Chapter 9, Problem 14STP

Summary Introduction

To hypothesize:

How an organism can be both a heterotroph and an autotroph

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. Autotrophs and heterotrophs differ in the way they obtain energy.

Answer to Problem 14STP

An organism can be both a heterotroph and an autotroph depending upon the environment it lives in. If it gets enough sunlight and has chlorophyll, oxygen and water available, it can sustain itself by being an autotroph. If it cannot photosynthesize food, it can feed on detritus and other organisms and become a heterotroph.

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. Autotrophs are organisms that make their own food through the process of photosynthesis in which light energy from the Sun is converted to chemical energy for use by the cell. Autotrophs that 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.

Organisms that obtain food from other organisms are called heterotrophs. They have to ingest food to obtain energy. The energy stored in autotrophs as glucose can be transferred to other organisms like heterotrophs when they are consumed as food.

An organism can hypothetically behave both as a heterotroph and an autotroph depending on the conditions available to it. If it has chloroplasts it can be an autotroph but if it can feed on other organisms it can behave as a heterotroph. For example, insectivorous plants like Venus- fly- trap can prepare their own food as well as depend on insects for their supply of nitrogen. So they are both autotrophs and heterotrophs.