Exam #2- Hort-100 Flashcards
Define Heterosporous
the plant produces both mega and microspores
What is a Microgametophye?
microgametophyte is pollen grains, this was a major evolutionary adaptation!!
Mega=???
Micro=???
Mega= Female
Micro= Male
List some characteristics of Seed plants
Heterosporous, Produce Microgameophyte, seeds! more vascular tissues.
Define pollen and its benefits.
The Microgametophyte that will produce sperm once it germinates. Pollen is the structure that made it possible for plants to make their final break with their aquatic origins because Pollen makes for efficient reproduction and moves gametes without water. Gymnosperm pollen has “wings” to help them float through the air.
Explain a Gymnosperm seed
land plants evolved placental transfer tissue which is a connection that provides nutrition to the embryo, Gymnosperm seeds are naked, which means the seed is not enclosed in the ovary.
What is wood?
Structural tissue found in the stems and roots, that is made of strong cellulose fibers that are embedded in a matrix of lignin.
Most gymnosperms are monecious, what does this mean?
Monecious (one house) means they produce both male and female cones. Monoecious plants are one single plant, with male and female flowers.
Strobilus=
Cone! (houses spores), take 4 months to 3 years to mature.
what are the four groups of gymnosperms?
- Cycad’s
- Ginko’s
- Gnetophyta
- Conifers
Briefly describe the Cycad’s
They are Dioecious, they grow slow and can live over 1,000 years and havent changed much since Jurrasic times.They trade food for pollination with thrips.
What is a Dioecious plant?
male or female plants (two houses), two plants with male flowers on one and female flowers on the other.
Describe the pollination relationship with Cycads and Thrips
Thrips enter the male cone to eat the pollen and they become covered, male plants heat up and produce a noxious chemical driving the thrips out, female plants produce a milder smell which attracts the thrips and then the female is pollinated.
Briefly describe the Ginkgo’s
Ginkgo biloba L. is the last of its kind, they are Dioecious, native to China, are deciduous, and have spur shoots. six ginkgo trees survived Hiroshima.
What are spur shoots?
spur shoots occur on two-year or older growthon ginkgo trees, and produce unlobed leaves and reproductive structures.A short, compact branch usually lateral to the main axis, with very short internodes, bearing leaves and/or flowers and fruit.
What are the three species of Gnetophyta?
Ephedra, Gnetum, and Welwitschia.
List some characteristics of Conifers
- Needle like or scaled leaves in a whorled arrangement.
- Woody plants with primary and secondary growth.
- Many produce resins for protection and defense.
- Monopodial growth from a strong apical dominance (center of the plant)
Describe Pollination for Conifers
Cones are at the top of conifers to allow access to wind pollination, when pollen transfers to the female cone…
1. Pollen lands near the micropyle where it imbibes water and germinates.
2. Pollen tube is formed and pollen travels down the micropyle.
3. 15 months later of the pollen tubes growing, 1 sperm nucleus divides and 2 sperm are formed.
4. ** both sperms swim down the pollen tube where one will fertilize the egg and the other will die!!**
What happens to the two sperm cells during the pollination of a conifer?
1 fertilizes the egg and the other one dies
define Sporangia
sporangia is a place that stores pores
Define the Ovule and its process in Conifer pollination/fertilization
Ovules contain megasporangia (2N), the megasporangia houses a megaspore mother cell (2N) which divides via meiosis producing megaspores (1N) which then go on to form the megagametophytes (1N). The megagametophyte produces the egg which will sit and wait for the male gametophyte to produce sperm. Fertilization comes 15 months after pollination.
What is the directed pollination hypothesis?
When the plant matches the pollinator.
What are the two classes of angiosperms?
- Monocotyledonae (Monocot)
- Eudicotyledonae (Dicot)
What does the first layer of a flower contain?
- Sepals (sterile, not male or female). All the sepals are collectively called the Caylx.
What does the second layer of a flower contain?
- Petals (sterile). all of the petals are collectively called the Corolla.
What does the third layer of a flower contain?
- Stamens (male parts)
- Anther
-Microsporangia
- Filament
What are the male parts of a flower?
Anther, Microsporangia, Filament. collectively called the
Androecium.
What does the fourth layer of a flower contain?
