IB Biology 6.2 and Option D.4

When intense physical activity is anticipated, which factor in the blood will increase the frequency of sinoatrial signals to heart muscle?

• A. pH

• B. Oxygen level

• C. Thyroxin

• D. Epinephrine

Tags

NGSS.HS-LS1-3

What causes heart ventricles to fill with blood?

I. Atrial contraction

II. Closing of atrioventricular valves

III. Opening of semilunar valves

• A. I only

• B. I and II only

• C. II and III only

• D. III only

What is the position of heart valves when blood pressure is highest in the aorta?

• A

• B

• C

• D

In which blood vessel connected to the heart does blood have the lowest carbon dioxide concentration?

• A. Pulmonary vein

• B. Vena cava

• C. Pulmonary artery

• D. Coronary vein

What blood flow does the right semilunar valve prevent?

• A. Backflow of blood to the right atrium during ventricular contraction

• B. Blood flowing from the aorta back into the heart when the ventricle is filling

• C. Blood flowing from the pulmonary artery to the right ventricle when the heart is relaxing

• D. Blood flowing from the right atrium to the vena cava when the right atrium contracts

What feature of arteries is most important in maintaining sufficiently high blood pressure?

• A. A wide lumen

• B. Elastic fibres in the wall

• C. Valves at intervals

• D. A thin wall

What causes heart ventricles to fill with blood?

I. Atrial contraction

II. Closing of atrio-ventricular valves

III. Opening of semilunar valves

• A. I only

• B. I and II only

• C. II and III only

• D. III only

After a red blood cell picks up oxygen in the lungs, which sequence shows the path it could take when passing through the heart during its circuit of the body?

• A. I → II → III → IV

• B. II → I → IV → III

• C. IV → III → I → II

• D. IV → III → II → I

The diagram shows changes in pressure in the left atrium, left ventricle and aorta during a single cardiac cycle. At what point during the cycle does the atrioventricular valve close?

• A

• B

• C

• D

How are fats and cholesterol transported in the blood?

• A. As groups of molecules inside vesicles

• B. As individual molecules coated in phospholipids

• C. As individual molecules bound to a protein

• D. As groups of molecules in lipoprotein complexes