Year 8 Science: Body Systems - Respiratory and Circulatory Systems

A comprehensive set of practice questions covering the Year 8 Science curriculum for respiratory and circulatory systems, including cellular respiration, anatomy, and blood components.

What is the chemical equation for cellular respiration?

$$\text{Glucose} + \text{Oxygen} \rightarrow \text{Energy} + \text{Carbon Dioxide} + \text{Water}$$

How does breathing differ from cellular respiration?

Breathing is the physical process of inhaling oxygen and exhaling carbon dioxide, while cellular respiration is the chemical reaction inside mitochondria that produces energy.

What is the primary function of the cartilage rings surrounding the trachea and bronchi?

To support the airways and ensure they stay open.

During inspiration, what happens to the diaphragm and intercostal muscles?

The diaphragm and intercostal muscles contract; the diaphragm moves downwards, while the ribs move upwards and outwards.

How do volume and pressure change in the thorax during expiration?

The volume of the thorax decreases, which increases the pressure, forcing air out of the lungs.

In the model lung experiment, what did the lower balloon and the plastic bottle represent?

The lower balloon represented the diaphragm, and the plastic bottle represented the thorax or chest cavity.

List four features of alveoli that make them well suited for gas exchange.

They have thin walls, a large surface area (millions of alveoli), are moist, and are surrounded by a network of capillaries.

What is emphysema and how does it affect gas exchange?

A condition where alveoli walls break down and become less elastic, reducing the surface area available for the exchange of $O_2$ and $CO_2$.

What structures do fish and insects use for gas exchange?

Fish use gills (gill filaments), and insects use spiracles, tracheae, and tracheoles.

What are the three components that make up the circulatory system?

A pump (heart), tubes (blood vessels), and fluid (blood).

What percentage of blood volume is made up of plasma, and what is its primary constituent?

Plasma makes up approximately $91\%$ of blood volume and consists mostly of water.

Describe the shape and function of Red blood cells.

Red blood cells have a biconcave shape and no nucleus to optimize oxygen carrying capacity; they contain the protein hemoglobin.

What is the lifespan of a Red blood cell and where are they produced?

They live for about $120\text{ days}$ and are produced in the bone marrow.

What is the specific function of platelets in the blood?

They are cell fragments vital for blood clotting, gathering to form a plug to prevent blood loss.

Which side of the heart has thicker walls and why?

The left side, because it must pump oxygenated blood at higher pressure to the entire body (systemic circuit).

What is the function of the septum in the heart?

It is a muscular wall that separates the right side of the heart from the left side.

Name the heart valves that prevent backflow between the atria and ventricles.

The tricuspid valve (right side) and the bicuspid valve (left side).

Compare the structure of arteries and veins regarding their walls and lumens.

Arteries have thick muscular walls and a small lumen; veins have thinner walls and a large lumen.

Why do veins have valves while arteries generally do not?

Veins have valves to prevent the backflow of blood as it flows slowly under very low pressure toward the heart.

What is unique about the pulmonary artery compared to other arteries?

The pulmonary artery carries deoxygenated blood (to the lungs), while other arteries carry oxygenated blood.

How thick are the walls of capillaries and why is this significant?

Capillary walls are one cell thick, which allows for the rapid diffusion and exchange of substances between blood and cells.

Name the specific blood vessels that carry blood to and from the kidneys.

The renal artery carries blood to the kidneys, and the renal vein carries blood away from the kidneys.