Question

Stomata opens because of (a) Oxygen in the air (b) Increased turgidity of the guard cells brought about by the cxposure to light (c) Vacuoles in guard cells (d) All the above

Short answer

The correct answer is (b) Increased turgidity of the guard cells brought about by the exposure to light.

Step-by-step solution

Analyzing the Options

First, go through all the provided options a), b), c) and d) one by one. oxygen in the air (a) and vacuoles in guard cells (c) although having roles in plant physiology do not directly influence the opening of the stomata.

Understanding the Role of Guard Cells' Turgidity

Recognize that the key factor that governs the opening and closing of the stomata are the guard cells. When the guard cells are filled with water, they become turgid and cause the stomata to open. This increased turgidity of guard cells is intensified by exposure to light, as it enhances the process of photosynthesis, which in turn increase the synthesis of glucose in the cell. The accumulation of glucose in the guard cells increases osmotic pressure within the cells, drawing in water and causing stomatal opening.

Identifying the Correct Option

After seeing the role of the guard cells turgidity, option (b) appears to be the most valid reason for the opening of the stomata.

Key concepts

Turgidity of Guard Cells

Understanding the mechanism behind stomata opening is essential in plant physiology, and it heavily involves the concept of turgidity of guard cells. Guard cells surround stomata, which are tiny openings on the surface of leaves and stem that allow for gas exchange essential for photosynthesis and respiration.

Turgidity refers to the state of being swollen with water. Turgid guard cells are responsible for opening the stomata. When these cells absorb water, they swell, bending apart from each other and widening the stomatal aperture. Conversely, when they lose water and become flaccid, the stomata close. This process is vital for regulating water vapor loss (transpiration), CO₂ uptake, and oxygen release in plants.

Several factors can influence the turgidity of guard cells, including light, CO₂ concentration, and internal circadian rhythms. However, light is a powerful trigger as it activates photosynthesis, increasing the sugar concentration inside guard cells and causing osmotic water movement into them, thereby increasing their turgidity.

Plant Physiology

Plant physiology encompasses the study of various biological functions within plant systems, including the stomata opening mechanism. This discipline covers how plants control water balance, manage nutrient uptake, and respond to environmental cues through processes like phototropism and root growth.

In the case of the stomata opening mechanism, it is an example of how plants adapt to simultaneous demands of conserving water and allowing for the intake of CO₂ necessary for photosynthesis. The opening of stomata is a finely tuned physiological response to external (light, humidity, temperature) and internal factors (hormonal signaling, ion distribution).

Understanding these processes is critical for fields like agriculture and horticulture, as it impacts crop yield, disease resistance, and overall plant health. Improving comprehension of how these mechanisms work can aid in developing crops that are more efficient in their water use and adaptable to changing climatic conditions.

Photosynthesis Process

The photosynthesis process is central to the existence of plants and for life on Earth as it is the means by which plants synthesize food from sunlight. This complex process occurs within the chloroplasts, primarily in the leaf cells. It involves the conversion of light energy into chemical energy, stored as glucose and used for the plant's growth and development.

Photosynthesis can be summarized by the equation: \( 6 CO_2 + 6 H_2O + light energy \rightarrow C_6H_{12}O_6 + 6 O_2 \). During this process, CO₂ is drawn in through the stomata, and water is transported from the roots. Photosynthesis is influenced by the availability of light, which is why stomata generally open in the daylight to increase CO₂ absorption.

Chlorophyll, the pigment responsible for the green color of plants, captures light energy, which initiates the photosynthesis process. This is why well-lit environments are often associated with rapid plant growth and health, as more energy is available for food production.