Biology 1011 Flashcards
1
Q
Why are plants important?
A
- for the conversion of the sun’s energy
- agriculture
-drugs, fossil fuels, clothing, etc - biodiversity
2
Q
What is botany? What does a botanist study?
A
Botany is the study of plants, however it ranges from evolution, ecology, genetics, anatomy, physiology, etc
3
Q
What are drugs in relation the the plant?
A
-A plants secondary compounds, not necessarily useful for metabolism, growth, or development.
- Produced as a poison or deterrent from being eaten, human use them for other things.
4
Q
What is a plant?
A
A group of organisms which share characteristics
5
Q
What does the cladogram of a plant look like?
A
3 major groups, chlorophyta, charophyte, and embryophyta
6
Q
What are green algae from the cladogram of plants?
A
Both chlorphyta and charophytes are green algae
7
Q
What are embryophyta on the cladogram?
A
These are land plants
8
Q
What are shared characteristics of all plants?
A
- starch as main energy storage molecule
- chlorophyll b, absorbs different wavelengths than a
- Cellulose as a major component of cell wall
- Thylakoid in states (grana)
9
Q
Why can’t sugar be an effective storage molecule?
A
It is too absorbent of water
10
Q
Describe starch as a plant feature
A
Polysaccharide (carbohydrate) of glucose residue
- 20 % amylose, 80% amylopectin
- starch is not absorbent, easily metabolized, and not very reactive
11
Q
What is chlorophyll b in respect to plant features?
A
Chlorphyll as is all photosynthetic eukaryotes, and chlorophyll b is an accessory pigment which passes energy to chlorophyll a because b absorbs different wavelengths of light from the sun
12
Q
What is cellulose in respect to plant features?
A
Polysaccharide which is a major component of the cell wall
- most common organic polymer,
13
Q
What are thylakoids in respect to plant features?
A
- grana
- membranes inside chloroplast, contain chlorophyll
14
Q
What are the closest ancestors of land plants?
A
- Charophytes are the closest relative of land plants
- a type of green algae
15
Q
What is evidence that charophytes are the closest ancestor to land plants?
A
They have the same chloroplast and nuclear DNA
- similar anatomical structure
16
Q
NOTE: land plants share a common ancestor with modern charophytes
A
17
Q
What are the similar structures between charophytes and land plants?
A
- cell plate
- plasmodesmata -extensions of cell membrane through pores in cell wall
- structure of flagellated sperm
- peroxisome enzymes
- rosette shaped cellulose synthesizing complexes
- sporopollenin in spore walls
18
Q
What is sporopollenin?
A
- durable polymer
- found in walls of plant spores and pollen
- chemically inert: stable, persists in environment
- essentially protects pollen from external factors (temperature, acidity, etc), protects from decay
19
Q
What are the advantages of plants moving to dry land (embryophyta)?
A
- air filters less sunlight than water
-air has more co2 than water - early terrestrial habitats lacked pathogens of predators
- soil is richer
20
Q
What were some challenges/adaptation in moving to land from embryophyta?
A
- land is not supportive –> turgor, cell walls, stems
- lose water on land –> vascular tissue, roots, stomates
- reproduction harder on land –> egg and embryo retained on parent
21
Q
What are some features of land plants?
A
1) cuticle - a waxy covering
2) multicellular, jacketed sex organs = gametangia
3) Embryophyte condition - zygote retained in maternal tissue (fertilized egg develops on mother)
4) alternation of generations
22
Q
What are gametangia?
A
plant sex organs
a) antheridium : male sex organ in land plants that makes sperm
b) archegonium : female sex organ that produces eggs
23
Q
What are the two kinds of gametangia ?
A
antheridium and archegonium
24
Q
What is a gametophyte?
A
the haploid phase of the plant, has haploid gametes
- makes gametes by mitosis
25
What happens when the gametophyte is fertilized?
