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58 Cards in this Set
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Collects solar energy and CO2 for photosynthesis Gaseous exchange Specialized functions |
Functions of leaves |
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Leaves |
They are the principal structure produced on stem where photosynthesis takes place. |
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Cacti |
They have leaves reduced to spines and its thick greeb, fleshy stems are where photosynthesis takes place. |
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Flattened blade |
General form of a leaf |
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The base of the leaf forms a sheath that envelops the stem |
What happens to the leaf when there is no petiole? |
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Monocot |
They have parallel vein leaves |
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Dicot |
Leaves have a multi branched network of major veins |
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Apex Margin Axillary bud Stipule Stem Petiole Base Midrib Veins Veinlet |
External anatomy of stem |
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Phyllotaxy |
Arrangement of leaves on a stem |
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Opposite Alternate/ Spiral Whorled Basal |
What are the different arrangement of leaves on a stem? |
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Opposite (maple) |
2 leaves at a node, on opposite sides of the stem |
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Alternate (or Spiral- Willow) |
1 leaf per node with second leaf being above the first but attached on the opposite side of the stem |
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Whorled (Catalpa) |
3 or more leaves |
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Leaf shape Spatial arrangement of leaves Patter of veins |
How do Plant Taxonomists identify and classify plants? |
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Simple leaves |
They have a single, undivided blade |
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Compound leaves |
They have several leaflets attached to the petiole. It has a bud where its petiole attaches to the stem, not at the base of the leaflets |
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Pinnately Compound Leaves Palmately Compound Leaves |
2 leaf types |
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Evenly Pinnate Oddly Pinnate Trippinate/ Trifoliate |
Types of Pinnately Compound Leaves |
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Pinnately Compound Leaves |
row of leaflets forms on either side of an extension of the petiole called the rachis |
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Palmately compound leaves |
the leaflets radiate from a single point at the distal end of the petiole Ex. Cannabis, cassava |
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Pechat Australia Dagmay Celery Lettuce Mangga Mayana |
Examples of simple leaves |
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Pinnate |
May leaflet |
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Venation |
Arrangement of veins in a leaf |
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Netted- venation (pinnately-veined or palmately-veined) Parallel venation Dichotomous venation |
Types of Venation |
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Netted-venation |
One or a few prominent midveins from which smaller minor veins branch into a meshed network |
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Pinnately-veined leaves |
Have a main vein called the midrib with secondary veins branching from it (e.g. elm) |
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Palmately-veined leaves |
Veins radiate out of base of blade (e.g. maple) |
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Parallel venation |
Veins are parallel to one another.
Characteristics of many monocots (grasses, cereal grains) |
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Dichotomous venation |
No midrib or large veins; Rather individual veins have a tendency to fork evenly from the base of the bladr to the opposite margin, creating a fan-shaped leaf Ex. Ginkgo |
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Monocot |
Its leaves are linear and no midrib |
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Dicot |
It has branch-like veins & palmate leaf shape |
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Cuticle Upper epidermis Palisade mesophyll cell Spongy mesophyll cell Lower epidermis Cuticld |
Internal structure of leaves |
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Cuticle |
Outermost layer of the upper and lower surfaces of the leaf. It is clear and waxy to prevent against water loss. |
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Epidermis |
Layer of cells one cell thick that provides protection for the inner tissues. Allow light to reach photosynthetic tissues |
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Palisade mesophyll cell |
Tightly packed, and filled with numerous chloroplasts for photosynthesis |
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Spongy mesophyll cell |
Irregularly shaped, have large air between spaces between them, and fewer chloropolasts. Contains the veins (vascular bundle +xylem and phloem) |
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Stomates |
Openings in the surface of the leaf and stems for gas exchange. Lower surface has more stomates Water vapor also passes out through these holes |
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Guard cells |
Surround the stomata that regulate the opening and closing of the stomata |
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Veins |
Contains vascular tissues Inside the spongy mesophyll cell |
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Photosynthesis Gaseous exchange |
Functions of Leaf |
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Respiration |
In this process, leaf takes in oxygen and releases CO2 at night |
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Photosynthesis |
In this process, leaves take in CO2 and releases oxygen (morning) |
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Transpiration |
Water vapor can be lost from the surface of the leaf |
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90% |
How many water is evaporated fron the plants? |
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The size of the opening of the stomated |
The rate of transpiration is regulated by.... |
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There is little water available, Temperature is low There is little light (closed @ night) |
Stomates are usually closed when.... |
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True |
Stomates are open during the day. |
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Guard cells |
Specialized epidermal cells Regulate the opening and closing of stomataa |
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Stomatal control |
Regulates water loss in plants and the rate of CO2 uptake.
Needed for sustained CO2 fixation during photosynthesis |
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True |
Plant can avoid dehydration by closing its stomata through the guard cells |
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Antocyanin |
Violet-pigment |
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Guard cells |
Kidney-shaped with thick inner walls and thick outer walls
They bow outwards that causes the stomate to open when they beocme full of water (turgid) |
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Osmosis |
Guard cells gain and lose water by.... |
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Guard cells |
Act as hydraulic valves They can sense light intensity, temperature, relative humidity, intercellular CO2 concentration |
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Bulliform cells |
Enlarged epidermal cells |
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Transpiration ratio |
Effectiveness of controlling water loss and allowing CO2 uptake for photosynthesis |
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CO2 is a larger molecule than watee |
Why does CO2 diffuses 1.6 times slower than water? |
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Abscisic acid |
A hormone that induces closure of stomata during water stress More of this hormones in desert plants |
