Consider the following statements related to ecology:
Which of the following statements about ecological transitions is true?
1. All the physical, chemical and biological factors that a species needs in order to live and reproduce is called ecological niche.
2. The boundary zone between two ecosystems is known as ecotone.
3. The forests in the Arctic’s are known as tundra.
4. A biome usually has a distinct climate and life forms adapted to that climate. Biome is more extensive and complex than an ecosystem.
Which of the above statements are correct?