Produces a zygote which form a sporophyte
26
What is a sporophyte?
- diploid phase of the plant, produces haploid
- makes spores by meiosis
27
What is alternation of generations?
- a process plants undergo in which there is a regular alternation between two distinct forms (gametophyte and sporophyte)
28
NOTE: spores undergo mitosis to form the gametophyte which is haploid. When gametes fuse they form a zygote which undergoes mitosis, which undergoes meiosis to form spores.
29
What is different about green algae in terms of alternation of generations?
-Green algae does not have alternation of generation, multicellular haploid but not multicellular diploid
30
describe the structure of the plant cell
- cell wall, inner membrane, vacuoles, plasmodesmata, cytosol
31
What is plasmodesmata?
- an extension of cell membrane through pores in cell wall
- a feature found in both charophytes and embryophytes
32
when do plants appear in the history of life?
- 1500 million years ago plants split from red algae in marine and moist environments
- 500 million years ago the colonization of dryer environments (consider the adaptations to plants when this occurred!)
33
What are the major events in history of plant life?
earth forms, photosynthesis, plastids appear, colonization of plants, fungi, and animals
34
How long ago did the earth form?
4.6 billions years ago
35
How long ago did photosynthesis appear?
3500 million years ago
36
When did the 1st plastid appear?
700-1500 million years ago
37
What are the 4 main components of the plant phylogram?
red algae, chlorophytes, charophytes, and embryophytes (land plants)
38
What is an alternation of generations?
- multicellular haploid and diploid stages
- seen in all land plants
39
What are gametophytes?
- multicellular haploid stage, makes gametes through mitosis
40
What are sporophyte?
Multicellular diploid, makes spores through meiosis
41
What are the two alternating generations found in the alternation of generations?
Gametophytes and sporophytes
42
What differentiates animals life cycle from plant life cycles?
Animal life cycles have unicellular stages where haploid cells fertilize, which then undergo mitosis, which eventually undergo mitosis to form haploid gametes
- plant life cycles are multicellular
43
How do plant life cycles work in detail?
- Spores (haploid) divide by mitosis to form gametophytes, which become fertilized to zygote, which undergoes mitosis Ito form a sporophyte Diploid) which undergoes meiosis to form spores
44
What are spores?
single cell that can divide to produce a multicellular organism with a protective coat
45
What are gametes ?
Single cell that can unite with another gamete to produce a diploid zygote
46
Does algae undergo alternation of generations?
Algae does not (it has +/- cells for asexual reproduction), the rest of the phylogram does have alternation of generations
47
How did alternation of generations originate?
Zygote delays meiosis and divides, grows into multicellular diploid (sporophyte)
48
What are the 4 major divisions of land plants?
moss, ferns, conifers,
49
What are some characteristics of moss?
- 15000 species, low growing, confined to damp areas, no true leaves
50
Is moss gametophyte or sporophyte dominant?
The moss is gametophyte dominant (they are haploid plants, sporophytes grow from the gametophyte)
51
Is moss homosporous or heterosporous?
Homosporous (1 size of spore)
52
Describe the moss life cycle
-Mitotic production of gametes, fertilized to form diploid.
-Become sporophyte which creates spores by meiosis (sporophyte grows out of gametophyte)
53
Why can't sporophytes grow independently?
The sporophytes are nutritionally dependant on the moss, they don't have vascular tissue
54
What was the next significant evolutionary step after moss?
vascular tissue: supports organism and supplies organism through xylem and phloem
55
Describe ferns
200,000 species, appear 400 million years ago, have vascular tissue
56
Are ferns sporophyte or gametophyte dominant?
Sporophyte dominant (diploid)
57
Are ferns homosporous or heterosporous?
BOTH!
58
Describe the fern life cycle
- spores turn into gametophytes through mitosis, fertilized to produce zygote--> sporophyte (diploid) which creates spores through meiosis (bottom of lead has dusty spores)
59
What is homospory?
