Question

Excretion involves the process in which (a) Harmful substances in the body are chemically changed. (b) Substances of no further use or those present in excessive quantities are thrown out of the body. (c) Harmful substances are stored in cells before being eliminated. (d) Expulsion of urine from the urinary bladder and sweat from the skin.

Short answer

The process of excretion involves option (b): Substances of no further use or those present in excessive quantities are thrown out of the body.

Step-by-step solution

Understand What Excretion Involves

Excretion in the context of biology refers to the process of eliminating or expelling waste matters. This process discards the waste products that the body does not need, those are of no further use, or those are in excess.

Go Through the Options

Review each of the given answer options individually, comparing them against the established understanding of excretion.

Identify the Correct Option

Compare each option with the explanation from step 1. Determine which answer best fits the definition of excretion. Based on the comparison, the correct answer is (b): Excretion involves the process in which substances of no further use or those present in excessive quantities are thrown out of the body.

Key concepts

Waste Elimination

Waste elimination is an essential part of maintaining a healthy state in living organisms. It refers to the process of removing substances that are no longer needed or that are in excessive amounts. This is crucial for preventing the accumulation of toxic materials that could harm the body. Many systems work together to manage waste elimination. Each type of waste is handled differently:

• Carbon dioxide: Expelled through the lungs.
• Excess salts and water: Removed via the kidneys and sweat glands.
• Solid waste: Processed and expelled through the digestive system.

This process ensures that the body's internal environment remains stable, highlighting its importance in overall well-being.
Moreover, efficient waste elimination supports other biological functions, such as cell metabolism and chemical balance. Through these, organisms avoid potential toxicity and disruptions to cellular processes. Regular removal of waste helps to ensure that each cell functions at its best efficiency.

Urinary System

The urinary system plays a crucial role in excretion, particularly for liquid waste. It is responsible for filtering blood to form urine, which is then expelled from the body. The main components of this system include:

• Kidneys: These act as filters that remove waste products and excess substances from the blood. Each kidney contains millions of filtering units called nephrons.
• Ureters: Tubes that carry urine from the kidneys to the bladder.
• Bladder: A muscular sac that stores urine until it is expelled from the body.
• Urethra: The duct through which urine exits the bladder and leaves the body.

The urinary system not only manages waste but also plays a part in regulating blood pressure and maintaining the balance of fluids and electrolytes in the body.
Through processes such as filtration, reabsorption, and secretion, the urinary system ensures that waste materials are efficiently removed while retaining nutrients and water that are essential for the body's functions.

Biological Processes

Biological processes refer to the everyday activities and functions that keep an organism alive and healthy. These processes involve intricate systems that work together seamlessly. Perhaps one of the most crucial biological processes is homeostasis, which ensures that internal conditions remain stable despite external changes.
Excretion forms a part of these biological processes and supports homeostasis by controlling the levels of various substances within the body.

• Metabolism: This process breaks down nutrients to provide energy but also results in by-products that need to be excreted.
• Respiration: Involves the exchange of gases, releasing carbon dioxide as a waste product.
• Digestion: Breaks down food, absorbing nutrients and expelling unused materials.

Understanding how biological processes operate offers insight into why waste elimination is so vital. These processes are interconnected, and efficient waste removal supports continual function and energy provision for all biological activities.