General Science Questions

On December 21, the earth is in an equivalent position on the opposite points in its orbit, So the South pole is tipped towards the sun and North pole away from it resulting in 24 hours of darkness at the North pole, as the sun is overhead on the Tropic of Capricorn. This phenomenon is winter solstice; while on June 21, North pole is tipped towards the Sun but the South pole is tipped away from the sun resulting in 24 hours of darkness on the South Pole, as the sun is overhead on the Tropic of Cancer.This phenomenon is summer solstice; while Aphelion is the position of the earth in its orbit when it is at its distant point from the sun.

Tendencies does not contribute to wellness among the given options.

It is due to the deficiency of Vitamin A. Retinol which is present in vitamin A. Its deficiency causes night blindness. It is available in carrots. 

Plants developing in dry conditions are called as xerophytes.

From the cornea, the light passes through the pupil. From there, it then hits the lens, the transparent structure inside the eye that focuses light rays onto the retina. The iris, or the colored part of your eye, regulates the amount of light passing through.