Plants: Lecture 3 Flashcards
Conifers are what kinds of plant? How fast is their reproduction and what kind of seed do they have?
Conifers are seed plants meaning they have seeds and pollens. They have vey slow reproduction, and are called gymnosperms as they have naked seeds (no covering on the seed).
How fast is angiosperm reproduction?
It is relatively fast, as pollen landing to the seed may take as little as a week or some months at the most.
What kind of seeds do angiosperms have?
They have covered seeds, which are covered by fruit.
When did Anthophyta appear?
The division Anthophyta (flowering plants) appeared roughly 150 million years ago, then exploding into many different species.
Timeline for Anthophyta?
- Arose 150 mya
- Made up less than 20% of all plant species 105 mya
- Made up more than 80% of all plant species 65 mya
What is the Angiosperm Terrestrial Revolution in simple words?
An increase in angiosperm species fuelled the increase in the number of species of other groups.
How did the angiosperm terrestrial revolution affect modern biodiversity?
Everything experiences the same increase in diversity after the flowering plants began increasing.
- Expansions occurred in conjunction with the plants.
What is the Angiosperm Terrestrial Revolution?
The angiosperm terrestrial revolution was the diversification of the angiosperms (increase in species) which coincided with a dramatic diversification of other organisms (increase in species).
How many species live on land rather than the sea?
85% of plant, animal and fungal species live on land rather than in the sea. Half of these species live in tropical rainforests.
What were the side effects of this?
- The biosphere expanded to a new level of productivity, with more energy being produced.
- It coincided with innovations in flowering plant biology and evolutionary ecology, such as flowers, efficiencies in reproduction, coevolution with animals (pollinators like bees and bats, and herbivores), photosynthetic capabilities, adaptability and the ability to modify their habits.
When did the explosive boost occur?
This boost occurred from 100-50 million years ago.
What did the rise of angiosperms trigger?
The rise of angiosperms triggered a macro ecological revolution on land and drove modern biodiversity…. to new, high levels, a series of processes we name here the Angiosperm Terrestrial Revolution.
Why are angiosperms so diverse and have so many species numbers?
- They have insect pollination
- A flexibility in seed production and dispersal
- Greater genetic and phenotypic flexibility in cell & shoot elongation
- More complex mechanisms for activating and repressing the genes
- Greater complexity of the flower
How many named and estimated species are there?
There are 300,000 named and 400,000 estimated species.
What are the reproductive organs in the Anthophyta? What is dominant and are the hetero or homo-sporous?
- Their reproductive organs are in their flowers
- They are sporophyte dominant, meaning they are what they see
- They are heterosporous
What is the microgametophyte and macrogamrtophyte in the flowering plants?
The microgametophyte = pollen or sperm
The macrogametophyte = 8 nuclei and 7/8 cells (eggs)
What is different about flowering plants (3n)?
All flowering plants have endosperm, which are 3n or triploid.
What is the androecium?
The male structures: anther and filament (stamen)
What is the Gynoecium?
The female structures: pistil/carpel, ovary, stigma
Male and female structures in flowers?
They are mainly hermaphrodidic. Male and female are on the same plant/flower.
Monocots vs. Eudicots?
Monocots have one seed leaf that comes out (monocotyledon)
Eudicots have two seed leaves that come out.
Examples of monocots?
- Grasses: Maize, wheat, rice, bamboo
- Orchids
- Irises
- Lilies
- Palms
Characteristics of monocots?
- One cotyledon
- Leaf veins are usually parallel
- Vascular tissue is scattered
- Root system is usually fibrous with no main root
- Pollen grain with one opening
- Floral organs (petals) usually in multiples of three
Examples of eudicots?
- Oaks
- Maples
- Dandelions
- Sunflowers
- Legumes
- Melons
- Potatoes
- Poppies
- Roses
Eudicot Characteristics?
- Two cotyledons
- Leaf veins are usually netlike
- Vascular tissue is usually arranged in a ring
- Taproot (one main root) usually present
- Pollen grain with three openings
- Floral organs usually occur in multiples of five or four.
Hermaphroditic flowers?
Male and female organs within the same flower means the flower is hermaphroditic.
- 85% of angiosperm species have cosexual/hermaphroditic flowers
Cosexual structures on plants?
The stigma is kept away from the anther to prevent selfing and the lowering of offspring fitness.
What is monoecy?
When separate male and female flowers exist on the same individual.
Ex. Paper Birch
What is dioecy?
Where male and female sex organs are on different individuals.
- Only present in ~5% of species
Ex. Willow
What is pollination?
The arrival of pollen on the stigma or receptive female cones (movement of pollen/sperm near the egg).
- Occurs only in seed plants
How does pollination occur in flowering plants?
- Insects (bees, moths, butterflies, flies, and beetles).
- Birds (hummingbirds, honeycreepers).
- Bats
- Wind
Reward and Advertisement of pollen?
The reward offered by the plant is sugary nectar & pollen.
The advertisement by the plant is having it be showy in colour and also possibly odorous.
Cost of reward and advertisements?
They are both very costly, but the plants need to be pollinated and is the solution to the issue.
What are pollination syndromes?
They are integrated sets of floral traits (morphology, colour, odour, size, rewards) associated with particular pollinator groups.
