1
Q
Endosymbiotic Theory and the evidence
A
states that a prokaryote engulfed a mitochondria / chloroplast and lived in symbiosis; this evidence is that the membrane bound organelles have their own DNA
2
Q
Examples of membrane bound organelles
A
Mitochondria, chloroplasts, vacuoles, ribosomes, endoplasmic reticulum
3
Q
Types of Plants
A
- Nonvascular Plants (eg. Peat moss, liver/horn warts)
- No vascular tissue
- Water/food move via osmosis/diffusion
- Must be near water and small - Spore-producing Plants (eg. Ferns, horse tails, club mosses)
- Gymnosperms (eg. Pine tree)
- Angiosperms (eg. Roses, apple trees)
4
Q
Alternation of Generations cycle
A
- Gametophyte (n) undergoes mitosis and makes egg (n) or sperm (n)
- Fertilization occurs to form a 1-celled zygote (2n)
- Zygote undergoes mitosis and turns into an embryo (2n)
- Embryo grows into a sporophyte (2n) via mitosis
- Sporophyte undergoes meiosis to form spores (n)
- Spores grow via mitosis into a gametophyte (n)
5
Q
Gametophyte def
A
Haploid plant generation that produces haploid gametes (2 types; egg and sperm)
6
Q
Sporophyte def + fun fact
A
Diploid plant generation that produced haploid spores through meiosis
the sporophyte grows out of the gametophyte body. The male gametophyte sperm fertilizes the female gametophyte and the sporophyte grows off of it.
7
Q
Plant Reproduction: asexual
A
- Non-Vegetative Propagation: roots, stems, and leaves can be modified into new plants
- Artificial Propagation: take desired tissue (scion), and cut and paste onto the parent body (must be same species)
8
Q
Plant Reproduction: sexual for seedless plants
A
Reproduction in a wet environment (water is required for the sperm to swim from the male gametophyte to the eggs
- Non-vascular: dominant gemetophytes plant (mosses)
- Smaller sporophyte depends on the gametophyte for food and support - Spore Producing: domainant sporophyte plant (ferns)
- Large leafy part is the sporophyte
9
Q
Plant Reproduction: sexual for seed plants
A
Reproduction in a dry environment
- Gymnosperms: unprotected (naked) seeds
- Angiosperms: protected (seed coat) seeds
10
Q
Monocot traits
A
of embryonic seed leaves: 1
Organization of vascular bundles in roots/stems: roots = ring, stem = scattered
Leaf venation: Parallel
Number of flower parts: 3 parts or sets of 3
Presence of wood (secondary growth): No
Root system: Fibrous
Examples: Asparagus, onions, grass, oats, wheat, corn
11
Q
Dicot traits
A
of embryonic seed leaves: 2
Organization of vascular bundles in roots/stems: roots = star formation, stem = distinct ring
Leaf venation: Palmate or Pinnate
Number of flower parts: 4 or 5 parts or sets of 4 or 5
Presence of wood (secondary growth): Yes
Root system: Taproot
Examples: Oak trees, strawberries, beans, legumes, carrots, dandelions
12
Q
Seed Dispersal methods
A
- Wind (milkweed, dandelion)
- Water (coconut seed)
- Animal fur (cocklebur seed)
- Being eaten (birds eat fruit with hard seeds that can’t be digested; when eliminated, can germinate in suitable soil)
13
Q
Angiosperm Life Cycle
A
- Pollen lands on the stigma. Germination occurs
- Stigma secretes nutrients which pollen absorbs
- Pollen’s cytoplasm extends to ovary via microphile
- 1 of Pollen’s 2 nuclei divides into 2 “sperm nuclei”
- 1 sperm nucleus fuses with ovum (egg) to produce zygote
- Other sperm nucleus fuses with ovule’s 2 nuclei to form “triploid endosperm”
- Zygote grows into embryo then into sporophyte
- Ovule develops into a seed and the ovary dries to form capsule for the seed
- Cycle repeats!
