Answer:
The correct answer is option a.
Explanation:
Osteoporosis refers to a condition that weakens the bone, and enhances the threat of unanticipated and sudden fractures, also known as porous bones. It leads to an enhanced loss of bone mass and strength. The disease often advances without any kind of pain or signs.
There is a direct association between the reduction of estrogen post menopause and the emergence of osteoporosis. Postmenopause, the breakdown or resorption of bone takes over the formation of novel bone. Estrogen diminishes the function and number of osteoclasts. Thus, the reduction in the levels of estrogen after menopause leads to bone loss.
Covalent bonds are formed when two atoms are able to <em>share</em> electrons.
Iroinic bonds are form when two atoms are <em> </em> electrons from each other to complete the bond. This results in a pair of ions.
<u>Covalent bonds:</u>
- Have a definite shape.
- Have a low melting point.
- At room temperature they are in a liquid or gas.
- They occur between two non-metals.
<u>Ionic bonds:</u>
- Have no definite shape.
- Have a high melting point.
- At room temperature they are solid.
- They occur between a metal and a nonmetal.
Answer:
D) In DNA, adenine, thymine, guanine, and cytosine join together and carry all of the genetic information. RNA is made from adenine, uracil, cytosine, and guanine and is used to make proteins.