Gas Exchange in Plants
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Gas Exchange in Plants. Plants do not have special respiratory or circulatory systems, and therefore must rely on the direct exchange of gases with their environment The and of plants depend on gas exchange with the air and the soil The surface of the root is covered with

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Gas Exchange in Plants

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Gas exchange in plants

Gas Exchange in Plants


Gas exchange in plants

  • Plants do not have special respiratory or circulatory systems, and therefore must rely on the direct exchange of gases with their environment

  • The and of plants depend on gas exchange with the air and the soil

  • The surface of the root is covered with

  • Root hairs increase the and also provide a moist surface area for

roots

rhizomes

root hairs

surface area

gas exchange


Gas exchange in plants

  • As long as the soil is and contains, the oxygen will diffuse from the air into the air spaces of the soil and then into the moisture film surrounding the soil particles and root hairs

  • The dissolved enters the by diffusion and is then passed on to other cells of the root

  • At the same time diffuses out of the root hairs and into the soil

aerated

water

oxygen

root hairs

CO2


Gas exchange in leaves

Gas Exchange in Leaves

photosynthesis

The main job of leaves in plants is

During photosynthesis, plants absorb and give off

During respiration plants absorb and give off

During the day both process occur in the

CO2

O2

O2

CO2

leaves


Gas exchange in plants

  • Because gas exchange is constantly occurring, the leaf has to protect itself against too much water loss, therefore it is covered with a waxy waterproof coating called the

  • The leaf also has tiny pores in it called that allow for the passage of gases in and out of the leaf

  • These stomata (singular ) are bordered by a pair of

  • The guard cells allow the pore to be opened to permit for or close to prevent

cuticle

stomata

stoma

guard cells

gas exchange

water loss


Gas exchange in plants

Cross section of a leaf:


Gas exchange in plants

  • Gases are held in the and can be used for either respiration ( ) or photosynthesis ( )

  • Every cell is close to air spaces so that the gases can readily into the cells and be used for either process

intercellular air spaces

O2

CO2

diffuse


Stomates guard cells

STOMATES & GUARD CELLS

Scattered about the lower epidermis are small openings called stomata.  It is through these holes that carbon dioxide enters the leaf, & oxygen & water vapor exit.

Each stoma is surrounded by a pair of guard cells.  When guard cells swell, the stomates open when the guard cells shrink, the stomates are closed.  Plants respond to changes in temperature & humidity by opening or closing their stomata (an example of maintaining ... homeostasis).


Gas exchange in stems

Gas Exchange in Stems

  • Every stem contains

  • The green flexible stems of grasses and other nonwoody stems photosynthesize and thus contain

  • Woody stems contain small white markings called

pores

stomata

lenticels


Gas exchange in plants

  • Lenticels are normally found where stoma were once situated when the stem was young and capable of photosynthesis

  • Diffuses into the stoma or lenticels and enter the here every cell in the stem is able to obtain gases they need for photosynthesis or respiration

O2

intercellular air spaces


Gas exchange in plants

Quest Review on Monday

Review Questions

Page 277 # 1-3, 5-7, 9, 10, 17, 20, 22, 29


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