Take this Exam: A-Level Biology: Gas Exchange and Mass Transport | Zestly

Question 1

The oxygen dissociation curve for adult haemoglobin is sigmoidal. What is the biological significance of this shape?

Accepted Answer

It allows for small changes in the partial pressure of oxygen to result in large changes in the amount of oxygen unloaded at respiring tissues.

Question 2

Why does fetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?

Accepted Answer

It allows the fetus to extract oxygen from the mother's blood across the placenta.

Question 3

During the cardiac cycle, what happens when the pressure in the ventricles exceeds the pressure in the atria?

Accepted Answer

The atrioventricular valves close to prevent backflow into the atria.

Question 4

Which of the following accurately describes the formation of tissue fluid at the arterial end of a capillary?

Answer

High hydrostatic pressure forces water and small solutes out of the capillary.

Answer

The osmotic pressure of the blood is higher than the hydrostatic pressure, drawing fluid in.

Answer

Plasma proteins remain in the blood, creating a water potential gradient.

Answer

Red blood cells move out of the capillary along with the fluid to supply tissues.

Answer

The hydrostatic pressure is lower than the tissue fluid pressure, causing net absorption.

Question 5

Which structural characteristic is common to both arteries and veins, and how does it relate to their function?

Answer

Both have a thick layer of elastic tissue to withstand high pressure from the heart.

Answer

Both contain valves to ensure blood flows in only one direction.

Answer

Both have an endothelium layer to provide a smooth surface for blood flow.

Answer

Both have a narrow lumen to maintain high blood pressure throughout the system.