MCDB 1B: Plant structure

zone of elongation

Beyond the tip of the root, where most of the growth occurs as root cells elongate and root apical meristem adds cells to the younger end

primary growth

Growth produced by apical meristems, which lengthen stems and roots.

zone of cell division

Includes the stem cells of the root apical meristem and their immediate products

In the plant cell, membrane potential is established by _______; in the animal cell, it is established by _________

Plant cell: proton pumps Animal cell: Sodium-potassium pumps

ground tissue system

Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support.

If you were to place nodes of a marijuana plant in a nutrient broth, what would occur?

Since the totipotent meristem cells are located within the nodes, new plants would be able to grow from the nodes.

True or false: Nearly all live plant cells act like animal "stem cells" in that they are totipotent.

True: The only cells that aren't totipotent are the determinant cells; which are found in limited areas such as leaves and flowers.

xylem and phloem organization in eudicots

Vascular bundles form a ring around the stem; phloem on outside and xylem on inside

What is the water potential of pure water in an open container?

Zero

chromoplast

a colored plastid other than a chloroplast, typically containing a yellow or orange pigment.

tissue

a group of cells consisting of one or more cell types that together perform a specialized function

stem cells

cells that are not incorporated into tissues and instead stay in either the apical or lateral meristem to produce more cells, remaining functionally undifferentiated

A plant cell placed in distilled water will a. expand until the solute potential reaches that of the distilled water. b. become more turgid until the solute potential reaches that of the distilled water c. become less turgid until the solute potential reaches that of the distilled water d. become more turgid until the pressure potential of the cell reaches its solute potential e. become less turgid until the pressure potential of the cell reaches the outside water potential

d

Which of the following factors has a direct impact on the orientation and expansion of plant cells? a.Initial cellulose microfibril orientation b.Lignin deposition c.Turgor pressure d.All of the options influence cell growth

d

Which statement regarding the primary cell walls of plants is false? a. They contain pectins. b. They contain hemicellulose. c. The primary cell walls of two adjacent cells are separated by the middle lamella. d.They contain high concentrations of hydrophobic lignins.

d (lignins are located in the secondary plant cell wall)

zone of differentiation

Cells in this zone undergo specialization into three primary meristems that give rise to three tissue systems in the plant: the epidermis, ground tissue, and xylem and phloem. (vascular)

pectin

present in plant cell walls; links cellulose together, cross-linking with microfibrils to form a mesh (along with hemicellulose)

lateral meristems

present in woody plants; allow for circumference growth once a plant is no longer growing in length (secondary growth)

root cap

protects delicate apical meristem as the root pushes through the soil during primary growth

organ

several types of tissues that together form a function

leukoplast

stores starch; devoid of color

cotyledon

the first leaf put out by a plant

water potential

the physical property that predicts the direction in which water will flow (affected by solute concentration and pressure potential)

meristem

undifferentiated tissue that allow for continuous division and differentiation, causing growth

apoplastic route

water and solutes move along the continuum of cell walls and extracellular spaces

xylem and phloem organization in monocots

xylem and phloem are scattered in connection to each other throughout the stem in bundles

plant cell wall

-25-30% cellulose (major structural component) -40-55% other polysaccharides -1-15% protein

vascular cambium

-Adds secondary xylem (wood) to inside and phloem to outside; adds from both sides so growth is bidirectional -Increases vascular flow and support

secondary plant cell wall

-Established when the cell is done growing -Highly regular array of cellulose -Locks cell in place -Contains lignin, which is hydrophobic, making it hard for water to enter -Only present in woody plants

Is cellulose hydrophilic or hydrophobic? How does this affect the organization of the cell wall?

-It has O and H which allows it to interact with water via hydrogen bonding -Allows for stacking of microfibrils on top of each other

Dermal tissue system

-Outer protective covering of plant -1st line of defense -In non-woody plants, single epidermis tissues

symplastic route

-Water and solutes move along the continuum of cytosol -Requires substances to cross a plasma membrane once, when they first enter the plant -After entering one cell substances can move from cell to cell via plasmodesmata

apoplast

-everything external to the plasma membranes of living cells -includes cell walls, extracellular space, and the interior of dead cells

plasmodesmata

-large channels that link cytosols of neighboring plant -30x larger than gap junctions, allowing bigger molecules to move between cells (i.e. viruses).

cork cambium

-replaces the epidermis with periderm (cork cells), which is thicker and tougher -growth occurs in one direction -protects the plant

symplast

-the entire mass of cytosol of all the living cells in a plant and plasmodesmata (cytoplasmic channels that interconnect them)

How do new cell walls form in dividing cells

1) Vesicles coalesce at the cell plate 2) Vesicles fuse to middle lamella (with some gaps) 3) Daughter cells secrete wall material at primary wall surface, resulting in an age gradient with the wall

What does the root system do

1) absorbs water and minerals from below the ground 2) receives imports of photosynthates from shoot system

how many cotyledons are located in a eudicot seed

2

desmotubule

A membrane extension connecting the endoplasmic reticulum of two plant cells that traverses the plasmodesmata. size can be altered

Plants and plant cells are unique as there are defined age gradients at each level that can be observed! In terms of the plant cell wall, what below is FALSE? a. the primary cell wall is older and located outside of the plant secondary wall b. is the site of a major plant compartment of the plant body, the symplast c. largely consists of a meshwork of hydrophilic cellulose, hemicellulose and pectin in a well-hydrated (water-rich) environment d. Have a lower pH than the cytoplasm e. None of the above are false

b

vascular tissue system

facilitates transport of materials through plant + provides mechanical support; consists of xylem phloem and stele

indeterminate growth

growth that is not limited to an embryonic or juvenile period

determinate growth

growth that stops after a certain size is reached

epidermis

layer of tightly packed cells; in roots, allows water/minerals to enter

apical meristems

located at the tips of roots and shoots; provide cells that enable primary growth

how many cotyledons are located in a monocot seed

one

cotransport

plant cells use energy in the H+ gradient and membrane potential to drive the active transport of many different solutes