Unit 2: Tissues Flashcards
plant tissues
composed of cells that are similar and perform a specific function.
group cells
tissues
organs
organ systems
plant tissue system
- dermal tissue
- epidermis
- periderm - ground tissues
- vascular tissue
transpiration, gas exchange and defense.
dermal tissue (skin)
- covers roots, stems, leaves, and fruits
- at the outer surface of the epidermal cells is a continuous layer (cuticle) made up of fatty material (cutin)
- Sometimes overlaid with a protective, waterproof coating of wax. Oil, resin, and salt crystals may also be deposited on the surface
___________: specialized epidermal cells, control air exchange (CO2 and O2) and water loss from plants
epidermis
stomata
functions of epidermis
- mechanical support
- protection from desiccation (drought) and against attack by virulent pathogenic organisms and insects
- gas exchange
- restriction of water loss by evaporation (transpiration) through stomates and water and mineral storage
formed during secondary growth replacing primary epidermis
periderm
cork
cork cambium
phelloderm
- inner to the dermal tissue and is compose of simple tissue like parenchyma
- store molecules (such as starch), photosynthesize (such as mesophyll cells), or support the plant.
- three types of ground tissue:
ground tissue
collenchyma, sclerenchyma, parenchyma
- consist of conducting elements xylem and phloem
- may be scattered in ground tissue or irregularly arranged forming a ring.
- in the latter arrangement, ground tissue is differentiated into _______ (outer to vascular tissue) and _____ (inner to vascular tissue)
- the ground tissue if leaves are called ________, bound by upper and lower epidermis
vascular tissue
cortex
pith
mesophyll
- plumbing system of the plant.
- allows water, minerals, and dissolved sugars from photosynthesis to pass through roots, stems, leaves, and other parts of the plant.
- It is primary composed of two types of conducting tissue: _______ and _______.
- veins on leaves
- xylem and the phloem form a structure called a ____________; in roots, this is termed the ____________ or ____________.
vascular tissue
xylem and phloem
vascular bundle
vascular stele or vascular cylinder
types of plant tissues
A. Meristematic (3)
B. Permanent
i. Simple
*parenchyma
-
-
+
+
*collenchyma
*sclerenchyma
-
-
ii. Complex
*xylem
-
-
*phloem
-
-
-
A. Meristematic
- apical
- intercalary
- lateral
B. Permanent
i. Simple
*parenchyma
- aerenchyma
- chlorenchyma
+ palliside
+ spongy
*collenchyma
*sclerenchyma
- fibers
- sclereids
ii. Complex
*xylem
- vascular cells
- bordered
*phloem
- sieve cells
- sieve-tube elements
- companion cells
-These are actively dividing cells, which are isodiametric in shape, rich in cytoplasm with small or no vacuoles.
-These cells consist of undifferentiated cells that are found at shoot tips, at root tips, in the vascular cambium, and in the cork cambium.
- differentiate into specialized tissues of three systems: dermal, ground, and vascular.
- plant regions of continuous cell division and growth.
______________ consists of plant cells that are no longer actively dividing.
meristematic
permanent tissue
- found at the tips of stems and roots and is responsible for primary growth e.g. plant length
apical meristems
- found at the basal portion of internodes and is responsible for the elongation of internodes in Poaceae members
- occur only in monocots, at the bases of leaf blades and at nodes (the areas where leaves attach to a stem). This tissue enables the monocot leaf blade to increase in length from the leaf base; for example, it allows lawn grass leaves to elongate even after repeated mowing.
intercalary meristems
- found at the vascular and cork cambium and is responsible for secondary growth
- facilitate growth in thickness or girth in a maturing plant.
lateral
- Tissues contain cells of similar structure, function and have common origin
simple permanent
- the fundamental tissue found in every part of the plant body like pith and cortex of the stem and root, mesophyll of leaves, flesh of fruits, floral parts and even in xylem and phloem
– involved in storage of starch, sucrose, protein, water, phenol derivatives and many mineral substances
– there is active respiration and protein synthesis
- usually thin-walled and vary in shape from spherical with many flat surfaces, to elongated, lobed, or folded
- compactly arranged or more commonly spaciously arranged with intracellular spaces as in cortex and pith
- cells possess dense cytoplasm and are active metabolites
parenchyma
- Intracellular spaces filled with air, are large in size and many in number
- Cells occupy a smaller area but provide the required strength to aquatic plants (for aeration and buoyancy)
aerenchyma
- Parenchyma cells that contain numerous chloroplasts, seen in leaves and sometimes in young shoots
__________: elongated and compactly arranged
__________: spaciously and irregularly arranged
chlorenchyma
pallisade
spongy
- cell walls are thickened due to deposition of pectin, narrower than parenchyma
- provide elastic support to stems & leaves due to variously thickened primary walls containing cellulose, hemicellulose, pectin & water
- usually found near the surface in the cortex around vascular bundles of leaf petioles and stems.
