Answer:
A
Definition of an Oran System:
An organ system is a group of organs that work together as a biological system to perform one or more functions. Each organ does a particular job in the body, and is made up of distinct tissues.
Around the age of six or seven years, our teeth start to loosen, eventually falling right out. These are what we call milk teeth. Their termination is not a cause for alarm, but rather, a natural process. Soon new teeth replace the ones that are lost. In fact, the deciduous teeth help the permanent teeth erupt in their normal position. Certain of the lower vertebrates, such as sharks and mud puppies, continuously produce new teeth. But most mammals have only two sets. It seems that as you go up on evolutionary scale, there is loss in capacity to replace teeth, scientists say. On the other hand, the teeth become more specialized. For example, in lower organisms, teeth are designed primarily for grabbing and slashing, while in higher animals, they are also adapted for chewing and grinding.
It has been known that in humans the first set of teeth do more than just allow a child to chew. They play a role in stimulating and guiding the growth and development of jawbones and permanent teeth. One of the biggest fallacies is the belief that because deciduous teeth are temporary, they are not important. If a child loses milk teeth prematurely, by accident or because of decay, his jaw and permanent teeth are likely to develop improperly. Prolonged treatment may be needed to set them right.
Another reason for our two sets of teeth is that there is not enough room in a child’s small mouth for the full set of permanent teeth – there are only 20 deciduous teeth, compared with 28 or 32 permanent teeth present in adults.
Hope this helps
<span>They are made up of nitrogenous bases, sugars, and phosphates. Nucleic acids are molecules like DNA and RNA. The sugars and phosphates form the "backbone", and the nitrogenous bases are what actually holds the genetic information.</span>
We cannot see the picture clearly it is blurry.
