Chapter 10, Problem 37A

Summary Introduction

To compare and contrast:

Theway plants and animals obtain energy

Introduction:

All living organisms need energy to carry out various biological functions.Almost all the energy in living organisms comes from the Sun. Energy flows from autotrophs to heterotrophs. In an ecosystem photosynthesis and cellular respiration form a cycle. Metabolic pathways result in continuous flow of energy within organisms.

Answer to Problem 37A

Plants obtain energy from the Sun whereas animals obtain energy from the food they eat. Plants store energy of the Sun in glucose molecules through photosynthesis and release this energy through cellular respiration for use by the cells.

Animals depend on plants for their energy requirements. They have to consume plant based food to obtain energy. Some animals are secondary and tertiary consumers of plants. All animals only undergo cellular respiration to release energy from organic molecules for use by the cells.

Explanation of Solution

All living organisms need energy to survive. Directly or indirectly all the energy comes from the Sun. Some organisms make their own food while some obtain food from other organisms. Plants make their own food through the process of photosynthesisin which light energy from the Sun is converted to chemical energy for use by the plant cell. Green plantsthat use the solar energy along with carbon dioxide and water to form glucose and oxygen are called photoautotrophs. Some autotrophs called chemoautotrophs use inorganic substances as sources of energy.Plants then undergo cellular respiration to release the energy stored in glucose for use by the cells.

Organisms that obtain food from other organisms are called heterotrophs. Animals fall under this category. They have to ingest food to obtain energy. The energy stored in plants as glucose can be transferred to other organisms like animalswhen they are consumed as food. Animals digest the food and release energy through cellular respiration. Cellular respiration is the catabolic pathway in which organic molecules are broken down to release energy. Oxygen is used for this process and it occurs in mitochondria of cells. Carbon dioxide and water is released during the process.