All of the above
Keeping their extremities relatively cold
Special bones in their nose that help them save water
Dense fat, with thick fur that covers all external surfaces
Tundra can be found on the tops of some mountains.
Treeless plain
Cold
Barren
Lots and lots
30%
20%
50%
10%
The changing fur has no real purpose
Shedding one color coat for another helps them stay camouflaged in most seasons
The cold causes fur to change colors
The animals try to keep up with the newest styles
Some plants of the tundra can perform photosynthesis at lower than normal light levels.
What happens to plants when they freeze
Any frozen soil
Soil that stays frozen for two or more years
Permanent frost