- Stigma
- Style
- Ovary
- Recepticle
The female parts are collectively called the Gynoecium.
What are the female parts of a flower?
- Stigma- where the pollen lands
- Style- the pollen tube grows down after pollination.
- Ovary- Contains ovules, megasporangia
- Receptacle- where everything comes together.
what is Embryogenesis
Embryogenesis means “taking shape”, it starts with the zygote but continues throughout a plant’s life. It is the development of a body plan. Occurs naturally as a result of single, or double fertilization, of the ovule, giving rise to two distinct structures: the plant embryo and the endosperm which go on to develop into a seed.
Define growth
Growth is an irreversible increase in size. in plants, growth means cell enlongation AND cell division.
Describe Phenotypic Plasticity
Phenotypic plasticity is when a plant grows in response to its enivronment. for example: trees growing close together in a forest will grow more sparse than trees growing far aoart in a field.
What is Morphological Diversity?
Morphological Diversity is a measure of the physical characteristics of organisms within a species. it is an important measure because it is used to identify changes in biological diversity in a given area.
Plant development occurs via three overlapping processes, what are they?
- Growth
- Differentiation
- Morphogenesis
Growth occurs at (blank)
Meristems
what are the two types of growth?
- Primary growth - happens at apical meristems, from the tips, reaching for resources
- Secondary growth - occurs at lateral meristem (growing outward), an increase in girth.
Explain Differentiation in terms of plant development
Differentiation is how certain cell types arise, which happens at the apical meristem where there are two types of meristem cells : Initials and Derivatives. As the Initialmeristem cells divide, one remains initial which maintains the meristem, and one becomes a derivative which differentiates into some part of the plant body.
What are the two types of apical meristems?
- Initial: maintains the meristem
- Derivative: differentiates into something else… ex, the plant body.
explain Morphogenesis in terms of plant development.
Morphogenesis is the origin and development of a plants form. It has to do with genetics and the environment (think phenotypic plasticity)
What is the purpose of the stem?
The main purpose is to provide support. Stems grow and provide mass, store water, carbs and minerals, conduct water and minerals.
What are the basic parts of a woody plant stem (twig)?
Terminal buds, axillary buds, leaf scars, nodes, and internodes.
Explain double fertilization in Angiosperms
After pollination, once the two sperm cells make it down the pollen tubes and to the ovary part of the flower, one spem cell fertilizes the egg, and the other sperm cell passes by and fuses with the two polar nuclei in the ovary, which results in an endosperm 3N.
What is the function of the endosperm that results from double fertlization in angiosperms?
the endosperm 3N that is produced is just nutrient tissue.
Differentiate between Pollination and Fertilization
Pollination is the pollen transfer to the female cone from the male cone. Fertilization is the fusion of an egg and sperm to get an embryo.
What is the function of Lenticles?
It functions as a pore allowing for the interchange of gases between the interior tissue and the surrounding air.
What is the function of bundle scars?
Bundle scars are circular or barred regions within the leaf scar where bundles of vascular tissue that had connected the leaf and the stem broke off, this is where xylem and phloem were giving nutrients to that leaf.
Briefly describe Heartwood and Sapwood
Both are Xylem, Heartwood is on the inside of the stem and is darker in color from clogged nutrients and is dead. Sapwood is also dead but is actively conducting water and nutrients. Sapwood gradually becomes heartwood as the tree groes. Remember that xylem is dead at maturity.
What is the function of the cork cambium?
cork cambium is a lateral meristem (actively dividing cells), is found in the epidermis and adds to the epidermis bark, stems add roots. Cork cambium builds bark.
Where are the youngest and oldest part of a tree in the stem?
Youngest part is the outside, oldest is the inside.
What is the function of Bark?
The function of the bark is protection from both abiotic and biotic factors, it prevents water loss, and is used in a wide variety of medicines, teas, dyes and cork.
Briefly describe Phloem
Phloem is a tiny 2-3 layers of cells consisting of two types of cells: The Sieve tube and Companion cell. The function of the Phloem is to carry sugars formed by photosynthesis from leaves to roots. think “Phloem Low-em”
What is sap?
Water + Sugars
Describe Translocation
Translocation is sap movement from the leaves DOWN (descent of sap). Source to sink via a high to low concentration gradient.
