Unit 1.2: Plant diversity and reproduction Flashcards
(76 cards)
1
Q
3 Plant Phyla:
A
(Phycophyta) (simple green algae - common ancestor)
Bryophyta
Pteridophyta
Spermatophyta
2
Q
4 Plant groups:
A
Bryophyta
Pteridophyta
Gymnospermae
Angiospermae
3
Q
Evolutionary Trends
SIMPLE –> COMPLEX
A
- Thallus – differentiated
(leaves, roots, stems) - No vascular bundles – present
- Homosporous – heterosporous
- motile gamete – non-motile
(H20 dependence) - Spores – naked seeds in cones – covered seeds in flowers
- Lower plants = adult gametophyte gen.
Higher plants = sporophyte gen. - No cuticle – cuticle
4
Q
Trends
AQUATIC –> TERRESTRIAL
A
- Water (turgor) loss
- Gamete movement (H@)?)
LOW = motile sperm
HIGH = no = pollen tube - Temp changes in enviro
(ecologically fit?)
5
Q
What do bryophytes have instead of vascular tissue?
A
Rhizoids, Fine outgrowths of “stem” to anchor the plant and “simple” leaf-like structures that contain chlorophyll
6
Q
Sporophyte:
A
Dependent on and grows out of visible plant
(hairs out of moss)
7
Q
Homosporous:
A
Spores are all the same size
(germinates into gametophyte and into a male & female gamete)
8
Q
Heterosporous
A
Spores are different sizes and differentiated into male & female
9
Q
Gametophyte
A
visible plant we can see
10
Q
Sori (sorus)
A
Sporangia in clusters
(under surface of sporophylls)
11
Q
Dehiscent:
A
Burst open, releasing spores
12
Q
Sporophylls
A
Spore-bearing leaves
13
Q
Megaspore:
A
Forms Ovule of seed plants
FEMALE
14
Q
Microspore:
A
Forms Pollen grains of seed plants
MALE gametophyte
15
Q
SEED
A
embryonic plant
- food storage tissue = endosperm
- seed coat (hard) = testa
16
Q
Dormant:
A
no metabolic reactions can take place as water is drawn out of it when seed is formed
17
Q
BRYOPHYTA
mosses
A
- No vascular tissue : Diffusion
- Short (no xylem)
- THALLUS –> RHIZOIDS (chlorophyll)
- no cuticle : surface absorbs
- Reproduction:
(sporophyte – gametophyte) - Homosporous
- H20 dependent : film
- Gamete + Gamete – zygote – embryo – sporophyte
18
Q
Vascular plants:
A
(cope in dry enviro)
- vascular tissue
True leaf
- xylem
- sunlight
- cuticle + stoma
Root
- absorbs H20 + minerals from soil
19
Q
PTERIDOPHYTA
ferns
A
(seedless)
- moist enviro
- homosporous
- True leaves & roots : photosynthesis
- New: coiled in bud
- vascular tissue
- reproduces: spores released from sori , embryo grows immediately
- H20 for fertilisation
- cuticle : absorption
sporophyte – spores germinate rapidly – tiny gametophyte – remains inside (F) gametes – Embryo
20
Q
Spermatophyta
A
(dry deserts)
(spores / seeds)
- heterosporous
- megaspore (protected in ovule)
- no H20 for fertilisation – pollen tube
- Pollen grains
- Embryo = Dormant
(until suitable enviro for germination)
21
Q
GYMNOSPERMAE
cycads, conifers, pine cones
A
- cone-bearing
- needle like leaves : single vein
- xylem tissue : TRACHEIDS = lignin
- longer & deeper roots
- sporangia in cones
- reproduction : sporophylls
- heterosporous
- F : megaspores : OVULE
- M : microspores : Pollen Grains
release & disperse - pollen tube
- Gymnosperms : naked seeds
- Protected from desiccation (DORMANT)
22
Q
ANGIOSPERMAE
flowers
A
- true leaves & roots
- xylem tissue
TRACHEIDS & Vessel elements
*Fruits (seeds enclosed in ovary)
*Flowers
23
Q
Plant Life Cycle
A
n (Gametophyte Generation)
Makes gametes
Fertilisation
Zygote
Mitosis
2n (Sporophyte Generation)
Makes spores
meiosis
n
24
Q
Bryophyta Life Cycle
A
2n - Sporophyte Generation
Zygote - DEPENDENT ON ADULT PLANT
Meiosis
n - Gametophyte Generation
Prominent Generation
Adult Plant Spores
Gametes
Fertilisation
- H20 needed
- motile sperms
25
Pteridophyta Life Cycle
FERNS
2n - Sporophyte Generation
Zygote
Prominent Generation
meiosis
homosporous
n - Gametophyte Generation
- PROTHALLUS
- Independent of adult plant
Fertilisation
- H20 needed
26
Gymnospermae Life Cycle
2n - Sporophyte Generation
Zygote
Prominent Generation
Adult plant
meiosis
Totally dependent on adult plant
n - Gametophyte Generation
- Spores
Heterosporous
(female cones : megaspore)
(make cones: microspore)
VERY REDUCED GEN - totally dependent on adult plant
Fertilisation
27
Angiospermae Life Cycle
(flowers make covered seeds)
- Most Prolific & Diverse
2n - Sporophyte Gen.
