Gymnosperms Flashcards
(65 cards)
1
Q
What are the four living phyla of the gymonsperms?
A
- coniferophyta, ginkgophyta, cycadophyta, gnetophyta
2
Q
What is the dominant generation in gymnosperms?
A
sporophyte - gametophyte is fully dependant on sporophyte
3
Q
Are the seedless vascular plants heterosporous or homosporous?
A
- all of them are heterosporous (develop endosporically)
4
Q
What kind of seeds do they produce?
A
- naked seeds
5
Q
Describe the vascular elements in the seedless vascular plant phyla
A
- coniferophyta, ginkgophyta, cyadophyta = tracheids
- gnetophyta: tracheids and vessel elements
6
Q
what do gnetophyta have in common with angiosperms?
A
- no archegonia and they have both tracheids and vessel elements
7
Q
What is primary and secondary xylem?
A
- primary xylem: tracheids
- secondary xylem: tracheids and vessel elements
8
Q
what is a casparian strip?
A
- forces water/nutrients to pass through endodermal cells, regulating entry into vascular system
9
Q
how does water enter the plant?
A
- enters through the root hairs of the root
10
Q
Are xylem cells dead or alive cells?
A
- xylem cells are dead at maturity, while phloem is made of live cells
11
Q
Describe the difference In structure between vessel elements and tracheids?
A
- vessel elements: short, wider (perforation plates)
- tracheids: long, tapered
12
Q
how is water pulled up a plant? what part of the leaf regulates this activity?
A
- water pulled up through transpiration, and adhesion of cells
- capillary action and weak hydrogen bonds
- stomata in the leaves drive evaporation and pull water up through the plant
13
Q
describe the parts of the stem
A
- pith, xylem, phloem, cortex, epidermis, vascular cambium
14
Q
What makes up the bark?
A
-phloem, cortex, epidermis
15
Q
What is the vascular cambium?
A
Between the outermost layer of xylem and phloem is the vascular cambium, when these cells divide the daughter cell alternates between becoming a xylem or phloem cell.
16
Q
what does older xylem become? how about younger xylem?
A
older = heartwood,
younger = sapwood
17
Q
What causes variation in xylem size? when might xylem be larger or smaller?
A
- the amount of water available changes the size: expands as more available water
- in spring xylem is larger
- later summer/fall narrower
- changes with water availability
18
Q
How do you determine the age of a tree?
A
- count the number of rings starting from the xylem
19
Q
what are the three cross sections of a stem?
A
longitudinal radial (middle), longitudinal tangential (side/middle), cross section (horizontal cut)
20
Q
what is unique about cycadophyta?
A
- emerges from woody stem
- emergence of leaves from a central base
21
Q
what do fern fronds emerge from?
A
- rhizomes
22
Q
What type of leaves are found on ginkgos?
A
- megaphylls: multiple veins
23
Q
Describe pine needles
A
- needle/scale like leaves of coniferophyta
24
Q
What kind of leaf are pine needles?
A
microphyllic
25
what is the function of endodermis? Hypodermis?
- endodermis: regulates movement of water, ions, hormones in and out of vascular tissue
- hypodermis: provides structural support and prevent water loss
26
Why are stomata recessed in pine leaves?
- to prevent water loss in harsh climates (wind/dry air)
27
What are the functions of the leaf?
gas exchange (stomata) and photosynthesis
28
how do conifers grow so tall?
- vascular tissue and secondary xylem
- determinate growth due to resource constraints
29
Where are male cones located in the tree?
lower in the tree to prevent self pollination
30
What do male pollen cones look like? How would you identify them?
What are the leaves called?
- they are small, flakey with pollen on them
- leaves are called microsporophylls
31
how are gnetophyta similar to angiosperms?
- no archegonia and they have both vascular elements and tracheids
32
how many microsporangia are on each microsporophyll?
- 2 microsporangia on each microsporophyll
33
describe the process of pollen formation on the male cone
- microsporophyll = microsporangia = microsporocyte - (meiosis)--> tetrad of microspores
34
What occurs to the tetrad of microspores?
