Lecture 10 - Embryos, Seeds, And Fruits Flashcards
(187 cards)
1
Q
When does embryogenesis begin?
A
When the zygote divides
2
Q
4 developmental processes of embryogenesis
A
Pattern formation, cell diversification, growth and morphogenesis, maturation
3
Q
embryogenesis: describe pattern formation
A
Axis defined, tissue layers organized, organs established
4
Q
embryogenesis: cell diversification
A
Cell types are defined
5
Q
embryogenesis: maturation
A
Storage reserves accumulate, desiccation
6
Q
embryogenesis: zygote divides into?
A
2 cells
7
Q
embryogenesis: upper cell at the chalazal pole and gives rise to?
A
The mature embryo
8
Q
embryogenesis: lower cell at the micropylar pole and produces the?
A
Suspensor
9
Q
What does the suspensor anchor?
A
The embryo
10
Q
The suspensor is a conduit for nutrient passage from the ________ to the ________?
A
Endosperm to the embryo
11
Q
Suspensor provides growth regulators to the?
A
Embryo
12
Q
Suspensor undergoes programmed cell death before what?
A
Embryo maturation
13
Q
Globular stage: describe embryo symmetry and shape
A
Radial symmetry - spherical
14
Q
Globular stage: what develops as the outer layer?
A
Protoderm
15
Q
Globular stage: what develops inside?
A
Procambium and ground meristem
16
Q
Globular stage: what does the upper tier of cells produce?
A
Cotyledons and shoot meristem
17
Q
Globular stage: what does the lower tier of cells produce?
A
Hypocotyl and root meristem
18
Q
Is the heart stage seen in monocots or dicots?
A
Dicots
19
Q
Describe heart stage symmetry
A
Bilateral
20
Q
What pattern is visible in the heart stage?
A
Apical-basal pattern
21
Q
What does the axis consist of in the heart stage?
A
Shoot meristem, cotyledons, hypocotyl, embryonic root (radicle), and root meristem
22
Q
What elongates in the torpedo stage?
A
Cotyledons and axis elongate
23
Q
What extends in the torpedo stage?
A
Primary meristems extend
24
Q
What happens to the embryo in the torpedo stage?
A
Embryo may remain straight or curve
25
What begins to accumulate during the torpedo stage?
Proteins, starch, and lipids
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What is completed in the maturation stage?
Synthesis of storage materials is computed
27
What happens to the seed during the maturation stage?
Seed becomes desiccated
28
Why does the seed coat harden during the maturation stage?
To protect embryo and stored food
29
Name the six dicot seed structures
Funiculus, epicotyl, hypocotyl, radicle, cotyledons, hilum
30
Dicot seed structures: what is the funiculus?
Stalk that attaches ovule to ovary
31
Dicot seed structures: where is the epicotyl region?
Region above the cotyledons and below the foliage leaf
32
Dicot seed structures: where is the hypocotyl region?
Region between the cotyledons and the radicle
33
Dicot seed structures: what is the radicle?
Embryo root
34
Dicot seed structures: what is the cotyledons And what is their function?
First leaves - store nutrients for the developing embryo
35
Dicot seed structures: what is the hilum ?
Scar left on seed after it detaches from the funiculus
36
What are the seven monocot seed structures (grasses)?
Suspensor, coleorhiza, scutellum, coleoptile, epicotyl, mesocotyl, radicle
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Monocot seed structures (grasses) - what is the suspensor?
Large multicellular structure
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Monocot seed structures (grasses) - what is the coleorhiza?
Sheath that surrounds the root and protects it from the soil
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Monocot seed structures (grasses) - how many cotyledons does the suspensor have?
Single cotyledon
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Monocot seed structures (grasses) - what is the scutellums shape?
Shield-shaped
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Monocot seed structures (grasses) - what is the scuttellums function?
Transfers nutrients from endosperm to embryo
42
Monocot seed structures (grasses) - what is the coleoptile?
Sheath that surrounds first leaves - protects them from the soil
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Monocot seed structures (grasses) - what is the epicotyl region?
