B3.1 Gas Exchange

Question 1

what is ventilation?

Answer 1

Ventilation is the process of moving air in and out of the lungs, enabling the exchange of oxygen and carbon dioxide between the lungs and the environment.

Question 2

How does ventilation occur?

Answer 2

Ventilation occurs through two main processes: inhalation, where the diaphragm and intercostal muscles contract to expand the chest cavity and draw air in, and exhalation, where these muscles relax, allowing air to be pushed out of the lungs.

Question 3

What is respiration?

Answer 3

Respiration is a biochemical process that occurs in cells, involving the conversion of glucose and oxygen into energy (ATP), carbon dioxide, and water. It includes both aerobic respiration (using oxygen) and anaerobic respiration (without oxygen).

Question 4

How does respiration differ from ventilation?

Answer 4

While ventilation refers to the physical movement of air in and out of the lungs, respiration is a chemical process that takes place within cells to produce energy.

Question 5

What is breathing?

Answer 5

Breathing is the physical act of inhalation and exhalation, facilitating ventilation. It involves the movement of air into the lungs for gas exchange and the removal of carbon dioxide.

Question 6

What is gas exchange?

Answer 6

Gas exchange is the process by which oxygen is transferred from the alveoli in the lungs to the bloodstream, and carbon dioxide is transferred from the blood to the alveoli to be exhaled. This occurs primarily in the alveoli, where the thin walls allow for diffusion of gases.

Question 7

What role does diffusion play in gas exchange?

Answer 7

Diffusion is the primary mechanism for gas exchange, where oxygen moves from areas of higher concentration (such as the alveoli) to areas of lower concentration (the bloodstream), and carbon dioxide moves in the opposite direction.

Question 8

Why do larger organisms need structures to maintain a large enough surface area for gas exchange?

Answer 8

Larger organisms have higher metabolic demands and require more oxygen. To meet these needs, they have evolved specialized gas exchange structures (like lungs) that provide a large surface area to facilitate efficient diffusion of gases.

Question 9

What is the function of permeability in gas-exchange surfaces?

Answer 9

Permeability allows gases to pass through the exchange surface easily, enabling efficient gas exchange between the organism and its environment.

Question 10

Why is a thin tissue layer important for gas-exchange surfaces?

Answer 10

A thin tissue layer minimizes the distance gases must diffuse, speeding up the rate of gas exchange

Question 11

How does moisture contribute to gas exchange?

Answer 11

Moisture on gas-exchange surfaces helps dissolve gases, facilitating their diffusion and making the exchange process more efficient.

Question 12

What is the significance of a large surface area in gas-exchange surfaces?

Answer 12

A large surface area increases the amount of gas that can be exchanged at any given time, enhancing the efficiency of gas exchange.

Question 13

Why must concentration gradients be maintained at exchange surfaces?

Answer 13

Maintaining concentration gradients ensures that gases continuously diffuse in the desired direction—oxygen into the bloodstream and carbon dioxide out—facilitating efficient gas exchange.

Question 14

How do dense networks of blood vessels help maintain concentration gradients at exchange surfaces?

Answer 14

Dense networks of blood vessels ensure a constant supply of fresh blood, which keeps oxygen levels low in the blood near the exchange surface, allowing more oxygen to diffuse in from the air or water.

Question 15

What role does continuous blood flow play in maintaining concentration gradients?

Answer 15

Continuous blood flow removes oxygen that has diffused into the blood and delivers carbon dioxide to be expelled, thus maintaining the concentration gradients needed for gas exchange.

Question 16

How does ventilation with air for lungs and with water for gills help maintain concentration gradients?

Answer 16

Ventilation refreshes the air in the lungs or the water over the gills, keeping the concentrations of oxygen high and carbon dioxide low at the exchange surfaces, promoting efficient gas diffusion.

Question 17

Where does gas exchange occur in humans?

Answer 17

Gas exchange in humans occurs primarily in the alveoli of the lungs.

Question 18

What structures of mammalian lungs are adapted to maximize gas exchange?

Answer 18

Structures include alveoli with thin walls for efficient diffusion, extensive capillary networks for increased surface area, and a moist lining to facilitate gas solubility.

Question 19

What is the structure of the airway that connects the lungs to the outside of the body?

Answer 19

The trachea is the airway that connects the lungs to the outside environment.

Question 20

Define ventilation, inspiration, and expiration.

Answer 20

Ventilation is the process of air moving in and out of the lungs. Inspiration is the act of inhaling air into the lungs, and expiration is the act of exhaling air out of the lungs.

Question 21

What is the relationship between gas pressure and volume?

Answer 21

According to Boyle’s Law, gas pressure is inversely related to volume; as the volume of the lungs increases during inspiration, the pressure decreases, allowing air to flow in.

Question 22

Describe the movement of the diaphragm and thorax during inspiration and expiration.

Answer 22

During inspiration, the diaphragm contracts and moves downward, while the thorax expands. During expiration, the diaphragm relaxes and moves upward, and the thorax contracts.

Question 23

What pressure and volume changes occur during inspiration and expiration?