Describe Sieve tubes and Companion cells in terms of phloem loading.
Sieve tubes are cells in the phloem that move sap and water, the Companion cell houses the organelles and assists with loading sugars, but they do not move sap. Sieve tubes would die without the companion cells.
Briefly explain Phloem loading
Sugars enter the sieve tubes near a sugar source (leaves) via active transport, when sugar concentrations increase, water moves into sieve tubes via osmosis. Pressure from the addition of water (xylem) pushes the sap down the sieve tubes. When the solution arrives at the sugar sink (fruit), cells actively transport solutes out of the sieve tubes.
The sweetness of a fruit has everything to do with the (blank) and how sugar is transported
Leaves
what is vascular cambium?
Vascular cambium is a part of a stem that is alive and actively dividing, it is 1 to 2 cells thick, and produces phloem to the outside and xylem to the inside.
Trees grow in (blank)
Diameter!
Explain Earlywood
Grows in the beginning of the growing season, takes advantage of higher moisture levels and has larger vessels.
Explain Latewood
Grows later in the season, lower moisture and has small vessels that are more efficient at pulling water.
What is Stomata?
Any of the microscopic openings or pores in the epidermis of leaves and young stems. Stomata have guard cells on the top and bottom of the pore that can close and open.
How does water travel up through xylem?
Water travels up the stem by Transpiration: water loss from stomata is the ascent of sap UPWARDS.
Explain the Cohesion Tension Theory.
One molecule of water moves out of a stomata, and one moves in taking its place (cohesion). One water molecule moves from the soil into the root to keep the chain in tact. Tension happens from the immense pressure in the vessels.
What are the two types of seedless fruit?
- Parthenocarpy
- Stenospermocarpy
Explain a Parthenocarpy fruit
May develop fruit without fertilization, parthenocarpy fruits are usually seedless
Explain a Stenospermocarpy fruit
The biological mechanism that produces seedlessness in some fruits, even though those fruits have undergone normal pollination and fertilization. The resulting embryo is aborted, but the fruit continues to grow. The remains of the undeveloped seed can be seen in the fruit
What is a climacteric fruit?
a fruit that needs ethylene to ripen.
What makes a perfect flower? and what is the evolutionary advantage of a perfect flower?
A perfect flower has functional male and female parts. The evolutionary advantage of a perfect flower is that it can self-fertilize. Perfect flowers are always monoecious.
What makes an imperfect flower?
Has both male and female parts but one is not functional and can never self-fertilize. The evolutionary advantage of imperfect flowers is that it opens them up to more genetic diversity.
Complete vs Incomplete flowers
A complete flower has all four functioning layers, an incomplete flower is missing one or more of the four layers.
The ovule and Megasporangia
Ovule > Megasporangium> Megaspore Mother cell> Megaspore> Megagametophyte> Egg
Microsporangia and the Pollen grain
Microsporangia> Microspore Mother Cell > Microspore > Microgametophyte > Sperm
What does the Micro/Megasporangia mother cell do after it has formed?
It gives rise to four micro/megaspores
What is an example of the directed pollination hypothesis?
The Sphinx moth and the Datura flower. The Sphinx moth has a very long tongue that can reach down into the flower and reach its nectar source. It can only be pollinated by this moth because no other insect can reach down far enough to reach the nectar source.
What is an example of Morphological diversity?
Trees and shrubs growing in a forest are in competition for light.
Define Dendrochronology
Dendrochronology uses tree growth rings to date events and environmental change.
What are tendrils?
Unusual “curly” stems are used for support and
climbing toward sunlight
What is a Pericarp?
A Pericarp is the wall of a ripened ovary that has three layers: Endocarp, Mesocarp, and Exocarp.
What is the definition of a Botanical berry?
Fleshy, no stone seed, one ovary, one flower.
Avocado, star fruit, grapes, bananas, cucumbers and tomatoes are all technically berries!
What is a drupe?
Fruits that are indehiscent (don’t open at maturity) and have a hard stoney seed, cherries, mangos, and pistachios are drupes!
What is an aggregate? (fruit)
Fruits that have a single flower but many ovaries fused together. Blackberries and strawberries are aggregates!
