Transpiration Process and Experiments

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does the potometer measure in plants?

The rate of water intake (correct)

The amount of sunlight absorbed

The humidity of the environment

The temperature of the leaves

How does increased temperature affect the rate of transpiration?

Has no effect on transpiration

Decreases the rate of transpiration

Is dependent on other factors only

Increases the rate of transpiration (correct)

Which factor would decrease the rate of transpiration?

Increased intensity of sunlight

Increased wind velocity

Decreased humidity in the air

Higher atmospheric pressure (correct)

What adaptation might a plant in a dry climate exhibit to reduce transpiration?

Leaves modified into spines Signup and view all the answers

What is the main significance of transpiration in plants?

It cools the leaf surfaces and assists in water absorption Signup and view all the answers

Which of the following describes the difference between transpiration and evaporation?

Transpiration is the loss of water from plant leaves; evaporation is from bodies of water. Signup and view all the answers

What occurs during guttation in plants?

Tiny droplets of water appear at leaf margins Signup and view all the answers

Which statement is true about the effect of wind on transpiration?

Rapid air movement increases the rate of transpiration. Signup and view all the answers

What is the primary mechanism through which stomatal transpiration occurs?

Diffusion of water vapour from intercellular spaces Signup and view all the answers

Which setup demonstrated that plants give off water vapour through changed cobalt chloride paper?

Both Setup A and Setup B Signup and view all the answers

Why does cobalt chloride paper on the lower side of the leaf turn pink faster than that on the upper side?

There are more stomata on the lower surface Signup and view all the answers

Which type of transpiration occurs directly through the surface of the leaves?

Cuticular Transpiration Signup and view all the answers

What role do guard cells play in the process of stomatal transpiration?

They regulate the opening and closing of stomata Signup and view all the answers

In which experiment did condensation not occur on the inner walls of the apparatus?

Set up C Signup and view all the answers

What is the significance of water vapour condensing on the walls of the bell jar in the experimental setup?

It shows that plants release water vapour during transpiration Signup and view all the answers

Which form of transpiration is primarily associated with older stems of plants?

Lenticular Transpiration Signup and view all the answers

Signup and view all the answers

Study Notes

Transpiration

Transpiration is the process of water loss in the form of water vapor from aerial plant parts.

Demonstration of Transpiration: Experiment 1

Drops of water form on the inside of a plastic bag placed over a plant.
No water collects on a plastic bag over an empty space.
Water vapor from the plant saturates the plastic bag and condenses.

Demonstration of Transpiration: Experiment 2

Experiment setups A and B showed water vapor condensation on the inner walls of bell jars.
Cobalt chloride paper turned pink in setups A & B, indicating water vapor presence.
No condensation or color change in setup C.
The color change (pink) of cobalt chloride paper shows transpiration.

Kinds of Transpiration

Stomatal Transpiration: Water vapor escapes through stomata (pores) in leaves.
Cuticular Transpiration: Water loss occurs directly from the leaf's surface.
Lenticular Transpiration: Water loss takes place through lenticels (pores) in stems.

Stomata

Stomata are pores surrounded by guard cells.
Stomata number can range from 1,000 to 10,000 per cm².

Mechanism of Stomatal Transpiration

Water vapor saturates air spaces within spongy mesophyll.
Water vapor diffuses into interconnected intercellular spaces and to the sub-stomatal space.
Water then evaporates and diffuses out through stomata.
Guard cells regulate stomatal opening and closing.

Experiment: Leaf Surface Transpiration

Cobalt chloride paper on the lower leaf surface turns pink faster than the upper surface.
This suggests more transpiration from the leaf's lower surface, attributed to more stomata.

Rate of Transpiration: Potometer Method

A potometer measures water uptake (closely related to transpiration rate).
Air bubbles move in a capillary tube as water is drawn.
Factors affecting transpiration rate include light intensity, temperature, wind speed, humidity, CO2 levels, and atmospheric pressure.

Factors Affecting Transpiration Rate

Light Intensity: Higher light intensity increases transpiration rate.
Temperature: Higher temperature increases transpiration rate.
Wind Velocity: Increased wind speeds increase transpiration.
Humidity: Low humidity increases transpiration rate.
Carbon Dioxide: Increased CO2 levels decrease transpiration rate.
Atmospheric Pressure: Lower atmospheric pressure increases transpiration rate.

Adaptations in Plants to Control Transpiration

Plants in dry climates have adaptations:
- Rolled or folded leaves
- Spines (instead of leaves)
- Reduced stomata
- Thick waxy cuticles

Significance of Transpiration

Transpiration cools leaves.
Creates a suction force pulling water up through the plant
Promotes water uptake and nutrient absorption by roots, affecting plant growth.

Differences between Transpiration and Evaporation

Transpiration: Water loss in vapor form from plants via stomata and lenticels.
Evaporation: Water loss from any surface to the atmosphere as water vapor.

Guttation and Bleeding

Guttation: Water loss as liquid from hydathodes in plants, most often at night following high humidity.
Bleeding: Water loss from a cut plant stem, i.e., in form of sap.

Differences between Transpiration and Guttation

Transpiration: Loss is water vapor.
Guttation: Loss is liquid water.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the fascinating process of transpiration, where plants lose water in the form of vapor. This quiz covers two experiments demonstrating transpiration and its different types, including stomatal, cuticular, and lenticular transpiration. Test your knowledge about how plants manage water loss!