7th Class Science Nutrition in Animals Feeding and Digestion in Microorganisms

       Introduction

Animals require food for their energy and growth. But, they are not capable of making food by themselves. Therefore, they have to depend on the plant kingdom for their food and nutrition. Every animal, directly or indirectly depend on plants for their nutritional needs. However, the requirements of different components of nutrients is not in equal quantity in an animal body. Some nutrients are required in very less quantity, wherein some are required in large quantity. The nutrients, which are required in less quantity in an animal body are called micronutrients or trace elements. For example, minerals and vitamins. Micronutrients are called protective food as they provide the nutrients for the body to fight disease. The nutrients, which are required in large quantity in an animal body are called macro nutrients. For example, carbohydrates, fats, proteins and water. In this chapter, we will study about the requirement of nutrients and its utilization in animals.

         Feeding and Digestion in Microorganism

Microorganisms are living organisms. They require food for energy and reproduction. Some bacteria can prepare its own food, hence, they have autotrophic mode of nutrition. Some bacteria depend on other organism for their food, therefore, they have heterotrophic mode of nutrition. For example, a well-known microorganism Amoeba is single celled found in pond water. Amoeba can change its shape and position. It has finger like structure, called pseudopodia, which is used to capture the food.

Look at the following picture of food digestion in an Amoeba:

Amoeba feeds on microscopic organisms. It pushes its pseudopodia to the food particle, engulfs it and food particle is trapped in a food vacuole. Foods are digested by the digestive enzyme secretes by the vacuole. Undigested food is expelled outside by the vacuole.

There are wide varieties of microorganisms, some are useful for us, and some are not. Bacteria present in human digestive system helps in the digestion process.

They feed on food taken by us.

      Amoeba feeds on which one of the following types of organism?

(a) Microscopic organisms

(b) Plants

(c) Amoeba can eat big mammals

(d) All of these

(e) None of these

Answer: (a)

Explanation

Amoeba feeds on microscopic organisms. Therefore, option (A) is correct and rest of the options is incorrect.

       Consider the following statements:

Statement 1: AII microorganisms have autotrophs mode of nutrition.

Statement 2: All microorganisms have heterotrophs mode of nutrition.

Which one of the following is correct about the above statements?

(a) Statement 1 is true and 2 is false

(b) Statement 1 is false and 2 is true

(c) Both statements are false

(d) Both statements are true

(e) None of these

Answer: (c)

Explanation

Some microorganisms can make their own food by the process of photosynthesis, therefore, they feed on autotrophs mode of nutrition. Whereas, some microorganisms depend on others for food, hence, they feed on heterotrophs mode of nutrition. Therefore, option (C) is correct and rest of the options is incorrect..