Region of embryo above the scutellar node
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Monocot seed structures (grasses) - which seed structure has a shoot apex and leaf primordia?
Epicotyl
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Monocot seed structures (grasses) -mesocotyl is the internode between which 2 structures?
Internode between the scuttlelar node and the coleoptile
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Monocot seed structures (grasses) - what is the radicle?
Embryo root
47
What is the seed coat formed and developed from?
Formed from Maternal structures, develops from integuments
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What is the seed coat protection for?
The embryo
49
What dues seed coat thickness depend on?
Environmental requirements of the seed
50
If a seed is wind dispersed what is the thickness of its coat?
Thin
51
If a seed is exposed to large amounts of water what will the seed coat be like?
Thick and water resistant
52
Is a cuticle present in the seed coat?
Often, yes
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4 surface characteristics of seed coats:
Hairs, ribs, spines, wings
54
What does the seed coat regulate into the seed?
Passage of gases and water
55
When the seed coat regulates passage of gases and water into the seed what does this determine?
Timing of germination
56
What is the endosperm for the embryo?
Food source
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The endospermis a food source for the embryo until what?
Until photosynthesis begins
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Describe the endosperm of an albuminous seed
Lots of endosperm presentat seed maturity
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What are 3 examples of an albuminous seed?
Castor bean, wheat, corn
60
Describe the endosperm of an exalbuminous seed
Little endosperm remains at seed maturity
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What are 2 examples of an exalbuminous seed?
Common bean, pea
62
What period do most seeds have To go through before they can germinate?
Dormancy period
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What does the dormancy period ensure for the seed?
Ensures conditions are favourable for growth of the seeding
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What are 6 ways the dormancy period maybe broken?
Period of Cold weather, passing through digestive tract, inhibitors being leached away by rain, mechanical cracking, fire, increased light
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Seed germination is the resumption of what?
Embryonic growth
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What external factors is seed germination dependent on?
Water, oxygen, temperature
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What is required for the metabolic activities of seed germination?
Water
68
What happens to permeability when the seed coat breaks?
Permeability to water increases
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During seed germination, what does water dilute?
Dilutes out growth inhibitors
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During seed germination, what do enzymes break down?
Food reserves
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During seed germination, what happens when the seed coat ruptures?
Oxygen uptake increases with exposure to air
72
What is optimal germination temperature?
25°c to 30°c
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Dicot seed germination: what is the first structure to emerge?
The root
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Dicot seed germination: 2 ways the shoot emerges from the seed
Epigeal germination, hypogeal germination
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Epigeal germination: what breaks through the seed coat?
Radicle
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Epigeal germination: what happens to the hypocotyl?
Elongates and becomes bent
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Epigeal germination: when the hook reaches the surface it:
Straightens
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Epigeal germination: what does the hook pull with it?
Pulls the cotyledons and epicotyl (not pushed through the soil)
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Hypogeal germination: what breaks through the seed coat?
Radicle
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Hypogeal germination: what happens to the epicotyl?
Elongates and forms a hook
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Hypogeal germination: what is raised above the soil when the epicotyl straightens?
Plumule
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Hypogeal germination: what happens to the cotyledons?
Remain underground
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Seed germination-grasses: what emerges first?
Coleorhiza
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Seed germination-grasses: radicle pushes through and develops into?
A small and temporary primary root
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Seed germination-grasses: what is the embryonic shoot enclosed in when it emerges from the seed?
Coleoptile
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Seed germination-grasses: what happens to the scuttellum and endosperm?
Remain underground
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Seed germination-grasses: what happens to the shoot apical meristem and young leaves?
Break through the coleoptile
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Seed germination-grasses: what do adventitious roots develop from?
Lower nodes of the stem
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What is a fruit?
A mature ovary
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Fruits are adaptations that result in what?
Protection and distribution of seeds
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What is abiotic seed dispersal?
Gravity, wind, water
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What is biotic seed dispersal?
Insects, birds, mammals
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What are characteristics of seeds that are dispersed by wind?
