Gas Exchange in Plants Practical Study

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Questions and Answers

What do green plants use during photosynthesis to produce oxygen?

Nitrogen

Phosphorus

Hydrogen

Carbon dioxide (correct)

What color indicates a higher than normal level of carbon dioxide in the hydrogencarbonate indicator?

Red

Purple

Green

Yellow (correct)

In which condition do green leaves take in carbon dioxide?

Under bright sunlight (correct)

During respiration

When wrapped in aluminium foil

In the dark

Which of the following tubes served as a control setup in the experiment?

Tube B Signup and view all the answers

What is the overall effect of green leaves on carbon dioxide levels in the presence of sunlight, as observed in tube A?

Carbon dioxide levels decrease Signup and view all the answers

What happens to the hydrogencarbonate indicator in tube C after five hours when the leaves are in the dark?

It turns yellow Signup and view all the answers

Why is it important to ensure that leaves do not touch the hydrogencarbonate indicator in the experiment?

To ensure accurate color change Signup and view all the answers

What may be concluded about gas exchange in plants during the night based on the results from tube D?

Plants release carbon dioxide Signup and view all the answers

What occurs in plants under light conditions regarding gas exchange?

The rate of photosynthesis is higher than the rate of respiration. Signup and view all the answers

What is the net gas exchange in plants during dark conditions?

Net uptake of oxygen and net release of carbon dioxide. Signup and view all the answers

What role do stomata play in plants?

They facilitate the movement of gases into and out of leaves. Signup and view all the answers

What is true about the net carbon dioxide exchange during photosynthesis?

There is a net uptake of carbon dioxide in photosynthesis. Signup and view all the answers

When observing stomata under a microscope, which magnification is suggested for the initial observation?

100X Signup and view all the answers

Which of the following describes the gas exchange in plants by stomata?

Stomata enable both carbon dioxide uptake and oxygen release. Signup and view all the answers

What is a key point regarding gas exchange in plants?

Gas exchange in plants is mainly through stomata. Signup and view all the answers

Which statement correctly describes the relationship between photosynthesis and respiration under light conditions?

Photosynthesis outpaces respiration, leading to a net oxygen release. Signup and view all the answers

Study Notes

Gas Exchange in Plants

Green plants carry out photosynthesis to create their own food.
Photosynthesis uses carbon dioxide and produces oxygen.
Respiration releases energy from food, using oxygen and producing carbon dioxide.
Gas exchange is important throughout the day.

Practical 7.9 Study

Aim: To determine how carbon dioxide levels change in tubes containing leaves, under light and dark conditions.
Apparatus: Boiling tubes, cotton thread, fresh green leaves, test tube rack, measuring cylinder (10cm³), hydrogencarbonate indicator, table lamp, aluminium foil.
Procedure:
- Add hydrogencarbonate indicator to tubes. Note the colour.
- Place leaves in some tubes (A & C).
- Seal tubes and avoid air leaks.
- Expose one set of tubes (A & C) to light, and the other set (B & D) to darkness.
- Observe the colour change after 5 hours

Hydrogencarbonate Indicator

Different colors correspond to different carbon dioxide levels.
Purple = lower than normal level
Red = normal level (about 0.04%)
Yellow = higher than normal level

Results and Discussion

- Tube A (light): The indicator colour changes to a vibrant purple, suggesting that the plant actively absorbed carbon dioxide from the surrounding environment as part of the process of photosynthesis. This change signifies the plant's ability to convert light energy into chemical energy, synthesizing glucose while releasing oxygen as a byproduct.
- Tube B (dark): In this tube, there is no noticeable change in the colour of the indicator, which remains red. This outcome indicates that the plant is not altering the levels of carbon dioxide present in its surroundings, likely due to the lack of light necessary for photosynthesis. The dark condition restricts the plant's ability to absorb carbon dioxide, thereby demonstrating the important role of light in the photosynthetic process.
- Tube C (light): Here, the indicator colour shifts to yellow, which reveals that the plant is releasing carbon dioxide as a result of respiration. This process typically occurs when plants convert glucose into energy for growth and metabolism, resulting in the production of carbon dioxide as a waste byproduct. It highlights the dual role of plants in both using and releasing carbon dioxide during different metabolic activities.
- Tube D (dark): In this instance, the indicator remains unchanged, retaining its red colour. This suggests that the plant does not alter the carbon dioxide levels, reinforcing the idea that, even in darkness, without the necessary light energy for photosynthesis, the plant cannot perform gas exchange efficiently. This showcases the metabolic limitations faced by plants during periods without light.
- The variations in colour changes across these tubes effectively illustrate the contrasting physiological responses of the plant to light and darkness. Such differences underscore the vital interplay between photosynthesis, which occurs in light, and respiration, which can occur both in light and dark conditions. Consequently, these observations help us understand the intricate balance of gas exchange in plants and how it affects the carbon dioxide concentration in the environment.
Gas Exchange in Plants Under Light Conditions
Plants carry out both photosynthesis and respiration..
The rate of photosynthesis is usually greater than respiration.
This leads to a net uptake of carbon dioxide and release of oxygen.

Gas Exchange in Plants Under Dark Conditions

Plants only carry out respiration, not photosynthesis
This results in a net release of carbon dioxide and uptake of oxygen.

Gas Exchange Through Stomata

Gases like carbon dioxide and oxygen are exchanged through pores called stomata.
These pores are located on leaves.

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Description

This quiz explores the gas exchange processes in plants, focusing on photosynthesis and respiration. It also includes a practical study to observe how carbon dioxide levels change under different light conditions. Participants will engage with hands-on experiments using hydrogencarbonate indicators to assess these changes.