Answer:
The problems that can be caused by Expansion or Contraction a;long with the solutions are:
Explanation:
- The railway tracks made of steel expand during the summer and contract during the winter. This can cause them to become curved during the summer thereby causing rail derailment.In order to prevent this, an air gap is kept in between the railway lines so that they get the space to expand without getting curved.
- The electric wires linking the telegraph posts are made up of metals and so they expand in the summer and contract in the winter, which can cause them to tear. This is why the wires are loosely fixed so that they can expand and sag in the summer and contract and tighten in the winter.
- Bridges are constructed with joints where some space is maintained to allow the easy expansion and contraction in summer and winter respectively.
Answer:
The correct answer will be option-D
Explanation:
In case the blood pressure drops in the body, the juxtaglomerular cells of the kidney start converting the prorenin into renin. This renin converts inactive angiotensin to angiotensin I which gets converted to angiotensin II by ACE enzyme.
The angiotensin II acts as vasoconstrictor narrowing the vessels and thus increasing the blood pressure. It also stimulates the secretion of aldosterone which increases the reabsorption of sodium ions and help increase the blood pressure of the blood.
Thus, option-D is the correct answer.
You mean histology right??
Histology:
Histology, also microanatomy, is the ponder of the life structures of cells and tissues of plants and creatures utilizing microscopy.
