Problem 87 - Objective Biology for NEET

Question

Effect of root pressure is visible (a) At night (b) At early morning (c) When evaporation is low (d) All of these

Step-by-Step Solution

Answer

The correct answer is (d) All of these. The effect of root pressure is visible during the night, in the early morning and when the rate of evaporation is low.

Step 1: Understanding Root Pressure

Root pressure is a phenomenon in plant biology where the higher concentration of solutes at the roots draws water from the soil into the plant's root system. It is also associated with the upward movement of water from roots to shoots in absence of transpiration.

Step 2: Analyzing the Options

Next, let's analyze the options given:(a) At night - Transpiration is low and root pressure is high, so the effect of root pressure is visible.(b) At early morning - During early morning hours, the rate of transpiration is low and hence, root pressure can drive water movement.(c) When evaporation is low - When evaporation is low, the rate of water intake by the roots can exceed the rate of its loss by transpiration, again leading to the buildup of root pressure.Given this analysis, it's clear that all of these options show conditions under which the effect of root pressure is visible.

Step 3: Final Answer

Hence, after evaluating all options and relating them with the concept of root pressure, it's pretty clear that the effect of root pressure is visible in all the given conditions.

Key Concepts

Transpiration

Transpiration is the process by which water moves through plants, eventually entering the atmosphere as water vapor. It primarily occurs in the leaves where tiny pores called stomata facilitate the exchange of gases and the evaporation of water.
These pores open to take in carbon dioxide needed for photosynthesis, but they also allow water to escape.

• Transpiration helps keep plants cool, as the evaporation of water from leaf surfaces carries away heat.
• It creates a negative pressure within plant vessels that assists in drawing water and nutrients up from the roots.
• The process significantly impacts local humidity levels, playing a role in the water cycle.

Understanding transpiration helps in explaining how roots maintain water pressure even when this process is reduced, such as at night or in early morning hours.

Water Movement in Plants

Water movement in plants is vital for their nutrient transport and overall physiology. It involves several mechanisms, with transpiration and root pressure being the key players.
Transpiration pulls water up the plant axis from roots to leaves thanks to the cohesive properties of water. However, when transpiration is minimal, such as during the night, root pressure can take charge.

• Water absorption occurs mainly at the roots, facilitated by osmosis due to higher solute concentrations.
• Root pressure is generated by the active transport of nutrient ions into the roots, creating a concentration gradient that draws in water.
• This pressure pushes water upward when the pull from transpiration is weak or absent, visibly promoting water movement to upper plant parts.

This dual action ensures plants have access to water and nutrients throughout varying environmental conditions.

Plant Biology

Plant biology is a vast field that includes understanding processes like transpiration and root pressure, crucial for plant survival and growth.
Plants have adapted to optimize water uptake and distribution efficiently. Root pressure and transpiration are both adaptations to tackle different environmental challenges.

• At night or early morning, when transpiration is low, root pressure becomes essential.
• Plants demonstrate the ability to manage water through different pressures and gradients, ensuring they maintain structural and metabolic balance.
• Understanding these processes is crucial for fields like agriculture and horticulture, where water management is key.

Through plant biology, we recognize how well plants are engineered to face not just daily but seasonal changes in their habitats.