2.2 Gas Exchange Flashcards
(18 cards)
Why do organisms need gas exchange?
Organisms need gas exchange to obtain oxygen for cellular respiration and remove carbon dioxide produced during respiration.
What factors influence the efficiency of gas exchange?
The efficiency of gas exchange depends on surface area, concentration gradient, and distance over which gases have to diffuse.
How do single-celled organisms exchange gases?
Single-celled organisms like amoeba exchange gases directly through their cell membrane by diffusion, due to their small size and large surface area relative to volume.
Why is diffusion sufficient for gas exchange in single-celled organisms?
Single-celled organisms have a high surface area to volume ratio, making diffusion efficient for gas exchange over short distances.
What is the structure involved in gas exchange in insects?
Insects have a system of tracheae, which are tubes that transport oxygen directly to tissues and remove carbon dioxide. The system is ventilated by spiracles and tracheoles.
How do spiracles help in gas exchange in insects?
Spiracles are small openings on the insect’s body that allow oxygen to enter and carbon dioxide to exit. They can open and close to prevent water loss.
How is the tracheal system in insects adapted for gas exchange?
The tracheal system provides a direct route for gas exchange to tissues, minimizing diffusion distances. Tracheoles are very small and can reach individual cells, ensuring efficient gas exchange.
What structures are involved in gas exchange in plants?
In plants, gas exchange occurs through stomata (pores on the leaf surface), with the aid of mesophyll cells, chloroplasts, and xylem (for water transport).
How do stomata contribute to gas exchange in plants?
Stomata allow carbon dioxide to enter for photosynthesis and oxygen to leave as a by-product. The opening and closing of stomata are controlled by guard cells to regulate water loss.
How is the structure of leaves adapted for efficient gas exchange?
Leaves have a large surface area, thin flattened shape, and a network of air spaces within the mesophyll, which facilitate the diffusion of gases like oxygen and carbon dioxide.
How do plants adapt to limit water loss during gas exchange?
Plants limit water loss by closing their stomata during dry conditions, reducing transpiration. The presence of a waxy cuticle on leaves also helps prevent water loss.
How do fish exchange gases?
Fish use gills to exchange gases. Water flows over the gills, and oxygen diffuses from the water into the blood, while carbon dioxide diffuses from the blood into the water.
What is the countercurrent flow mechanism in fish?
The countercurrent flow mechanism in fish ensures a constant concentration gradient for gas exchange by having water flow over the gills in the opposite direction to the blood in the gill filaments.
How are gills adapted for efficient gas exchange in fish?
Gills are adapted by having many gill filaments and lamellae (folds), which increase the surface area for gas exchange. The thin walls of the lamellae allow efficient diffusion of gases.
How do mammals exchange gases?
Mammals exchange gases through their lungs. Oxygen is taken in via the trachea, branching into bronchi, then bronchioles, and finally the alveoli, where gas exchange occurs.
How is the structure of the alveoli adapted for gas exchange in mammals?
Alveoli have a large surface area, thin walls (one-cell thick), and are surrounded by a dense network of capillaries, allowing for efficient gas exchange by diffusion.
How does the process of ventilation support gas exchange in mammals?
Ventilation maintains the concentration gradient by bringing in fresh air rich in oxygen and removing air with high carbon dioxide levels, supporting continuous diffusion in the alveoli.
What is the role of hemoglobin in mammalian gas exchange?
Hemoglobin binds with oxygen in the lungs, forming oxyhemoglobin, and releases oxygen in tissues with a low oxygen concentration, aiding efficient gas transport and delivery.
