Plant form and function (part 1) Flashcards
1
Q
Basic plant information
A
- Eukaryotic
- Most are multicellular but some are unicellular (green algae)
- Vast majority are photosynthetic providing much of the world’s O2 and chemical energy
2
Q
Plant Groups
A
- Non Vascular (bryophytes, green algae)
- Vascular
Seedless (Lycophytes and Pterophytes)
Seeded (Gymnosperms and Angiosperms)
3
Q
Differences between vascular and non-vascular plants
A
- Vascular have a material transport system
- Vascular plants have roots, non-vascular have rhizoids (tiny hairs that anchors the plant)
- Non-vascular plants are typically found in damp conditions
- Most non-vascular plants are asexual (spores) or vegetative propagation (budding)
4
Q
Plant origins
A
Non-Vascular
- Reflects evolutionary history colonizing land: direction diffusion of materials and rhizoids
Vascular
- Reflects evolutionary history as terrestrial
organisms that draw resources from within the ground and air
5
Q
Roots
A
- Anchors plant into soil
- Absorbs minerals and water
- Requires carbohydrates from stem, can store starches
- Primary root = radicle: originates in embryo, first root to emerge, branches lateral roots
Two Main systems:
1. Taproot: On main vertical root (stability) and lateral roots (carry out most of the absorption. PROS: increased height, CONS: costly
2. Fibrous root: Consists of many smaller roots emerging from the stem. Primary root dies and is replaced. PROS: easier to grow, more difficult to kill, CON: not tall
Specialized roots:
1. Prop Root
2. Aerial Root
3. Pneumatophores Roots
4. Green Roots
6
Q
Stem
A
- Requires water and minerals from roots
- Raised and separate leaves; exposing them to sunlight
- Raised reproductive structures, facilitating
dispersal of pollen and fruit
*Consist of an alternating system of: - Nodes: where leaves grow
- Internodes: space between nodes
- Apical bud: Location where shoot
growth occurs - Axillary bud: Precursor of a branch or
lateral shoot at the junction between the stem and a leaf
Specialized underground stems:
1. Bulb
2. Stolon/Rhizome
3. Tubers
7
Q
Leaves
A
- Main photosynthetic organ
- A flattened lamina (blade) with specialized cells that contain chloroplasts for photosynthesis
- A petiole: stalk that attaches the leaf blade to the stem at the node
8
Q
Dermal tissue
A
- Tissue that covers and protects plant: damage, water loss, gas exchange
- Thin epidermis, waxy cuticle, specialized guard around stoma or cork cells
9
Q
Vascular tissue
A
- Transports food, water, hormones and minerals between roots and shoots
- Provides structural support
- Xylem: minerals and water, dead, root to shoots (upwards), one direction, negative pressure, center of vascular bundle, + lignin
- Phloem: sugars, living, from leaves to where it needs to be, unidirectional, turgor pressure, outside edge of vascular bundle, transports amino acids, mRNA and hormones
10
Q
Ground tissue
A
- Parenchyma: filled tissue, spongy
- Collenchyma: growing support, high in cellulose
- Sclerenchyma: main support, high in lignin; dies after it matures
- Pith: internal to vascular tissue
- Cortex: external to vascular tissue
11
Q
Parenchyma cells
A
- Forms the cortex in roots, the pith and cortex in stems, the mesophyll of leaves, the pulp of fruits
- Living cell that perform most metabolic functions, e.g., most photosynthesis occurs in these cells
- Stores starches in stem and roots
12
Q
Collenchyma cells
A
- Elongated cells with thick primary cell walls (↑ cellulose or pectin)
- Often found under the epidermis, or the outer layer of cells in young stems and in leaf veins
- Living polyhedral cells that support young parts of the plant shoot (elongate with the stems and leaves as they grow)
*Affected by mechanical stresses
13
Q
Sclerenchyma cells
A
- Also act as supporting cells, but are much more rigid than collenchyma cells
- Often occur in regions of the plant that have stopped growing
- Dead at maturity (but rigid walls remain as a ‘skeleton’ that supports the plant)
14
Q
Xylem cells
A
- Two types: tracheids and vessel elements; both tubular, elongated cells
- Thick cell walls that allow water to flow (dead at maturity)
15
Q
Phloem cells
A
- Sieve cells or also called sieve tube elements
- Alive at maturity, but lack nucleus, ribosomes, vacuole, cytoskeletal elements to allows for more room for nutrients to pass through
*Connected by sieve plates
