TranspirationTranspiration

Plant StructurePlant Structure Terms:

Epidermis – Skin or layer on the outside.

Vascular Tissue – components required to help transport nutrients and water through the plant.

Seeds – Used for reproduction.

Leaf – Contains chlorophyll used for photosynthesis.

Roots – Absorbing nearby nutrients.

Root Hair – Increase surface area. Rapid absorption.

Root Cap – harder substance, with a low area to penetrate the soil and go deeper.

PhotosynthesisPhotosynthesis

Formula for photosynthesis:

Carbon dioxide + Water + Sun

Glucose + Oxygen

PhotosynthesisPhotosynthesis Plants produce their very own food source Plants produce their very own food source

from the photosynthetic process. from the photosynthetic process.

The products of photosynthesis include:The products of photosynthesis include:Oxygen and GlucoseOxygen and Glucose

Oxygen might be a waste product for the Oxygen might be a waste product for the plant, but helps plant, but helps sustain life for us!sustain life for us!

Glucose is a simple sugar – food source!Glucose is a simple sugar – food source!

Stomata – microscopic pores found on the under side of leaves

Xylem Vessel – tube like structures running from the bottom of the stem (roots) to the top of the plant.

Guard cells – a mechanism which opens and closes (or controls) the rate at which vapour exits.

Capillary Action in the plant roots.

Images of StomataImages of Stomata

Stomata FunctionsStomata Functions Opening/Closing StomataOpening/Closing Stomata - allows - allows

CO2 to diffuse into the leafCO2 to diffuse into the leaf

- water vapor to diffuse out of the leaf. - water vapor to diffuse out of the leaf.

Located Located underunder the leaf. If it were on the top side the the leaf. If it were on the top side the plant would plant would lose to much waterlose to much water. .

Guard cellsGuard cells are partially light activated, plants under are partially light activated, plants under direct sunlight would constantly have their stomata direct sunlight would constantly have their stomata open – letting out to much water which could dry the open – letting out to much water which could dry the plant.plant.

Capillary ActionCapillary ActionXylem:

Carries water and dissolved minerals up from the roots through the stem to the leaves and provides support for the softer tissues.

Comparing Xylem and PhloemComparing Xylem and Phloem

How might we measure or test How might we measure or test for transpiration within a plant?for transpiration within a plant?

With the person next to you or in your With the person next to you or in your groups. groups.

DiscussDiscuss ways in which we could test ways in which we could test and/or measure the rate of and/or measure the rate of transpiration within plants. transpiration within plants.

Measuring TranspirationMeasuring Transpiration

Measuring TranspirationMeasuring Transpiration

PotometerPotometerA potometer is a device that measures the rate at which a plant draws up water.

Since the plant draws up water as it loses it by transpiration, you are able to measure the rate of transpiration.

Factors that affect the rate of Factors that affect the rate of transpiration transpiration

LightLightWindWind

TemperateTemperateHumidityHumidity

Soil WaterSoil Water

Light Affecting TranspirationLight Affecting Transpiration

LightLight

Plants transpire Plants transpire more rapidlymore rapidly in in the light than in the dark. This the light than in the dark. This is largely because light is largely because light stimulatesstimulates the opening of the the opening of the stomata.stomata.

Light also speeds up Light also speeds up transpiration by warming the transpiration by warming the leaf. leaf.

Wind Affecting TranspirationWind Affecting Transpiration WindWind

When there is no breeze, the air surrounding When there is no breeze, the air surrounding a leaf becomes a leaf becomes increasingly humidincreasingly humid thus thus reducingreducing the rate of transpiration. the rate of transpiration.

When a breeze is present, the humid air is When a breeze is present, the humid air is carried away and replaced by drier air. carried away and replaced by drier air.

Temperature Affecting Temperature Affecting TranspirationTranspiration

Temperature Temperature

Plants transpire Plants transpire more rapidly at more rapidly at higher temperatureshigher temperatures because because water evaporates more rapidly water evaporates more rapidly as the temperature rises. as the temperature rises.

At 30°C, a leaf may transpire At 30°C, a leaf may transpire three times as fast as it does at three times as fast as it does at 20°C. 20°C.

Soil Water Affecting TranspirationSoil Water Affecting Transpiration Soil WaterSoil WaterWhen absorption of water by the roots fails When absorption of water by the roots fails

to keep up with the rate of transpiration, to keep up with the rate of transpiration, the stomata close. the stomata close.

This immediately This immediately reduces the rate of reduces the rate of transpirationtranspiration. Since water is also used . Since water is also used to maintain the structure of a plant, it can to maintain the structure of a plant, it can begin to begin to wiltwilt when water is lost rapidly. when water is lost rapidly.

Example of Wilting PlantsExample of Wilting Plants

Plant AdaptationsPlant Adaptations Desert plants must reduce their loss of Desert plants must reduce their loss of

water by;water by;

Containing smaller stomata, but also Containing smaller stomata, but also reduce the total number of their reduce the total number of their stomata.stomata.

Some species only open their Some species only open their stomata during night, which reduces stomata during night, which reduces the amount of water lost (due to the amount of water lost (due to colder temperatures).colder temperatures).

Plant AdaptationsPlant Adaptations Leaf surface area  Leaf surface area                Thickness of epidermis Thickness of epidermis             Stomatal frequency           Stomatal frequency          

Stomatal size         Stomatal size         

Stomatal position Stomatal position