Plants Flashcards
What was the origin of photosynthesis?
- cyanobacteria - global game changers
- developed multicellurity and cell specialization
- “Great oxidation event” oxygen in earth atmosphere, complex life possible
Explain endosymbiosis (include primary and secondary)
It is the origin of chloroplasts. Originated when ‘protist’ engulfed a cyanobacterium. Primary endosymbiosis is when it is engulfed and then has 2 membranes. Then secondary endosymbiosis. 1) the photosynthetic protist is engulfed, the nucleus is lost, and the organelle now have 4 membranes.
What are some photosynthesized that make a lot of oxygen?
- Trees
- Plants
- Eukaryote photosynthesizers
Phytoplankton
- Single celled
- Marine environments
- 50% of global photosynthesis
- made up of: photosynthetic bacteria (cyanobacteria) and diatoms (single celled photosynthetic eukaryotes)
Brown Algae
- chloroplast w/ 4 membranes
- multicellular
- brown colour - carotenoid pigment fucoxanthin
What has the fastest growth rate of any seaweed and is a keystone species?
Kelp!
Alternation of generations
- type of life cycle for some plants and algae
- alternates between gametophyte form and sporophyte form
Gameotophyte vs sporophyte
Gameotophyte= multicellular haploid (n) form (made by mitosis) Sporophyte= (2n) diploid, produce spores by meiosis
What are spores?
Single (n) cells that grow without fertilization
Red Algae
- uni and multicellular
- red colour from carotenoid pigment phycoexythin
- coraline red algae = helps build coral reefs, attract coral larvae, patch things up like bandaid
What is a non-vascular plant?
It means that it does not flower
Viridiplantae
“green plant”
monophyletic group
green algae (in water) (uni and multi cellular)
land plants are major photosynthesizers
Define byrophytes
non-vascular plant
define tracheophytes
vascular plant
Describe the transition to land plants
Green plants (algae) -> land plants (non-vascular) -> vascular plants (seedless) -> gymnosperms (seed plants)
Name some advantages and disadvantages to plants moving onto land
Advantages: - Huge uncolonized area - light - C02 - less herbivory Disadvantages: - UV radiation - Dehydration - Dispersal - Gravity - Nutrients
How did plants survive in the sun after they transitions to land?
They made compounds that absorbs UV light
Define a Cuticle (key innovation)
- prevents water-loss but inhibits gas exchange
- watertight covering above ground land plants
- made up of hydrocarbons, lipids and wax produced by epidermal cells
What are the 3 innovations for plants to reproduce on land? Tell me about them.
1) Spores: tough coat, resist drying, dispersed hundreds of km by wind
2) Gametes: specialized reproductive organs that all modern land plants have but angiosperms. Either male or female.
3) Embryos nourished by parent plant. retain the eggs now, they do not shed in water or soil.
Byrophytes
Mosses, liverwortes, non vascular
No vascular tissue, no true roots, absorb nutrients and water through “leaves”, small (slow growing), lived in damp habitats.
What is the reproduction of Bryophytes?
- alternation of generations - gametophyte dominant
- can be unisexual or bisexual
- spores for dispersal
- need water
Why did non vascular plants evolve to vascular plants?
They faced many challenges such as competition, drier env. so needed to be taller and deeper.
Describe the key innovation: branching
- enabled different stems to specialize
- roots along the ground to get nutrients
- grow up to outcompete neighbours for the sun
- plants are now bigger so the seeds disperse further
- grow in diff shapes
Define stomata
- full evolution of cuticle
- helps seal in water
- pores on leaf surface to regular water and gas exchange
Key innovation: vascular tissue
- specialized reinforced conductive tissue
- functions: transport & support
- structural support once the plants increased in height
Define Xylem
Plant tissue that transfers water and nutrients from roots to all over the plant body
Roots
- nutrient, water acquisition, support
- network trees together (boreal forest)
- had multiple independent evolutions though Devonian
Define: Devonian
Age of the forest
- Early: 1m plants
- Mid: shrubs, then roots and leaves evolved
- Late: first forests, fist tree-like plants
Gilboa trees
First type of tree
8m tall
no leaves or wood just increasingly fine branches
What is the advantage of sporophyte dominant?
