Origin of Life

In 1953, S.L. Miller created electric discharge in a closed flask containing $CH_4$, $H_2$, $NH_3$ and water vapour at 800 °C, and observed the formation of amino acids.

Chemoautotrophs were the earliest autotrophic microorganisms on the earth; they did not carry out photolysis, so they did not release oxygen. Hence both statements are correct.

Protobionts are aggregates of abiotically produced organic molecules surrounded by a membrane-like boundary. Coacervates (Oparin) and microspheres (Sidney Fox) are their models.
Their boundary partially isolated them from the surroundings.
They could separate combinations of molecules from the surroundings and concentrate them inside.
They could maintain an internal environment different from the outside, and showed simple metabolism-like reactions.
However, they lacked nucleic acids, i.e. a hereditary mechanism for exact replication. They could only grow and break into smaller pieces, which is not true reproduction.
The first non-cellular forms of life that could replicate arose later, when self-replicating molecules such as RNA appeared.
So the incorrect statement is that they were able to reproduce.

The concept of chemical evolution was proposed by Oparin of Russia and Haldane of England.
According to them, the first form of life could have come from pre-existing non-living organic molecules such as RNA and proteins.
The formation of life was preceded by chemical evolution, i.e. the formation of diverse organic molecules from inorganic constituents.
The conditions on the primitive earth were high temperature, volcanic storms, lightning and a reducing atmosphere containing $CH_4$, $NH_3$, water vapour and $H_2$.
Under these conditions simple chemicals combined to form amino acids, sugars and nitrogenous bases, which further combined into macromolecules. Miller and Urey supported this experimentally in 1953.
So chemical evolution is based on the possible origin of life by the combination of chemicals under suitable environmental conditions.

According to Oparin and Haldane, the primitive atmosphere of the earth was a reducing atmosphere.
It contained methane ($CH_4$), ammonia ($NH_3$), hydrogen ($H_2$) and water vapour, but no free oxygen.
Energy from lightning, UV radiation and volcanic heat made these gases react to form simple organic molecules (chemical evolution). This was tested by Miller and Urey in 1953.
Free oxygen appeared much later, after cyanobacteria began oxygenic photosynthesis.
So oxygen was not present in the primitive atmosphere.

According to the Oparin–Haldane theory, the first living forms arose in the primitive ocean, which was rich in organic molecules formed by chemical evolution.
These first organisms could not make their own food. They obtained energy by breaking down the organic molecules already present, anaerobically. So they were chemoheterotrophs.
Autotrophs (including photoautotrophic cyanobacteria) evolved later, when the organic food in the sea became scarce.
So the first life on earth was chemoheterotrophs.