Questions

Exercise is a subset of physical activity that is planned, structured and repetative.

A star is a self luminous astronomical object and shines due to internal radiation from the enrgy sources. All stars are held together by their own gravity called Gravitational force.

There are lots of reasons behind the flood in any area but the main reason is a heavy downpour or rapid snowmelt can flood canyons with a mixture of soil, rock, and water is a major cause of floods.

When the spring times come, sometimes there's a lot of warmth that suddenly comes, especially nowadays when there are things such as global warming. So the snow melts and large amounts of water can flood the fields that are often found at the foot of a mountain or similar things.

But they may also be caused by deforestation, drainage channel modification from a landslide, earthquake or volcanic eruption. Examples include outburst floods and lahars.

The size of the pupil of the automatically adjusts itself according to the intensity of light passing through it; if the intensity is more, the size is less, if less, it is more. So in our case the pupil should dilate i.e , increase in size to be able to see in the dark. This switchover takes some time. But here the entry into the dark room is immediate. So the eye has no time to adjust itself and hence is not able to see at all for a while. 

All living cells arise from pre-existing cells is one component of the cell theory.

The Cell Theory is one of the basic principles of biology.

The Cell Theory states:

1. All living organisms are composed of cells. They may be unicellular or multicellular.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.