Prominent Generation
Meiosis
- Male gametes microspores
- anthers, pollen sacs, pollen grains
Megaspore
- ovary, ovules, female gametes
n - spores - Heterosporous
fertilisation : Pollen tube
- fruit with seeds
28
Seeds Dispersed:
1. Wind
2. H20
3. Animals
SPIKES - attach, grip, land
29
Spermatophyta
1. Pollen
2. Pollen tube
3. SEED : food, dormancy
make pollen = make sex cells
female = OVULE - female structure
(megaspore)
Lands on cone & Fuses : delivery system
Ripe & Open ovule
+ fertilisation droplet (pollen tube)
- Delivery system ensures fertilisation without H20
ZYGOTE -- SEED (seed coat: TESTA)
food (endosperm) - waiting for plant to come out of dormancy until germination conditions
EMBRYO -- GROW -- DEVELOP
30
Success / Survival of LAND PLANTS
1. Prevent Desiccation -- Survival
2. Survive -- can Reproduce
3. Reproduction --
less / no H20 dependence for
Pollination : Higher Land plants
Fertilisation : ALL land plants
31
Pollination vs Fertilisation
Pollination : Delivery of Pollen
Fertilisation : Fuse
32
Decreasing Dependence on H20 for fertilisation
LESS EVOLVED LAND PLANTS
Bryophyta & Pteridophyta
H20 must be available
- Male gametes swim to female gametes
(motile gametes)
33
Decreasing Dependence on H20 for fertilisation
MORE EVOLVED LAND PLANTS
Spermatophyta:
Gymnospermae, Angiospermae
- dryer enviros
- independent of H20
1. Pollen grains made
2. Fertilisation droplet: (land & stick when ready) , ensures fertilisation without H20
3. Pollen tube
4. Ovule (deep inside)
5. No Water
6. Seed
7. Pollen Formation
(reproduce sexually on LAND and ensure high level of diversity & survival)
34
Plant Reproduction:
Reproduction is the ability of plants to make a new generation of themselves
35
Number of Parent Plants : ASEXUAL
one
36
Reproductive organs : ASEXUAL
Plant parts: vegetative reproduction
leaves: whole leaf used (african violet
roots: tubers (sweet potato) , suckers
stem: bulbs, stolons, rhizomes
37
Rate of process : ASEXUAL
Faster
- no gamete formation or pollination
38
Outside agents : ASEXUAL
None needed
mitosis : no gametes made
39
Ability to adapt to enviro : ASEXUAL
NO
Offspring genetically identical to parent
If environment changes, organisms cannot adapt and will die
40
When is the method an advantage : ASEXUAL
In an unchanging (stable) environment as the individuals suited to enviro are preserved
41
Energy output: ASEXUAL
Low
42
Possibility of evolution : ASEXUAL
Low
Usually no genetic variation
43
Number of parent plants : SEXUAL
2 different sex organs
44
Reproductive organs: SEXUAL
Flowers
- Sex organs make gametes
45
Rate of Process : SEXUAL
Slower
Gamete formation and pollination occur
46
Outside Agents : SEXUAL
Outside pollinators for pollination
meiosis: gametes are made
47
Ability to adapt to environment: SEXUAL
YES
Offspring genetically different to parents.
