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Plant Biology > Internal Organization of Stems > Flashcards

Internal Organization of Stems Flashcards

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1
Q

What is the Epidermis?

A

A protective single layer of parenchyma cells on the outermost layer of the plant.

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2
Q

What is the function of the epidermis?

A

Aids in interchanging materials from the outside of the cell to the inside

Protects the plant from fungi and bacteria invasion

Prevents water loss

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3
Q

What is the substance that covers the epidermis?

A

A waterproof cutin builds up on the surface of the epidermis making a waxy layer or waxy cuticle

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4
Q

What is the waxy cuticle?

A

A waterproof layer of cutin on the surface of the epidermis which prevent desiccation and gas exchange from everywhere but the stomata.

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5
Q

What is a stomatal pore?

A

An opening on the underside of the leaf which allows for gas exchange.

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6
Q

What are Guard cells?

A

These are cells that surround the stomatal pore controlling its size and therefore gas exchange.

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7
Q

How do guard cells function?

A

These cells swell by absorbing water which allows the stomatal pore to be open allowing CO2 and O2 to be exchanged and water to leave.

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8
Q

What happens when the water level is low?

A

The guard cells are unable to stay open and so the pore is closed

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9
Q

When are the guard cells closed?

A

The guard cells close at sunset and during water stress

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10
Q

What are trichomes?

A

These are the projections from epidermal cells or hairs

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11
Q

What is the function of trichomes?

A

Primary function is protection

  • Deter herbivores
  • Minimize water loss
  • Protect from over exposure to sunlight (shade underlyinh cells)
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12
Q

What is the Cortex?

A

The cortex is under the epidermis and is made up of parenchyma and collenchyma

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13
Q

What is Aerenchyma?

A

This is cortex with loosely packed cells and large intercellular spaces.

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14
Q

What are the two types of vascular tissue in the plant?

A

Xylem and phloem

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15
Q

What are vascular tissue responsible for?

A

Transporting materials throughout the plant.

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16
Q

What is the xylem vessel made up of?

A

The xylem vessel is made up of two types of conducting sclerenchyma: tracheids and vessel elements. These are dead cells at maturity

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17
Q

What is a tracheary element?

A

This is the name of mature conducting sclerenchyma

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18
Q

How does the tracheary element develop?

A

1- The young parenchyma cell goes through one cycle of mitosis and is arrested in G0.

2- The cell then begins to grow and elongate becoming longer and narrower and soon the secondary wall is deposited to re-enforce the thin primary wall.

3- The cell then dies and the protoplasm degenerates leaving a hollow tube

4- Areas on the primary wall remain without any secondary wall so that water can enter and exit the elements as the secondary wall is impermeable to water

-

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19
Q

Where does the xylem get its strength from?

A

The secondary cell wall

20
Q

Annualar thickening

A

Simplest of the tracheary elements

Only a small amount of secondary wall is present

Organized into ring

Does not provide a lot of strength

21
Q

Helical thickening

A

The secondary wall is 1 to 3 rings in the primary cell wall

22
Q

Scalariform

A

Scalariform thickening is stronger as the extensive secondary wall underlies most of the inner surface of the primary wall (ladder-like pattern)

23
Q

Reticulate

A

Secondary wall is deposited in a mesh-like manner

24
Q

Bordered pits

A

Area in the primary wall that do not have secondary wall are weak points which allow for water to pass through. They are surrounded by extra secondary wall material.

25
Q

Pit membranes

A

The primary walls and middle lamella between the two pits

26
Q

Pit pairs

A

Aligned set of pits

27
Q

How does water move through the vessel elements?

A

Vessel elements are vertically stacked and the ends of the cells are removed so there is a continuous tube called perforations allow water to move with less friction than the tracheids.

28
Q

What is a vessel?

A

A stack of vessel elements. They absorb water from the parenchyma cells

29
Q

Tracheids

A

These are cells that have a primary and secondary wall. Die at maturity and have pits along their side wall for lateral transfer.

30
Q

Perforations

A

These are formed at the last stage of differentiation where often an entire end of the cell wall is digested creating a large opening.

31
Q

What is something all plants with vascular tissue have in common?

A

Tracheids

32
Q

Which type of plant only has vessel elements? WHy?

A

Flowering plants to transport water long distances from root to stem

33
Q

Which plant only has tracheids?

A

Conifers

34
Q

What are the 2 types of conducting elements in phloem?

A

Sieve element members and sieve cells

35
Q

What does sieve element refer to?

A

Sieve element member or sieve cells

36
Q

What do Phloem develop from?

A

Develop from parenchyma cells that remain metabolically active at maturity.

37
Q

Sieve pores

A

These are enlarged plasmodesmata

38
Q

Sieve areas

A

A collection of sieve pores in one place

39
Q

Sieve cell

A

These are cells which have a similar structure to tracheids but they have seive areas distributed along their cell surface

40
Q

Sieve element members

A

These are cells which have sieve plates with large pores at both ends of the cell and are stacked on top of each other in a vertical column.

More effective way of transporting phloem sap

41
Q

What is unusual about sieve elements?

A

Their nucleus degenerates so there is no complex metabolism and they remain alive but neighboring cells exert nuclear controlled.

42
Q

What cells are sieve cells associate with?

A

Albuminous cells

43
Q

What cells are sieve element members?

A

Companion cells

44
Q

What is the function of companion cells and albuminous cells?

A

They are involved in loading and unloading sugars into the sieve elements

45
Q

Structure of neighboring cells?

A

Smaller than the sieve elements
Prominent nucleus
Dense cytoplasm filled with ribosomes
large plasmodesmata

46
Q

How are conducting cells connected to the controlling cells?

A

Walls between conducting cells and controlling cells have a lot of complex passages that are sieve areas on the conducting side and large plasmodesmata on the controlling side

Plant Biology (6 decks)

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