Problem 88 - Objective Biology for NEET

Question

Guttation is seen in (a) Vein opening near the tip of grass blade (b) Leaves of many herbaceous plant (c) Both (a) and (b) (d) Leaves of trees

Step-by-Step Solution

Answer

The correct answer is (c) Both (a) and (b).

Step 1: Understanding guttation

Guttation is a process in plants where water droplets are excreted from the tips or edges of leaves. This typically occurs when soil moisture levels are high, atmospheric humidity is high and transpiration is low (commonly during nights).

Step 2: Identify the venues of guttation

Guttation commonly occurs in the vein opening near the tip of grass blades, as well as in leaves of some herbaceous plants. Trees typically do not exhibit guttation due to factors such as their higher transpiration rates.

Step 3: Select the correct answer

Given the understanding of guttation in plants, options (a) and (b) both correlate with the venues of guttation. Therefore, option (c) which combines both is the correct answer.

Key Concepts

Water transport in plants

Plants have a unique way of moving water from their roots to the leaves. This is a crucial process because water is essential for photosynthesis, nutrient transport, and keeping the plant's structure firm. The transport of water occurs through specialized tissues called xylem.
Xylem vessels, which are like tiny tubes, carry water upward from the roots. This movement is driven by two main processes: capillary action and root pressure. Root pressure pushes water up the plant when the soil is very wet. Capillary action comes into play due to the forces between water molecules and the walls of xylem vessels.

• Water uptake starts at the roots.
• The roots absorb water from the soil, leading it into the xylem.
• The xylem vessels then transport water to other parts of the plant.

It's fascinating how plants manage their water transport systems, especially considering the various water needs depending on the species and environment.

Herbaceous plants

Herbaceous plants are a specialized group within the plant kingdom. Unlike woody plants, these plants have soft structures and mostly green stems. This is because they lack lignin, the substance that hardens the cell walls of woody plants. Some everyday examples include grasses, dandelions, and some perennial flowers. Herbaceous plants tend to grow only during specific seasons and often die back in others.
These plants rely heavily on their environment for fulfilling their water needs. Since they do not develop woody tissues, they spend less energy on structural support, which allows them to grow quickly.

• Tend to have flexible, soft stems.
• Usually have a shorter lifespan relative to woody plants.
• Often show guttation due to their high water intake and release.

As they grow and thrive where conditions are favorable, their ability to perform guttation becomes more apparent.

Transpiration

Transpiration is one of the critical processes in plant physiology that involves the loss of water vapor from the plant to the atmosphere. This usually happens through openings on the leaves known as stomata. Transpiration serves many purposes; it helps cool the plant, enables mineral and nutrient transport, and aids in pulling water from the soil.
It's important to know that transpiration primarily takes place during the day when sunlight prompts the openings of stomata. Conditions such as high temperature, low humidity, and wind speed can increase the rate of transpiration. However, when conditions are opposite, such as during high humidity at night, transpiration slows, and guttation might be observed.

• Occurs mostly during daytime.
• Gets impacted by environmental factors like temperature and humidity.
• Is vital for nutrient absorption and thermal regulation.

Understanding transpiration helps us grasp how plants manage water loss and cope with various environmental conditions.