The ecologically fixed and genetically irreversible species are called

Altitude sickness is an example of:

Which of these is/are considered the major biomes of the world?

Read the following statements with respect to the features of biomes and select the correct option for tropical rain forests:
$a.$ Buttress roots
$b.$ Vines,lianas and epiphytes are abundant
$c.$ Highly leached soils
$d.$ Soil has high base content
$e.$ $30-40 \; m$ tall canopy structure with $2-3$ strata only

Large woody vines are commonly found in .......

In lower organisms,the formation of thick-walled spores helps them to survive in unfavorable conditions. What is this process called?