Plant Development: Angiosperms Flashcards
1
Q
How many essential elements do plants require?
A
17
2
Q
Define essential element
A
A chemical that is required for a plant to complete its life cycle
3
Q
Define macronutrients
A
essential elements required by plants in relatively large quantities
4
Q
How many macronutrients are there?
A
9
5
Q
What are the 6 macronutrients and what is their main collective function?
A
- C
- H
- O
- N
- S
- P
They are major components of organic compounds that form the plant structure
6
Q
What are the other 3 macronutrients?
A
- Ca
- K
- Mg
7
Q
List the 9 macronutrients
A
- C
- H
- O
- N
- P
- S
- Ca
- Mg
- K
8
Q
Define micronutrients
A
essential elements required by plants in relatively small quantities
9
Q
What are the 8 micronutrients?
A
- Cl
- Fe
- Mn
- B
- Zn
- Cu
- Ni
- Mo
10
Q
T or F: plant life cycles have alternation of generations of 1 unicellular stage and 1 multicellular stage
A
FALSE.
Life cycles have alternations of generations between 2 multicellular stages
11
Q
What are the two generations of life cycles?
A
Haploid gametophyte
Diploid sporophyte
12
Q
Is the sporophyte generation haploid or diploid?
A
Diploid
13
Q
Is the gametophyte generation haploid or diploid?
A
Haploid
14
Q
What does the sporophyte stage produce? And through which process?
A
Diploid sporophyte produces SPORES by MEIOSIS
15
Q
Are spores diploid or haploid? Explain
A
Haploid because they are produced when diploid sporophytes undergo meiosis
Meiosis = one 2n cell –> four 1n cells
16
Q
By which process do spores grow? And what will they turn into?
A
Haploid spores grow by MITOSIS into the MULTICELLULAR GAMETOPHYTE
17
Q
Why does the gametophyte have the ploidy it has?
A
The HAPLOID gametophyte is produced when the haploid spores undergo mitosis.
Mitosis = one 1n cell –> two 1n cells
So the gametophyte must be haploid
18
Q
What does the gametophyte produce and by which process?
A
Produces gametes by mitosis
19
Q
What ploidy do gametes have? Explain
A
they are haploid because they are produced by the haploid gametophyte which undergoes mitosis
20
Q
What forms when two gametes fuse together?
A
A unicellular, diploid zygote
21
Q
What ploidy will the zygote have?
A
Diploid
because two 1n cells fuse = 2n
22
Q
By which process will the zygote grow? What will it become?
A
Diploid zygote grows by mitosis to become the diploid sporophyte
23
Q
Why does the sporophyte have the ploidy it has?
A
The sporophyte is diploid because it develops from the DIPLOID zygote undergoing mitosis
Mitosis = one 2n cell –> two 2n cells
24
Q
Which stage is dominant in angiosperms?
A
The diploid sporophyte stage
25
T or F: angiosperms are homosporous
FALSE.
They are heterosporous
26
Define heterosporous
Angiosperms produce microspores (male) and megaspores (female) that differ from one another
27
Define flowers
The reproductive shoots of angiosperm sporophytes (2n) that contain petals to attract pollinators
28
Define stamen and list the parts of the stamen
The male reproductive structure of flowers that includes:
- anther
- filament
29
Define pistil and list the parts of the pistil
the female reproductive structure of flowers that includes:
- stigma
- style
- ovary
30
What are the four components of flowers?
1. pistil
2. stamen
3. petals
4. sepals
31
What function does the filament have?
Filaments hold up the anther
32
How many microsporangia does each anther contain?
2-4
33
Define microsporangia
pollen sacs contained in the anther of flowers
34
What ploidy are microsporocytes?
diploid
35
Where are microsporocytes contained?
within the microsporangium
36
Which process do microsporocytes undergo to produce what?
DIPLOID microsporocytes undergo meiosis to produce HAPLOID microspores
37
How many microspores will each microsporocyte produce?
4 haploid microspores
38
Each microspore will undergo which process to become what?
Each haploid microspore undergoes MITOSIS to become a (haploid) MALE GAMETOPHYTE
39
What ploidy will the male gametophyte be?
