Biology 11 - Plants.txt
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Biology 11 - Plants.txt
Biology 11 Plants
Biology 11 - Plants
Alternation of generations:
1. Haploid gametophyte produces male or female gametes (n) by mitosis.
2. Male gamete fertilizes female and they form a zygote which grows into a sporophyte (2n).
4. Diploid sporophyte produces spores (n) by meiosis.
5. Spore grows into gametophyte (n).
Major plant kingdom divisions:
Non-Vascular Plants (bryophytes)
Vascular Plants (tracheophytes)
- Seedless Plants (pteridophytes)
- Plants with Seeds (spermatophytes)
- Naked Seeds (gymnosperms)
- Enclosed Seeds (angiosperms)
Nonvascular - Embryophytes.
Rhizoids instead of developed roots.
Diverse environments such as bog, tundra, exposed rock, and deep shade.
Help initiate soil-formation and used as fuel.
Grow flat and close to the ground.
Rarely more than 30 cells thick.
Horn-like structures jutting from their base.
Mosses, liverworts, and hornworts are restricted in size because:
They lack a vascular system to move water, nutrients, and sugars.
Seedless Vascular Plants (ferns and reletives)
Vascular tissue allows them to grow tall (upto 10m).
Spores dispersed by wind.
Sporophyte generation is dominant stage while gametophite generation is tiny and short lived.
Gametes require water to fertilize @sp? because male gametes swim with flagella.
Types of plant vascular tissue:
Xylem - Dead cells that conduct water and dissolved minerals absorbed by the roots.
Phloem - Living tube cells and companion cells that conduct sugars produced in the leaves.
Vascular plant parts:
Roots - penetrate soil to anchor plant and reach water.
Leaves - provide a large surface area for photosynthesis.
Stems - rigid tissues that raise and support the leaves.
Allow sexual reproduction away from water.
Provide protection against environmental conditions.
Male - Pollen Cones:
microspore mother cells undergo meiosis to produce haploid pollen grains.
Female - Seed Cones
In each ovule a megaspore mother undergoes meiosis producing one megaspore.
Pollen traped in sticky sap secreted by female cone fertilize megaspore to form diploid zygote.
Zygote grows into embryo inside ripened ovule which is now called a seed.
Naked seeds fall out of cone but may take years to become a mature cone producing plant.
1 - Monocot
2 - Dicot
90% of plant species.
Fruit and flowers attract animals disperse seeds and carry pollen.
The fertilized ovary of an angiosperm.
How flowers work @Picture@
In the anther chambers microspore mother cells undergo meiosis to produce haploid pollen grains.
In the ovule megaspore mother cell undergoes meiosis to produce one megaspore.
Wind, insects, birst, or bats transfer pollen to sticky surface of the stigma.
Self-pollination if pollen is from the same plant or cross-pollination if it is from a different plant.
Fertilized zygote developes into an embryo in the ripened ovule which is now called a seed.
the ovary and other surrounding parts develope into a fruit enclosing the seed.
Asexually produces plants with desired characteristics by physically joining different plants so they grow as one.
: Shoot of grafted plant.
: Root of grafted plant.
Only closely related plants that have a cambium can be grafted.
The process whereby a community of plants in an area gradually change over time.
This can be promoted by forest fires and severe storms.
These changes do not follow a predictable sequence.
If the plant community becomes stable it is called a climax community.
Plant communities rarely remain stable for long.
Only occurs in areas where there was no revious plant community.
Pioneer spore producing plants such as lichens create soil.
Moving from this to a forest takes thousands of years.
Occurs when a plant community is disturbed (by fire, storm, or human activity for example)
Vascular seed producing plants return without needing pioneer species.
A forest may develop in as little as 100 years
Stomata are openings allowing CO2 and H
O vapour to enter plant leaves.
A stoma is formed between two guard cells.
Durring the day water enters the guard cells causing them to swell and bend opening the stoma.
At night water leaves the guard cells and the stoma closes to prevent water loss.
Outermost layer of leaf.
Prevents water evaporating.
Leaf Epidermis Tissue
- Lots of chloroplasts for photosynthesis
- Lots of mitochondria for cellular respiration
- Loosely packed cells.
- Spaces between cells store H
O vapour, O
, and CO
Leaf Vascular Bundles
Made up of xylem and phloem.
Form veins that deliver water and nutrients throughout leaf.
Leaf Guard Cells
Found in lower epidermis of leaf.
Open and close stomata to control flow of gases and vapours in and out of leaf.
Water Movement in Plants
Water enters plants though root system.
Water drawn up plant by cohesion and adhesion.
: negative oxygen in one water molecule attracts the positive hydrogen in another.
: water molecules stick to xylem walls.
Water exits leaves through stomata.
Light triggers an electron transport mechanism.
Water is the electron provider for photosysthesis.
Oxygen is a by-product.
Carbon dioxide is incorporated into molecules that eventually become sugar.
Glucose in Plants
Manufactured in the cytoplasm.
Transported in phloem.
Used by mitochondria to make ATP (for energy transfer)
Excess stored as sugar in fruit or as starch in roots.
Equations for Photosynthesis and Cellular Respiration
O + energy → C
O + energy
Bulb (thick fleshy leaf scales)
- Food storage
Spines (sharp, woody, non-photosynthetic)
- Defense, Water Retention
- Attracting pollinators
- Paper flower
- Venus fly trap
Phylloclade / Cladode (stem that looks and acts as leaf)
- Butchers broom.
Rhizome (thick underground stem grows horizontally)
Corm (short swollen vertical stem of several nodes at or below ground)
- Climbing and support
- Grape vine
- Absorb water from rain or mist
- Opiphytic orchid
Pneumatophores (air-breathing roots with air spaces connected to submerged roots)
Plant Epidermal Tissue
Produces the cuticle which:
- protects against infection
- prevents water loss
- restricts gas exchange.
In plants with secondary growth epidermis is replaced by periderm (bark).
Plant Ground Tissue
Parenchyma - Storage and photosynthesis.
Collenchyma - Flexible support (growing).
Sclerenchyma - Inflexible tough support (not elongating).
Plant Vascular Tissue
Cells are dead at maturity.
- Tracheids - narrow angled end walls.
- Vessel elements - wider, somtimes lack end walls entirely, only found in angiosperms.
Transport glucose from leaves to other parts of plant
- Sieve tube cells - no nuclei, separated by sieve plates.
- Companion cells - control functions of sieve tube cells.
Vascular Tissue Arrangement
Stem - vascular bundles scattered through stem. No cambium.
Stem - vascular bundles in a ring with xylem and phloem seporated by cambium which produces more of both.