Write down your assumptions about what may limit the spread of life on Earth beyond the specified boundaries of the biosphere

The spread of life on Earth beyond the boundaries of the biosphere limits the lack of oxygen in the upper boundaries, the absence of sunlight in the lower ones.
The biosphere is the living shell of the earth. Only the hydrosphere — the water shell of the planet — is completely populated by living organisms. Living organisms can be found even at the bottom of the Mariana Trench. Inside the solid shell – the lithosphere – the distribution of living organisms limits the lack of oxygen and the temperature of the earth’s core. And the spread of life up is limited by the lack of oxygen at a high altitude and the action of ultraviolet radiation, therefore, living organisms do not occur above the ozone layer in the atmosphere.