If enviro changes, variation helps organisms adapt and survive
48
When is the method advantageous: SEXUAL
In a changing (unstable) enviro as individuals with variation can adapt to new conditions
49
Energy outputs : SEXUAL
High
Energy needed to make flowers
50
Possibility of evolution: SEXUAL
Good
Genetic variation
51
Asexual Reproduction in plants
ADVANTAGES
1. All plants can reproduce
2. One parent plant needed
3. Simple, quick , cheap to make offspring
- Mitosis & growth processes only
4. Little energy needed for reproduction
- no gametes, pollination, fertilisation
5. Genetically identical plants made
- Characteristics stay same
6. Plants reproduce all year round
- (Not seasonal, no dormancy)
7. Useful mutations occur in all in gen
- Quick (within 1 generation)
8. No outside agents needed for reproduction
- pollinators, wind, water
52
Asexual Reproduction in Plants
DISADVANTAGES
1. No variation in offspring
- if enviro conditions change, all plants may not be suited to change and will die
2. Genetic weaknesses present
- All new generations will inherit the same genetic weaknesses of the parent so disease-susceptibility may kill all plants at once as all are genetically identical
53
Sexual Reproduction
ADVANTAGES
1. Variation occurs in new generations
- both parents contribute to characteristics of offspring when gametes are formed.
2. Plants : greater survival rate
- as enviro changes, some will be suited to new conditions and survive and reproduce more of themselves
3. Variation - resistant to disease
- Some plants die and some will survive and replicate
4. Mutations occur that can be USEFUL / HARMFUL / HARMLESS
- Harmful mutations can be bred out of
- Useful mutations bred into offspring within one or few generations
5. Seeds are widely dispersed
- Offspring develop in spaces away from parents so competition for space, water , sunlight reduced.
54
Sexual Reproduction
DISADVANTAGES
1. Lots of energy is needed
- to make special reproductive organs and sex cells
2. Slower than asexual reproduction
- Many processes involved
(pollination, fertilisation, make seeds)
3. Outside agents needed
- to carry pollen / seeds
- pollination / fertilisation may not occur reducing reproductive success in the plant species
4. Unfavourable characteristics (harmful recessive traits) and harmful mutations passed to offspring
- during fertilisation of male and female gametes
55
Whorl:
Rings of modified leaves
56
stamen:
ANDROECIUM
(male part / whorl)
57
Anther:
contains pollen sac
Male organ where pollen grains are formed
58
Filament:
Flexible stalk
(holds anther up)
59
carpel / pistil
(female part / whorl)
GYNAECIUM
60
Stigma:
Sticky surface to which pollen adheres
61
Style:
Slender section joining stigma to ovary
- held correctly for pollination
62
Ovary:
female organ where ovules are formed.
- contains female gametes
- after fertilisation , matures into fruit with seeds.
63
Ovule:
contains female gametes
After fertilisation - SEED formed
64
Calyx:
Green - outer whorl
- protects unopened bud
65
receptacle:
(flat part)
supports & attaches floral whorls
66
corolla:
(petals) = whorl modified leaves
attracts pollinators
67
Sepals:
Whorl of modified leaves
68
Perianth:
Collective term **
SEPARATE calyx & corolla
69
Perigone:
calyx & corolla FUSED
(tube structure stays closed)
70
bisexual / unisexual
both sex organs present?
71
Bryophytes post fertilisation:
Two gametes form fuse to form a zygote that develops into an embryo. Embryo grows immediately into sporophyte. It will die if the conditions are unfavourable.
72
What is a true leaf?
Organised to receive optimal sunlight and absorb co2
Network of xylem: water for photosynthesis
Phloem: removes sugars produced by photosynthesis
Waterproof Cuticle
Stoma: regulate gaseous exchange
73
What is the root?
Organ structures to absorb minerals and water from soil.
Absorbed by root hairs and taken via xylem to leaves.
Faster & taller
74
While spores are easy to disperse, they have little food to establish themselves:
When a spore reaches a wet area it germinates rapidly and begins photosynthesising straight away to gain energy for the next phase of the life cycle.
Therefore, lives in damp environments.
75
Xylem tissue of gymnosperms consists of:
Tracheids (containing lignin) with no vessel elements
76
Roots of gymnosperms:
Longer roots that grow deeper into soil to reach more water in drier areas.