14
Q
Stigma def
A
female reproductive part
15
Q
Pollen def
A
sperm produced in anther; consists of 1 tube cell and 2 nuclei cells
16
Q
Micropyle def
A
tiny opening in the ovary
17
Q
Ovum def
A
female reproductive egg cell
18
Q
Ovule def
A
female part that develops into a seed
19
Q
Endosperm def
A
stores nutrients for the developing seed
20
Q
Radicle def
A
minature root
21
Q
Plumule def
A
small shoot
22
Q
Cotyledons def
A
seed leaves
23
Q
Fruit def
A
fertilized ovary of a flower
24
Q
Simple Fruits def
A
fruits that develop from a single ovary in a single flower (tomatoes, plums, pears)
25
Aggregate Fruits def
fruits that develop from many ovaries in a single flower (raspberries)
26
Plant organs + evolution
- In a plant, they are the stems, roots, and the leaves
- Made up of specialized cells and tissues that have a particular function in the organism
- All structures have evolved over time to do the function optimally
27
Stems: function
1. Structural support for leaves, flowers, seeds, fruits
2. Transport of water and dissolved minerals from the root + carbohydrates from the leaves to the rest of the plant
3. Some stems have chloroplasts and carry out photosynthesis (green stems)
4. Some stems can store food
28
Stems: types
1. Herbaceous Stems
- Green, soft, flexible
- Produced by plant in first year of growth; after the stem may remain herbaceous or develop into a woody stem
- Causes primary growth
2. Woody Stems
- Brown, thick, hard, tough
- Consist of primary + secondary tissue
- Most of the tissue is secondary and produced by lateral meristems
- Causes secondary growth
- Produced only in second and subsequent years of trees, shrubs, some vines
29
Primary Growth def + process
All cells + tissues are produced by the apical meristems in the tips of the root and stems
- Tip is rapidly dividing
- Elongation of the cells occur
- Pushes cells upward or in the case of the root, down!
30
Vascular Bundles def
Bundles of xylem (center) or phloem (outside) and are surrounded by supporting tissue (aka ground/parenchymal tissue)
31
Herbaceous stems can be found in...
1. Monocots
- Vascular bundles are scattered throughout stem
- No vascular cambrium; does not grow wider
2. Herbaceous Dicots
- Vascular bundles form a ring around the stem
- Vascular cambium is only found in the rings of the vascular bundles to make new vascular tissue for secondary growth
32
Woody stems can be found in...
Woody dicots only
33
Secondary growth process
- Vascular bundles grow to make a ring around the woody stem
- Consist of a thin layer of tissue called vascular cambrium (type of meristematic cell) that founds between xylem and phloem and allows plants to develop woody stems aka bark
- Grow in width
- Produced new layer of vascular tissue referred to as secondary xylem and secondary phloem
34
Types of Woody Stems: Sapwood
- Young, functional xylem that transports water and dissolved minerals
- Growth of new xylem results in a layer of sapwood or annual rings being formed
- Age of tree
- Weather during the year xylem were produced
- Width of annual rings determine length of growing season
35
Types of Woody Stems: Heartwood
- Consists of mature, not hollow, dead cells that is unable to conduct water
- Provides structural support to the tree to prevent snapping
- Is the older xylem that is filled with oils, resins, and other chemicals
- This is because new xylem is created and pushes against the old xylem
- If not filled, would get crushed and the core would be weak
- The chemicals resist decay and gives heartwood a different colour
36
Stem Modifications
1. Store water for long periods of time (eg. cacti)
2. Form Rhizones
- Thick, fleshy stems that grow on or just below soil surface (underground)
- Vegetative propagation
- Can survive the winter because they have long roots
- eg. Iris, lilies, grasses
3. Form Tubers
- Modified for food storage
- Grow underground so it’s protected from winter
- Have “eyes” that are buds that grow into new shoots
- Vegetative propagation
- eg. Potatoes
4. Form Bulbs
- Grow underground
- Vegetative propagation
- Have small stems surrounded by layers of modified leaves
- eg. Tulips, daffodils, onions
37
Root Types: Taproot
- Main root that grows out of germinating seed and develops into a long, thick root
- Found in dicots
38
Root Types: Fibrous Roots
- Consists of many thin, thread-like, branching roots of the same size with many secondary and tertiary roots
- Found in monocots
39
Root Types: Modified Root
- Provide extra support for a plant to store food and water
40
Root Types: Adventitious Roots
- Grow from tissue other than roots, such as stems or leaves
| - eg. Corn grows roots on their stems to help support the plant
41
Root Structure: Root Hairs
- Formed by specialized epidermal cells
- Absorbs water and minerals from the soil
- Allows fast absorption by increasing surface area of the root
- Evolved this way because plants can’t walk to get water
42
Root Structure: Epidermis
- 1 cell layer thick; outermost layer of roots
- Protects inner cells of the roots
- Absorbs water and minerals from the soil
43
Root Structure: Cortex
- Increases layers within epidermis
- Stores sugars
- Helps transport water and minerals from the epidermal cells to the center of the root
- Actively transports minerals and water will follow by osmosis
44
Root Structure: Endodermis
- Specialized inner layer of the cortex
- Cells are coated with wax to form casparian band
- Wax is nonpolar; thus not soluble in water = waterproof
- Casparian Band: controls water movement by preventing water from moving between endodermal cells
- Actively transports minerals and water will follow by osmosis
45
Root Structure: Vascular Cylinder
- Contains plants’ vascular tissue (xylem + phloem)
- Once water has entered the vascular cylinder, it can’t move back into the cortex cells
- One way street: water is constantly coming in; hard to go against gradient created by active transport
- Xylem will take water from the cortex to stem to leaves
46
Leaves: functions
1. Make carbohydrates for the plant
2. Site of transpiration which evaporates the water molecules
3. Allow for gas exchange
4. Provide food and oxygen for other living organisms
47
Leaves Structure: Cuticle
- Waxy substance produced by the epidermis
- Acts as protective layer for inner cells
- Prevents water loss (wax is nonpolar, therefore water proof!)
