What is dissolved in blood plasma?
A. carbon dioxide, erythrocytes and platelets
B. amino acids, glucose and urea
C. carbon dioxide, oxygen and heat
D. glycogen, antibodies and urea
Answer/Explanation
Markscheme
B
What is the state of the atrio-ventricular and semilunar valves when the left ventricle contracts?
Answer/Explanation
Markscheme
D
The diagram below shows the human heart. What structures are indicated by the labels X, Y and Z?
Answer/Explanation
Markscheme
D
Dialysis membrane was set up to model digestion and absorption in the small intestine.
What is a limitation of this model?
A. There can be no active transport.
B. Maltose will pass through the membrane.
C. Lipase should be present with protein.
D. The membrane is not permeable to starch.
▶️Answer/Explanation
Markscheme
A
A dialysis membrane can be used to model digestion and absorption in the small intestine. It is an accurate model because both are partially permeable so smaller particles can pass through the membrane whilst larger particles cannot; the membrane therefore allows the passive movement of solutes in diffusion, and water molecules in osmosis.
Question
For what reason do large organisms need specialized gas exchange structures?
A. They have a large surface area to volume ratio.
B. There is a short distance to the centre of their body
C. They have a relatively small surface in contact with the outside
D. Their skin is impermeable to respiratory gases.
▶️Answer/Explanation
C
Question
What occurs at gas exchange surfaces in the lungs of mammals?
I. Gases diffuse across a moist surface.
II. Concentration gradients are maintained by ventilation.
III. Water is lost.
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
D
Question
What is always a consequence of the evaporation of water from mesophyll cells in leaves of a healthy plant?
A. Plasmolysis occurs in mesophyll cells.
B. Photosynthesis stops.
C. Stomata close to reduce transpiration.
D. Water moves up the stem in the xylem.
▶️Answer/Explanation
D