Haploid
40
What are the two cells that compose the male gametophyte?
1. tube cell
| 2. generative cell
41
What occurs during the maturation of the male gametophyte?
1. generative cell passes into tube cell
2. spore wall is completed
3. tube cell now has freestanding cell within it
42
What three things compose a pollen grain
composed of a spore wall, generative cell, and a tube cell
the male gametophyte
43
What ploidy is a pollen grain?
haploid
44
After a pollen grain is released from the microsporangium, what occurs?
1. pollen is ideally transferred to a stigma of the same species
2. the tube cell produces pollen tube that grows down the style and towards the ovary
3. inside the tube cell, the generative cell divides by MITOSIS and produces two sperm cells
4. sperm is released near the female gametophyte
45
Which part of the male gametophyte/pollen grain divides by which process to produce what product?
The GENERATIVE CELL divides by MITOSIS to produce 2 SPERM CELLS
46
How quickly can the pollen tube grow through the style?
~1 or more cm/hour
47
Define spore wall
Consists of material produced by the microspore and anther
Helps with dispersal and protects sperm against desiccation
48
Which 4 structures make up an ovule?
megasporangium
megasporocyte
integuments
micropyle
49
What is the female gametophyte?
The embryo sac
50
What does the ovule contain that surrounds the megasporangium?
2 integuments
51
What will the integuments develop into?
the seed coat if the egg is fertilizd
52
What is the micropyle?
The gap between the integuments that allows the tube cell to enter the ovule
53
Where are the megasporocytes located?
Within the megasporangium of the ovule
54
One megasporocyte will undergo which process to produce what?
Will undergo MEIOSIS to produce 4 HAPLOID MEGASPORES
55
What happens to the megaspores produced by the megasporocyte?
3 of the 4 will degenerate because the fourth has taken all of the cytoplasm
The surviving megaspore will continue on
56
What happens to the surviving megaspore?
It will divide by mitosis BUT NOT CYTOKINESIS to produce ONE CELL WITH 8 HAPLOID NUCLEI
57
T or F: the surviving megaspore will divide by mitosis and cytokinesis
FALSE. It will divide by mitosis but not cytokinesis
58
What is the result of the division of the megaspore?
It will divide by mitosis to produce:
one cell with 8 haploid nuclei
59
What happens to the product of the megaspore when cytokinesis occurs?
Membranes will form by cytokinesis between the nuclei to form
7 cells, one of which will have 2 nuclei
60
What are the 2 nuclei called?
The polar nuclei in the central cell
61
What determines what each cell will become in the megasporangium?
A gradient of the hormone Auxin will determine what each cell will become
62
Where does auxin originate?
near the micropyle
63
Define synergids
two cells by the micropyle that are beside the egg and help attract the pollen tube to the egg
64
What is the female gamete?
the egg
65
Define antipodal cells
Three cells at opposite end of the gametophyte from the micropyle that have an unknown function and usually degenerate
66
Define polar nuclei
two nuclei that share the cytoplasm of the large central cell
67
What will the polar nuclei become if fertilization occurs?
develop into the source of nutrition for the embryo if fertilization occurs
68
Define pollination
the transfer of pollen from an anther to a stigma, this can occur by wind, animals, or water
69
Define pollen
Microscopic particles that contain sperm
70
Approximately how many angiosperm species pollinate by wind?
~20%
71
Approx how many angiosperm species pollinate by water?
<1%
72
Approx how much of angiosperm pollination is biotic?
~80%
73
How does biotic pollination work?
Uses animals to transfer pollen to another flower
can be through trickery, reward, can sometimes be fatal
74
If pollen transfer is successful, what occurs?
The pollen grain produces the pollen tube which will grow to the ovary
75
Define double fertilization
the union of one sperm with the angiosperm egg's nucleus and one sperm with the 2 polar nuclei of the central cell
76
What is the purpose of double fertilization?
To ensure resources aren't wasted developing endosperm in ovum that has unfertilized eggs
If the polar nuclei are fertilized, it is highly likely that the egg is also fertilized
77
T or F: eggs have a block to polyspermy, but the central cell does not
True
78
What occurs first when the pollen lands on a suitable stigma?