1 size of spore from meiosis, (mosses, most ferns)
60
What is heterospory ?
2 sizes of spore from meiosis
(some ferns, all seed plants )
61
Describe the phylogeny of land plants
mosses, then ferns, then seed plants
62
What do seed plants have ?
Seed plants have both seeds and pollen
63
What is a seed?
- embryo + nutrition +seed coat
- develops from ovule
- seed plant is site of female meiosis
64
What female parts are found in the seed?
female gametophyte, female sex organs, egg, and embryo
65
what is pollen?
- mature male gametophyte (travels through megagametophye to fertilize egg_
- few cells in size
66
Describe conifers
- 500 species, reproductive organs in cones
67
Are conifers gametophyte or sporophyte dominant?
Sporophyte dominant
68
Are conifers heterosporous or homosporous?
heterosporous
69
What are megagametophyteS?
makes egg in archegonium nourishes embryo
70
What are microgametophytes?
pollen grain (makes sperm)
71
What are gymnosperms?
naked seeds
72
What are seeds?
embryo nourished by megagametophyte
73
Are seed conifers slow or fast reproduction?
fast
74
what comes next on the phylogenetic tree after ferns?
gymnosperm, then angiosperms
75
What are angiosperms?
flowering plants
76
What is the most recent ancestor of the angiosperm?
Anthophyta are the most recent common ancestor
77
around how long ago did anthophyta first appear?
150 million years ago
78
What is the angiosperm terrestrial revolution?
The proposal that many diverse organisms showed major diversification fuelled by the angiosperm terrestrial revolution - promoted mass diversification of organisms, and vice versa
79
what percent of plants, animals, and fungi are found on land?
85%
80
What are the 3 tissue systems found in vascular plants?
1) Dermal tissue
2) Vascular tissue
3) Ground tissue
81
Describe dermal tissue, what does it form?
- single layer, secreted cuticle (waxy)
- forms the epidermis
82
Describe vascular tissue
- xylem and phloem, support and supply
83
Describe Ground tissue
- tissue other than dermal or vascular (all else), bulk of young plant, fills space between decal and vascular tissues, mostly parenchyma storage, photosynthesis and support
84
What cell types are made from ground tissue?
parenchyma
collenchyma
sclerenchyma
85
What cell types are made from vascular tissue?
- tracheids and vessel elements
- sieve elements
86
What are epidermal cells?
- outermost cells
- single layer covering leaves, stems, and roots of non woody plants
-functional for waterproofing, protection from pathogens
- other roles: hairs, nectary, guard cells
87
What are some other roles for epidermal cells?
Form trichomes (hairs), nectary, and form guard cells (for gas exchange)
88
What is the cuticle?
- formed by epidermal cells, outermost part is wax
- protects against water loss, pathogens, UV radiation
89
What are secretory trichomes ?
- specialized hairs formed by epidermal cells, various functions
90
What are parenchyma cells ?
- type of ground tissue
- many functions, often specialised
- responsible for most metabolic processes
- usually lack secondary wall
- can divide and differentiate at maturity
91
Wht are the functions of collenchyma cells ?
- support, especially for young and growing organs
- type of ground tissue
92
What are the features of the collenchyma cells?
- thick, uneven primary wall
- no secondary wall,
- always occur below epidermis
-often occur in strands
- alive at maturity: can elongate
93
What is the layering order of a stem?
epidermis, collenchyma, parenchyma, and vascular tissue
94
What is the function of a sclerenchyma cell?
- support, protection (of tissues no longer elongating)
- hard cell type
- ground tissue
95
What are the features of the sclerenchyma?
- type of ground tissue, thick secondary wall with lignin, cannot elongate at maturity, 2 forms: fibres and sclereid
96
Describe the trachea and vessel elements of the vascular tissue
- for support and supply of water and minerals
- dead at maturity
- secondary wall lignified, often spiral
- two kinds: tracheids and vessel elements
97
Why is the material which conducts water and minerals mostly dead?
