Science Year 8

The human circulatory system circulates:

• Blood

• Nerve cells

• Undigested food

Answer explanation

The circulatory system pumps blood from the heart to the lungs to get oxygen and sends oxygenated blood through arteries to the rest of the body.

The liquid part of blood is

• Plasma

• Only water

• Hemoglobin

Answer explanation

The liquid part of blood is plasma. It is made up of water, salts and proteins.

The blood cells that carry oxygen and carbon dioxide are:

• Red Blood Cells

• White Blood Cells

• Colorless

Answer explanation

Red blood cells, deliver oxygen throughout your body. Your red blood cells also transport carbon dioxide to your lungs for you to exhale.

Clotting is the function of:

• Platelets

• Red Blood Cells

Answer explanation

Blood clotting is a process that prevents excessive bleeding when a blood vessel is injured.

A person with a low white blood cell count would have difficulty:

• fighting disease

• breathing

• moving

Answer explanation

White blood cells help the body fight infection and other diseases. Low white blood cells means high risk of being infected.

The blood vessel with the thinnest wall is the:

• vein

• capillary

• artery

Answer explanation

The thin walls of capillaries enable nutrients and oxygen to pass from the blood into the tissues. This thus enable waste products to diffuse out from tissues into the blood.

The blood vessel with valves to allow one-way blood flow is the:

• capillary

• artery

• vein

Answer explanation

Veins contain valves that ensure blood flows in only one direction.

How many atria are in the human heart?

• 0

• 1

• 2

Answer explanation

A human heart has two atria:

the left atrium receives blood from the pulmonary circulation;

the right atrium receives blood from the venae cavae of the systemic circulation.

The heart chamber with the thickest muscular wall is the:

• left ventricle

• right ventricle

• aorta

Answer explanation

The heart chamber that has the thickest muscle wall is the left ventricle. The left ventricle is responsible for pumping the blood around the heart and so it needs to have a strong muscle wall. 

If the thoracic wall but not lungs is punctured

• The lungs get inflated.

• The man dies as lungs get collapsed.

• The breathing rate decrease.

• The breathing rate increase.

Answer explanation

The puncture in thoracic wall, would mean the wound to the pleural/chest wall, as it is defined so for its function of respiration. This would eventually lead to the damage of pleural membrane which in turn would disrupt the pressure balance of gases, which would lead to the collapsing of the lungs. Thus, the man would eventually die.