Which among the following is a large area of trees and plants growing closely together? 

Which among the following lives in areas where the sun penetrates deep into the waters? 

Which one of the following is found along the western and the eastern continental margins of the mid latitudes?

Which of the following lives only in the tropical seas? 

Which among the following cannot survive in waters with temperatures below 20^o C? 

Plants living in desert are called :

Which among the following has an intimate relation with the quantum of rainfall? 

What is the combination of the three spheres where life forms exist and interact with each other and with their environment? 

Which of the following extends across North America and Eurasia in a wide belt? 

Which of the following term is used to denote plants of a particular region or period?