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.