Because its made of the vascular tissue, which die at maturity
98
What are pits with respect to vascular tissue ?
- holes in the secondary wall where only primary wall remains. Allows for water passage.
99
What is lignin ?
- found in vascular tissue and ground tissue (sclerenchyma)
- class of complex polymers
- 2nd most abundant natural polymer
- deposited in cell walls: fills spored and binds cellulose, hemicellulose, and pectin
- strengthens wood and bark
- can occur in cell walls of non woody plants
100
What are sieve-tube elements?
- the next cell formed by vascular tissue
- transports sugars, minerals, organic compounds
- alive at maturity
- companion cell: parenchyma
101
What are the 'stem cells' of plants?
- plants grow from meristems
102
What are meristems ?
- the ultimate source of all parts of mature sporophytes
- undifferentiated (differentiate later)
- retain ability to divide "forever"
103
Explain the division of meristems ?
the cell divides and creates one meristem and one daughter cell. This daughter cell can adopt different function/role and differentiate.
104
Describe the steps of programmed cell death
1. cytoplasmic streaming
2. the secondary wall is formed
3. death (vacuole implosion) --> now can conduct water
105
What are the types of meristems?
Apical meristems and lateral meristems
106
What are apical meristems (AM)?
- root AM and shoot AM
- primary growth of root and shoot
- makes 3 other meristems
107
What is the lateral meristem?
- vascular cambium and cork cambium
- used for secondary growth
108
What are the 3 meristems which are derived from the AM meristem?
1. Protoderm --> dermal tissue
2. Procambrium --> vascular tissue
3. Ground meristem --> ground tissue
**all tissue cells derived from meristems made from AM
109
Is the youngest or oldest tissue at the tips of plants?
- youngest tissue is at the tip
110
** review diagrams of AM
111
What is the function of root hairs ?
to increase surface areas (note that root hairs only develop after elongation so they are not shaved off)
112
Describe Apical Meristems?
- root AM and shoot AM
- responsible for primary growth
- All vascular plants (ferns, seed plants, etc)
113
Describe lateral meristems
- vascular cambium and cork cambium
- responsible for secondary growth
- only in confers and some woody eudicots
- make wood and bark
114
Do monocots have lateral meristems?
NO! no monicots are woody therefore do not produce vascular cambium or cork cambium
115
What is the role of secondary growth and where does it occur?
- responsible for production of wood and bark
- occurs in woody eudicots and all conifers
116
In what type of plants does primary growth occur in?
In all vascular plants
117
What is the role of cork cambium?
It acts as a protective layer, makes up part of the bark
118
What happens to the primary xylem after the secondary xylem develops?
It eventually disintegrates
119
Describe secondary growth in stems
- cork cambium adds secondary dermal tissue
- vascular cambium adds secondary xylem and phloem
120
What occurs to the vascular cambiums it divides?
- its daughter cells become phloem cell of xylem cell
121
What does secondary growth produce more of?
- generally produces more xylem
122
What does the vascular cambium produce?
1. secondary xylem (wood) to inside
2. secondary phloem to outside
3. more vascular cambium (to increase circumference)
4. Rays - parenchyma for lateral transport
123
What are rays?
Can be seen in the cross section of wood, allow for lateral (sideways) transport
124
in the vascular cambium, what do fusiform initials and ray initial make?
Ray initials make rays (in xylem and phloem)
- fusiform initials make tracheas and vessel elements (xylem) and sieve elements (phloem)
125
What is the role of lignin in cell walls in woody plants?
- gives strength ti wood and bark (note: also can occur in non-woody cell walls)
126
What are growth rings (in trees)?
- early growing season cells made (vessels/tracheids) are larger in diameter, diameter decreases later in the year
127
How of you spot the vascular cambium?