It will absorb water (imbibition) and germinate by producing the pollen tube which will grow towards the ovary
79
After the pollen tube begins to grow, what happens?
the nucleus of the generative cell divides by mitosis to produce 2 sperm
80
How does the pollen tube 'know' how to find the micropyle?
Chemical attractants from the synergids cause the tip of the pollen tube to grow towards the micropyle
81
How does the pollen tube pass into the embryo sac?
One synergid will die to allow space
82
What is the ploidy of a fertilized central cell?
Triploid
the fusion of one 1n sperm cell with the two polar nuclei (1n + 1n) = 3n
83
What will the fertilized central cell become?
the endosperm
84
Define endosperm
the food storing tissue of the seed that develops from the central cell
ex. stores carbs, proteins, or fats stored here
85
After fertilization, what will the ovules develop into?
Seeds
86
After fertilization, what will the ovary develop into?
Fruit
87
After fertilization, what will the integuments develop into?
Seed coat
88
After fertilization, what happens to the micropyle?
It closes
89
After fertilization, what will happen to the triploid nucleus of the central cell?
it will divide by mitosis and form a multinucleate cell
cytokinesis will partition the cytoplasm and form the endosperm
90
When does embryo development begin?
When mitosis asymmetrically splits the zygote into the basal cell and the terminal cell
91
Is the division of the zygote into the basal cell and terminal cells asymmetrical or symmetrical? Which is larger?
Asymmetrical
The basal cell is larger
92
Define basal cell
The larger cell that is produced by the mitotic division of the zygote
93
What is the function of the basal cell?
It produces the suspensor which anchors the embryo to the parent plant and transfers nutrients from the parent and from the endosperm to the embryo
94
Define terminal cell
The smaller cell that is produced by the mitotic division of the zygote
95
What will the terminal cell become?
The embryo
96
What does the asymmetrical division of the zygote establish?
Polarity so that the typical root-shoot axis of plants establishes
97
What happens if the first mitotic division of the zygote is symmetrical?
The embryo develops as a ball and has neither roots nor leaves (shoots)
98
What does the terminal cell develop into?
The terminal cell divides several times to form the spherical pro-embryo which attaches to the suspensor
99
What are cotyledons and when do they form?
Cotyledons are seed leaves, the first leaves that develop
they begin to form after the terminal cell develops into the spherical pro-embryo
100
What happens when the embryo elongates?
The shoot and root apices form with apical meristems for primary growth
101
Define apical meristems
the point of primary growth on the shoots and roots of plants
Tissue in tips of roots and buds of shoots that allows for primary growth
102
Define dormancy
When the embryo stops growing and its metabolic reactions nearly stop
103
T or F: seed dormancy can last between a few days to thousands of years depending on the species
True
104
Mature seeds dehydrate until only about ___% of its weight is water
5-15%
105
What are 5 examples of specific cues that can break dormancy?
Heavy rainfall for desert plants
Intense heat or smoke where fires are common
Exposure to prolonged cold in areas with harsh winters will trigger spring germination
Light for plants that can only grow through small amounts of soil
Digestive tract of animals can cause the seed coat to weaken
106
Why is seed dormancy adaptive?
The seeds can wait for the best conditions to increase the chance of plant survival
Soil will have a seed bank to restock after disturbances
107
Define germination
Where seed, spore, or pollen starts to sprout and grow
108
When does germination begin in seeds?
When dry seeds imbibe (uptake water) causing the seed to expand and rupture the seed coat
109
What does imbibition trigger in seeds?
Water triggers metabolic changes in the embryo that cause it to start growing again
Enzymes digest stored nutrients in cotyledons or endosperm
Nutrients are transferred to growing parts of embryo
110
What is the first organ to emerge from the seed?
The embryonic root (radicle)
111
What is the name for the embryonic root?
Radicle
112
What is the second organ to emerge from the seed?
The shoot tip that is protected by a cap
113
What is primary growth?
Lengthwise increase of roots and shoots
114
How does primary growth occur?