- primary supporting tissue in stems, leaves and floral parts of dicots, whereas in stems and leaves of monocots collenchyma is usually absent (instead, sclerenchyma is present in monocots)
- living supportive tissue that has elongated cells and an unevenly thickened primary cell wall.
- main function is the mechanical support of young stems and leaves via turgor.
collenchyma
- function in mechanical support due to thick lignified secondary walls, which contain large amounts of cellulose and lignin
- dead supportive tissue that consists of longsclerenchyma fibersor short, crystal-like.
- fibers occur in groups (bundles).
- may be branched or not and occur individually or in small clusters.
- Each cell has a uniformly thicksecondary wallthat is rich in lignin.
- main function is a support of older plant organs, and also hardening different parts of plants (for example, make fruit inedible before ripeness so no one will take the fruit before seeds are ready to be distributed).
- Fibers inside phloem are sometimes regarded as a _________________
sclerenchyma
separate sclerenchyma
- usually long and spindle shaped structures with tapering ends (with pits)
- found in water-conducting tissue (xylem) and food-conducting tissue (phloem) along leaf veins and margins, and surrounding vascular bundles in stems
fibers
- shorter than fibers that occur singly or in groups
- commonly found in fruit wall, seed coat, epidermal scales and occasionally found in cortex, pith and mesophyll
- known types are the asterosclereids, macrosclereids, osteosclereids and brachysclereids
sclereids
3 basic types of plant tissues
_____________: cell walls
_____________: intracellular spaces
_____________: cell walls within lignin
collenchyma tissue
parenchyma tissue
sclerenchyma tissue
- Cells that are grouped here are of various types in their structure, shape and function, and have different origin, but together, they perform a common function like vascular and secretory tissues
Complex or Vascular Tissue or conducting tissues
Xylem (Water-conducting tissue)
- tracheary elements
- composed of tracheids
- vessel elements (which conduct water and nutrients)
- fibers (which provide support)
- living parenchyma cells (which store food)
- sclereids may also be present
- cells of the xylem tissue, _________, are elongated, have bordered wall pits for water conduction, and are aligned side by side
- also, water- and mineral conducting cells of the xylem, namely, the ______________, have bordered pits in their cell walls
- the vessel elements are aligned end-to-end to form long tubes
- the xylem sap passes vertically through the vessel elements via end perforations that may be parallel slits or a single large opening
vascular cells
tracheids
vessel elements
- the primary walls of tracheids and vessel elements have depressions called primary pit fields.
- when secondary walls are formed, the bordered holes (pit apertures) consist of a pit chamber and a pit membrane
bordered pits
- composed of sieve elements of sieve cells or sieve tube elements for food conduction, fibers, and parenchyma cells
- companion cells are associated with sieve tube elements
- latex-producing cells (laticifers) and sclereids may be present
Phloem: Food-conducting Tissue
- found in the phloem of conifers and primitive vascular plants such as ferns.
- elongated and thin-walled.
- (and associated albuminous cells) are the ancestral sugar-conducting cells and are found in all nonflowering vascular plants.
- long elongated cells found in gymnosperms and other seedless vascular plants.
sieve cells
- found in more advanced flowering plants. Both sieve cells and sieve-tube elements form long end-to-end columns called ___________
- ___________, consisting of primary pit fields, occur in the end walls of sieve tube elements
- short specialised cells that are found only inangiosperms.
Sieve-tube elements
sieve tubes
sieve plates
- a specialized type of parenchyma, may be present in varying numbers in association with sieve tube elements.
companion cells
Tissues that may occur in different parts of the plant but still have a common function which is to secrete substances
SECRETORY STRUCTURES
large cells containing a wide variety of substances such as oils, tannins, resins and mucilages
secretory cells
hairs which secrete fragrant volatile oils
trichomes/glandular hairs
tissues that secrete water via a process called guttation (occurs through modified stomata that are always
open)
hydathodes
- secretory structures that contain latex (is actually cytoplasm containing a mixture of different substances plus rubber) or alkaloids
ex. Euphorbia, poinsettia and dandelion plants (white latex);
laticifers
- many sided (14 common); thin primary walls, living at maturity
- throughout the plant; most common type of cell and tissue
- most metabolic processes; storage, wound healing, and regeneration
PARENCHYMA TISSUE
parenchyma
- elongate; primary wall unevenly thickened (thicker in corners); living at maturity
- in patches near outside of stems, along veins of leaves; example: “strings” in celery
- support of young growing plant (primary plant body); flexible support for soft organs
COLLENCHYMA TISSUE
Collenchyma
- cuboidal, with thick secondary wall; either living or dead at maturity
- throughout the plant; example: the gritty texture of pears
- ## form hard layers of shells (as in peanuts) and pits of fruit (such as peaches); occur in small groups around wounds
- long with lignified thick secondary wall; usually dead at maturity
- associated with xylem and phloem; example: “strings” in leaves of grasses
- support; storage
SCLERENCHYMA TISSUE
- Sclereid
