Plant Origins
What group do we think is most closely related to land plants?
Charophycean (Green Algae-Protist) See slide 13 on L12
What is an example of a bryophyte?
Hornworts, Liverworts, Mosses
What life cycle is dominant in all living vascular plants?
Sporophyte
*Sporophyte is larger and independent of the gametophyte; gametophyte is greatly reduced
A seed is a mature _______ and a fruit is a mature _______.
Ovule, ovary
Which group of plants does 80% of the world's food come from?
Angiosperms
What is alternation of generations?
A complex type of life cycle in which a multi-cellular haploid stage alternates with a multi-cellular diploid stage.
What stage of the life cycle is dominant?
Gametophyte, sporophyte is dependent upon the gametophyte.
What are xylem and phloem? What do they conduct?
Vascular Tissue
*Xylem: Conducts water and nutrients from root to shoot
*Phloem: Conducts carbohydrates and nutrients from shoot to root
What two parts of the flower are used for reproduction?
Carpel-Female
Stamen-Male
How many years ago did the first land plants emerge?
370 MYA
*More exposure to sunlight (not filtered by water or plankton)
*Atmosphere with abundant CO2
*Mineral Soil
*Few herbivores and pathogens (at least initially)
What must bryophyte sperm have in order to swim to the archegonia?
WATER
Name the two extant phyla within the seedless vascular plants.
Phylum Lycophyta- lycopods and club mosses
Phylum Pterophyta- ferns, whisk ferns, and horsetails
Name 2 key differences between angiosperms and gymnosperms.
*Flowers: Increase success of pollination
*Fruits: Covered seeds to aid in seed dispersal
*Double fertilization: Formation of zygote and endosperm
What is the importance of roots and leaves in vascular plants?
Roots: Anchor plant, enable absorption of water and nutrients from the soil.
Leaves: Increase surface area to capture solar energy
In what ways did plants change the terrestrial environment? (Give 2)
*Plant roots create habitat, stabilize landscape
*Plants are a source of oxygen (photosynthesis) and take CO2 out of the atmosphere
*Provide food (Tissues and store starch)
Give a reason moss if of ecological importance.
*Peat Bogs
*Store CO2 and stabilize CO2 in the atmosphere
*Over-harvesting may be ecologically detrimental
What is the difference between heterosporous and homosporous?
*Heterosporous: Two types of sporophylls, two types of spores-Male and Female (Angiosperms
What is a seed? What is pollen?
*Seed: Protects the embryo from desiccation and allow it to be retained and nourished by parent plant
*Pollen: Male gamete that is desiccation resistant-transported by wind or animal pollinators
Describe a plasmodesmata.
Microscopic channels that connect the cells of Charophyceans and land plants. (See L12 slide 16 for a picture).
Define the four groups of plants. (Bryophytes are Seedless/seed and nonvascular/vascular).
Bryophytes-nonvascular, seedless
Ferns and Fern allies-vascular, seedless
Gymnosperms-vascular, naked seeds
Angiosperms-vascular, "covered" seeds
Give the phylum names of the three bryophyte groups.
Phylum Anthocerophyta-Hornworts
Phylum Hepatophyta-Liverworts
Phylum Bryophyta-Mosses
What structures, found on ferns, are described as clusters of sporangia?
Sori
Describe the reproductive cycle of angiosperms.
Diploid stamen (male) and ovary (female) develop haploid microspore and megaspore respectively through meiosis. Mitosis produces egg and more pollen which will then combine via fertilization. Through mitosis, the zygote develops into a seed surrounded by fruit which will germinate into diploid sporophyte.
Describe double fertilization as it is found in angiosperms.
One sperm nucleus + egg = zygote (2N)
One sperm nucleus + 2 polar bodies =endosperm (3N)