By division and differentiation of cells from apical meristems
115
What type of growth occurs in herbaceous plants?
Primary growth
116
What type of growth occurs in woody plants?
Primary and secondary growth
117
What is the root cap?
It covers the tip of the root to protect the apical meristem as the roots push through soil during primary growth
118
Where does growth occur in regards to the root cap?
Behind the root cap in three zones
119
What are the three zones of root growth?
1. zone of cell division
2. zone of elongation
3. zone of differentiation
120
What occurs in the zone of cell division?
Includes the root apical meristem cells
new cells are produced in this region by mitosis and cytokinesis
121
What occurs in the zone of elongation?
typically occurs a few mm behind zone of cell division
Most of cell growth occurs here pushing the root tip further into the soil
122
Which of the 3 zones does most of the cell growth occur?
Zone of elongation
123
How long can cells elongate in the zone of elongation?
>10x their original size
124
Growth in the zone of elongation occurs during which phases?
G1, S, and G2 of interphase
125
What occurs in the zone of differentiation?
Cells have specialized in structure and function at the end of the zone of elongation so the cells become distinct cell types in differentiation.
Root hairs form and grow here
126
Which zone do cells become distinct cell types?
Differentiation
127
Which zone do root hairs form and grow?
Differentiation
128
What 4 tissues does primary growth produce?
1. epidermis
2. cortex
3. vascular tissue
4. endodermis
129
T or F: an apical meristem is present at each shoot tip
True
130
Define leaf primordia
the location of leaf development
fingerlike projections along the sides of apical meristems
131
What causes shoot elongation?
The lengthening of the cells below the shoot tip between the internodes
132
Where are axillary buds located in relation to apical meristems?
Some distance away because the closer an axillary bud is to an apical meristem, the more inhibited its growth is
133
Define development
Specific series of changes by which cells form tissues, organs, and organisms that occurs because of genetic info, external environment and hormones
134
Define growth
irreversible increase in size
135
T or F: a single genotype can produce different phenotypes in different environments
true
136
Does cell migration occur in plant and/or animal development?
Plant: no because of cell walls
Animal: yes (some)
137
Does asymmetric morphogenesis occur in plant and/or animal development?
Plant: no
Animal: yes
138
Can one cell from an adult produce an entire individual in plant and/or animal development?
Plant: yes
Animal: no
139
Does differential gene expression occur in plant and/or animal development?
Both: yes
140
Do transcription factors play a role in plant and/or animal development?
Both: yes
141
Do plants and/or animals have the ability to develop throughout entire life?
Plant: yes (indeterminate growth) - plants can die back and regrow to survive adverse conditions (cannot move away)
animal: no (determinate growth) - animals can migrate or hibernate to avoid adverse conditions
142
Can cells dedifferentiate and redifferentiate in plants and/or animals?
Plants: yes, changing cell types so that plant parts or entire plants can regrow
Animals: no, development is rigid and inflexible
143
virtually every aspect of plant growth and development is under the control of what?
Hormones
144
T or F: molecular processes underlying plant and animal responses are often heterologous
FALSE. often homologous
145
What are hormones?
signalling molecules that are transported through plants to activate signal transduction pathways
146
What are 4 types of plant hormones?
1. auxin
2. cytokinins
3. gibberellins
4. ethylene
147
What are 3 roles of auxin?
to stimulate cell elongation in young shoots and roots
to sustain growth
to organize the body layout
148
Where is auxin produced? where does it travel to?
Produced primarily in shoot tips
Travels from the shoot tips to the base at ~1cm/h
149
What is the function of cytokinin?
A growth regulator that stimulates cytokinesis
150
Where are cytokinins produced?
In actively growing tissues
151
In correct ratios with auxin, what can cytokinin cause?
differentiation
152
What is the function of gibberellins?
Works with auxin in stem elongation and fruit growth and breaks dormancy in seeds after imbibition
153
What are 3 functions of ethylene?
Causes fruit to ripen which will cause the production of more ethylene
Causes shoots to thicken and grow sideways to get around obstacles when germinating
Causes death of cells (xylem, leaf drop in the fall)
154
When is ethylene produced?
When plants are stressed
