Unit 4- Plant Tissues Flashcards
1
Q
What is division of labour?
A
Specialization of cells to carry out a specific function
- tissues are structurally adapted to perform a specific function
2
Q
What is an organ?
A
Many tissues grouped together to form a structure with a specific function
3
Q
What is an organ system?
A
Groups of organs with closely related structures working together to perform a specific function
4
Q
What is meristematic tissue?
A
- Actively dividing cells forming new cells through mitosis
- Cells are not yet differentiated/ specialized to perform a specific function
- Found in growth regions of plant: root, stem + shoot
5
Q
What is permanent tissue?
A
- Derived from meristematic tissue
2. Result of cell enlargement + cell differentiation ( has a specific function)
6
Q
What is simple tissue?
A
- Cells of the same type
- Perform the same function
- parenchyma, sclerenchyma, collenchyma
7
Q
What is complex tissue?
A
- Cells of different types
- Perform more than one function
- epidermal tissue, vascular tissue
8
Q
What is the structure of apical meristems?
A
- Small + cubic
- Thin- walled
- Large, prominent nucleus
- Dense cytoplasm
- No vacuoles
- No intercellular spaces
9
Q
What is the function of apical meristems?
A
Primary growth
- increase in stem and root length
10
Q
Where are apical meristems found?
A
Tips of roots and shoots
11
Q
Where are lateral meristems found?
A
- Sides of roots ad stems
2. Cambium- found between xylem and phloem in vascular bundles
12
Q
What is the structure of lateral meristems?
A
- Long and flattened
- Thin-walled
- Large, prominent nucleus
- Dense cytoplasm
- Numerous small vacuoles
- No intercellular spaces
13
Q
What is the function of lateral meristems?
A
- Secondary growth- increase in width of plant
- Vascular cambium- produce xylem + phloem
- increase diameter of stems
and roots in perennials - Cork cambium- thick layer of bark in stems
14
Q
Where is epidermal tissue found?
A
• covers the surface of a plant organ
15
Q
Structure of the epidermal cell?
A
- Thick outer wall
- Only 1 cell layer thick
- Tightly packed together
- May be modified
- stomata of leaves
- root hairs of roots
16
Q
What are the functions of epidermal tissue?
A
- Protection of plant organs from desiccation & physical damage
- Produces cuticle layer- prevents plant from losing water through transpiration
- Single, transparent layer without chloroplasts
- allows light to penetrate mesophyll tissue
17
Q
What is stomata?
A
- Tiny opening on a leaf
- Formed by guard cells ( modified epidermal cells)
- Found mainly in lower epidermis of leaves
18
Q
Structure of stomata?
A
- Unevenly thickened walls
- inner (ventral) thicker than outer (dorsal) wall - Chloroplasts - not transparent
- Stoma- pairs of bean shaped cells
- Stomata like pore
19
Q
Function of stomata?
A
- Regulates/ controls gaseous exchange + transpiration by opening and closing of he stomata like core
20
Q
Where are root hairs found?
A
Roots
21
Q
Structure of root hairs?
A
Unicellular outgrowths
22
Q
Function of root hairs?
A
Outgrowths- increase surface area for water absorption
23
Q
Where is parenchyma tissue found?
A
- In all plant organs
- pith + cortex of stem
- roots
- mesophyll of leaves - Forms bulk of leaves
24
Q
What is parenchyma tissue?
A
- Simplest type of living tissue
- Living cells
- Basic tissue of plants
- Can be elongated in one plane
- e.g. Palisade cells in leaf
• aerenchyma- parenchyma tissue of plants growing in waterlogged soils
• chlorenchyma- parenchyma cells with chloroplasts
25
What is the structure of parenchyma tissue?
1. Large vacuoles when mature
2. Thin permeable cellulose walls
- lateral movement of water and minerals
3. Large intercellular airspace = loosely packed
- allow for gases (CO2 & O2) to circulate
4. Isodiametric
- sponge cells
26
Function of parenchyma tissue?
1. Packing tissue- fills spaces between other tissues
2. Storage tissue- stores water/ sugar/ starch in roots, stems or leaves
3. Intercellular air spaces store gases for photosynthesis + respiration
- spaces allow water to pass through
27
What is a tissue?
A group of specialized cells with similar structures which perform one or more specific functions
- can be made from same cells or different cells
• Parenchyma= ground tissue vs xylem +phloem= vascular tissue
28
What is chlorenchyma tissue?
1. Specialized parenchyma cells with chloroplasts
2. Contains chloroplasts for photosynthesis
3. Forms bulk of leaves
29
What is the function of chlorenchyma tissue?
1. Palisade mesophyll cells: many chloroplasts for photosynthesis
2. Spongy mesophyll cells: many airspaces allowing gaseous exchange
30
What is collenchyma tissue and where is it found?
1. Supporting tissue made up of living mature cells
2. Found in young herbaceous stems under epidermis of leaves and stems
&
3. In young herbaceous cells
31
Structure of collenchyma tissue?
1. Unevenly thickened cell walls
- corners thicker than rest of cell wall
2. Adapted for support of growing organs = flexible thickenings
- good strengthening- as it strengthens, it allows other tissues to grow
3. 2 structural differences between it and parenchyma:
• it is longer
•unevenly thickened
32
Function of collenchyma?
1. Mechanical strengthening
2. Support
3. Protection
Of leaves and stems
33
What is sclerenchyma tissue and where is it found?
1. Tissue made up of dead mature cells
| 2. Found in fruits, seeds, stems and leaves of plants
34
Structure of sclerenchyma?
