Lecture 10 - Embryos, Seeds, And Fruits Flashcards
When does embryogenesis begin?
When the zygote divides
4 developmental processes of embryogenesis
Pattern formation, cell diversification, growth and morphogenesis, maturation
embryogenesis: describe pattern formation
Axis defined, tissue layers organized, organs established
embryogenesis: cell diversification
Cell types are defined
embryogenesis: maturation
Storage reserves accumulate, desiccation
embryogenesis: zygote divides into?
2 cells
embryogenesis: upper cell at the chalazal pole and gives rise to?
The mature embryo
embryogenesis: lower cell at the micropylar pole and produces the?
Suspensor
What does the suspensor anchor?
The embryo
The suspensor is a conduit for nutrient passage from the ________ to the ________?
Endosperm to the embryo
Suspensor provides growth regulators to the?
Embryo
Suspensor undergoes programmed cell death before what?
Embryo maturation
Globular stage: describe embryo symmetry and shape
Radial symmetry - spherical
Globular stage: what develops as the outer layer?
Protoderm
Globular stage: what develops inside?
Procambium and ground meristem
Globular stage: what does the upper tier of cells produce?
Cotyledons and shoot meristem
Globular stage: what does the lower tier of cells produce?
Hypocotyl and root meristem
Is the heart stage seen in monocots or dicots?
Dicots
Describe heart stage symmetry
Bilateral
What pattern is visible in the heart stage?
Apical-basal pattern
What does the axis consist of in the heart stage?
Shoot meristem, cotyledons, hypocotyl, embryonic root (radicle), and root meristem
What elongates in the torpedo stage?
Cotyledons and axis elongate
What extends in the torpedo stage?
Primary meristems extend
What happens to the embryo in the torpedo stage?
Embryo may remain straight or curve
What begins to accumulate during the torpedo stage?
Proteins, starch, and lipids
What is completed in the maturation stage?
Synthesis of storage materials is computed
What happens to the seed during the maturation stage?
Seed becomes desiccated
Why does the seed coat harden during the maturation stage?
To protect embryo and stored food
Name the six dicot seed structures
Funiculus, epicotyl, hypocotyl, radicle, cotyledons, hilum
Dicot seed structures: what is the funiculus?
Stalk that attaches ovule to ovary
Dicot seed structures: where is the epicotyl region?
Region above the cotyledons and below the foliage leaf
Dicot seed structures: where is the hypocotyl region?
Region between the cotyledons and the radicle
Dicot seed structures: what is the radicle?
Embryo root
Dicot seed structures: what is the cotyledons And what is their function?
First leaves - store nutrients for the developing embryo
Dicot seed structures: what is the hilum ?
Scar left on seed after it detaches from the funiculus
What are the seven monocot seed structures (grasses)?
Suspensor, coleorhiza, scutellum, coleoptile, epicotyl, mesocotyl, radicle
Monocot seed structures (grasses) - what is the suspensor?
Large multicellular structure
Monocot seed structures (grasses) - what is the coleorhiza?
Sheath that surrounds the root and protects it from the soil
Monocot seed structures (grasses) - how many cotyledons does the suspensor have?
Single cotyledon
Monocot seed structures (grasses) - what is the scutellums shape?
Shield-shaped
Monocot seed structures (grasses) - what is the scuttellums function?
Transfers nutrients from endosperm to embryo
Monocot seed structures (grasses) - what is the coleoptile?
Sheath that surrounds first leaves - protects them from the soil
Monocot seed structures (grasses) - what is the epicotyl region?
Region of embryo above the scutellar node
Monocot seed structures (grasses) - which seed structure has a shoot apex and leaf primordia?
Epicotyl
Monocot seed structures (grasses) -mesocotyl is the internode between which 2 structures?
Internode between the scuttlelar node and the coleoptile
Monocot seed structures (grasses) - what is the radicle?
Embryo root
What is the seed coat formed and developed from?
Formed from Maternal structures, develops from integuments
What is the seed coat protection for?
The embryo
What dues seed coat thickness depend on?
Environmental requirements of the seed
If a seed is wind dispersed what is the thickness of its coat?
Thin
If a seed is exposed to large amounts of water what will the seed coat be like?
Thick and water resistant
Is a cuticle present in the seed coat?
Often, yes
4 surface characteristics of seed coats:
Hairs, ribs, spines, wings
What does the seed coat regulate into the seed?
Passage of gases and water
When the seed coat regulates passage of gases and water into the seed what does this determine?
Timing of germination
What is the endosperm for the embryo?
Food source
The endospermis a food source for the embryo until what?
Until photosynthesis begins
Describe the endosperm of an albuminous seed
Lots of endosperm presentat seed maturity
What are 3 examples of an albuminous seed?
Castor bean, wheat, corn
Describe the endosperm of an exalbuminous seed
Little endosperm remains at seed maturity
What are 2 examples of an exalbuminous seed?
Common bean, pea
What period do most seeds have To go through before they can germinate?
Dormancy period
What does the dormancy period ensure for the seed?
Ensures conditions are favourable for growth of the seeding
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
Seed germination is the resumption of what?
Embryonic growth
What external factors is seed germination dependent on?
Water, oxygen, temperature
What is required for the metabolic activities of seed germination?
Water
What happens to permeability when the seed coat breaks?
Permeability to water increases
During seed germination, what does water dilute?
Dilutes out growth inhibitors
During seed germination, what do enzymes break down?
Food reserves
During seed germination, what happens when the seed coat ruptures?
Oxygen uptake increases with exposure to air
What is optimal germination temperature?
25°c to 30°c
Dicot seed germination: what is the first structure to emerge?
The root
Dicot seed germination: 2 ways the shoot emerges from the seed
Epigeal germination, hypogeal germination