Algae and Non-vascular Plants

Question 1

sexual reproduction

Answer 1

via asexual vegetative reproduction OR
diversify via sexual reproduction

(diversify not necessarily from other plants; meiosis I, crossing-over will -> recombination of alleles)

Question 2

Leaving “sea of moderation” concerns

Answer 2

• prevent sun damage -> ozone layer
• stay moist
• access to water & nutrients
• stay upright
• propagate & spread

Question 3

Freshwater green algae OR marine algae better for living on land

Answer 3

freshwater!
land water usually not saline
shallow, freshwater env: +light and temp fluctuations

Question 4

strategies against photodamage

Answer 4

• pigments like carotenoids (light harvesting/sun protection)
• light avoidance, plastid movement (cytoplasmic streaming)

Question 5

example strategy against staying moist

Answer 5

lichen (NOT moss): composite organism
- green algae/cyanobacteria + fungi in symbiotic relationship
- extreme conditions, desiccate to 2% dry weight, upper thallus becomes opaque and blocks light & photosynthesis)

Question 6

non vascular plants: bryophytes

Answer 6

moss plants
- NO LIGNIN
- non-vascular
- instead of xylem: some have water-conducting cells (hydroids) or absorb water through surface cells
- instead of phloem: some have food-conducting cells (leptoids)

Question 7

similarities (bryophytes & “higher” vascular plants

Answer 7

• protected male and female reproductive structures
• multicellular embryo is protected within female parent
• sporophyte (1n) produces spores by meiosis
• store food reserves from photosynthesis as starch in plastids
• some have stomata for gas exchange (transpiration)
• some have waxy cuticle to prevent water loss

Question 8

similarities (bryophytes & green algae)

Answer 8

• thalli
• no roots, have anchoring rhizoids
• similar cellulose wall composition
• similar chloroplast anatomy (thylakoids stacked into grana) + chlorophyll a, b, carotenoids
• some pyrenoids in chloroplasts
• reproduction: asexual (fragmentation) and sexual (alternation of generations)

Question 9

bryophyte: alternation of generations - gametophyte

Answer 9

gametophyte (1n) dominant in life cycle
- multicellular gametangia at apices of gametophytes
- produce mitotic male gametes in antheridium and one female gamete (egg) in archegonium
- gametes can be produced on one plant or distinct female/male plants
- water is required for sexual repro

Question 10

bryophyte: alternation of generations - sporophyte

Answer 10

sporophyte (2n) product of fertilization:
- sporophyte remains attached to gametophyte
- sporophyte gives rise to gametophytes through meiosis (spores)
- can asexually reproduce (fragmentation)

Question 11

Non Vascular Plants (bryophytes) phyla

Answer 11

Hepticophyte: liverworts
Bryophyte: mosses
Anthocerophyta: hornworts

Question 12

phylum hepticophyte: liverworts

Answer 12

• most have flattened lobed thalli
• in thalloid liverworts, growth is prostrate and one-celled rhizoids on lower surface anchor plant
• sexual reproduction (archegonia - eggs in rows hanging down; antheridia - contain sperm found on upper surface)
• asexual (gemmae)

Question 13

phylum bryophyta: mosses

Answer 13

• peat, rock, true
• gametophytes have waxy cuticle
• “leaves” one cell thick
• stem-like axis without phloem or xylem often has central strand of conduction tissue w leptoids and hydroids
• know life cycle!!!

Question 14

phylum anthocerophyta: hornworts

Answer 14

• horn/grass-like sporophyte (2n) grow up from the gametophyte (1n) base
• only land plant w chloroplast containing a pyrenoid
• sporophyte has stomata
• meristem keeps growing up, increases sporophyte from base
• diploid elaters, intermingled w spores, help disperse
• asexual repro (fragmentation)