plant anatomy Flashcards
what is the primary and secondary cell wall made up of
primary= cellulose
secondary= lignin
what is the middle lamella
the cementing layer of pectin and calcium between adjoining cells
what is the role of the tonoplast
binds the vacuole by a vacuole membrane called the tonoplast
what is a meristem
specialist zones of mitosis which produces undifferentiated cells leading to growth and development of plants when the new cells differentiate and form specific tissues
what are the different types of meristem
1) apical aka primary
2) intercalary
3) cambium
what does the apical meristem do
dividing cells result in increased length of root and shoot tips
what does the cambium meristem do
actively dividing cells produce lateral growth therefore increasing girth of the plant
what is the intercalary meristem
located at the base of internodes and base of leaves and also, like the cambium, increase girth however are located on mature tissues
what is meant when a group of cells are composed of initials and derivatives
cells which remain in the meristem are termed initials and continue to divide as a meristematic cells
cells which are displaced from the meristem, and become a differentiated body cell are called derivatives
what does the apical/primary meristem form
forms primary tissues
what does the protoderm form
the epidermis
what does the ground meristem form
ground tissues
what does the procambium form
the primary xylem and phloem
what is the ground tissue called in the leaf, stem and root
leaf = mesophyll
stem- cortex and pith
root = cortex
what are the different types of ground tissues
1) parenchyma
2) collenchyma
3) sclerenchyma
outline what the parenchyma is
- a type of ground tissue found in the cortex, pith and vasuclar rays which is involved in photosynthesis, storage and secretion
- alive at maturity
outline what the collenchyma is
- living at maturity with unevenly thickened primary cell walls with great plasticity ideal for strengthening growing tissues and organs
- it is found below the epidermis and in bands next to the vascular bundles
outline what the sclerenchyma is
a type of gorund tissue which is elastic and provides strength to mature organs that have stopped grwoing
- the primary cell wall is usually lignified and thick
what are the two types of sclerenchyma tissues and what are the differences
fibres
- long and elastoc allowing bending and rentention of normal shape
sclereids
- short and isodiamertic providing hard protective coats
what is a xylem
a type of vascular tissue which is dead at maturity and responsible for water and mineral transport as well as mechanical support
what is a phloem
cells with living protoplasts at maturity and are responsible for the transportation of photosynthesis products and other organic compounds
what does the procambium (primary meristem) give rise to
primary xyelm and phloem
outline the structure of xylem vessels
1) in angisperms it is made up of tracheids and vessel elements which are elongated empty cells with lignified secondary cell walls
- vessels have porforations called perforation plates
what are pits in xylem
thin areas where the secondary lignified wall is missing allowing water to pass through into trachieds
what is the different types of sieve elements in angio and gymnosperms
the conducting cells are sieve elements composed of either sieve cells in gymnosperms or sieve tube members in angiosperms
what do sieve areas have
pores which allow protoplasmic connection between adjacent sieve elements
what are companion cells
associates with sieve tube members, they are modified paraenchyma cells which regulate translocation of materials
what is the epidermis
the outermost layer of the primary plant body which varies in structure and function
what are trichomes
appendages of the epidermis which have many functions such as protection, reflection secretion and absorption
what is the function of roots
organs specialsed for anchorage, absorption, storage and conduction
how does the structure of roots differ in gymnosperms and angiosperms
gym and dicots usually in a taproot system
angio= fibrous
what does the mucigel sheath and root cap do
protects the developing root
what does the primary structure of a root consist of
epidermis, cortex and central stele
what is a central stele
made up of vascular tissue and surrounded by a pericyle it is the central part of the root containing the tissues derived from the procambium
outline the secondary structure of roots
meristematic activity in of the cambium between the xylem and phloem gives rise to secondary xylem and phloem
what are adventitous roots
roots formed later from other places during gorwth and development
outline the structure of stems
- stem is an axis with nodes and internodes
-leaves produced at the nodes - buds are miantue shoots with dormant apical meristem
outline the structure of a leaf
consist of a petiole (stalk) and lamina (blade)
sometimes modified with spines or bladders ect
made up of primary tisses
vasucular tissue in the midrib and viens
what ground tissue is the mesophyll made up of
parenchyma tissue
what is an abscission zone
comprises of an abscission layere where leaf breaks of as well as a protective layer which preserves the stem
what cells make up the secondary xylem and phloem
1) fusiform initials =
2) ray initials
what is the difference between fusiform and ray initials
1) fusifrom = undergo periclinal (parallel division) which give rise to secondayr xyelm and phloem
2) ray = periclinal divisons generate parenchyma cells
where does the cork cambium arise
the cortex bewlow the epidermis and produces the periderm as cork cells
what is the phelloderm
a thin walled inner layer of cells produced by the cork cambium
what does the periderm do
the corky outerlayer of a plant stem formed in the seocndary thickening which crushes and replaces hte perimary epidermis and cortex increasing diameter