Look to the outside of the last ring, it is a single celled 'ring'
128
How many vascular cambium are there ?
Only one, which is pushed further every growth period
129
Describe the structure of a woody stem from outside to inside
cork, cork cambium, phloem, secondary xylem (growth), and pith
130
What is cork cambium?
AKA phellogen - protection in woody plants
- new lateral meristem
- arise from cylinder of cortex cells outside vascular cambium and secondary phloem
- produces the periderm (3 layers)
131
Describe the 3 layers of the periderm
1. phellodem to inside (woody species) = thin layer of living parenchymal cells
2. cork cambium itself
3. cork to outside = supersized dead cells, protects woody plant
132
Why is cork necessary in woody plants?
- to protect it, there is no epidermis
133
Describe the anatomy of bark
Bark consists of all tissues outside the vascular cambium
- living phloem, and the periderm ( consist of cork cambium, cork)
134
What plant produces cork?
Oak trees produce a lot
135
What is the journey from apical meristem to the vascular cambium?
apical mersitem --> procambium( primary phloem/primary xylem) --> vascular cambium (rays, secondary phloem, secondary xylem)
136
What is the journey from apical meristem to the periderm?
Apical Meristem --> ground meristem --> ground tissue (pith and cortex) - cortex---> periderm (cork cambium and cork)
137
What is the second law of thermodynamics?
movement of fluids in plants follow
-energy spontaneously glows from concentrated to spread out (passive!!)
138
How does the second law apply to life?
- movement of fluids in plants follow the 2nd law
- most equitable distribution of energy corresponds to maximum entropy
139
What are the 3 transport routes in a plant?
transmembrane (in and out of membranes), symplastic (within membranes), apoplectic (in between individual membranes)
140
What direction does the xylem move its cargo?
Only upwards
141
What direction does the phloem move its cargo?
Any direction
142
What is water potential?
- unit megapascal
- refers to water's ability to do work
- energy and entropy intimately linked
- determines direction of movement fo water
- water flows from regions of high to low water potential
- combines effects of solute concentration and pressure
143
What is the equation for water potential?
Water Potential = solute potential + pressure potential
144
what is plasmolysis?
loss of water from cell by meiosis
145
Why does a cell placed in sugar water constrict/deflate
Not turgid because water moves from area of high water potential to lower potential (moves out of cell)
146
How would one increase the turgidness of the cell once more?
Placing it into our water would cause water to move once more from high potential to low potential, causing the cell to become turgid again
147
Is the movement of water from high to low potential spontaneous?
yes it is spontaneous
148
What does spontaneous water movement mean for the plant?
It expends no energy in moving water!
149
Where does the ascent of sap occur?
In the xylem
150
Be able to identify eudicot, monocot, and conifer
151
When does water travel upward in the xylem in vascular plants? In flowering plants?
Vascular = tracheids, flowering plants = vessel elements
152
What mechanisms does water and minerals use to enter the root? (laterally)
2 processes, apoplast and symplasm
153
What is apoplast?
Non living continuum outside cytosol, including cell walls, xylem cells, extracellular spores (between cells basically)
154
what is symplast?
Continuum of cytosol connected by plasmodesmata (moves within cells)
155
What is the endodermis?
- cylinder 1 cell thick
- Contains stele: all material inside endodermis
156
What composes the stele?
xylem and phloem, pith, and pericycle (origin of lateral roots)
157
What is the casparian strip?
- a wax found in walls of endodermis
- where primer wall and middle lamella are
- waterproof and impermeable to ions
- all water and ions entering xylem must pass through endodermal cells
- cell membrane can 'filter' what and how much enter --> once it enter are discharged into xylem and to rest of plant
158
How cool is Lilly Spoelstra ?
Um like super cool
159
What is the mutualism between plants and fungi called? What is it for?
- mycorrhizae
- mutualism between plants and fungi
- increases surface area, aids absorption of minerals
160
What is the pathway of water and minerals in herbaceous plants?