Answer 23

During inspiration, lung volume increases and pressure decreases, causing air to flow in. During expiration, lung volume decreases and pressure increases, causing air to be expelled.

Question 24

Define tidal volume, vital capacity, inspiratory reserve, and expiratory reserve.

Answer 24

Tidal volume is the amount of air inhaled or exhaled during normal breathing. Vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation. Inspiratory reserve is the additional air that can be inhaled after a normal inhalation, and expiratory reserve is the additional air that can be exhaled after a normal exhalation.

Question 25

What methods can be used to measure tidal volume, vital capacity, and inspiratory and expiratory reserves?

Answer 25

Methods include spirometry, which measures air volumes during breathing, and using devices like a peak flow meter for tidal volume.

Question 26

In leaves, oxygen typically moves out of the leaf, while carbon dioxide moves into the leaf.

Answer 26

Epidermis: A protective layer that minimizes water loss.
Waxy cuticle: Reduces water evaporation.
Stoma: Openings that allow gas exchange.
Guard cells: Regulate the opening and closing of stomata.
Air spaces: Facilitate the movement of gases.
Spongy mesophyll: Provides a large surface area for gas exchange.
Veins: Transport water and nutrients.

Question 27

What does a plan diagram show regarding the distribution of tissues in a leaf?

Answer 27

A plan diagram shows the arrangement of tissues in a leaf without detailing individual cells.

Question 28

What is transpiration?

Answer 28

Transpiration is the process of water vapor being lost from plant surfaces, primarily through stomata.

Question 29

How does water evaporation relate to transpiration?

Answer 29

Water evaporation from leaf surfaces contributes to transpiration, as the loss of water vapor creates a negative pressure that pulls more water up from the roots.

Question 30

What abiotic factors affect the rate of transpiration?

Answer 30

Factors include temperature (higher temperatures increase the rate of evaporation and transpiration) and humidity (lower humidity increases transpiration).

Question 31

What are the advantages of opening and closing stomata at different times of day?

Answer 31

Opening stomata during the day allows for gas exchange and photosynthesis while minimizing water loss, whereas closing stomata at night helps conserve water when photosynthesis is not occurring.

Question 32

How is stomatal density calculated from a leaf cast or micrograph?

Answer 32

Stomatal density is calculated by counting the number of stomata in a given area of a leaf surface and expressing it as the number of stomata per unit area (e.g., per square millimeter).

Question 33

How can micrographs or casts of leaf surfaces be interpreted to compare stomatal density?

Answer 33

Micrographs or casts can be analyzed by counting stomatal openings and comparing the number of stomata across different leaf surfaces, allowing for a comparison of stomatal density.

Question 34

What is the structure and function of hemoglobin?

Answer 34

Hemoglobin is a protein in red blood cells composed of four polypeptide chains that bind to oxygen, allowing for its transport from the lungs to tissues.

Question 35

What is affinity in the context of hemoglobin?

Answer 35

Affinity refers to the strength of the bond between hemoglobin and oxygen; higher affinity means hemoglobin is more likely to bind to oxygen.

Question 36

How does cooperative binding alter hemoglobin’s affinity for oxygen?

Answer 36

Cooperative binding means that when one oxygen molecule binds to hemoglobin, it increases the likelihood that additional oxygen molecules will bind, enhancing the overall affinity of hemoglobin for oxygen.

Question 37

How do adult and fetal hemoglobin differ in terms of oxygen affinity?

Answer 37

Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, allowing the fetus to extract oxygen from the maternal blood more effectively.

Question 38

What is allosteric binding of CO2 to hemoglobin?

Answer 38

Allosteric binding of CO2 occurs when CO2 binds to hemoglobin, causing a conformational change that reduces its affinity for oxygen, facilitating oxygen release in tissues where it is needed.

Question 39

What is the Bohr shift?

Answer 39

The Bohr shift refers to the phenomenon where increased levels of carbon dioxide and decreased pH result in hemoglobin releasing oxygen more readily.

Question 40

What is the mechanism and benefit of the Bohr shift?

Answer 40

The Bohr shift enhances oxygen delivery to active tissues that produce more carbon dioxide, ensuring that regions of high metabolic activity receive sufficient oxygen.

Question 41

How does the Bohr shift affect the oxygen dissociation curve?

Answer 41

The Bohr shift causes the oxygen dissociation curve to shift to the right, indicating that hemoglobin will release more oxygen at a given partial pressure compared to normal conditions.

Question 42

What is partial pressure?

Answer 42

Partial pressure is the pressure exerted by a single type of gas in a mixture, commonly used to describe the concentration of oxygen in the atmosphere or in blood.

Question 43

What are the relative partial pressures of oxygen in different locations?

Answer 43

At sea level, the partial pressure of oxygen is approximately 160 mmHg. In the alveoli, it is about 100 mmHg, in alveolar blood capillaries about 40 mmHg, and in respiring tissue, it can drop below 40 mmHg.

Question 44

How do the oxygen dissociation curves of adult and fetal hemoglobin differ?

Answer 44

Fetal hemoglobin’s dissociation curve is positioned to the left of adult hemoglobin’s curve, indicating a higher affinity for oxygen, which facilitates oxygen transfer from mother to fetus.