Biology HL 11/12: Gas Exchange

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Questions and Answers

What is the main function of gas exchange in organisms?

To obtain important gases and remove waste gases (correct)

To synthesize proteins

To produce energy through metabolic reactions

To regulate body temperature

What is the advantage of having a high surface area to volume ratio in gas exchange?

It relies on diffusion across the body surface (correct)

It increases the distance for gas diffusion

It reduces the rate of gas exchange

It increases oxygen consumption

What is a characteristic of effective gas exchange surfaces?

Large surface area and permeability (correct)

Small surface area

Impermeable surface

Thick tissue layer

What is the role of stomata in plants?

To regulate gas exchange by opening and closing Signup and view all the answers

What is the driving force behind gas diffusion?

Concentration gradient Signup and view all the answers

What is the significance of a moist surface in gas exchange?

It helps to dissolve gases before diffusion Signup and view all the answers

What ensures the continuous exchange of gases in the lungs?

Continuous blood flow Signup and view all the answers

What is the role of type I pneumocytes in the lungs?

To secrete alveolar fluid Signup and view all the answers

What happens to the pressure in the lungs during inhalation?

It decreases Signup and view all the answers

What happens to the diaphragm during inspiration?

It contracts and moves downward Signup and view all the answers

What happens to the external intercostal muscles during quiet breathing?

They relax and the rib cage moves down Signup and view all the answers

What happens to the volume of the thoracic cavity during exhalation?

It decreases Signup and view all the answers

What happens to the internal intercostal muscles during inspiration?

They relax and the rib cage moves up Signup and view all the answers

What happens to the air during forced exhalation?

It moves forcefully out of the lungs Signup and view all the answers

What is the primary function of the nasal cavity?

To warm and filter the air Signup and view all the answers

What is the purpose of the epiglottis?

To cover the trachea when swallowing Signup and view all the answers

What is the function of the diaphragm?

To facilitate breathing including both inspiration and expiration Signup and view all the answers

What is the purpose of the bronchiole network?

To branch into many alveoli for gas exchange Signup and view all the answers

What is the function of the trachea?

To carry air into the lungs from the nasal and buccal cavities Signup and view all the answers

What is the purpose of the alveoli?

To facilitate gas exchange between air and blood Signup and view all the answers

What is the function of surfactant in the alveoli?

To facilitate gas exchange by reducing surface tension Signup and view all the answers

What is the process called that includes both inspiration and expiration?

Ventilation Signup and view all the answers

Study Notes

Gas Exchange

Allows organisms to obtain important gases and remove waste gases produced in metabolic reactions through diffusion
Organisms with a high surface area to volume ratio rely on diffusion across body surface to obtain and release gases
Specialized structures like lungs with highly folded branched surfaces have evolved in larger organisms to exchange gases

Properties of Effective Gas Exchange Surfaces

Large surface area provides more membrane space for gases to diffuse across
Permeability: exchange surface must have pores or openings that allow gas exchange
Thin tissue layer reduces the distance gases need to move
Moist surface helps dissolve gases before diffusing across exchange surface

Concentration Gradient

Diffusion occurs through a difference in concentration of gas between two areas
Gas moves from higher to lower concentration
Continuous blood flow helps maintain a concentration gradient

Ventilation

Ensures air or water with the desired gas is moved across the exchange surface
In mammals, lungs are responsible for gas exchange between air and bloodstream

Lungs

Alveolar fluid surfactant moistens the surface of the alveoli, allowing gases to dissolve
Type I pneumocytes secrete alveolar fluid containing surfactant, a mixture of lipids and proteins
Bronchiole network: each bronchiole branches into many alveoli, creating a larger surface area for gas exchange
Alveoli: tiny sacs where CO2 and O2 are exchanged between air and blood

Respiratory System

Nasal cavity: filters air, warms it, and allows air to enter the respiratory system
Buccal cavity: allows passage of air into the trachea
Pharynx: the throat is the passage which air travels from the mouth and nose into the trachea
Epiglottis: a flap of cartilage that covers the trachea when swallowing, preventing food from entering the trachea
Larynx: the voice box, a hollow tube that lets air pass from the pharynx to the trachea, containing vocal cords
Trachea: the windpipe, an airway that carries air into the lungs, with C-shaped cartilaginous rings for structural strength

Ventilation Process

Includes both inspiration and expiration
Involves the diaphragm, intercostal muscles, and abdominal muscles

Breathing Mechanism

Inspiration: diaphragm contracts, external intercostal muscles contract, and internal intercostal muscles relax, increasing the volume of the thoracic cavity and decreasing pressure, allowing air to rush into the lungs
Expiration (quiet breathing): diaphragm relaxes, external intercostal muscles relax, and internal intercostal muscles contract, decreasing the volume of the thoracic cavity and increasing pressure, pushing air out of the lungs
Forced expiration: diaphragm relaxes, external intercostal muscles relax, and internal intercostal muscles contract, forcefully decreasing the volume of the thoracic cavity and increasing pressure, pushing air out of the lungs

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Description

This quiz covers the importance of gas exchange in organisms, including the role of surface area to volume ratio and specialized structures for diffusion. Learn how organisms obtain essential gases and remove waste products.