oxygen and sunlight
Yes, there must be greenhouse gases in the atmosphere. Without a greenhouse effect the planet would be unable to sustain life. The greenhouse effect is required for life as we know it.
No, it doesn't even have a substantial atmosphere.
atmosphere
Life
The term is "biosphere." It refers to the zone within the Earth's atmosphere, hydrosphere, and lithosphere where life exists.
Because, Earth is at a right distance from the size of our sun which where water could exist and our atmoshpehere with many gases and not just CO2. Mars could sustain life but need to reduce the level of co2 in its atmosphere to sustain fresh, liquid water.
The Earth needs an atmosphere to sustain life by providing oxygen, regulating temperature, and protecting us from harmful radiation. The atmosphere also helps distribute heat and water across the planet and plays a crucial role in the water cycle.
The thick atmosphere has enough oxygen so than living things can happen.
Earth comprises of atmosphere. Air and water provides favorable conditions.
Apart from water, you need oxygen in the air to sustain life on earth. With these two indispensable features, both mankind,animals and botanical reserves sustain life on this planet.
The troposphere is the layer of the atmosphere closest to Earth's surface where life is sustained. It contains the air we breathe and the weather phenomena we experience.
Earth has many things which are necessary to sustain life. Water is essential for life, as well as an atmosphere with abundant oxygen and it is the perfect distance from the sun to provide us with enough heat and energy to survive.