- Transparent to let in sunlight
48
Leaves Structure: Epidermis
- Produces cuticle
- Protects inner cells of leaf
- No chlorophyll
- Transparent to let in sunlight
49
Leaves Structure: Palisade Mesophyll
- Thin cell walls made of parenchyma cells
- Closely packed
- Lots of chloroplasts for photosynthesis
50
Leaves Structure: Spongy Mesophyll
- Thin cell walls made of parenchyma cells
- Loosely packed
- Air spaces for gas exchange
- Fewer chloroplasts than palisade mesophyll
51
Leaves Structure: Veins
vascular bundles made up of phloem and xylem
52
Leaves Structure: Petiole
structure that connects blade of leaf to the stem
53
Identifying leaves?
1. Type
- Simple (1 part)
- Compound (multiple parts)
2. Arrangement
- Opposite (directly across on a stem)
- Alternate (staggered on a stem)
- Whorled (3+ leaves evenly spaced on a stem)
3. Leaf Venation: pattern of veins in a leaf
- Palmate (veins branch off common point)
- Pinnate (veins branch off central vein)
- Parallel (veins are all parallel to each other)
4. Shape
- Toothed (jagged)
- Lobed (smooth)
54
Hypertonic vs Hypotonic + always __ to something + end goal of osmosis
- Hypertonic: high solute, low solvent
- Hypotonic: low solute, high solvent
- Always relative to something
- To make water isotonic
55
Water Transport: Roots
- Tips of root hairs absorb essential minerals from the soil via active transport which needs energy provided by carbs stored in cortex
- Water moves from the soil into root hairs by osmosis (hypertonic)
- Bulk Flow: water then moves through cell wall (not cytoplasm because that is too slow) of the cells in the cortex
- Water reaches endodermal cells which are surrounded by casparian bands which forces water to cross cytoplasm
- Once the water crossed the endodermis, the casparian band prevents it from diffusing back into the soil
- Water moves into xylem located in middle of root
- The accumulation of water and minerals creates a pressure called root pressure
- Pushes sap up xylem
- Causes guttation where water droplets exude from leaves (aka transpiration)
- Can push 4m high
56
Water Transport: Stems
- Capillary Action: movement of water up the xylem of plant stems as a result of adhesion and cohesion
- Adhesion: attraction of water molecules to smooth, polar surfaces (such as xylem walls)
- Xylem can be very long (30m) but very thin (20 micrometers) which allows water to move up the narrow xylem very quickly
- Cohesion: attraction of water molecules to each other as a result of hydrogen bonds
- Cohesion of water molecules in long cylindrical xylem results in water column holding together continuously from the ground to tip of leaves
57
Water Transport: Leaves
- Transpiration: evaporation of water from stomata of leaves
- Most of water entering leaves is lost through this process
- Due to heat given off plant; determines rate of transpiration
- Transpirational Pull: occurs as water evaporates from the leaves
- Spaces between leaf cells are 100% saturated with water which, when the sun comes up and the stomata gradually opens for CO2, quickly transpires one water molecule after another
- Lost water is quickly replaced by water in mesophyll cells, one water molecule after another
- This lowers concentration of water molecules in mesophyll cells which is replaced by unbroken chohesive chain all the way up from the root hairs
58
Carbohydrate Loading def
movement of carbohydrates from the source to the sink in the phloem
59
Source def
areas in the plant where sugars are made (anyplace with chloroplasts)
60
Sink def
areas of the plant that depend on input of carbohydrates to meet their nutritional needs (ie. seeds, fruits, roots)
61
Pressure-Flow Theory: def
The carbohydrates move along a gradient of hydrostatic pressure between the source (high hydrostatic pressure) and the sink (low hydrostatic pressure)
62
Pressure-Flow Theory: steps
1. The manufactured sugars from the mesophyll cells in the leaves are actively transported into sieve tube cells; the energy comes from companion cells.