- diploid cells can respond to the environment better
-
What are some types of vascular seedless plants?
- Clubmosses, wisk ferns, horsetails
- clubmosses are oldest group of vascular plants that have living members, evolved first leaves
- ferns have similar roots to seed plants, sporophyte, sterile + fertile leaves, dominant in NZ ecosystem, interbreeds with many things
What are some advantages to a plant having a higher height?
- access to light, shade out competitors, better wind dispersal of spores and seeds
Rise of trees
Tree: plant w/ stem and branching canopy that can reach large heights thanks to specialized cells
First: Gilboa trees, they did not have true wood. They had trunks filled with Xylem strands.
Carboniferous forests
- Ancient fern forest dominated wetlands most of Pangea
- 50m tall, thin stem supported by ligin
- shallow roots
- died, sank into swamps and never decayed because bacteria + fungi could not break down the ligin
- 90% coal came from this forest
What is wood?
- trees have ring of dividing ells beneath bark called vascular cambrium
- produced new xylem tissue and phoelem tissue
- xylem: nutrients/water go up
- phloem: sugars flow down
- wood is made of xylem
- trees build support (girth) as they grow in height
Archaeopteris
Extinct genus of fern like trees, first true tree, link between ferns and gymnosperms
Key innovation: Heterospory
Spores are now different sizes
1. Megaspores
2. Microspores
Leads to evolution of seeds/pollens
Evolution of seeds
Megaspores -> fertilized ovule (seed)
- Many megaspores go to one, germinates, surrounded by protected ‘integument’, then into ovule is the seed
Evolution of pollen
Microspores -> pollen
- Microspores evolve into pollen grains
- Pollen grains allowed efficient reproduction in dry habitats
Gymnosperms
“naked seed”
- modern seed-bearing plants that do not have flowers or ovaries
What are the four extant groups of gymnosperms?
1) Cyrads
- large cone at apex of trunk
- seperate male and female parts
- motile sperm
- mostly tropical now
- large part of diet for herbivorous dinosaurs
2) Ginkos
- most closely related to cycads
- 1 extant species
3) Gnetales
4) Conifers
- most diverse group
- woody, cone bearing
- dominates worlds largest forest biome (boreal forest)
What is adaptive radiation and give one example?
- When one lineage produces an unusually high amount of descendents species adapted to many habitats
Example: angiosperms
Angiosperms
Flowers and fruits
Advantanges of pollen and seeds
- do not need water to reproduce
- varied dispersal of male gametes
- better dispersal of seeds
Three key adaptations from seedless plants, to plants with seeds
1) more efficient xylem
2) flowers (most associated w/ speciation)
3) fruits (transport water, pollen, seeds efficiently)
What are the reproductive organs of a flower and the four structures?
Male: Stamen
Female: Carpel
(can have one or both)
- Four structures: Carpel, stamen, sepals, petals
Pollination
Pollen transfers from another compatible, receptive stigma, outcross pollination = pollen and stigma on different plants
Floral traits
Can attract good pollinators, deter bad visitors, manipulate visitors to maximize pollen transfer.
Colour, scent, shape, markings, positions.
Impacts speciation, reproductive isolation, pollinator shifts, changes in flower morphology
Experiment: the colour impacted the visitor!
Fruits
- angiosperm ovules develop an ovary
- after fertilization, ovary tissue ripens into fruit
- function: protect developing seed, seed dispersal
Key differences between monocots and dicots
Monocots: - 1 cotelydon - parallel leaf veins - multiple of 3 leaf patterns Dicots: - 2 cotelydon - branching leaf veins - multiple 4 or 5 petals
Who evolved from who? (monocots and dicots)
- monocots= monophyletic
- monocots come from dicots
- change! identified eudicots ( most of those plants use to be identified as dicots)
