Cells & Tissues of the plant body Flashcards
What is a cell?
is the smallest unit of life that can replicate independently
What is a plant tissue?
groups of cells that are structurally and/or functionally distinct.
What is primary growth?
Initiated by the apical meristems and primarily involved with extension of the plant body— often the vertical growth of a plant
What is secondary growth?
thickens the stem and root, results from
the activity of lateral meristem
What is the meristem?
The tissue in most plants containing undifferentiated
cells.
It is found in zones of the plant where growth can take place.
What are apical meristems?
Meristems (tissue of undifferentiated cells) that are:
- Found at the tips of all roots and stems
- Involved primarily with extension of the plant body
What are “initials” cells?
Cells that maintain the meristem by providing a constant source of new cells
What are “derivative” cells?
New body cells derived from initials
What benefit is there to using apical meristem culture to produce new plants?
They are a virus free segment of the plant, therefore if original plant is viral, this will produce genetically identical yet virus free.
What are the 3 primary meristems and the primary tissues they supply?
Protoderm –> Epidermis
Ground meristem –> Ground tissues
Procambium –> Primary xylem and phloem
What does plant growth involve?
- cell division and enlargement
- irreversible increase in size
What is morphogenesis?
Plant development to assume a particular shape or
form.
Involves the expansion of tissue which is then followed by another event called ‘differentiation’
What is differentiation?
Cells change to specialise
Differentiation begins during cell enlargement
The fate of a plant cell is determined by its final position in the developing organ
What is a simple tissue?
Composed of only one type of cell
What is a complex tissue?
Composed of two or more cell types
What are the 3 tissue systems?
-The ground (or fundamental) tissue system
-The vascular tissue system
-The dermal tissue system
What is the ground tissue system comprised of?
Parenchyma,
Collenchyma and Sclerenchyma
What is the ground tissue system comprised of?
Parenchyma,
Collenchyma and Sclerenchyma
What is the ground tissue system comprised of?
Parenchyma, Collenchyma and Sclerenchyma
What is the ground tissue system comprised of?
Parenchyma, Collenchyma and Sclerenchyma
What is the ground tissue system comprised of?
Parenchyma,
Collenchyma and Sclerenchyma
What is a parenchyma cell?
They:
- Variable in shape and size
- Capable of cell division
- Occur as continuous masses (e.g. in the cortex and pith)
- have primary walls, some parenchyma cells also have secondary walls
- Have the ability to become embryonic cells and to develop into an entire plant
- Involved in Photosynthesis, Storage, and Secretion
What is a collenchyma cell?
They:
- are Typically elongated
- Unevenly thickened walls
- Non- lignified primary walls
- Well adapted for the support of young, growing organs.
- Occur in discrete strands or as continuous cylinders beneath the epidermis in stems and petioles (leaf stalks).
What are sclerenchyma Cells? Describe….
- Sclerenchyma cells can form continuous masses
as sclerenchyma tissue or occur in small groups, or individually, or among other
cells. - Develop in any or all parts of the primary and secondary plant bodies and often lack protoplasts at maturity.
- thick, often lignified, secondary walls.
Important
- strengthening and supporting elements in plant parts that have ceased elongating
What is a plant fibre?
Essentially a type of sclerenchyma
Xylem does what?
Transfers water and minerals up the plant.
Where is xylem derived from in primary body vs secondary plant growth?
The procambium for primary
The cambium for secondary.
Vessel elements are apart of xylem, describe them.
- Perforated
- These perforations generally occur on the end walls, forming long continuous columns or tubes called vessels.
- Generally more efficient conductors of water than the tracheids
Tracheids are a part of xylem, describe them.
- Lack perforations
- The only water conducting cell found in seedless vascular plants and gymnosperms
What is the function of phloem?
Conducts food/energy around the plant.
What is protophloem?
The first formed, primary phloem.
What is metaphloem?
Differentiates after protophloem
It is the only phloem conducting food in adult plant parts for plants without secondary growth
Sieve cells are apart of phloem, describe them.
- The only food conducting cells in gymnosperms
- contains narrow pores that are uniform in structure.
What are albuminous cells?
- Specialised parenchyma cells
- play a role in delivery of substances to sieve elements (in phloem)
- Die when their associated sieve elements die.
What is the dermal system comprised of (plant parts)?
This is the epidermis and constitutes the tissue of:
- leaves, floral parts, fruits and seeds
- stems and roots until they undergo considerable secondary growth
Describe epidermal cells
- Compactly arranged,
- aerial parts are covered with a waxy cuticle
- The epidermis controls elongation of the entire organ in stems and sheaths
Describe guard cells and their function.
Regulate the small pores (stomata) in order to allow gas exchange and water loss.
Describe trichomes and their function.
These are any hairs on the plant, including:
- little root hairs that help with the absorption of water and minerals from soil
- Leaf hairs to provide defense against insects and to secrete salt from leaf tissues (think salt bush). Or help catch insects for carnivorous plants.
What is periderm?
A secondary protective tissue that replaces epidermis in stems an roots undergoing secondary growth.