How are pollination syndromes an example of convergent evolution?
These traits in flowers have evolved separately many times and can thus occur in unrelated plant species.
Pollination by bees example: pollination syndrome?
- various shapes which can be specialized or not
- Various colours, including yellow, blue, and orange (not red)
- Either no odour or highly specialized
Pollination by bats or moths?
- Tubular shape that opens at night
- Yellow or white colour to be easily seen
- Strong and sweet odour
- Large quantity of heavy nectar
Pollination by birds?
- Tubular shape
- Red is the most common colour, and yellow
- No odour
- Large quantity of weak nectar
Pollination by wind?
- Not showy shape
- No odour
- No nectar
- Very large quantity of pollen because there is no direct recipient
Variation among plants?
- Some plants are pollinated by many animal species
- Some pollinated by one animal species
- Some provide no reward: deceit pollination
Pink Lady’s Slipper Orchid?
- Trick bees into going to a certain petal that offers no nectar, but the process results in pollination anyways.
The angiosperm life cycle contains double fertilization?
- 2 sperm nuclei in pollen.
- 1 fertilizes the egg to create the diploid embryo
- 1 fertilizes the central cell to create the triploid endosperm
Angiosperm Ovules and Ovaries?
- Ovules become seeds
- Ovaries become fruits
Dispersal of seeds and fruits?
Wind - maple and cottonwood
Water - coconut and water lily
Animals - blueberry and cockleburr
Fruits with more than 1 seed?
- Watermelon
- Zucchini
- Squash
- Banana
- Bell Pepper
- Grape
- Pea Pod
- Apple
- Orange
- Tomato
Fruits with one seed?
- Grass grains (wheat, corn, rice)
- Acorns
- Peach
- Cherry
- Coconut
Nourishing the embryo: Conifers vs. Angiosperms?
Conifers: megagametophyte (1n)
Angiosperms: endosperm (3n)
Endosperm is the principal foodstuff of our civilization?
- More than half of the direct daily calories worldwide
- Especially the three cereal grasses: rice, wheat and corn
- Thes were domesticated ~10,000 years ago in Mesopotamia.
Endosperm that we eat?
Popcorn, white flour, avocado pit (not eaten)
What was gained by plants when moving from water to land?
- Cuticles
- Sporopollenin
- Jacketed sex organs (antheridia, archegonia)
- Embryo retention
- Stomates (stomata)
- Vascular tissue (xylem, phloem)
- Seed & Pollen
- Flower
- Fruit
Conifers vs. Flowering Plants?
- Conifers have a cone and flowering plants have flowers for their reproductive structures
- The conifers’ micro-gametophyte is pollen, which is the same as flowering plants.
- Pollen dispersal for conifers is only wind, while flowering plants also have animals.
- The conifers are nourished by a multicellular mega-gametophyte whilst flowering plants are nourished by an 8 nuclei, 7 cell endosperm.
- Conifer seeds are naked, whilst flowering plant seeds are covered by fruit.
3 variations of alternations of generations?
a. Bryophytes have a sporophyte that is dependent on the gametophyte.
b. Ferns have a large sporophyte and has a small, independent gametophyte.
c. Seed plants have a reduced gametophyte that is dependent on the sporophyte.
What are the two systems in vascular plants?
There are roots (above) and shoots (below).
- They differ anatomically
Different types of stems?
Rhizome: Underground and shoot up at auxiliary nodes.
Stolon: Along the surface
Tuber: Storage
Adaptations of roots?
- Prop roots
- Storage roots
- Green roots
- Pneumatophores
- “Strangling” aerial roots
Plant cell walls are mainly made of?
They are mostly made up of cellulose - a polysaccharide of glucose units.
Each microfibril is made of adjacent, parallel cellulose molecules
Facts about the plant cell wall?
It is extracellular, meaning it is outside of the membrane.
There are 2 kinds:
- Primary wall: thin, in all cells
- Secondary wall: thicker, in some cells (for strength).
Cell wall shape?
The cell wall determines and maintains cell shape
Support and Strength cell wall?
The cell wall provides support and mechanical strength (allowing plants to get tall, and hold out thin leaves to obtain light).
Resisting water pressure, Cell wall?
The cell wall prevents the cell membrane from bursting (resists water pressure).
Rate and direction of cell growth?
The cell wall controls the rate and direction of cell growth and regulates cell volume.
Plant’s architectural design?
The cell wall is ultimately responsible for the plant architectural design.
Physical barrier: Cell wall?
The cell wall is a physical barrier to:
a. Pathogens
b. Water in suberized (waxy) cells
- The wall is very porous and allows the free passage of small molecules.
Carbohydrate storage: Cell wall?
The cell wall provides carbohydrate storage - the components of the wall can be reused in other metabolic processes (especially in seeds).
What are the five derived traits of seed plants?
Reduced gametophytes: male and female gametophytes are nourished and protected by the sporophyte.
Heterospory: microspore is male and macrospore is female.
Ovules: gymnosperm is the integument, megaspore, and megasporangium.
Pollen: pollen grains make water unnecessary for fertilization.
Seeds: they survive better than unprotected spores, and can be transported long distances.
