Gas Exchange

The following graph shows four oxygen dissociation curves for respiratory pigments. Which curve represents the oxygen dissociation curve for myoglobin?

• A

• B

• C

• D

What is the function of chloride shift?

• To balance the pH level in erythrocyte

• To balance the electrochemical charges in erythrocyte

• To balance the carbon dioxide concentration in cells

• To bind with H+ ions forming hydrochloric acid

The following drawing shows a portion of the under surface of a leaf at two different times of day. In this drawing, the arrows indicated by

• label V, point to non-respiring cells.

• label W, point to photosynthetic cells

• label X, show the direction of movement of potassium ions

• label Y, show the direction of movement of starch molecules.

In Bohr’s effect, the affinity of hemoglobin towards oxygen is reduced because

• The shape of hemoglobin is altered by high concentration of CO₂

• Hemoglobin acts as a pH buffer in erythrocytes

• Ferum ion in haemoglobin is attracted to chloride ions that diffuse in erythrocyes

• The concentration of carbamino-hemoglobin increases in erythrocytes

The graph shows oxygen dissociation curves of fish and human. The oxygen dissociation curve of fish is to the right of human because

• Fish haemoglobin has a higher affinity to oxygen

• Oxygen concentration in water is lower than in air

• At low oxygen partial pressure, human haemoglobin is more saturated than fish haemoglobin

• At low oxygen partial pressure, fish haemoglobin binds to less oxygen compared to human haemoglobin

The diagram shows the oxygen dissociation curves of adult haemoglobin, foetal haemoglobin and myoglobin. Which of the following statements are true of the curves above?

I P is for myoglobin, Q is for foetal hemoglobin and R is for adult hemoglobin

II P is for foetal hemoglobin, Q is for adult hemoglobin and R is for myoglobin

III Based on affinity towards oxygen, P > Q > R

IV Based on ability to dissociate from oxygen at point T, P > Q > R

• I and III

• I and IV

• II and III

• II and IV

Which of the following is true of the opening and closing mechanism of stomata?

• When concentration of carbon dioxide reduces, potassium ions diffuse into the guard cells and stomata opens

• When concentration of carbon dioxide reduces, potassium ions diffuse into the guard cells and stomata closes

• When there is water deficiency, abscisic acid is secreted and stomata opens

• When water content in the guard cell increases, abscisic acid is secreted and stomata closes

The opening of the stoma involves

• The increase of osmotic concentration in the guard cell

• The decrease of turgor pressure in the guard cell

• The sugar diffusion out of the guard cell

• The transportation of the active ion K+ out of the guard cell.

Which of the following explains Bohr effect?

• The regulating of constant pH in blood

• The haemoglobin affinity towards carbon dioxide

• The influence of carbon dioxide concentration on the dissociation of oxyhaemoglobin

• The increase in dissociation rate of carbon dioxide due to the influence of ferum ions

The graph is showing an oxygen dissociation curve. Choose the correct statement from the following based on the graph.

• Decrease in the blood pH shifts the graph to the right showing haemoglobin's affinity towards oxygen has reduced.

• Increase in the blood pH shifts the graph to the right showing haemoglobin's affinity towards oxygen has increased.

• Increase in release of oxygen from haemoglobin shifts the graph to the left

• Decrease in the blood pH shifts the graph to the left showing that the affinity of haemoglobin towards oxygen has increased