IB Biology SL B3.1 Gas Exchange Questions

Practise IB Biology SL B3.1 by linking diffusion and ventilation to gas-exchange surfaces, spirometry, leaf adaptations and transpiration questions.

Exam points

Distinguish ventilation, gas exchange and cell respiration; trace oxygen and carbon dioxide diffusion.
Relate alveolar area, thin moist walls, capillary contact and surfactant to rapid diffusion.
Explain how ventilation and blood flow maintain oxygen and carbon dioxide gradients.
Trace inspiration and expiration from muscle action through thoracic pressure to airflow.
Interpret spirometry to calculate lung volumes and compare ventilation as exercise intensity rises.
Explain stomatal control and trace gas exchange through leaf stomata and air spaces.
Identify leaf tissues on diagrams and relate their positions to light capture and gas exchange.
Predict how environmental changes affect transpiration and plant water loss.
Estimate stomatal density from counts and a known field of view.

Covered syllabus points

B3.1.1—Gas exchange as vital function B3.1.2—Properties of gas-exchange surfaces B3.1.3—Maintaining concentration gradients B3.1.4—Mammalian lung adaptations B3.1.5—Lung ventilation B3.1.6—Lung volume measurements B3.1.7—Leaf gas exchange adaptations B3.1.8—Leaf tissue distribution B3.1.9—Transpiration B3.1.10—Stomatal density

[Maximum number: 3]

Outline the process of gas exchange necessary for aerobic respiration in a unicellular eukaryotic organism.

[Maximum number: 1]

Emphysema is a condition where the alveoli of the lungs are destroyed, resulting in patients feeling out of breath. The micrograph shows air pockets resulting from emphysema.

What is a direct consequence of the destruction of alveoli?

Decrease in surface area for gas exchange

Increased blood flow to the lungs

Increase in pulmonary surfactant production

Decrease in ventilation rate

[Maximum number: 4]

Compounds of carbon, hydrogen and oxygen are used to supply and store energy.

Describe how a concentration gradient of oxygen is maintained between the lungs and blood capillaries.

[Maximum number: 3]

Describe three features of alveoli that adapt them to gas exchange.

[Maximum number: 8]

Explain the need for a ventilation system and the mechanism of ventilation of the lungs in humans

a. (cellular) respiration drives the need for gas exchange/absorption of oxygen and removal of $\mathrm{CO}_{2}$ ;
b. gas exchange depends upon a ventilation system;
c. lungs/alveoli provide surface area for gas exchange (with capillaries/blood);
d. ventilation system maintains a high concentration of oxygen in the alveoli;
e. bloodstream links alveoli to cells;
f. inhalation by contraction of diaphragm;
g. inhalation occurs with contraction of external intercostals/relaxation of internal intercostals;
h. (these) increase the volume/reduce the pressure in thorax, pulling air into lungs;
i. exhalation caused by relaxation of the diaphragm;
j. exhalation occurs with relaxation of external intercostals/contraction of internal intercostals;
k. (these) decrease volume/increase pressure in the thorax, forcing air out of lungs;

[Maximum number: 2]

(a)

The graph shows the changes that take place in the volume of the lungs and pressure in the alveoli during one breath at rest.

[ 2 ]

(i)

State the tidal volume in litres.

[ 1 ]

(ii)

Calculate the ventilation rate.

[ 1 ]

[Maximum number: 1]

The image shows a cast of the lower surface of a leaf from a busy Lizzie (Impatiens walleriana) plant as seen under a light microscope with a magnification of $600 \times$ .

Circular microscope field of leaf epidermis showing irregular interlocking cells, dark nuclei and several pairs of guard cells around elongated pores.

On the image, label a guard cell.

[Maximum number: 1]

The image shows the transverse section of a leaf. Which letter identifies the palisade mesophyll?

[Maximum number: 4]

Water is one of the most abundant molecules on Earth. Living organisms must maintain homeostatic levels of water to survive.

Outline how environmental factors affect the rate of transpiration in plants.

[Maximum number: 1]

The image shows a cast of the lower surface of a leaf from a busy Lizzie (Impatiens walleriana) plant as seen under a light microscope with a magnification of $600 \times$ .

Outline how stomatal density in busy Lizzie leaves can be estimated within a known field of view.

All question bank results loaded

a	oxygen must be taken up AND carbon dioxide must be released
b	gases pass through a cell membrane by simple diffusion
c	require a concentration gradient; OR pass from high concentration to low concentration
d	without requiring energy; OR passive process
e	large SA: vol ratio

Covered syllabus points

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question (a)

Question (i)

Question (ii)

Question 7

Question 8

Question 9

Question 10