Bryophytes

Question 1

What internal structures do bryophytes lack?

Answer 1

vascular tissue and lignin

Question 2

Instead of xylem, how do bryophytes transport water?

Answer 2

diffusion

Question 3

Briefly describe the steps of bryophyte sexual reproduction

Answer 3

1. sperm is kept in the antheridium
2. sperm is released and picked up by water
3. neck canal cells in the archegonium break down to allow sperm to pass through
4. sperm reaches the venter in the archegonium where eggs are kept and fertilizes the egg

Question 4

What ploidy are the components involved in bryophyte sexual reproduction?

Answer 4

neck canal cells = n
archegonium = n
antheridium = n
sperm = n
egg = n
zygote = 2n

Question 5

What is the dominant generation in bryophytes?

Answer 5

gametophyte

Question 6

How does the gametophyte provide nutrients for the bryophyte?

Answer 6

photosynthesis, symbiosis with N-fixing bacteria (i.e Nostroc), rhizoids

Question 7

What adaptations do bryophytes have to live out of water?

Answer 7

• intercellular air spaces
• cuticle
• epidermal pores

Question 8

What shapes do liverwort gametophytes come in?

Answer 8

leafy or thalloid

Question 9

Briefly explain the arrangement of chloroplasts in thalloid liverworts

Answer 9

• concentration of chloroplasts along the surface of the thallus
• few chloroplasts present below the surface layer

Question 10

How do thalloid liverworts manage gas exchange?

Answer 10

• constantly open air pores
• no stomata or guard cells

Question 11

Briefly describe the function and feature of rhizoids

Answer 11

• no vascular tissue
• used for anchoring the thallus in absense of roots
• do not assist in water uptake or nutrient absorption like roots do

Question 12

How do thalloid liverworts grow?

Answer 12

out of marginal meristems found in notches along the edge of the thallus

Question 13

How do thalloid liverworts reproduce asexually?

Answer 13

budding:
gemmae (gametophyte buds) found in gemmae cups get dispersed via rain and grow into a new individual plant

spores:
spores (n) are released by sporophyte and dispersed with help from elater cells (2n) that flex with humidity

Question 14

Describe the reproductive structures of thalloid liverworts

Answer 14

male:
- antheridia are found underneath the antheridiophore (splash pad)
- sperm tissue in antheridia is surrounded by a jacket layer attached to a stalk

female:
- archegonia are found underneath the archegoniophores
- eggs are found in the venter of archegonia, with a neck canal leading out of it

Question 15

How do thalloid liverworts reproduce sexually?

Answer 15

• water on antheridiophores picks up sperm released from the antheridia
• sperm is carried to archegonia
• neck canal cells in the archegonia break down to allow sperm to swim into the venter
• sperm fertilizes the egg and forms a zygote
• zygote undergoes mitosis to form a sporophyte

Question 16

What are the different parts of a liverwort sporophyte?

Answer 16

• placenta (provides nutrients as structure is not photosynthetic)
• foot
• seta (stalk)
• capsule (sporangium)

Question 17

Are thalloid liverworts heterosporous (different sized spores) or homosporous (same size spores)?

Answer 17

homosporous

Question 18

What ploidy are the following structures:

a) archegoniophore
b) placenta
c) foot
d) seta
e) elater
f) sporangium
g) spore

Answer 18

a) archegoniophore = n
b) placenta = n
c) foot = 2n
d) seta = 2n
e) elater = 2n
f) sporangium = 2n
g) spore = n

Question 19

What sexual lifestyles can thalloid liverworts have?

Answer 19

either unisexual (individual is either male or female) or bisexual (individual has both male and female gametangia)

Question 20

What sexual lifestyles can leafy liverworts have?

Answer 20

only unisexual (either female or male gametangia)

Question 21

What differences do leafy liverworts have compared to thalloid liverworts?

Answer 21

• no air pores on gametophytes as leaves are one cell thick
• sporophytes are found inside folded tubes from the gametophytes instead of in the branched out archegonia
• gemmae are found at the tips of the leaves vs. in gemmae cups
• only unisexual
• antheridia and archegonia are not formed from antheridiophores/archegoniophores

Question 22

What general structure do hornworts have?

Answer 22

thalloid gametophyte and horn-like sporophytes projecting out

Question 23

How do hornworts prevent water loss?

Answer 23

• stomata w/ guard cells
• cuticle on epidermis
• intercellular air space for gas exchange
• mucilage (pectin) in gametophytes to absorb + maintain moisture

Question 24

What sexual lifestyle do hornworts have?

Answer 24

either unisexual (male or female gametangia) or bisexual (have both gametangia)

Question 25

How is the location of archegonia/antheridia different between liverworts and hornworts?

Answer 25

liverworts = both are elevated structures coming out of thallus on seta hornworts = both are within the thallus

Question 26

What is the difference between sporophyte location between liverworts and hornworts?

Answer 26

liverworts = sporophyte grows within archegonia and remains there hornworts = sporophyte grows within archegonia and then grows upward out of thallus

Question 27

How do the sporophytes of liverworts and hornworts grow similarly?

Answer 27

both rely on the placenta to provide nutrients and cell growth is found at the meristem

Question 28

What is the ploidy of the following structures: a) thallus b) gemma cup c) gemmae

Answer 28

a) thallus = n b) gemma cup = n c) gemmae = n

Question 29

How do moss sporophytes germinate (what structure are involved)?

Answer 29

protonema branch out from spore and rhizoids grow off of protonema

Question 30

What is a costa?

Answer 30

the central multicellular rib on moss 'leaves'

Question 31

What conductive (not vascular) cells do mosses have?

Answer 31

hydroids = water transport, dead at maturity (similar to tracheary elements) leptoids = food transport (comparable to sieve tube elements), have thick cell walls stereids = structural support using thick PSW (similar to fibres)

Question 32

What sexual lifestyle can mosses have?

Answer 32

either unisexual (individual has either male or female gametangia) or bisexual (both gametangia on the same individual)

Question 33

What are paraphyses?

Answer 33

non reproductive hairs found on moss gametangia

Question 34

What are the components of moss sporophytes?

Answer 34

- capsule (contains spores) - seta (stem) - calyptra (outermost protective cap) - operculum (cap over the peristome) - peristome teeth (spore dispersal) - columella + sporogeneous tissue (both undergo meiosis to produce spores) - stomata

Question 35

What is the ploidy of the following structure: a) seta b) calyptra c) operculum d) peristome teeth e) capsule f) spore

Answer 35

a) seta = 2n b) calyptra = n (remnant of archegonium) c) operculum = 2n d) peristome teeth = 2n e) capsule = 2n f) spore = n

Question 36

What is the order of the layers around a moss sporophyte capsule?

Answer 36

outermost = calyptra middle = operculum innermost = peristome teeth

Question 37

What is the scientific name for peat moss?

Answer 37

Sphagnum

Question 38

What do hyaline cells do in sphagnum cells?

Answer 38

absorb water