2: bryophyte madness

Question 1

provide an overview for bryophytes

Answer 1

• among the first land plants
• evolved ~450 million years ago from green algae, around same time as amphibians
• simple, require water

Question 2

describe the atmospheric CO2 at the time that bryophytes arrived

Answer 2

• CO2 levels began to drop and oxygen began to climb, indicating this is when they evolved

Question 3

What are rhizoids?

Answer 3

• found in gametophytes, produce compound that dissolve rock and form pockets of soil for attachment
• basically false roots that aid in attachment

Question 4

What is an epiphytic plant?

Answer 4

• like bryophytes
• grow on trees, rocks, for mechanical support, do not take nutrients

Question 5

Which bryophyte is a source of fuel? Also, what can bryophytes tell us about air quality?

Answer 5

sphagnum moss (peat moss!)
- if bryophytes are abundant, then air quality is good

Question 6

do bryophytes tolerate harsh conditions? Which ones can?

Answer 6

most do not tolerate harsh conditions and require warm, moist environments but SOME can survive cold and dry deserts
- andraidae (granite moss) are known to tolerate harsh conditions

Question 7

what are bryophytes transitional between?

Answer 7

• transitional between green algae and vascular plants

Question 8

What process caused bryophytes to evolve from green algae?

Answer 8

-peroxisomes develop to detoxify with phosphoglycolate ( a toxic byproduct of photorespiration)

Question 9

How are bryophytes similar to green algae?

Answer 9

• mitotic spindles remain during cell division
• cell wall composed of cellulose
• have phytochromatin: green blue important for spore germination
• have chloroplasts, well developed grana : chl a, b, carotenoids
• motile cells

Question 10

what are 5 challenges of living in a terrestrial environment?

Answer 10

• spatial distribution of resources
• limited dispersal for gametes
• limited support for plant
• desiccation from the air
• difficult for offspring dispersal
• evolved strategies to address these (vascular tissue, wood/ligning, flowers, seed/fruit, epidermis tomato and cuticle)

Question 11

Describe alternation of generations

Answer 11

• gametophytes produce spores by mitosis which produce zygotes which grow into a sporophyte
• sporophyte produces spores by meiosis: spore become gametophyte

Question 12

what does isomorphic mean?

Answer 12

• this means that the gametophyte and sporophyte look identical and they must be chemically identified

Question 13

Describe the level of dominance in bryophytes and vascular plants

Answer 13

• bryophytes: gametophyte is dominant, sporophyte is completely dependant on gametophyte
• vascular: sporophyte, gametophyte dependant on sporophyte

Question 14

what protects spores from desiccation?

Answer 14

• sporopollenin

Question 15

What are the three phyla of bryophytes? Are they closer related to algae or vascular plants?

Answer 15

• marchantiophyta: liverworts: more closely related to green algae

Bryophyta: moss

and anthocerophtya: hornworts: more closely related to vascular

Question 16

What are plants with branching sporophytes and multiple sporangia called?

Answer 16

polysporangiophytes

Question 17

Describe the relation, number of species, the categories of liverworts, AND the branching

Answer 17

• marchantiophtya are most closely related to green algae
• ~5200 species
• 3 major types in 2 categories: leafy thallus and thalloid thallus
• dichotomously branched

Question 18

describe the gametophyte and gametangia of the marchantiophyta

Answer 18

• gametophyte is dominant and independant
• dichotomously branched
• gametophytes are unisexual: antheridiophore are cup shaped, archegoniophore: umbrella

Question 19

What are antheridiophore and archegoniophore?

Answer 19

• antheridiophore hold the antheridia
• archegoniophore hold the archegonia
• in marchantiophytes, antheridiophore is cup shaped, archegoniophore is umbrella shaped

Question 20

what does it mean for marchantiopophyta to be unisexual?

Answer 20

• they have separate male and female gametophytes!

Question 21

describe the thallus of marchantiophyta

Answer 21

• dicthotomouly branched, no vascular tissue etc, have rhizoids, thalloid or leafy thallus, haploid

Question 22

Describe the life cycle of marchantiophyta

Answer 22

• unisexual gametophyte : male and female gametophtyes - embryo forms within the archegonia to develop the sporophyte (which has a foot, elaters, spores, seta, and calyptra)

Question 23

describe asexual reproduction in marchantiophyta

Answer 23

• uses Gemma cups which have gamma in them
• simple fragmentation
• splash gamma out which become new gametophytes (skip sporophyte stage!)

Question 24

What is the relationship between embryo size and calyptra size

Answer 24

larger embryos have larger calyptras

Question 25

What do elaters do?

Answer 25

- help 'twist' spores out when they're mature in marchantiophyta

Question 26

Describe the phylum Bryophyta

Answer 26

- Mosses - sphagnidae (peat moss), andraeidae (granite moss), Bryophyta (true moss- vast majority of species) - some have specialized fake vascular tissue (hydroids and lepton)

Question 27

What are the two classes of sphagnidae?

Answer 27

- sphagnum - ambuchania

Question 28

Describe where sphagnidae live, and their capsules

Answer 28

- sphagnidae lives in bog, covers 1-3% of the earth - distinctive red/brown capsules

Question 29

what is a pseudopodium?

Answer 29

gametophyte derived stalk that raises the sphagnum spore capsule

Question 30

What kinds of cells make up the sphagnidae?

Answer 30

- leaves are 1 cell layer thick - composed of large dead cells, and living narrow, red or green pigmented cells

Question 31

Describe the 5 uses of sphangidae

Answer 31

- soil amendment/planting medium -high water holding - phenolic compounds (antioxidant/antibacterial) - diaper, dressing , packing material (dead cells make it highly absorptive) - source of fuel - carbon sink (reduces CO2)

Question 32

Describe bog people

Answer 32

- man found preserved in bog (sphagnidae) due to tannic acids

Question 33

Describe andraeidae

Answer 33

- granite moss - live on rocks in extreme conditions - four vertical slits in sporangium

Question 34

what is unique about andreaidae?

Answer 34

- it can live in extreme conditions and it has 4 vertical slits in its sporangium

Question 35

Describe true mosses

Answer 35

bryidae - contains most species of moss 0 no true vascular tissue but has specialized tissue for food and water conduction (hydroids and leptoids)

Question 36

Quick! Draw the bryidae life cycle!!

Question 37

Is the sporophyte dependant on the male or female gametophyte?

Answer 37

- female because she has the archegonia within which the zygote develops - males have the splash cups yo

Question 38

In fertilisation in bryophytes, how do the sperm know where to swim?

Answer 38

- egg releases malic acid, sperm fertilizes and the archegonia nourishes/protects embryo

Question 39

how are spores dispersed in capsules?

Answer 39

calyptra falls off, in dry conditions the operculum bursts off and spores are dispersed as the peristome opens (in wet conditions peristome is closed though)

Question 40

what are splash cups?

Answer 40

- common in bryidae, antheridia are kept in splash cups and when rain splashes in them sperm on water droplets are dispersed

Question 41

what are paraphyses?

Answer 41

- sterile hairlike filaments surrounding reproductive organs of lower plants (Bryophyta, algae, fungi) - protection, helps hold water around the stem

Question 42

Describe hornworts

Answer 42

- horn shaped sporophytes - sporophytes have stomata - gametophytes more horizontal than vertical - in some species N fixing bacteria live within cavities in gametophytes

Question 43

How do bryophytes resist desiccation?

Answer 43

- many resist desiccation because of heat shock proteins - Most dead, lifespan short lived, add water, revived!