Organisation: Practice Questions

Which of the following terms describes a group of cells with a similar structure and function working together to perform a specific task?

The human heart is part of a double circulatory system. Which blood vessel is responsible for carrying oxygenated blood from the lungs to the left atrium of the heart?

The heart acts as a double pump in the human circulatory system. If the right ventricle fails to pump blood effectively, which specific physiological consequence is most likely to occur first?

Bile is an essential substance for the efficient digestion of lipids. In which organ is bile produced, and what is its primary role in neutralising stomach acid?

A student investigates the effect of pH on amylase activity. If the starch is completely broken down in \( 2 \text{ minutes} \) at \( \text{pH } 7 \) and in \( 8 \text{ minutes} \) at \( \text{pH } 5 \), which statement best explains the rate of reaction?

Define what a tissue is in biological terms and state how it differs from an organ.

A patient suffers from a faulty heart valve that does not open fully. Explain the physiological consequence of this condition on the body's cells.

A specific 15 cm segment of a plant's xylem tissue is found to have a total internal volume of \( 0.045 \text{ cm}^3 \). If the rate of transpiration allows this volume of water to be replaced every 12 seconds, calculate the rate of water flow through this tissue in \( \text{cm}^3/\text{min} \).

The human heart is part of a double circulatory system that pumps blood through various vessels to facilitate gas exchange and nutrient delivery.

(a) Describe the specific pathway of blood from the point it enters the right atrium until it leaves the heart to travel to the rest of the body. Name the chambers and the main blood vessels involved. (4)

(b) Explain why the wall of the left ventricle is significantly thicker than the wall of the right ventricle. (2)

(c) A patient has a faulty heart valve that does not close properly. Explain the effect this would have on the volume of oxygenated blood being pumped to the body. (2)

Multicellular organisms have specialized exchange surfaces to allow efficient transport of substances. In humans, the lungs contain millions of alveoli adapted for gas exchange.

(a) Explain how the structure of the alveoli and the capillary network surrounding them increases the rate of diffusion of oxygen into the blood. Refer to three specific structural adaptations in your answer.

(b) A single spherical alveolus has a radius of \( 0.05 \text{ mm} \).
Given that the surface area of a sphere is \( 4\pi r^2 \) and the volume of a sphere is \( \frac{4}{3}\pi r^3 \), calculate the surface area to volume ratio for this alveolus. Use \( \pi = 3.14 \). Show your working.

(c) Using your understanding of surface area to volume ratios, explain why single-celled organisms do not require specialized gas exchange systems, whereas large multicellular organisms do.