Question

Metabolism occurs on the expense of (a) Nutrition (b) Water (c) Energy (d) Hormones

Short answer

Energy

Step-by-step solution

Understanding the Question

The first step is understanding the question and identifying the answer from our basic biological knowledge. We know that metabolism is a set of life-sustaining chemical reactions in living organisms. Therefore, we have to look for something that these reactions would 'use up' or expense.

Identifying the Correct Answer

Looking at our choices, we can immediately eliminate water and hormones. Water doesn't fuel reactions, it is required in certain metabolic reactions but not expended. Similarly, hormones are not expended to drive reactions; they are biological messengers that regulate metabolic processes. Nutrition is a source of substances necessary for energy and growth and its components do participate in metabolic reactions, however, the term 'nutrition' in a general sense mandates the presence of water and other nutrients, not just the energy-yielding ones. Therefore, the most correct answer should be energy.

Confirming the Correct Answer

While nutrients from nutrition might be a source of energy, they are not the primary expense during metabolism. A closer answer would be energy. Energy gets used up to drive the chemical reactions that constitute metabolism. Thus, Energy is the correct answer.

Key concepts

Energy in Metabolism

Metabolism is a complex process carried out by living organisms primarily to sustain life. It involves a series of chemical reactions that convert food into energy, which is then used to power various cellular processes.
During metabolism, energy is a vital component that fuels everything from muscle contraction to the replication of DNA. Energy originates mainly from nutrients and is captured in the form of adenosine triphosphate (ATP).
- **ATP** is often referred to as the "energy currency" of the cell. It stores and provides energy when and where required. - The process of converting the stored energy in chemicals into ATP is called cellular respiration.
Metabolism is divided into two broad categories:

• **Catabolism**: This process breaks down molecules into smaller units, releasing energy in the process. It's akin to using the stored energy to power cellular tasks.
• **Anabolism**: Here, smaller molecules are built up into bigger ones, requiring an input of energy, usually provided by ATP.

Understanding energy's role in metabolism helps elucidate how our bodies maintain function and react to meet energy demands.

Chemical Reactions in Living Organisms

Chemical reactions are at the heart of metabolic processes. Metabolism consists of a vast network of reactions that transform compounds and release or consume energy. These reactions are facilitated by enzymes, which are biological catalysts.
Enzymes accelerate reactions by lowering the activation energy required. This makes it easier for molecules to undergo the necessary transitions to become new products. Without enzymes, many reactions would occur too slowly to sustain life.
- **Types of Metabolic Reactions**:

• **Oxidation-Reduction Reactions**: Also known as redox reactions, these involve the transfer of electrons between molecules and are essential in energy production, especially during cellular respiration.
• **Hydrolysis**: This involves the breakdown of compounds through the addition of water, significant in digestive processes.
• **Condensation Reactions**: Conversely, these involve the removal of water to form bonds, playing a crucial role in forming macromolecules like proteins and DNA.

The intricate interplay of these reactions ensures organisms effectively manage energy and resources, adapting to various environmental and physiological changes.

Nutrient Utilization in Metabolism

Nutrients are the building blocks of life, serving both as energy sources and as essential components for synthesis and growth. In metabolism, the body utilizes carbohydrates, proteins, and fats, converting them into usable energy or building materials.
- **Carbohydrates**: Primarily broken down into glucose, which is a primary energy source that fuels cellular respiration. - **Proteins**: Often used for building tissue, but can also be catabolized for energy under specific conditions. - **Fats**: Converted into fatty acids and glycerol, providing a dense energy source, utilized when carbon sources are low.
Metabolism ensures these nutrients are broken down and assimilated effectively, supporting growth, repair, and energy equilibrium.
- By converting nutrients into ATP, the energy is made available for body functions such as maintaining body temperature, breathing, and moving.
Understanding nutrient utilization helps in optimizing dietary choices to enhance and maintain metabolic efficiency, emphasizing the necessity for a balanced diet in sustaining health and vitality.