Gaseous Exchange In Plants

Question 1

What is the main photosynthetic organ in most vascular plants

Answer 1

Leaves

Question 2

What is the site of gaseous exchange

Answer 2

Stomata in the upper and lower epidermis

Question 3

What is the ground tissue between the upper and lower eoidermis

Answer 3

Medophyll

Question 4

What type of cell is found in the mesophyll tissue

Answer 4

Parenchyma cells specialized for photosynthesis

Question 5

Where are stomata mainly found in dicot leaves

Answer 5

In the lower epidermis

Question 6

What are the two distinct layers found in mesophyll

Answer 6

Palisade
Spongy

Question 7

Location of palisade mesophyll

Answer 7

The upper part of the leaves just beneath the upper epidermis

Question 8

What is in the palisade mesophyll tissue

Answer 8

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

Question 9

What is the location of spongy mesophyll

Answer 9

Between palisade layer and lower epidermis

Question 10

How are the cells arranged in spongy mesophyll

Answer 10

Loosely arranged with many air spaces.

Question 11

Difference in organelle composition between spongy and palisade mesophyll

Answer 11

Palisade mesophyll have more chloroplast

Question 12

What is the vain arrangement in plants

Answer 12

Highly veined
Net like venation

Question 13

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

Answer 13

In mesophyll layer
Protected by bundle sheath layer

Question 14

Where are the stomata found in monocot leaves

Answer 14

Both lower and upper epidermis

Question 15

Features of mesophyll cells in monocot leaves

Answer 15

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

Question 16

What is a stomata

Answer 16

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

Question 17

What are gaurd cell

Answer 17

Modified epidermal cells which have a distinct shape

Question 18

What is the only epidermal cell that contain chloroplasts

Answer 18

Guard cells

Question 19

What is the typical shape of the guard cells in angiosperms

Answer 19

Bean shaped

Question 20

What is the structure of the guard cells wall

Answer 20

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

Question 21

What is the function of guard cell

Answer 21

Regulate the diameter of stomata by changing shape

Question 22

Define gaseous exchange

Answer 22

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

Question 23

Sites of gaseous exchange in plants

Answer 23

Stomata
Lenticels
Small amount through cuticle

Question 24

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

Answer 24

No special system present
Move entirely by diffusion

Question 25

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

Answer 25

No special system present Move entirely by diffusion

Question 26

What influences the stomatal opening and closing

Answer 26

Change in turgor pressure of the guard cells

Question 27

Mention how stomata opens

Answer 27

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

Question 28

How does the stomata close

Answer 28

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

Question 29

What is the K+ influx hypothesis

Answer 29

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

Question 30

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

Answer 30

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

Question 31

How does stomatal closing occur by loss of K+

Answer 31

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

Question 32

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

Answer 32

Abscisic acid ABA

Question 33

What are the roles of ABA in stomatal closing in drought

Answer 33

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

Question 34

Factors that affect stomatal action

Answer 34

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