1. soil
2. root hair and mycorrhizae
3. cortex
4. endodermis
5. xylem
6. atmosphere
161
How do minerals and water move up a plant?
- transpiration-cohesion-tension mechanism
162
What were the hypotheses of the movement of minerals and water up a plant?
- capillary action
- pumps (from bottom/from top)
- transpiration-cohesion-tension mechanism
163
What is the process of transpiration pull?
negative pressure (tensions) at the air rate interface in the lead is basis of transpiration pull, which draws water out of the xylem
164
What are the steps of ascent of sap in the xylem?
- water evaporates from most cells in stomates (transpiration)
- water potential lower at air water interface, tension in xylem
- hydrogen bonds hold water molecules together (cohesion)
- xylem under tension gradient: pressure potential lowest at top, water pulls up by pressure gradient ( difference in pressure potential, NOT solute potential)
- water and minerals enter roots by osmosis
165
Is transpiration passive or active?
PASSIVE SPONTANEOUS
166
The tracheids and vessel elements are ______ cells.
Dead
167
True or False : water flow in xylem can go any direction
FALSE: can only go up!
- phloem can go anywhere!
168
What signals the stomata to open during the day?
- decreased CO2 levels
- Increased sunlight
- circadian rhythm
169
What occurs in the stomata in dry conditions?
K+ leaves the stomata, causes stomata to close
170
Describe what, where and how of phloem transport
What: sugar in solution and other compounds
where: Sieve/tube elements
How: Pressure-flow hypothesis
171
What are the two vascular tissues?
Xylem and Phloem
172
Describe the xylem
Composed of tracheids and vessel elements, transports water and mineral in an upward (only) direction, using transpiration-cohesion-mechanism
173
What transports sap?
The xylem
174
Describe the steps of phloem transport
1. active loading of sugar from companion cell parenchyma - water follows by osmosis
2. uptake of water
3. Unloading of sugar
4. water recycled
175
Why is the water placed back into the xylem instead of the sink cell?
The plant makes the water potential lower in the xylem, allowing water to follow back into the xylem as the sucrose is concentrated into the sink cell
176
What causes the sugar water to move down the phloem in the first place?
sugar and water moves from source to sink due to high water pressure at the source, which forces the phloem sap to move towards the sink (positive pressure)
177
What is the general direction that sugar water moves down?
moves down
178
Describe the differences between xylem flow and phloem flow
Xylem uses negative pressure and phloem uses positive pressure
179
What is the importance of photosynthesis?
- source of oxygen in atmosphere
- 50% terrestrial plants, 50% marine phytoplankton and macro algae
- first step in moving energy into the living world, source of all energy in ecosystem
180
Name the photosynthesis reaction
6CO2 + 12 H2O +ATP --> C6H12O6 + 6H2O +6O2
181
What molecule does oxygen come from in photosynthesis?
O2 comes from water molecules
182
What is the role of electron transfer in photosynthesis?
- CO2 gets reduces into C6H12O2
- H2O gets oxidized into O2
183
What are the 2 steps of photosynthesis?
1. Light reaction
2. Calvin cycle (dark reaction)
184
Describe the role of chloroplasts in the steps of photosynthesis(Where the processes occur)
Light reaction occurs in the thylakoid membrane and the dark reaction occurs in the stoma (outside the grand)
185
What are the basic steps of the light reaction?
1. light hits chlorophyll molecule
2. electrons bounded from higher energy Leven and OFF cal molecule
3. Cal steals e- from H2O
4. Water molecule falls apart (photolysis) to produce O
5. Electrons and H+ from H2O transferred to NadP+ to form NADPH
6. ADP +Pi yields ATP through photophosphorylation
186
What is photolysis?
