Natural gas is a fossil fuel used as a source of energy for heating, cooking, and electricity<span> generation. It is also used as fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals.</span>
Answer:
A. A prokaryote lacks a well-defined nucleus.
C. A prokaryote lacks cell organelles.
Explanation:
A prokaryote has DNA or RNA just floating in the cytoplasm. There is no nucleus to hold them inside. A prokaryote also lacks a mitochondria and other organelles, so it is different from a eukaryote.
Pond ecosystem considered as an open ecosystem because pond is always open . There is an interaction of pond with atmosphere , due to which it ecosystem becomes open.