2. Solute concentration increases in source region of sieve tube (hypertonic) so water moves into the sieve tube from xylem by osmosis
3. This increase in water increases hydrostatic pressure and there is nowhere for the solution to go but away
4. Depending on the sink, sugars are unloaded from sieve tubes by passive OR active transport
5. Sieve tubes become hypotonic (high solvent) to the sink tubes, which causes water to move out of sieve tube cells and into the sink by osmosis
6. This decreases hydrostatic pressure in sieve tube at the sink region
Sink will always be sink because source is always making sugars and water will follow
63
Germination def
process by which seed begins to grow and develop into a plant
64
Hormones def
chemical compounds between cells and tissues
65
Plant hormones def
either stimulate or inhibate growth; interaction of plant hormones regulate growth of the plant
66
Factors affecting plant growth
- nutrients
- soil pH
- sunlight
- hormones (ethylene, abscisic acid, cytokinins, gibberellins, auxins)
67
Plant Growth: Auxin
- Stimulates upward growth of plants
- Inhibits growth of side branches
- Produced in region of plant called apical meristem
- Found at the root or shoot tips of a plant
- If you cut the apical meristem, you remove auxin which leads to growth of side branches
68
Plant Growth: Cytokinins
- Stimulates cell division by stimulating production of proteins needed for mitosis and cytokinesis
- Delays ageing of leaves and fruit
69
Plant Growth: Gibberellins
- Stimulate seed germination
| - Promote the growth of taller and stronger plants
70
Plant Growth: Ethylene
- Prevents further growth and causes ripening of fruit
| - Ripening is basically “ageing”; you stop growing
71
Plant Growth: Abscisic Acid
- Maintains seed dormancy
| - Kept in inactive form, stops germination (not right conditions)
72
Plant Growth: Trophism def + types
Plant’s growth response to external stimulus
1. Phototrophism: a plant’s growth response to light
2. Gravitropism: a plant’s growth response to gravity
73
Plant Growth: Nutrients
- Soil water is a source of dissolved nutrients
- Macronutrients: nutrients needed in large amounts (eg. nitrogen)
- Micronutrients: nutrients needed in smaller amounts (eg. Chlorine)
74
Plant Growth: pH
Plants grow well in a narrow range of pH (6-7)
75
Xylem: structure
- The cells align end to end for fluid passage
- Both cell types die at maturity, leaving only non-living cell wall
- Hollow
76
Xylem: types of cells
- Tracheids: found in xylem of all vascular plants
| - Vessel Elements: found in xylem of flowering plants only
77
Xylem: defs of transport
- Diffusion: net movement of particles from high to low concentration, until equilibrium is reached
- Osmosis: diffusion of water molecules
- These two processes occur naturally
- Active Transport: movement of sugars and other nutrients across cell membranes
- Through the consumption of energy
78
Phloem: cell types
1. Sieve Tube Elements: have plates at both ends with holes for nutrients to flow through
2. Companion Cell: associated with sieve tube and carries out life functions to maintain both cells
- Has a nucleus
79
Guard cells def
Specialized epidermal cells that surround a pore called stoma (stomata)
- Control the size of stoma;
- When guard cells are swollen, the pore opens allowing for gas exchange, photosynthesis, water diffusion out
- When guard cells are shrunken, the pore closes preventing loss of water (water does not come in this way)
80
Vascular Plant Body: Vascular Tissue
- Internal system of tubes that run lengthwise throughout the stem of the plant
- Connects roots and the leaves
- XYLEM and PHLOEM are types of vascular tissue
81
Vascular Plant Body: Dermal Tissue
- Outer covering of plant (aka skin in humans)
| - Epidermis: the single layer of dermal tissue that makes up plant’s outer covering
82
Vascular Plant Body: Meristematic Tissue
- Make up meristems
1) Apical Meristem: area found at root/shoot tips which grows longer
2) Lateral Meristem: increase width or roots and stems
a) Vascular Cambium: produces new vascular tissue
b) Cork Cambium: forms a protective layer on the outside of stems/roots
83
Vascular Plant Body: Ground Tissue
- Forms most of the inside of the plant
- Functions: photosynthesis, storage, support
- All 3 cell types make up this tissue
84
Vascular Plant Body: Sclerenchyma Cells
- Have thick secondary cell wall
| - Die at maturity however their thick rigid cell walls remain which helps support the mature plant
85
Vascular Plant Body: Collenchyma Cells
- Make up long celery strings; occur in long cylinders/strands
- Provide flexibility for plant, allowing it to bend without breaking
86
Vascular Plant Body: Parenchyma Cells
- Basis for many plant structures and capable of wide range of functions
- Flexible, thin walled, tightly packed together
- In leaves and stems: chloroplasts to carry out photosynthesis
- In roots and fruits: lack chloroplasts but have large central vacuole to store substances like water and starch (sugar so fruits are SWEET)
87
Germination: process
- When environmental conditions are right, seed will cease dormancy
- Imbibition: absorb water which activates enzymes, causing seed to swell
- Seed coat splits
- Emergence of radicle which develops into primary root
XBiology
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