Problem 9 - Objective Biology for NEET

Question

Which of the following substance is used in half leaf experiment to absorb \(\mathrm{CO}_{2} ?\) (a) \(\mathrm{HCl}\) (b) \(\mathrm{KOH}\) (c) \(\mathrm{HNO}_{3}\) (d) \(\mathrm{H}_{2} \mathrm{SO}_{4}\)

Step-by-Step Solution

Answer

The substance used in half leaf experiment to absorb CO2 is \(\mathrm{KOH}\) (Potassium Hydroxide).

Step 1: Understand Half Leaf Experiment

The Half Leaf Experiment is a scientific test to study the process of photosynthesis. One half of a leaf is enclosed in a chamber and exposed to light, while the other half is left in normal conditions. This setup allows measuring the rate of photosynthesis in variable conditions.

Step 2: Role of Substances

In such experiments, a substance is needed to absorb the produced Carbon Dioxide (CO2). By absorbing CO2, the substance aids in creating a CO2 free environment within the chamber.

Step 3: Identify Correct Substance

Among the options provided (HCl, KOH, HNO3, and H2SO4), the substance that is traditionally used to absorb CO2 in a Half Leaf Experiment is KOH (Potassium Hydroxide). KOH has a strong affinity to CO2, thus it's used to create a carbon dioxide free environment inside the chamber in such experiments.

Key Concepts

Half Leaf Experiment

The Half Leaf Experiment is a fascinating way to explore the process of photosynthesis, which is the method by which plants convert light into chemical energy. In this experiment, a leaf is partly enclosed in a chamber that is exposed to light, while the other half remains in the open, under normal conditions.
This allows scientists to understand how light and the absence or presence of certain environmental factors influence photosynthesis. The Half Leaf Experiment helps in assessing the rate of photosynthesis by varying conditions within the chamber as compared to the exposed side of the leaf.

• Exposure to light: This part of the experiment helps to understand the role light plays in energizing photosynthesis.
• Environmental variables: By controlling variables such as CO2 levels inside the chamber, the process of photosynthesis can be studied in-depth.

This method effectively highlights the different factors that can influence photosynthesis, making it easier to study each element's contribution separately.

CO2 Absorption

Carbon dioxide (CO2) absorption is crucial in the Half Leaf Experiment because it helps to create an environment with controlled CO2 levels. By removing or limiting CO2, you can gain clear insights into its role in photosynthesis.
In the experiment, CO2 absorption allows scientists to:

• Control the rate of photosynthesis by altering the availability of carbon dioxide.
• Observe the effect of CO2 scarcity and study how reduced levels alter the photosynthesis process.
• Understand how plants might respond in environments with fluctuating CO2 levels.

Being able to manipulate and measure CO2 levels is vital for accurately assessing plant responses and measuring the overall impact on photosynthesis. This understanding is critical for advancing our knowledge about how plants adapt to different environmental circumstances.

Potassium Hydroxide

Potassium Hydroxide (KOH) plays a key role in the Half Leaf Experiment due to its ability to absorb carbon dioxide effectively. Among the options provided like HCl, HNO3, and H2SO4, KOH is traditionally used because of its strong reactivity with CO2.
KOH serves several important purposes in the experiment:

• Creates a CO2-free environment in the experiment chamber to study photosynthesis without the influence of carbon dioxide.
• Aids in contrasting the reaction of the leaf subjected to depletion of CO2 versus the part that remains under semi-natural conditions.
• Directs focus on other essential elements of photosynthesis, such as light intensity and temperature, by temporarily removing one key factor, which is CO2.

By using Potassium Hydroxide, scientists can more accurately study the plant’s behavior under altered environmental conditions, shedding light on the versatility and adaptability of photosynthesis.