Chapter 31 reading Flashcards
what are the closest living relatives of plants?
green algae, plants evolved differently to survive in air
what are the 4 major transformations to plants?
- Alteration of generations
- Evolution of xylem & phloem in the sporophyte generation
- evolution of seeds & pollen
- Evolution of flowering plants
explain how alteration of generations differs plants from algae
every plant species alternates between two multicellular forms: a haploid gametophyte generation that makes gametes and a diploid sporophyte generation that makes spores
what does the xylem do?
transports water and dissolved nutrients
what does the phloem do?
transports carbs produced by photosynthesis
what is the advantage of xylem and phloem?
can transport over greater differences than by diffusion, xylem allows vascular plants to pull water from the soil
what did evolution of seeds and pollen allow plants to do better than algae?
fertilization can now take place without releasing swimming sperm into environment. increased probability of next sporophyte generation establishing successfully
What are features unique to flowering plants (angiosperms)?
flowers, carpels, double fertilization leading to endosperm, xylem vessels, fruits
how long ago did angiosperms evolve? and land plants?
angiosperms - 140 million years old
land plants - 465 million years old
how did angiosperms affect other plant life?
outcompeted other types of plants but also diversified life by increasing no. of species that can coexist (they were necessary for formation of modern-day tropical forests)
What are the 3 types of Bryophytes?
Liverworts, mosses, hornworts
what are characteristics of Bryophytes?
dependence on surface water for hydration and life cycle dominated by a persistent, photosynthetic gamete, no xylem or phloem, small and tough (<5cm tall), some species have a thallus (flattened photosynthetic structure)
how many different species of Bryophytes are there?
15,000
what are provisions for reproduction in bryophytes?
only haploid gametophyte is free-living, sporophyte attached to and dependent on gametophyte
What types of bryophytes have a thallus?
none in mosses, some in liverworts, all hornworts
how do bryophytes absorb adn restrict water?
from moisture or rainfall, by surface tension
restrict by a cuticle
what are some places bryophytes can grow?
can grow on rock surfaces, branchs of trunks or trees (due to lack of need fro roots) however poor competitors for light
How do Bryophytes exhibit cases of Convergent evolution with vascular plants?
-some mosses depend on insects to trasnport spores
-cells specialised for the internal transport of carbohydrates and water i some of the largest mosses and leafy liverworts
-stomata are present on the sporophytes of hornworts and some mosses, particularly in places where a waxy cuticle also develops
How does sphagnum moss play an important role in the carbon cycle?
through peat bogs
what is a peat bog?
in the wetlands where dead organic matter accumulates rather than decomposes.
what do sphagnum moss do in a peat bog? and how?
a key role in creating the wet and acidic conditions that slow rates of decomposition
specialised cells hold onto water and secrete protons that acidify surrounding water and produce phenols slowly decomposing under waterlogged conditions
what is significance of peat bog total size and then total carbon impact?
only 2-3% of earths land surface peat bogs but contains 65% that of total greenhouse gas combustion produces per year
what do changes in temperature cause for peat bogs?
changes in the water table effect meaning peat bogs are releasing more CO2
What are the two groups of spore dispersing vascular plants?
Lycophytes (+ ferns and horsetails)
Gymnosperms and angiosperms
WHat are Lycophytes?
disperse by spores and rely on swimming sperm for fertilization
What are Gymnosperms and angiosperms?
seed plants, disperse seeds and rely on the aerial transport of pollen for fertilization
What allows fo runderstanding of evolution of early vascular plants?
Rhynie chert fossils
what are some characteristics of early vascular plants?
small <15cm tall
consist of photosynthetic stems and branched, forming sporangia tips
no leaves
roots extended along ground surface
stems had cuticle with stomata
branched sporophyte contained lignified cell walls but no vascular tissues
what does rhynie chert fossils show abot Lycophytes?
evolved leaves and roots independently of all other vascular plants
how many lycophyte species today?
1200
How did Lycophytes form large trees?
convergent evolution of vascular cambium and cork cambium, 40m tall trees dominated swamps
