They are formed by natural processes like anærobic decomposition. They contain energy from ancient photosynthesis. They can literally be around 650 million years old.
The answer is density-dependent factor
The correct answer is A. Lac repressor.
Lac repressor prevents lac gene which are found in the DNA of Escherichia Coli from being expressed for many times.
Lac repressor is termed as DNA which binds proteins. It allows the expression of genes from coding which are made for proteins to be involved in metabolism of lactose which is in bacteria.
When there is no lactose which is available in the cell, then the genes are being repressed. Lactose are being converted to allolactose if they are available.
