Lecture 2: Origin of land plants, Bryophytes

Question 1

true or false; in all bryophytes sporophytes are semiparasitic

Answer 1

true

Question 2

where have land plants evolved from?

Answer 2

aquatic green algae

Question 3

What does the sporophyte produce

Answer 3

produce spores via meiosis

Question 4

What does the gametophyte produce

Answer 4

gametes via mitosis

Question 5

What are the two major groups of bryophytes

Answer 5

liverworts and mosses

Question 6

What are all the bryophyte groups

Answer 6

liverworts
mosses
hornworts

Question 7

What is the most dominant life cycle for bryophytes

Answer 7

gametophyte (free living: non dependent on anything else)

Question 8

true or false; the gametophytes of bryophytes do not have true vascular tissue

Answer 8

true

Question 9

What do gametophytes produce

Answer 9

antheridia (male); archegonia (female)

Question 10

When does the sporophyte develop?

Answer 10

after the fertilization of the gamete (archegonia)

Question 11

What is the evidence that aquatic green algae (Charophytes) are the ancestors of all land plants

Answer 11

• same green pigments, chlorophyll a and b, in chloroplasts
• same type of cell division (mitosis)
• same type of flagellate cells
• common pattern of life cycle with an alternation of haploid and diploid generations
• stages of the life cycle in bryophytes and ferns still require water to effect gamete transfer

Question 12

how much in % are the bryophyte species in NZ

Answer 12

10%

Question 13

What are the characteristics of bryophytes

Answer 13

• most ancient group of land plants
• usually grow in wet or damp terrestrial sites but can also be aquatic
• often have no cuticle (waterproofing layer) to prevent dessication
• but can also be found in extreme environments
• gametophytes is the dominant phase of the life cycle. Very simple morphology
• sperm are free swimming, flagellate and need water for fertilization

Question 14

What does alternation of generations mean?

Answer 14

multicellular haploid organisms that appear in alteration with diploid forms

Question 15

what is the purpose of the hydroids and leptoids of mosses?

Answer 15

conduct water and food respectively

Question 16

What is a life cycle?

Answer 16

transfer of information from one generation to the next, involves the process of reproduction

Question 17

Types of reproduction

Answer 17

asexual or sexual

Question 18

What does asexual reproduction mean?

Answer 18

reproduction produces identical offspring

• these are sometimes called clones
• involves only mitotic cell division

Question 19

What does sexual reproduction mean?

Answer 19

reproduction allows each generation to be genetically different

Question 20

What are the three key features of meiosis

Answer 20

• reduces chromosome number by half
• recombines genetic information from two parents
• results in the production of gametophytes that produces gametes

Question 21

What do you call plants that undergo meiosis

Answer 21

sporophytes

Question 22

What do you call plants that undergo mitosis

Answer 22

gametophytes

Question 23

Where is sporic meiosis found?

Answer 23

organisms that have alternation of generation between sporophyte (2n) and gametophyte (n)

Question 24

What are the two types of spores

Answer 24

microspore (male)

megaspore (female)

Question 25

What does heterospory mean

Answer 25

2 different types of spores produced (male and female)

Question 26

What does homospory mean

Answer 26

1 type of spore is produced (either male or female)

Question 27

In mosses which is larger; sporophyte or gametophyte

Answer 27

gametophyte (free living)

Question 28

true or false; the moss sporophyte is dependent on the gametophyte; hence it is not free living

Answer 28

true

Question 29

what does dioecious mean?

Answer 29

have separate male and female plants (like many mosses)

Question 30

true or false; sperm is biflagellate (having 2 falgella)

Answer 30

true

Question 31

how are sperm transferred to the neck of the archegonia

Answer 31

by a water splash

Question 32

What does a diploid zygote develop into

Answer 32

three regions; foot, seta, capsule

Question 33

Why does seta elongate

Answer 33

to aid spore dispersal

Question 34

What do capsules contain

Answer 34

sporocytes that undergo meiosis to give haploid spores

Question 35

what do you call the central core?

Answer 35

sterile columella

Question 36

What happens when the calyptra falls off?

Answer 36

the capsule lid or operculum dries out when mature and falls off

• reveals the peristome
• sensitive to humidity which causes it to open and close
• helps in spore discharge

Question 37

true or false; the peristome teeth change shape in response to changing humidity levels

Answer 37

true

- this helps disperse spores

Question 38

when do the the peristome curl up again?

Answer 38

when it is moist

- uncurls slowly when it is dry

Question 39

What happens when spores germinate

Answer 39

gives rise to thread like protonema

- which produces buds which grow into the gametophyte plant

Question 40

How do liverworts differ to mosses?

Answer 40

differ in their structure and spore dispersal

- use elaters rather than peristome teeth to disperse their spores

Question 41

What are gemmae cups a form of?

Answer 41

asexual reproduction

Question 42

What does elaters mean?

Answer 42

structure that forces the dispersion of spores