IB Biology: B3.1-Gas Exchange as a Function of Living Organisms

What systems do multicellular organisms like mammals have for gas exchange?

• A gas exchange system for oxygen uptake and carbon dioxide removal, along with a circulatory system.

• A simple diffusion process through the skin and body surface.

• A respiratory system that only functions during sleep.

• An external gill system similar to that of fish.

What do all aerobic organisms require for ATP production during respiration?

• A constant supply of oxygen.

• Carbon dioxide

• Glucose

• Nitrogen

Why must carbon dioxide produced in respiration be removed from the body?

• Because it is poisonous.

• Because it is a waste product that can cause harm in high concentrations.

• Because it is needed for photosynthesis.

• Because it helps regulate body temperature.

What is gas exchange?

• The process of converting food into energy in cells.

• The diffusion (passive movement) of gases (CO2 and O2) into and out of cells, essential for respiration.

• The circulation of blood throughout the body.

• The absorption of nutrients from the digestive tract into the bloodstream.

How do single-celled organisms perform gas exchange?

• Oxygen is actively transported into the cell while CO2 is expelled through vesicles.

• Oxygen diffuses from the fluid outside the cell, through the cell surface membrane, into the cytoplasm, and CO2 diffuses out.

• Single-celled organisms do not perform gas exchange; they rely on anaerobic processes.

• Gas exchange occurs through specialized structures called gills.

Why is diffusion alone not sufficient for gas exchange in multicellular organisms?

• Because it is too slow to meet the metabolic demands of cells.

• Due to the low surface area to volume ratio, diffusion is not enough to deliver O2 and remove CO2, especially to deeply embedded cells.

• Because gases cannot diffuse through liquid environments.

• Because diffusion only works effectively in unicellular organisms.

How do plants adapt for gas exchange?

• Plants have adaptations that allow the exchange of atmospheric gases for both respiration and photosynthesis.

• Plants have thick cuticles to prevent gas exchange.

• Plants only exchange gases at night during respiration.

• Plants rely solely on their roots for gas exchange.