The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
They are ectotherms.
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All of the chemical reactions in an organism required to sustain life
Answer: Option A and D.
Soups chemical synaptic transmission.
Sparks direct electrical transmission.
Explanation:
Intercellular communication refers to the communication and interaction that exists between two cells in the body. It could be hormonal or synaptic transmission.
Synapse is the site where electric nerve impulses are transmitted between two nerve impulses.
There are two synapse possibilities which are electrical and chemical.
The Sparks and soups mean that the scientific discovery over the transmission of nerve impulses as to whether they are electrical impulses (Sparks) or chemical impulses(soup).
Chemical synaptic transmission means there is no physical touch in the space chemical are released and move to the neighbouring cells.
Electrical transmission means neuron physically touch and give way for flow of impulses between cells.
There are living organisms that do these processes alongside one another to sustain a balanced cycle.
