Question

When guard cells swell, __________ a. transpiration ceases b. sugars enter phloem c. stomata open d. root cells die

Short answer

When guard cells swell, stomata open (Option c).

Step-by-step solution

Understanding Guard Cells

Guard cells are specialized cells located on leaf surfaces. They surround stomata, which are small openings that allow gas exchange. The primary role of guard cells is to regulate the opening and closing of stomata.

Identifying Swelling Mechanism

Guard cells swell when they take in water, usually in response to light and photosynthesis activities. Upon swelling, they change shape, causing the stomata to open.

Evaluating Options

Let's evaluate the options: - a. Transpiration ceases: Opening of stomata increases transpiration rather than cease it. - b. Sugars enter phloem: Although sugars do move into the phloem, this is not directly a result of guard cells swelling. - c. Stomata open: When guard cells swell, they bend and cause the stomata to open. - d. Root cells die: This is unrelated to guard cells.

Choosing the Correct Answer

Based on the evaluation, the correct option when guard cells swell is option c: stomata open. This is because swelling of guard cells results in the opening of the stomatal pore.

Key concepts

Stomata

Stomata are tiny openings or pores located mainly on the surface of leaves and stems. They play a crucial role in the life of a plant by allowing gas exchange between the plant and its environment.
Through stomata, carbon dioxide enters the plant, which is essential for photosynthesis. Oxygen, a byproduct of photosynthesis, exits through these pores. Moreover, stomata facilitate the process of transpiration, where water vapor is lost from the plant.

• The opening and closing of stomata are controlled by guard cells, which change shape in response to environmental conditions.
• This regulation ensures that the plant can maintain an optimal balance of water retention and gas exchange.

Stomata are vital for plant survival and efficiency in photosynthesis and transpiration.

Transpiration

Transpiration is the process by which water vapor is released from plant leaves through the stomata. It plays a significant role in water movement within the plant, from roots through stem to leaves and into the atmosphere. This movement of water is essential for the transport of nutrients and maintaining plant turgidity.

• Transpiration helps cool the plant on hot days, as the evaporation of water has a cooling effect.
• It also creates a negative pressure, or suction, that helps draw water and minerals up from the roots.

During the day, transpiration rates are typically higher due to the increased need for cooling and photosynthetic activity.

Photosynthesis

Photosynthesis is the process by which plants convert light energy into chemical energy in the form of glucose. This process takes place in the chloroplasts of plant cells and involves the intake of carbon dioxide and water.

• Sunlight acts as a catalyst to facilitate the conversion of carbon dioxide and water into glucose and oxygen.
• Oxygen is released as a byproduct, which is essential for life on Earth.

Photosynthesis not only provides energy for the plant itself but also forms the foundation of the food chain for other organisms. It emphasizes the importance of open stomata to allow the necessary carbon dioxide to enter the plant.

Plant Physiology

Plant physiology refers to the study of plant functions and the underlying processes that enable plants to thrive. It involves understanding key functions like water movement, nutrient transport, and photosynthesis.

• Core processes include the regulation of stomatal opening and closing by guard cells.
• Plant physiology explores how internal and external factors impact plant growth and health, such as light, temperature, and water availability.

Understanding plant physiology allows us to grasp the complex interactions within plants and their reactions to environmental changes, ensuring their survival and productivity.