Accommodation in the eye lens is the process of adjusting its shape to focus on objects at different distances. This adjustment is controlled by the ciliary muscles. When focusing on nearby objects, these muscles contract, thickening the lens. For distant objects, the muscles relax, flattening the lens, ensuring clear vision at varying distances.

A torch emits a divergent light beam, where light rays spread out as they move away from the source. This spreading allows the flashlight to illuminate a wider area, making it useful for various tasks. Divergent beams are common in flashlights, ensuring efficient coverage and visibility in the dark.

A concave mirror is used in a solar cooker. Specifically, a concave mirror focuses sunlight onto a small area, increasing the intensity of the sunlight and generating heat. This concentrated sunlight is then used for cooking in solar cookers, harnessing solar energy for practical applications.

The image formed by a plane mirror (also known as a flat mirror) is called a "virtual image." A virtual image is an image that is not real but appears as if it were. It is formed behind the mirror, and it appears to be the same size as the object being reflected. This image is upright (erect) and reversed from left to right, but it is not a tangible object; it exists as a result of the way light rays reflect off the mirror's surface.

If the image formed in a mirror is always erect (upright) and equal in size to the object, the mirror is a flat mirror (plane mirror). Flat mirrors reflect light without distorting the image, producing an erect image that is the same size as the object and reversed from left to right.

Flat Mirror (or Plane Mirror): Reflects light without distorting the image. The image formed is erect (upright) and of the same size as the object, but reversed from left to right.

Convex Mirror: Also produces an erect image. The image formed is virtual (cannot be projected onto a screen), smaller than the actual object, and upright.

Both flat and convex mirrors can create upright (erect) images of real objects.

Actually, the locomotor part of a hydra is not its tentacles. Hydras move by a remarkable way called "looping." They attach one end of their body to a surface and then release the other end, allowing it to move and attach again. This looping movement is facilitated by the contraction and expansion of the body, rather than the use of tentacles. Tentacles are specialized structures primarily used for feeding and defense in hydras.

Cats (and many other animals) have a layer of cells behind their retinas called the tapetum lucidum. This layer enhances night vision by reflecting light that passes through the retina back into the eyes. When light enters the eye, some of it is absorbed by the retina's cells, allowing the brain to process visual information. However, the tapetum lucidum reflects the remaining light back through the retina, giving the photoreceptor cells a second chance to detect the light. This reflection of light enhances their night vision capabilities and is what causes a cat's eyes to appear to glow in the dark or in low light conditions.