Problem 111 - Objective Biology for NEET

Question

The position and frequency of stomata can be determined by (a) Calculating the loss of water (b) Cobalt chloride paper method (c) Photometer (d) Porometer

Step-by-Step Solution

Answer

The correct method for finding the position and frequency of stomata is (b) Cobalt chloride paper method.

Step 1: Analyze All Options

Review all four options individually. Option (a) suggests the loss of water could determine the stomata position and frequency, but this is incorrect. Options (c) and (d) referring to Photometer and Porometer, while these are scientific devices, they are not specifically used for this purpose.

Step 2: Select the Correct Option

From reviewing, it is clear that option (b), the Cobalt chloride paper method, is an accurate method for determining the position and frequency of stomata. This method involves using Cobalt chloride paper, which changes color in presence of water, demonstrating where the stomata are located.

Key Concepts

Cobalt chloride paper method

The Cobalt chloride paper method is a simple and effective tool for studying stomata, tiny openings on the surfaces of leaves. These crucial openings control the movement of gases, including water vapor, in and out of the plant.

The method revolves around a special paper treated with cobalt chloride that changes color when exposed to moisture. In a dry state, the paper is blue. However, when it absorbs moisture, it turns pink. This color change property allows scientists to easily locate stomata on a leaf's surface.

• Firstly, cobalt chloride paper is placed on the leaf's surface.
• Next, plastic or glass is placed over the paper to ensure accurate measurement.
• As the stomata release water vapor, the paper changes color wherever stomata are present.

The method is a practical tool for determining stomatal location and frequency since you can visually observe these changes distinctive to regions with higher stomatal density.

Water loss measurement

Understanding how much water plants lose through their stomata is essential for understanding plant health and efficiency. The rate of water loss can indicate various physiological states of the plant.

Water loss measurement often involves calculating how much water a plant transpires over a given period. Unlike the cobalt chloride paper method, this doesn't directly determine stomatal position but can reflect how actively stomata are functioning.

• Various methods, such as gravimetric or potometers, can measure water loss.
• Gravimetric methods involve measuring the weight loss of a plant as it loses water.
• Potometers measure the rate of water uptake, assuming it's equal to the water lost through transpiration.

Being able to calculate water loss helps diagnose issues like overexposure to sunlight or dehydration, which can influence stomatal function.

Stomatal position and frequency determination

Determining the position and frequency of stomata on a leaf is crucial for understanding the photosynthetic capacity and gas exchange potential of a plant. Stomata are typically more dense on the bottom surface of leaves, but their actual position and number can vary across plant species and environments.

Several methods exist for determining stomatal patterns:

• The cobalt chloride paper method visually highlights stomatal areas, offering a quick way to assess stomatal distribution.
• Direct microscopic examination involves creating impressions of the leaf surface to count stomata under a microscope.
• Another popular technique is using nail varnish or another type of polish to peel off an impression of the leaf surface, which can be observed microscopically.

Understanding these patterns helps researchers in fields like agriculture and environmental science as they seek to optimize plant growth and environmental resilience.