Biology Questions and Answers

Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several pro-vitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision.

Maltose is composed of two molecules of glucose.

An animal with radial symmetry really has no right and left side or head and rear end. This animals do not move, so they can reach into their environment from all sides. Starfish is an example of a radial symmetrical organism. They can be attached to a substrate, like the sea anemone, or float, like jellyfish. It also occurs in simple animals including the aquatic cnidarians, which include hydra, corals, jellyfish and sea anemones, and Ctenophora, which are comb jellies.

One of the common traits amongst the cnidarians is their symmetry. Hydras, like all cnidarians, display radial symmetry.

A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat.

Trichocyst, a structure in the cortex of certain ciliate and flagellate protozoans, consists of a cavity and long, thin threads that can be ejected in response to certain stimuli. Trichocysts may be widely distributed over an organism or restricted to certain areas (e.g., tentacles, papillae, around the mouth).