Question

mention two criteria used for classification of algae

Answer 1

Algae are classified on the following factors:-

1) Form of stored food in them. 
&
2) Their Cell wall composition 

Answer 2

Answer:  

The two criteria used for classification of algae cell wall composition and pigments present in the algae and photosynthetic approach.

Explanation:  

The algae are the primary organisms present in the classification. They are the most primitive organisms that live in the water. The organism prepares its own food through a process of photosynthesis using the pigments which they have majorly chlorophyll.

The algae has a unique structure which stores food and excretes by the formation of vacuoles.