Structure and tissues in plants Flashcards
What is a tissue
A tissue is group of one or more cell types which carry out specific functions
How do we call the structures of plant root and shoot with meristematic properties
Apices
Buds
Meristems
What are meristems?
Undifferentiated tissues ,consisting of cells which constantly divide under suitable conditions and produce new cells.
Functions of meristems
Help in plant growth
Produce new plant cells which differentiate into new plant tissue
Do meristems always divide?
No, meristems do have dormant period
Give 8 characteristics of meristems?
Are living Are isodiametric ( roughly spherical ) Are structurally and functionally undifferentiated Have central nucleus Have dense cytoplasm Have the ability to multiple Have thin primary cell wall Large central vacuole absent
Write the location of the following meristematic tissues?
Apical meristems
Lateral meristems
Intercalary meristems
Apical meristems-located at root tips and shoot tips
Lateral meristems- Found laterally in stem and root of the plants
Intercalary meristems- base of the stem of grass, in nodes of grasses and bamboo
What is the type of meristems involved in following functions?
1) primary growth of shoot and root ( increases the length of the plant)
2) secondary growth of shoot and root ( increases the circumference of roots and stems )
3) production of secondary xylem and secondary phloem during secondary growth
4) production of tough periderm during secondary growth
6) rapid growth of damaged leaves
1) apical meristems
2) lateral meristems
3) vascular cambium [lateral meristems]
4) cork cambium [ “]
5) intercalary meristems
To which direction do cell division occur in primary growth of roots ?
New cells are produced to both sides of the root apical meristems.
What are the structures included in the zone of cell division in primary growth of roots?
Root apical meristems and it’s derivative
What do the cells produced outwards differentiate into in primary growth of plant?
Differentiate into root cap
Name the meristematic tissue found only in monocot plants?
Give the location of this tissue
Intercalary meristems
At the base of leaf blades
Nodes
Stems of bamboo
Define primary growth of roots?
Elongation of root due to the activity of primary meristems located on root apex is called primary growth of roots
What do the epidermis of root possess?
Root hair for absorbing soil solutions
Do not possess stomata Because roots are underground parts which do not involve in gas exchange
What happens to the cells produced inward to the apical meristems in primary growth of roots
Undergo elongation, in the zone of cell elongation
Then cells become specialized in the zone of cell maturation
And finally becomes mature cells
What do the epidermis of stem possess?
Stomata for gas exchange.
What do the following primary structures in dicot root and stem develop into after secondary growth?
Epidermis
Periderm
Root hair
Roots
Stomata
Lenticels
Pericycle in root
Lateral roots
Pericycle in stem
Lateral shoot
What do the following primary structures in shoots develop into after secondary growth?
Leaf primodia
Leaves
To which direction do cell division occur in primary growth of shoot?
Only towards the stem.
reason : they do not need a cover to protect them from sunlight because leaf primordia acts as a cover
To which direction do primary growth of roots occur in plants?
Cell are produced both outwards and inwards to the apical meristems.
Name three tissue systems in plants?
Dermal tissue system
Ground tissue system
Vascular tissue system
Give an example for dermal tissue before and after secondary growth
Before : epidermis
After: periderm
Name 3 specialized cells found in the epidermis?
Guard cells ,trichomes, root hair
Give 5 features of epidermis?
Protective outer covering of stems and roots in plant body and leaves
Tightly packed cells without intercellular spaces
A single cell layer tissue
Epidermal coating in aerial parts are covered by cuticle
Has specialized cells in them.
Give functions of epidermis?
Defense against physical damage and pathogens
Cuticle helps to prevent water loss
Root hairs involve in absorption of water and mineral
Guard cells help in gaseous exchange
Trichomes ( hairs and glands )
Hairs reduce water loss, shiny hairs reflect excess light
Trichomes secrete chemicals involves in defense against insects, pathogens and herbivores.
Name two types of ground tissues?
Pith ( inner to vascular tissue)
Cortex ( outer to vascular tissue )
Name three main types of cells in ground tissue?
Parenchyma cells
Collenchyma cells
Sclerenchyma cells
Name four main types of functions carried out by ground tissues?
Storage
Photosynthesis
Support
Short distance transport
Give 5 features of parenchyma cells
Living at functional maturity
Mature cells have relatively thin and flexible primary cell wall ( most cells lack secondary cell wall )
Cell wall has a uniform thickness without any lignification or suberisation
Have a large central vacuole
Plasmodesmata are present between neighboring cells
Has intracellular spaces
Give five functions of Parenchyma cells?
Perform metabolic functions (photosynthesis) [ as they are living ]
Storage [ stems and roots contain plastids, leucoplast to store starch]
Wound repair [ as they have the ability to divide and differentiate]
Used in tissue culture practice [ As they have the ability to divide and differentiate]
Provide mechanical support [ turgidity in vacuoles]
Define primary growth of shoot
Elongation of shoot as result of the activity of primary meristems located in the shoot apex is called primary growth of shoot
Give six features of Collenchyma cells?
Living at functional maturity
generally elongated
Have a thicker flexible primary cell wall
Cell wall is unevenly thickened at the corners of the cell only by cellulose.
Lignification or suberization is absent.
Plasmodesmata are present between adjoining cells
Usually intercellular spaces are absent
Function of collenchyma cells
Give mechanical support to the stem and leaf without restraining growth.
[ cell wall has thicker primary cell wall hence it provides support, cell wall is flexible without lignification or suberization therefore do not restrain the growth]
Give 4 features of sclerenchyma cells
Secondary cell walls are produced after cell elongation
Secondary cell walls are thickened by large amounts of lignin
They are dead at functional maturity
Plasmodesmata are absent
Plasmodesmata Are absent
Name two types of sclerenchyma cells?
Trachieds and fibers
Function of sclerenchyma cells
These cells are specialized to provide support and strength
What are the locations where we can find collenchyma cells
In young stems and petioles strands of collenchyma cells are found just below their epidermis
Found in veins of dicot leaves
Where can we find epidermis in plants
In stems and root in primary plant body
In leaves of all plants
State the parenchyma cells perform photosynthesis
Palisade and spongy mesophyll
State the parenchyma cells which stores starch
Cells in roots and stem which contain plastids(leucoplast) in them
Locations where parenchyma cells are found
Mesophyll cells found in leaves and young stems
Fleshy part of fruit and seed (endosperm)
Pith and cortex of root and stem
Locations where sclerenchyma cells are found
Nut shells
Coconut shell
Fibers