- each tetrad in the microspore become a winged pollen grain (from 2 prothallial cells and a tube cell and a generative cell)
35
Is a male cone a strobilus?
yes
36
What cells make up the male pollen?
- two prothallial cells (non functional, left over), generative cell (forms two sperm cells through mitosis), and a tube cell
37
How are sperm pollen dispersed? what conditions are they dispersed?
- two air bubbles aid in dispersal by wind
- dispersed in dry, windy conditions
38
What is the male gametophyte in gymnosperms?
- pollen
39
when are sperm cells released from pollen?
when the pollen reaches the ovule
40
how are sperm cells dispersed in bryophytes and seedless vascular plants? what is different in gymnosperms?
- a) in water
b) gymnosperms use wind
41
where are the female cones found on the tree?
- upper portion of the tree to prevent self pollination
42
What are the stages of seed development (year 1-3)?
year 1: cones small, at the end of branches
- sporophyte tissue, NOT gametophyte tissue yet
- develops megasporocyte which undergoes meiosis to form 4 megaspores, 1 survives
year 2: gametophyte formation (pollination)
year 3: fertilization/seed development
43
What triggers the production of the gametophyte in the female cones?
- pollination
44
Describe the second year cone's appearance
- larger but the scales (megasporopohylls) remain closed, sometimes with sap attached
45
Describe the 3rd year cone's appearance
- scales are open and seeds are dispersed
- two lighter patches on scales are sterile bracts: where 4 megaspores develop only 1 survives and the remaining 3 are degenerated
46
What are sterile bracts?
- woody megasporophyll
- the two light patches on the bottom half of the megasporophylls: 4 megaspores develop here
47
what makes up the ovule?
- the ovule is the megasporangium
- megaspore mother cell (megasporocyte) and integument (which becomes seed coat)
- the entire ovule is surrounded by the integument which becomes the seed cot
48
how does the archegonium form?
- the pollen attaches to micropyle (opening) --> forms 4 megaspores --> 3 disintegrate --> last megaspore develops megagametophyte
49
Describe the archegonia
- two eggs within the archegonia
- within the megagametophyte
- remits of megaspore
- within ovule (megapsorangium)
- fleshy arms = integument (becomes seed coat)
- two pollen tubes originate at microtubule - grows towards archegonia
50
What is the ovuliferous scale?
- the woody megasporophyll that the megagametophyte sits on
51
what does endosporic development for megagametophytes mean?
- megagametophyte develops within the megasporangium
52
Are there ovaries in pine?
- there is no ovary, only ovules which become the seed
53
what parts of the ovule is diploid? Haploid?
diploid - megasporangium and integument
haploid: megagametophyte and remaining megaspore
54
what is the role of the mega gametophyte in the seed?
- provides nutrients to the embryo (the new sporophyte)
55
Describe the seed that forms?
- two arms = cotyledon (first leaves)
- epicotyl: is the bump between the cotyledon
- radicle: the red spot at the base, developing root
56
What are the cotyledons?
- first leaves
57
What is the space between cotyledons called?
- the epicotyl
58
What is the radicle?
- the red spot at the base of the seed, developing root
59
Describe juniper berries?
- blue at maturity
- not fruit, fleshy cones!!
60
what are the four types of branching?
- alternate, dichotomous, opposite, whorled
61
do gymnosperms have antheridia?
no, the spore produces sperm from the generative cell so antheridia are not produced, only archegonia
- an gnetophytes have no archegonia!!
62
how are gnetophytes different from the other gymnosperms and similar to angiosperms?
- they have tracheids and vascular tissue AND no archegonia
63
how many vascular bundles are within a single pine needle?
- two vascular bundles (bean shaped, at the centre)
64
what are the 10 (!) parts of the pine needle?
- ectoderm, hypoderm, mesoderm, endoderm, vacuole bundle, xylem (the darker cells of the bean), phloem, resin duct, stoma, transfusion tissue
65