- water molecule falls apart to produce oxygen
187
Provide an light reaction summary
H2O + light + NADP+ + ADP + Pi --> O2 + NADPH +ATP
188
What is the role of chlorophyll a?
absorbs mostly violet-blue and red, reflects or transmits green, accessory pigment (ch b and carotenoids) broaden absorption
189
What pigments help with absorption?
Chlorophyll b and carotenoids help increase the amount of light that can be absorbed
190
Why are plants green ?
Chlorophyll a reflects green
191
What wavelengths is photosynthesis driven by and why?
Visible wavelengths because the pigments can only absorb light from the visible spectrum
192
What are the 3 products of the 1st step of photosynthesis?
O2, ATP, and NADPH
193
Describe the role of dark reactions
AKA the Calvin cycle
- makes sugar
- occur in stoma of chloroplast
- use NADPH and ATP from light reactions
- supplies light reactions with NADP+ and ADP
194
Write the reaction of the dark reaction
CO2 + NADPH + ATP --> CH2O (sugar) + NADP+ ADP + Pi
195
What is rubisco?
A special, dual nature protein used. binds to O2
196
What is photorespiration?
- A wasteful process. Rubisco attaches O2 to RuBP.
- metabolic pathway that consumes O2, releases Co2, makes no ATP, wastes energy, decreases photosynthetic output
197
what is the plants solution to photorespiration?
- new enzyme PEPC used that attaches CO2 to PEP
198
What is C4 synthesis?
- basically when CO2 is used there's a lot of O2 left in stoma so rubric wants to attach.
- in mesophyll cells: O2 exits (light reaction) , CO2 enters, no rubisco available to consume O2!
- In the bundle sheath cells rubisco waits to bind to CO2 and enter it into the Calvin cycle
199
In C4 synthesis where is rubisco ?
In the bundle sheath cells
200
In C4 synthesis where does CO2 enter and oxygen can leave without trouble?
Mesophyll cells
201
Describe the steps of the C4 pathway
1. in mesophyll cells PEPC adds CO2 to PEP
2. 4 carbon compound conveys CO2 into the bundle sheath via plasmodesmata
3. In bundle sheath cells, CO2 is released and enters the Calvin cycle via rubisco
202
What is the difference between C4 and CAM ?
- C4 process occurs in a spatial separation of steps
- CAM cycle occurs in a temporal separation of steps (during the day the plant synthesis CO2 (in the Calvin cycle) and stoma are closed, during the night stoma open and allows in CO2 and release O2)
203
What are a few plant responses to herbivores?
physical defence: thorns, trichomes
chemical defence: distasteful compounds, toxic compounds
204
What is an example of a plant 'recruiting' defence from harmful herbivores?
Caterpillar which eats the plant has a chemical in its saliva, which the plant uses to synthesize volatile attractants which summon parasitic wasps which lay eggs in the caterpillar.
205
What is a hormone?
- organic substance made in one place and transported to another, where its effects growth and other processes
206
What are the steps of hormone action?
1. Reception: hormone binds to protein receptor, proteins conformation changes
2. transduction: stimulate production of relay molecules
3. Response: molecules trigger various responses to original signal
* plants have many signal transduction pathways which help response to environmental stimuli
207
What is the process of hormone action called?
Signal transduction pathway
208
What are the 2 hormones discussed?
Ethylene, Abscisic acid (ABA)
209
What is ABA?
Abscisic acid, stimulates regulation of stomata.
Dry conditions: ABA stimulates K+ to leave guard cells, closing stomata
210
What is ethylene ?
in most plants
- Leaf abscission, triple response in seedlings, fruit ripening, root hair products
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Describe the process of leaf abscission?
Leaf decay is a process of auxin:ethylene ratio. Auxin inhibits ethylene process, so when auxin is not produced anymore this leads to programmed cell death.
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Describe the triple response in plants
1. slowing stem elongation
2. stem thickening
3. horizontal stem growth
** allows for plant to grow 'around' things (stimulated by ethylene)
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Describe the process of fruit ripening
Ethylene promotes ripening and is a product of fruit ripening
- Autocatalytic: promotes its own production
- increases respiration
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What does it mean when something is vascular?