1. Evenly thickened wall formed by cellulose and lignin secreted by protoplast
2. Has lumen which formed by a gap left by dead protoplasm
- the lignin is impermeable to water, therefore the cell contents die
35
Function of sclerenchyma?
1. Strengthening
| 2. Protection
36
What are sclerenchyma fibers and where are they found?
1. Cannot undergo mitosis
- when mature their protoplast a disappear
2. Occur in groups
3. Common in vascular tissue where elongation has stopped
4. Found in xylem and phloem
5. Found in leaves, stem, root and fruit
37
Structures of sclerenchyma fibers?
1. Elongated
2. Pointed tips
3. Narrow lumen
4. Lignified cell walls
5. Tapered end walls which interlock
6. Tough & strong but flexible
7. Elastic- able to stretch a lot and return to its original length
38
Function of sclerenchyma tissue?
1. Strength
2. Support
3. Protection
Especially in vascular bundles
39
Economic importance of sclerenchyma fibers?
1. Jute
2. Flax
3. Sisal
Make
1. Rope
2. Twine
3. Linen
40
Where are sclereids found?
1. Protective outer coverings of seeds
2. Cortex of stems
3. Hard shells of fruits
41
Structure of sclereids?
1. Not elongated
2. Various shapes
3. Thick, Lignified cell walls
4. Prominent pits
5. Heavily Lignified cell walls
- lumen may be small/ completely filled in by cell walls
42
Function of sclereids?
1. Strength
2. Support
3. Protection
In fruits and nuts
43
Difference between collenchyma and sclerenchyma cells?
Collenchyma. Sclerenchyma
Cell. •flexible. •strong
Wall. • non-Lignified •hard & rigid
•Lignified
Proto- •living •none (mature)
Plasm. • able to divide through. •more permanent
Mitosis. •incapable of cell
division
44
What is permanent compound tissue?
1. Composed of more than 1 type of cell
45
Function of vascular/ conducting tissue?
1. Conduct substances in liquid form
46
What are vascular bundles?
1. Xylem & phloem
2. Discrete structures in plant stems
3. Can also include cambium
47
Function of xylem?
1. Transports water & dissolved mineral salts from roots to stem
2. Strength
3. Support
48
Where is xylem found?
In vascular bundles of roots, stems and leaves
49
Structure of xylem?
1. Unevenly thickened with lignin
| 2. No cross walls/ perforated cross walls
50
What are xylem vessel elements and where are they found?
1. Non-living mature vessels (protoplasm dies)
| 2. Found in xylem tissue of roots stems and leaves
51
Xylem vessel structure?
1. Elongated cylindrical cells
2. Long tubular structure
3. Perforated cross walls
- join end to end to for long tubes
4. Cell walls thickened by lignin
5. Have pits for lateral transport of water
52
Function of xylem vessels?
Primary
1. Most important cell for transport of water & mineral salts from roots to plant
- form continuous hollow conducting tubes for rapid transport of mineral solutes.
Secondary
2. Strength & support ( due to its thickened cell walls
3. Forms wood in woody plants
53
What is a reached and where is it found?
1. Non- living mature cell
| 2. Found between xylem tissues- roots, stems and leaves
54
Structure of a xylem tracheid?
1. Elongated, spindle shaped
2. Tapered ends which overlap
3. Non- perforated cross walls
4. Cell walls thickened by lignin
5. Do not form continuous tubes
6. Pits- lateral transport of water
55
Function of tracheid? (Xylem)
1. Part of translocation of water and dissolved mineral salts from roots to parts of plants
2. Strength & support (due to its thickened cell walls)
56
What is xylem parenchyma?
• found between xylem vessels & tracheids within xylem tissues of roots stems and leaves
1. Store various substances
57
What are xylem fibers?
• between xylem vessels and tracheids within xylem tissue of roots stems and leaves
• xylem fibers ARE sclerenchyma fibers
1. Strength & support
- esp. In stems & branches
58
What is phloem and where is it found?
1. Conducts food substances such as glucose from leaves ( where photosynthesis takes place) to storage organs & growing regions
• found in vascular bundles of roots, stems and leaves
59
What are sieve tube elements and where are they found?
1. Living cells when mature
| 2. Found within phloem tissues of roots, stems and leaves
60
What is the structure of sieve tubes?
1. Elongated + cylindrical
2. Outside lined with cytoplasm (thin layer)
- very large vacuoles
3. Thin primary cellulose walls
4. No nuclei + most organelles
5. Metabolically active
6. Pits with plasmodesmata
7. Perforated cross walls
- between mature individual cells
- highly perforated=form sieve plate
- sieve pores= pores in plates
61
Function of sieve tubes?
1. Most important cells for translocation of dissolved organic food from leaves to aerial and other parts of plants
62
What is the companion cell and where is it found?
1. Controls function of sieve tube
| 2. Next to sieve tubes + phloem tissue of roots, stems + leaves
63
What is the structure of companion cells?
1. Highly modified parenchyma cells
2. Relatively small
3. Thin cell wall
4. Large nucleus
5. Pits with plasmodesmata
64
What is the function of the companion cell?
1. Role in translocation of food
| 2. Nucleus of companion cell controls metabolic activities of surrounding sieve tubes
65
What is phloem parenchyma?
1. Found in phloem tissue of roots, stems and leaves
| 2. Stores various substances
66
What are phloem fibers?
1. In phloem tissue of roots, stems and leaves
2. Phloem fibers= sclerenchyma fibers
3. They give strength and support, especially in stems and branches
