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Plants Form And Function > Gaseous Exchange In Plants > Flashcards

Gaseous Exchange In Plants Flashcards

1
Q

What is the main photosynthetic organ in most vascular plants

A

Leaves

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2
Q

What is the site of gaseous exchange

A

Stomata in the upper and lower epidermis

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3
Q

What is the ground tissue between the upper and lower eoidermis

A

Medophyll

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4
Q

What type of cell is found in the mesophyll tissue

A

Parenchyma cells specialized for photosynthesis

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5
Q

Where are stomata mainly found in dicot leaves

A

In the lower epidermis

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6
Q

What are the two distinct layers found in mesophyll

A

Palisade
Spongy

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7
Q

Location of palisade mesophyll

A

The upper part of the leaves just beneath the upper epidermis

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8
Q

What is in the palisade mesophyll tissue

A

Consist of elongated cells that are arranged in one or more layers

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9
Q

What is the location of spongy mesophyll

A

Between palisade layer and lower epidermis

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10
Q

How are the cells arranged in spongy mesophyll

A

Loosely arranged with many air spaces.

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11
Q

Difference in organelle composition between spongy and palisade mesophyll

A

Palisade mesophyll have more chloroplast

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12
Q

What is the vain arrangement in plants

A

Highly veined
Net like venation

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13
Q

In which cell layer is the veins found. And how are they protected

A

In mesophyll layer
Protected by bundle sheath layer

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14
Q

Where are the stomata found in monocot leaves

A

Both lower and upper epidermis

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15
Q

Features of mesophyll cells in monocot leaves

A

Not differentiated into palisade and spongy mesophyll
Chloroplast are abundant in all mesophyll cells
Parallel venation

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16
Q

What is a stomata

A

Stomata are pores surrounded by guard cells in the epidermis of leaves and stems of plants which can open and close

17
Q

What are gaurd cell

A

Modified epidermal cells which have a distinct shape

18
Q

What is the only epidermal cell that contain chloroplasts

A

Guard cells

19
Q

What is the typical shape of the guard cells in angiosperms

A

Bean shaped

20
Q

What is the structure of the guard cells wall

A
  1. Cell walls are unevenly thickened
  2. Inner cellulose cell wall is thicker and less elastic than outer cells wall
  3. Some of the cellulose microfibrils are radially arranged to form inelastic hoops around gaurd cells
21
Q

What is the function of guard cell

A

Regulate the diameter of stomata by changing shape

22
Q

Define gaseous exchange

A

The exchange of gasses between the cells of the organism and the environment

23
Q

Sites of gaseous exchange in plants

A

Stomata
Lenticels
Small amount through cuticle

24
Q

What is the mode of transport for O2 and Co2 within plants

A

No special system present
Move entirely by diffusion

25
Q

What is the mode of transport for O2 and Co2 within plants

A

No special system present
Move entirely by diffusion

26
Q

What influences the stomatal opening and closing

A

Change in turgor pressure of the guard cells

27
Q

Mention how stomata opens

A
  1. Water flows into the guard cell by osmosis
  2. Turgor increases
  3. Expand non uniformly
  4. Relatively inelastic inner walls make them bend
  5. This draws them aways from each other
  6. Pore opens
28
Q

How does the stomata close

A
  1. Guard cell loses water
  2. Turgor decreases
  3. Inner walls straighten
  4. Pores close
29
Q

What is the K+ influx hypothesis

A

During daytime guard cells actively accumulate K+, from neighbouring epidermal cells and lower their water potential that leads to inflow of water by osmosis from surrounding epidermal cells

30
Q

What provides the energy required for accumulation of K+ in guard cells

A

The transfer of electrons during photosynthesis of chloroplast in guard cell.

31
Q

How does stomatal closing occur by loss of K+

A

loss of K+ from guard cell to neighbouring epidermal cells leads to exosmosis of water. Turgor pressure decrease, closing stomata

32
Q

What is the acid that plays a role in K+ influx mechanism

A

Abscisic acid
ABA

33
Q

What are the roles of ABA in stomatal closing in drought

A
  1. ABA is produced in roots and leaves in response to water deficit
  2. Production of ABA leads to closing of stomata by removal of K+ in guard cells
  3. This prevents wilting if plants
34
Q

Factors that affect stomatal action

A

Light ( stimulate accumulation if K+ in guard cells)
CO2 concentration (decrease=open stomata)
Internal clock of guard cells
Environmental stress like drought, high temperature, wind

Plants Form And Function (9 decks)

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