It has support in the form of xylem and phloem (for support and supply)
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What nourishes the embryo of a flowering plant ?
Seed nourished by endosperm (3n)
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What nourishes the embryo in conifers?
the megagametophyte
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What are gymnosperms?
- cone bearing plants with naked seeds
ex: conifers, have female and male cones!
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Describe the process of gamete production in plants
- Sporophyte undergoes meiosis to produce spores
- spores multiply (meiosis) into gametophytes
- gametophytes produce gametangia (archegonium and antheridium) - sex organs of plant
- gametangia produce gametes
- gametes join to form zygote
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What is a megasporangium?
- ovule present within ovary, consists of an embryo sac formed from megaspore
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What are the parts of the ovule in a flowering plant?
Ovule consists of
- megasporangium
- megaspore
- integument
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What is the middle lamella?
cementing layer between primary walls of adjacent cells
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what are the characteristics of fungi?
1 ) heterotrophs (do not make their own food)
2) eukaryotic
3) multicellular or unicellular
4 ) cell wall made of chitin
5) external digestion of food
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What are the basic units of multicellular fungi?
- basic unit: hypha
- mycelium is the mass of the hyphae
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What is a 'fruiting body' on a fungi?
- fruiting body comes and goes, allows for reproduction
ex: mushroom cap
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What are the 2 kinds of hyphae ?
1. septate hyphae: has nucleus separate by pores
2. coenocytic hyphae : has no porous walls, only nuclei
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How does fungi grow?
- extends itself, often digests the thing it extends into
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What the general life cycle of fungi? Is it asexual or sexual reproduction?
Both asexual and sexual!
- primarily the haploid (n) undergoes mitosis and clones itself to produce spores
- in sexual two spores comes together and the cytoplasm fuses, so both nuclei are sitting in one cytoplasm (n + n) --> eventually they fuse and produce a zygote
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What is the process called where two cytoplasm fuse, but do not produce a zygote, in sexual fungal reproduction?
Plasmogamy
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What is karyogamy?
during sexual reproduction of fungi, when the nuclei fuse to produce a diploid zygote
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Does the zygote undergo mitosis in fungi?
NO it does not become multicellular, it undergoes meiosis.
- has no multicellular diploid phase, NO alternation of generations
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Describe the spores in fungi
haploid (n), each contains novels, dehydrated cytoplasm and protective coat
- some can remain dormant for long
- produced both sexually and asexually
- multiple purposes
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What is the purpose of a spore ?
1) to move to a new food source
2) avoid adverse environments
3) new genetic combination
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Do fungi have gender or gendered gametes?
No, fungi have + and - gametes
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What are some examples of asexual reproduction in fungi?
- spores in sporangia
- budding
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What are the 5 phyla of fungi?
1) chytrids
2) zygomycetes
3) glomeromycetes
4) asomycetes
5) basidiomycetes
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Describe the phylum chytridiomycota
= chytrids
-1000 species
- single cells or colonies with hyphae
- flagellated spore (haploid, asexually produced)
- aquatic and In soil
- decomposers
- major cause of amphibian decline
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Describe the phylum zygomycota?
= zygomycetes
- 1000 species
- coenocytic hyphae
-decomposers, parasites
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Describe the phylum glomeromycota
= glomeromycetes
- 160 species
- coenocytic hyphae
- asexual only
-obligate symbionts mycorrhizae (arbsucular mycorrhizae)
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Describe the phylum basidiomycota
= basidiomycetes
- 30,000 species
- decomposers and ectomycorrhizai
- dikaryotic mycelium
- multicellular and some Yeasts
- septet mycelia (cross walls)
- multicellular sexual production: fruiting body = basidiocarp (mushroom, puffball)
-asexual reproduction: condo formed by hyphae
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