A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment. So it’s the last one.
An unknown mtDNA sample sample is matched to a sample of mtDNA that was found at the crime scene.<span> This is how mitochondrial DNA (mtDNA) typing is used in forensic science.</span>
<span>Unlike nuclear DNA typing, mtDNA isolation is quite easy because its number is quite large. mtDNA copies rang from 100 to 10,000 per cell. It is also more stable and stronger than the nuclear DNA; that is why even unsolved cases from years ago use mtDNA typing as reference for possible conclusion.</span>
Answer:
The atmospheric oxygen initially came from the water molecule
Explanation:
Condition on the primitive Earth , about 4 billion year ago were such which favored chemical evolution. . When the temperature of the Earth was less than 100 degree Celsius. Its atmosphere had nitrogen in the form of ammonia, carbon in the form of carbon dioxide and oxygen in the form of water vapour. There was no free oxygen available and so the atmosphere was reducing.
Then spontaneously biomolecules originated which further gave rise to protobionts. These protobionts evolved into several unicellular organisms among which one was cyanobacteria.
Cyanobacteria are considered as the organisms which added the first molecule of free atmospheric oxygen into the atmosphere. They carried out photosynthesis and split the water molecules to release oxygen as the bye product of the process.
In women, a recessive allele on one X chromosome is often masked in their phenotype by a dominant normal allele on the other. This explains why women are frequently carriers of X-linked traits but more rarely have them expressed in their own phenotypes. There are about 1,098 human X-linked genes.