The region consisting of long and severe winters and a growing season consisting of a few months of summers constitutes:

Which of the following is a characteristic of a biological community?

Give scientific reasons: Freshwater animals cannot survive for long in seawater.

In a sea shore,the benthic animals live in sandy,muddy and rocky substrata and accordingly developed the following adaptations:
$(a)$ Burrowing
$(b)$ Building tubes
$(c)$ Holdfasts / peduncle
Match the suitable substratum against each adaptation.

Define/Explain: Ecological niche.

In bacteria,fungi,and lower plants,various kinds of thick-walled spores are formed which help them to survive unfavourable conditions. This phenomenon can be called ...........