- Fiber
- specialized, e.g. open and close stomata; cutinized outer walls; alive at maturity; leaf epidermal cells transparent, without
- outer layer of primary plant body, herbaceous plants; broken and lost in secondary body development
- protection; usually a single layer of cells; root hairs are out-growth of epidermal cells
EPIDERMIS
Parenchyma, guard cells, trichomes (hairs),
- living cork cambial cells produce heavily suberized cork cells that are dead at maturity
- bark of woody plants; first layers beneath the epidermis, later layers deeper; many cork cambia, not a single cylinder like vascular cambium
- protection for older stems and roots; replaces epidermis
PERIDERM
Parenchyma, cork cells, sclereids, cork cambium
- elongate, lignified secondary wall with pits; dead at maturity; end walls with perforations
- throughout the plant; elements lined up end to end form a vessel in xylem
- conduct water and minerals; secondary walls add strength and support to plant body; principal cell type of angiosperm xylem
- long, tapering with lignified walls; have pits, but no perforations; dead at maturity
- in xylem throughout the plant
- principal water and mineral conducting element in gymno-sperms and seedless vascular plants; of secondary importance to vessels in angiosperms
+ thin walled, living parenchyma and elongate, dead fibers are accessory storage site
+ in xylem throughout the plant
+ parenchyma: storage, repair; fibers: strength and non-conducting support
XYLEM
- Vessel element
- Tracheid
+ Parenchyma, fibers
- elongated; primary wall only; sieve areas on end walls called a sieve plate; living at maturity but lack a nucleus
- in phloem throughout the plant; elements lined up end to end form a sieve tube
- conducts dissolved carbohydrates and other foods in ngiosperms
- living with variable, usually elongated shape; primary wall only; connected by plasmodesmata to sieve-tube elements
- in phloem throughout the plant; derived from same mother cell as sieve-tube element
- apparently sends ATP and signal substances to the enucleate sieve-tube elements thus controlling cellular metabolism of the sieve tube elements in angiosperms
+ elongated and tapering, living at maturity; primary cell wall with sieve areas; lacks a nucleus; cytoplasmn with much tubular endoplasmic reticulum
+ in phloem throughout the plant
+ conducts dissolved carbohydrates and other foods in gymnosperms
PHLOEM
- Sieve-tube elements
- Companion cells
+ Sieve cell
- Refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules
- The regulation of passage through the membrane is due to selective membrane permeability - a characteristic of biological membranes which allows them to separate substances of distinct chemical nature
permeable materials: ___________
non-permeable materials: __________
transport mechanisms
H2O, CO2, O2, NH3, cholesterol
ions, mid to large polar molecules, amino acids, proteins and polysaccharides
2 categories of transport mechanism
passive active
____________: Do not require the cell to do work for the substance to enter or leave the cell
- Instead the energy involved comes from the kinetic energy of the molecules in solution
3 types:
passive
a. Simple diffusion
b. Osmosis
c. Facilitated diffusion
_________: Involve the cell to use cellular energy usually in the form of ATP to power special protein pumps
active
a. Active transport
b. Filtration
c. Exocytosis
d. Endocytosis
- Phagocytosis
- Pinocytosis
- The movement of molecules (solutes) from an area of a higher concentration to an area of lower concentration; a very slow process but may be an effective transport mechanism across microscopic distances
diffusion
Factors affecting Rate of Diffusion:
- Agitation
- Temperature
- Size of particles
- Molecular weight of particles
- Concentration gradient
Movement of water (solvent) from an area of higher concentration to a lower concentration through a semi-permeable membrane
osmosis
types of solution
hypotonic solution (bloat)
isotonic solution
hypertonic solution (shrinkage)
a type of passive transport that allows substances to cross membranes with the assistance of specialtransport proteins
Facilitated Diffusion
- Requires ATP to move molecules (solutes) from an area of lesser concentration to an area of greater concentration
- Observes a movement against concentration gradient
Active Transport
- The process of filtration also requires energy, but the energy does not come directly from ATP, instead, mechanical pressure
- Water and dissolved materials are forced through a membrane from an area of higher pressure to lower pressure
filtration
- a process by which cells absorb molecules (such as proteins) by engulfing them.
- It is used by all cells of the body because most substances important to them are largepolarmolecules that cannot pass through thehydrophobicplasma or cell membrane.
endocytosis
2 types of endocytosis
phagocytosis
pinocytosis
- The mechanism used by many protists (e.g. amoeba) to acquire nutrients
- In humans and other multicellular animals phagocytosis is an important defense mechanism against infection
phagocytosis
Processof taking in fluid together with its contents into the cell by forming narrow channels through its membrane that pinch off into vesicles, and fuse with lysosomes tha hydrolyze or break down contents
pinocytosis
- is the durable process by which a cell directs the contents of secretory vesicles out of the cell membrane.
- These membrane-bound vesicles contain soluble proteins to be secreted to the extracellular environment, as well as membrane proteins and lipids that are sent to become components of the cell membrane.
exocytosis