Light-weight, wings (maple), pappus-modified calyx-dandelion, whole plant blown (tumbleweed)
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Seed dispersal: shooting seeds
Seeds forcefully ejected
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Seed dispersal: water dispersal
Float because air is trapped in the fruit (coconut)
Rain
96
Seed dispersal: what type of fruits attract birds or mammals to eat it?
Sweet, fleshy fruits
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How do animals disperse seeds?
Seeds pass through digestive tract or are regurgitated
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Ripe fruit is often __________ _________, unripe fruit is often ___________
Brightly coloured, bitter
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Seed dispersal: describe mechanical attachment on animals
Hooks, barbs, spines, hairs, sticky substances
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Seed dispersal: how do ants disperse seed?
Seed coated with nutrients, ants carry to nest where it will germinate
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Types of seed dispersal (4):
Wind, shooting seeds, water dispersal, animals
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Does a fruit include additional flower parts?
May or may not
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What fruit type retain additional flower parts?
Accessory fruits
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What fruit type develops without fertilization or seeds in them?
Parthenocarpic fruit
105
Parthenocarpic fruit examples
Some orange varieties, banana
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What does the pericarp surround?
The seed
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What is the pericarp divided into?
Exocarp, endocarp, mesocarp
108
What is the exocarp?
Outer skin
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What is the endocarp and its texture?
Layer adjacent to seed - may be hard or papery
110
What is the mesocarp?
Fleshy portion between exocarp and endocarp
111
What does a simple fruit develop from?
Develops from one carpel or pistil
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2 types of compound fruit:
Aggregate fruit, multiple fruit
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compound fruit: what does an aggregate fruit develop from?
Develops from a number of separate carpels of one gynoecium
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compound fruit: what do multiple fruits consist of?
Consist of gynoecia of more than one flower
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compound fruit: where are the ovaries fused in multiple fruits?
Ovaries fused on the axis where flowers were borne
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Describe simple fruits
Either fleshy or dry
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5 example of fleshy fruits (simple fruit)
Berries, hesperidium, pepo, drupe, pome
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Are fleshy or dry fruits often edible?
Fleshy
119
Simple fruit: the ovary wall of berries becomes?
Almost completely fleshy
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Simple fruit: where are the seeds in berries?
Embedded in fleshy tissue
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Simple fruit: examples of berries
Grapes, tomatoes
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Simple fruit: describe the outside of a hesperidium fruit
Covered with a leathery rind
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Simple fruit: describe texture of partitions that separate the carpels in hesperidium fruit
Tough and fibrous
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Simple fruit: 3 examples of hesperidium
Oranges, lemon, grapefruit
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Simple fruit: describe the outside of a pepo fruit
Covered by hard and thick rind
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Simple fruit: describe the ovary wall below rind of a pepo fruit
Ovary wall is soft and fleshy
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Simple fruit: where are the seeds of a pepo fruit?
Seeds fill the locule of each carpel
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Simple fruit: 3 examples of pepo fruit
Cucumber, pumpkin, watermelon
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Simple fruit: what is a drupe?
Fleshy fruit with hard, stony pit containing a seed
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Simple fruit: describe the covering of a drupe and what it is derived from
Covered by thin skin
Derived from outer layer of ovary - exocarp
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Simple fruit: what is the soft fleshy portion of a drupe derived from?
Derived from middle ovary layer- mesocarp
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Simple fruit: what is the hard pit of a drupe derived from?
Derived from inner ovary layer- endocarp
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Simple fruit: a single seed of a drupe is found where?
Inside the pit
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Simple fruit: what is a pome derived from?
Derived from the ovary and the perianth
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Simple fruit: a pome derived from the ovary and the perianth is called?
An accessory fruit
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Simple fruit: the fleshy portion of a pome is from the?
Perianth
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Simple fruit: describe the endocarp of a pome
Tough membrane
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2 ways dry fruits are classified
Dry dehiscent fruit, dry indehiscent fruit
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What is a dry dehiscent fruit?
Fruit opens along a seam and sheds seeds into the environment
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What is a dry indehiscent fruit?
