7.5 respiration in plants

8/13/2019 7.5 Respiration in Plants

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7.5 Respiration inPlant


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Energy Requirement in Plant


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The intake of O2by plants for

respiration

No specialised organ for gaseous exchange

take in O2through leaves, stems and roots.

Gaseous exchange by diffusion through

stomataand lenticels.


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Lenticels

-Raised pores found on the stems and roots

-Cells around it are arranged loosely to allow

diffusion of gases


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When stomata are open, they connect air

spaces within inside the leaf and

environment.

Air space are continuous with those stems

and roots.

O2from atmosphere diffuses into the air

spaces and then dissolves in the film of water

around the mesophyll cells.

Aerobic respiration takes place. Concentration gradient: cell , air spaces

=allow O2diffuse continuously


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During the day, CO2 from aerobic resp. isused in photosynthesis

The excess CO2 diffuses into the air spacesand then atm.

Aerobic resp. is usually carried out by allplants throughout the day & night

Anaerobic resp = for short period

e.g : during flooding, survive for severaldays when completely submerged in water


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Respiration & Photosynthesis

in plants

Dependent on each other

Photosynthesis produced raw materials for

resp, and resp produced raw materials forphotosynthesis

Presence of light = photosynthesis

No light = respiration


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THE REGUL TORY MECH NISM IN RESPIR TION

THE IMPORT NCE OF M INT INING HE LTHY RESPIR TORY SYSTEM

RESPIR TION IN PL NTS

Although plants cannot photosynthesise without sunlight, respiration continues because

plants need energy constantly for living processes.

Gaseous exchange between plants cells & the environment occurs by diffusion mainly

through the stomata (in the epidermis of the leaves & stem of herbaceous plants)& lenticels (pores found on the stems & roots of plants).

Aerobic respiration is usually carried out by all plants throughout the day & night.

Anaerobic respiration is carried out by plants under certain condition for short period.

- in a floods when plants completely submerged in water.

- rice plants in water logged paddy field

- during the initial stage of seed germination (in airtight seed coat)

NIGHT

photosynthesis does not

take place, only respiration.

CO2is released into the

atmosphere.

LOW INTENSITY

rate of photosynthesis =

rate of respiration.

exchange of gases occur

in the leaves.

HIGH INTENSITY

rate of photosynthesis is higher

than the rate of respiration.

CO2 is taken in from theatmosphere & O2is released

into the atmosphere.


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Comparison between

photosynthesis & respiration

PHOTOSYNTHESIS RESPIRATION

1. Occurs in all green plant

2. Stores energy

3. Water & carbon dioxide as raw

materials.4. Glucose & oxygen as products

5. Light energy is required

6. Takes place in the chloroplasts

7. Presence of chlorophyll is

required8. CO2+water sunlight

chlorophyll

glucose + water + oxygen

1. Occurs in all living organisms

2. Releases energy

3. Glucose & oxygen as raw

materials.4. Energy, water & CO2 as products

5. Light energy is nor needed

6. Takes place in the mitochondria

7. Presence of chlorophyll is not

required8. O2+ glucose

CO2+ water + energy

7.5 respiration in plants

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