30

• Sporophyll: Modified leaves that bear sporangia

- Sori: Produced by sporophylls; usually on undersides of sporophylls

Question 31

Homosporous Spore Production

Answer 31

• Sporangium on sponophyll
• Single type of spore
• Typically bisexual gametophyte
• Eggs or Sperm

Question 32

Heterosporous Spore Production

Answer 32

• Megasporangium on megasporophyll
• Megaspore (Microspore –> male game.)
• Female gametophyte
• Eggs