BIOLOGY Volume 1 - A Guide to General Biology - 2004

7. AUTOTROPHIC NUTRITION

Chapters 7 and 8 focus on Nutrition, The process of acquiring energy and matter. In Chapter 9, we will examine Respiration, during which energy is released from the energy-rich compounds obtained through food intake.

7.1. Why do living organisms need energy?

Energy can be defined as the capacity to do work. All living organisms can be viewed as working machines that constantly require an influx of energy. This is essential for them to continue functioning and thereby sustain their lives. Energy is neither created nor destroyed, but is transformed from one form into another (the law of conservation of energy). Forms of energy can vary widely, including chemical, thermal, electrical, light, or sound energy. A simple example of energy conversion is the burning of a match, during which the chemical energy stored in the match HEAD is transformed into thermal, light, and sound energy.

Here are some processes for which living organisms require energy:

1) the synthesis of substances for growth and repair, such as Protein Synthesis;

2) the active Transport of substances into and out of The Cell against diffusion gradients, such as the operation of the (Na⁺, K⁺)-pump (Section 5.9.8);

3) phagocytosis, pinocytosis, and exocytosis (Section 5.9.8).

4) the electrical transmission of nerve impulses;

5) mechanical Muscle contraction and the beating of flagella and cilia;

6) thermal energy released during respiration, which is used to maintain a constant body Temperature in birds and mammals;

7) Bioluminescence, The production of light by living organisms such as fireflies and certain deep-sea marine animals;

8) electrical discharge, such as in the electric eel.

The Role of ATP as an energy carrier in Cells is described in Section 9.2.