I am confident that I can describe three basic life processes carried out by plants, including how these processes depend on each other.
I know the structures of plants, and how they function to promote survival, defense, and reproduction.
I am confident that I can describe a variety of ways that plants respond to external stimuli, and how these responses relate to life processes.
Plants perform three basic life processes: photosynthesis, respiration, and transpiration. These processes are interconnected and rely on each other for the survival and growth of the plant.
Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose (a type of sugar) and oxygen. This process occurs mainly in the leaves, facilitated by a specialized pigment called chlorophyll. Photosynthesis is crucial for the plant's survival as it provides the necessary energy for all other life processes. Oxygen, produced as a byproduct of photosynthesis, is released into the atmosphere.
Respiration is the process by which plants break down stored glucose, releasing energy for various metabolic activities. This process takes place in the cells of all plant tissues, including leaves, stems, and roots. Just like in animals, respiration in plants involves the uptake of oxygen and the release of carbon dioxide. The oxygen required for respiration is obtained through the stomata, tiny openings on the surface of leaves. The carbon dioxide produced during respiration is used in photosynthesis, creating a symbiotic relationship between the two processes.
Transpiration is the loss of water vapor from the plant's surface, primarily through tiny pores called stomata. It occurs mainly in the leaves and is responsible for the upward movement of water from the roots to the rest of the plant. Transpiration helps to transport important nutrients and minerals, maintain cell turgidity, and cool the plant. Additionally, the loss of water through transpiration creates a suction force that pulls water up from the roots, enabling water and nutrient uptake.
Plants also exhibit various responses to external stimuli, ensuring their adaptation and survival in changing environments. These responses include tropisms, which are growth movements in response to directional stimuli such as light (phototropism), gravity (geotropism), and touch (thigmotropism). For example, phototropism allows plants to grow towards a light source to maximize their exposure to sunlight for photosynthesis.
Plants can also respond to stimuli through tropic movements, which involve changes in the orientation of plant parts. Examples include the movement of leaves or flowers in response to changes in temperature or light intensity. Additionally, plants can exhibit nastic movements, which are independent of the direction of the stimulus. Examples of nastic movements are the closing of leaves in response to touch (thigmonasty) or temperature change.
These responses to external stimuli are essential for plants to optimize their growth, obtain resources, avoid predators, and successfully reproduce. By being able to adapt to their surroundings, plants can ensure their survival and the continuation of their species.