Botany 300 Exam 2

The two primary conducting systems in land plants are __ and __.

xylem, phloem

Xylem is responsible for the __ of water from the soil to the leaves.

transpiration

__ transports sugars made by photosynthesis from green tissues to other parts of the plant.

Phloem

Gymnosperms mainly consist of __ as their water conductors.

tracheids

Angiosperms have __ and __ as water conductors.

tracheids, vessel elements

The driving force of transpiration is the difference in __ of water.

free energy

__ in xylem can occur when the water column is pulled too hard due to dry conditions.

Cavitation

Vessel elements have __ that allow for bulk flow of water.

perforation plates

Two types of tracheids are __ and __.

imperforate, perforate

Xylem __ cells are living at maturity and involved in xylem metabolism.

parenchyma

The relationship between tracheary element diameter and water conductance shows that larger elements offer __ resistance to water flow.

less

The primary functions of xylem are water conduction, mineral transport, and __.

support

Vessel element __ are patterned for strength and water movement.

side walls

Xylem parenchyma cells are responsible for __ and response to pathogens.

storage

What is transpiration?

The movement of water upwards from the roots, caused by negative pressure due to evaporation

What does xylem do?

Pulls water and nutrients up from the roots and provides structural support

Most xylem cells are what kind of tissue?

Sclerenchyma

What is imperforate xylem?

Cells that lack perforations in their cell walls, aiding in structural support and water transport

What is perforate xylem?

Cells that contain perforation plates, facilitating efficient water transport and nutrient conduction

Where do we find perforate xylem?

Angiosperm vessel elements

What type of xylem cells are gymnosperms lacking?

Perforate tracheary elements

How many imperforate tracheary elements do angiosperms have?

Three - tracheids, fiber-tracheids, and libriform fibers.

When water sticks to itself, it’s called __.

cohesion

When water molecules stick to other polar substances, it’s called __.

adhesion

What is “bound water”?

The water that has adhered to the polar components of plant cell walls in a tracheary element and does not move

How do plants change their tracheary elements to avoid cavitation events?

By changing the size with the seasons - larger when there’s water and smaller when it’s dry

What primary meristem forms the epidermis?

The protoderm

The epidermis facilitates the exchange of __.

gases

The upper side of the leaf is the __ side.

adaxial

The lower side of a leaf is called the __.

abaxial

The parenchymatic cells making up the bulk of the leaf are called __ cells.

spongy mesophyll

The parenchyma against the upper epidermis (adaxial) side of the leaf are called __ cells.

palisade mesophyll

What are the primary function of the palisade mesophyll cells in leaves?

Photosynthesis

What is the protective coating on the outside of the epidermis?

The cuticle

Is the cuticle hydrophilic or hydrophobic?

Hydrophobic

The cuticle is made of __ and __.

cutin, waxes

What is the primary function of a cuticle?

Preventing water loss

What are waxes called when deposited outside the cuticle?

Epicuticular waxes

How is cutin formed?

Complex polymer of hydrophobic fatty acids, randomly constructed from monomers (like lignin is)

Can air penetrate the cuticle?

No

Aside from protecting the epidermis from wind and water, what else does the cuticle protect from?

Pathogens (senses degraded cutin polymers)

What is different between the epicuticular waxes and the cuticle?

The waxes are made up of different molecules that are even more hydrophobic

Aside from preventing water loss, how else might epicuticular waxes help a leaf?

Providing protection from bright UV light

The epidermis is made up of __ cells, guard cells, and stomata.

Pavement

There are no __ between pavement cells.

Intercellular spaces

Guard cells contain many __ to help with the energy needed for movement.

chloroplasts

How is the pore formed on the stomata?

The middle lamella between the guard cells is dissolved

How do the guard cells open and close?

By regulating the vacuole

Low __ triggers the guard cells to bring in excess potassium (K⁺) ions.

internal CO₂ concentrations

Potassium ions cause the guard cells to swell by causing a __.

solute concentration gradient

What happens when guard cells swell?

They open the stomatal pore

Aside from CO2, __ and __ can also trigger stomatal movement.

light, water

High amounts of __ signal the plant to keep stomata closed to prevent further water loss.

abscisic acid (ABA)

What are some of the adaptations to protect stomata?

Wax chimneys, crypts, rolling leaves, (some) trichomes, and sunken stomata

__ are responsible for opening and closing grass leaves due to water availability.

Bulliform cells

__ are the pavement cells directly surrounding the stomatal guard cells.

Subsidiary cells

Stomata in grasses are unique because they have __ cells around the guard cells.

subsidiary

The epidermis of submerged plants is unique because it does not have a __ or __.

cuticle, stomata

Calcium carbonate crystals inside a lithocyst is called a __.

cystolith

Projections from the plant epidermis are called __.

trichomes

True or false: Trichomes can only be unicellular.

False. They can be unicellular or multicellular.

The two primary functions of trichomes are __ and __.

protection, secretion

Root hairs are considered this type of structure.

Trichomes

Root hairs form directly from the __ cells.

epidermal

The primary meristem for the vascular tissue is the __.

procambium

True or false: Nectaries only produce water, not true nectar.

False, nectaries are named for their production of nectar

What is the primary function of a hydathose?

To secrete water through the leaf veins when transpiration is difficult

What do laticifers do?

Produce latex