B3.1 Gas Exchange

What is the primary purpose of the respiratory system?

• To transport oxygen to cells and remove carbon dioxide
• To transport food and oxygen
• To remove waste from the body
• To transport hormones

Answer explanation

The respiratory system's main function is to supply the body with oxygen and remove carbon dioxide to allow for cellular respiration.

Tags

NGSS.HS-LS2-5

Which process describes the exchange of gases between the alveoli and the bloodstream?

• Gas exchange
• Ventilation
• Cellular respiration
• Breathing

Answer explanation

Gas exchange refers to the transfer of oxygen and carbon dioxide between the alveoli and the blood by diffusion.

Which factor does not affect the rate of diffusion?

• Surface area
• Concentration gradient
• Thickness of the membrane
• Size of the organism

Answer explanation

Diffusion depends on surface area, concentration gradients, and membrane thickness. The size of the organism is not directly relevant.

Which adaptation increases the efficiency of gas exchange in fish?

• Large capillary network
• Thicker respiratory membrane
• Low concentration gradient
• Smaller surface area

Answer explanation

Fish gills are adapted with a large capillary network and a counter-current system to maximize oxygen absorption.

Tags

NGSS.HS-LS4-4

Why do alveoli have a large surface area?

• To increase the rate of diffusion
• To reduce the diffusion path
• To reduce moisture loss
• To slow down gas exchange

Answer explanation

A large surface area ensures efficient gas exchange by maximizing the area available for oxygen and carbon dioxide diffusion.

What happens to the diaphragm during inspiration?

• It contracts and flattens
• It relaxes and arches upwards
• It contracts and moves upwards
• It relaxes and moves downwards

Answer explanation

During inspiration, the diaphragm contracts and flattens, increasing the volume of the thoracic cavity and drawing air into the lungs.

What role does surfactant play in the lungs?

• Reduces surface tension in the alveoli
• Increases oxygen binding to hemoglobin
• Decreases lung elasticity
• Absorbs carbon dioxide

Answer explanation

Surfactant reduces the surface tension within the alveoli, preventing their collapse and aiding in efficient gas exchange.

Which of the following is a characteristic of an efficient gas-exchange surface?

• Thin membrane
• Low surface area
• Thick tissue layers
• High water content

Answer explanation

Thin membranes minimize the distance gases must travel, which speeds up diffusion.

How does the Bohr shift affect oxygen dissociation?

• It shifts the curve to the right, increasing oxygen release in tissues
• It shifts the curve to the left, increasing oxygen binding
• It decreases hemoglobin's affinity for carbon dioxide
• It causes hemoglobin to bind less oxygen in the lungs

Answer explanation

The Bohr shift causes hemoglobin to release more oxygen in tissues where carbon dioxide is high and pH is low.

Which structure increases the surface area for gas exchange in plants?

• Stomata
• Xylem
• Guard cells
• Phloem

Answer explanation

Stomata are openings in plant leaves that allow gas exchange, maximizing surface area for diffusion.