BIOL 112 Exam 3 Review

What group of algae are land plants most closely related to?

Charophytes.

What are the 4 shared characteristics between charophytes, chlorophytes, and plants?

Multicellular, cell walls with cellulose, chloroplasts, starch as primary storage.

When did multicellular green algae first expand onto land?

~470 mya.

From where did multicellular green algae first expand on to land?

From shallow seas into rivers and lakes.

What are 3 major challenges plants faced with transitioning to land?

Desiccation, no water for structural support, sperm can no longer swim

What are the 5 advantages of land over aquatic environments for plants?

Higher CO2 concentration, greater access to sunlight, greater access to minerals, no herbivores (initially), no competition (initially)

What is ‘alternation of generations’ and how does it differ from the charophyte life cycle?

Alternation of generations is having both a haploid gametophyte stage and diploid sporophyte stage. Charophytes are only multicellular in haploid stage, the zygote is unicellular and diploid.

What is the antheridium and what does it produce?

Male gametangium. Produces and holds flagellated sperm.

What is the archegonium and what is its function?

Female gametangium. Protects egg. Zygote produced here.

What is the role of the apical meristem?

Responsible for continuous cell division on tips of roots and shoots. Allows for directional growth.

What is the waxy cuticle and why is it important?

Waxy film over plants that helps hold in water to prevent dessication.

What are secondary metabolites in plants and give 2 examples?

Chemicals to protect against predators, parasites, etc. Ex: Latex rubber, caffeine

What are mycorrhizae and when did they evolve?

Fungi that form mutualistic relationships with plants to aid in getting water and nutrients. Date back to first land plants.

What is sporopollenin?

A tough polymer that protects spores and pollen grains from desiccation and UV damage.

What structures contain sporopollenin?

In walls of haploid spores and pollen grains.

List all 8 derived characteristics of land plants.

Alternation of generations, walled haploid spores, multicellular gametangia, sporophyte embryos inside female gametophyte, apical meristems, waxy cuticle, secondary metabolites, mycorrhizae

What is the dominant stage in bryophytes?

Gametophyte.

What are the 3 key features shared by all bryophytes?

Ground-covering, need water for reproduction, rhizoids

Name the 3 phyla of bryophytes?

Liverworts, Hornworts, Mosses.

Describe the moss life cycle.

Spore germinates → protonema (threads) → bud → gametophyte → antheridia and archegonia → sperm swim to fertilize egg → zygote → sporophyte → meiosis in capsule → release haploid spore → repeat

What is xylem and what does it transfer.

Vascular tissue that transports water throughout the plant.

What is phloem and what does it transport?

Vascular tissue that transports sugars, amino acids, and other organic materials throughout the plant.

What is the difference between the microphyll and megaphyll?

Microphyll: leaf with one strand of vascular tissue; only lycophytes. Megaphyll: leaf with highly branched vascular system; more photosynthesis

What is a sporophyll?

Leaf modified to bear sporangia. Ex: lycophytes have cone stuff

What is the difference between homosporous and heterosporous?

Homosporous - Produce one type of spore. Heterosporous - Produce multiple types of spores.

What are the 4 characteristics shared by all seedless vascular plants?

Branched sporophyte independent of gametophyte, sporophyte dominant, transport in xylem and phloem, true roots & true leaves

Name the 2 phyla of seedless vascular plants.

Lycophytes (club mosses, spike mosses, quillworts) and Monilophytes (whisk ferns, horsetails, ferns).

Describe the key features of ferns.

Homosporous. Large megaphylls (fronds). Sporangia clusters on underside of sporophylls.

Describe the fern life cycle from sporophyte to new sporophyte.

Large fern sporophyte → sporangia on underside of frond → meiosis → haploid spores → germinate → small, heart-shaped, independent gametophyte → antheridia & archegonia → sperm swim to egg → zygote → new sporophyte