Fruits retain their seeds after ripening
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dry dehiscent - legume: 2 lines of dehiscence where?
Where the fruit splits open
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dry dehiscent - legume: what is it derived from? What is there 2 rows of?
Derived from single carpel, 2 rows of ovules
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dry dehiscent - legume: characteristic of 2 examples
Peas, beans
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dry dehiscent - capsule: composed of how many carpels?
Composed of more than one carpel
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dry dehiscent - capsule: seeds may be shed when the capsule splits:
Longitudinally
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dry dehiscent - capsule: what is another way some seeds can be shed?
Through holes in the top of the capsule
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dry dehiscent - follicle: how many carpels is it developed from? How and when does it split?
Single carpel, splits down one side at maturity
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dry dehiscent - follicle: what direction is the split?
Lengthwise
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dry dehiscent - silique: how many carpels is it formed from?
Formed of 2 fused carpels
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dry dehiscent - silique: 2 sides of the fruit are split off when?
At maturity
151
dry dehiscent - silique: where are the seeds attached?
To a persistent central portion
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dry dehiscent - silique: example
Seen in mustard family (brassicaceae), Canola
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dry indehiscent - achene: what is an achene?
Small single seeded fruit
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dry indehiscent - achene: where are the seeds?
Seed lies in locule except for its attachment to the funiculus
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dry indehiscent - achene: describe seed coat attachment
Not attached to the pericarp
156
dry indehiscent - achene: what does the fruit resemble?
A seed
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dry indehiscent - caryopsis (grain): seed coat is firmly United where?
To the fruit wall
158
dry indehiscent - caryopsis (grain): describe the fruit wall
Thin and transparent
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dry indehiscent - caryopsis (grain): produced by members of which family?
Grass family
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dry indehiscent -Samara: what is a typical trait of this fruit?
Winged
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dry indehiscent -Samara: what do wings develop from?
Ovary wall
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dry indehiscent -Samara: how are these fruits dispersed?
Wind dispersed
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dry indehiscent -Samara: how many seeds do they have?
Contains a single seed
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dry indehiscent - nut: what other fruit does it resemble?
Resemble achene but are larger
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dry indehiscent - nut: describe the fruit wall
Stony fruit wall
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dry indehiscent - nut: in acorn and chestnut the shell is the:
What does it develop from?
Coat of the fruit
Develops from ovary wall
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dry indehiscent - nut: what is covering the hard shell in walnuts and pecans
A husk
168
What are aggregate fruits results of?
Results from joining together of several ovaries of the same flower
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Aggregate fruits: how many carpels does the flower have?
Flower has several carpels
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Aggregate fruits: what does each ovary contain and what do they develop into?
Contains a single ovule that develops into a seed after fertilization
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Aggregate fruits: what happens as the ovaries increase in size?
They attach to each other
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Aggregate fruits can also be:
Accessory fruits
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Example of an aggregate fruit
Raspberry
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Why is raspberry an aggregate fruit?
Each fruit in the aggregate is a drupe with a stony pit
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Example of an accessory aggregate fruit
Strawberry
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Ovaries of the strawberry flower develop into?
Achenes
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Achenes of the strawberry are embedded where?
Embedded in the surface of the enlarged floral receptacle
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What do multiple fruits develop from?
Develop from a cluster of flowers
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What do individual fruits of multiple fruits in the cluster develop from?
From one ovary and accessory parts of the flower
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Example of a multiple fruit
Pineapple
181
Multiple fruits: a pineapple is a cluster of?
Cluster of mature ovaries
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Multiple fruits: what are the accessory parts of a pineapple?
Receptacle, parts of the sepals and bracts
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Multiple fruits: what is on top of the pineapple?
Green bracts
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All plants exhibit an alternation of:
Generations in their life cycles
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Alternation of generations: A diploid sporphyle generation alternates with a?
Haploid gametophyte generation
186
Diploid sporophyte generation
Spore- forming phase
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Haploid gametophyte generation
Gamete-forming phase
