Questions

Collisions occur at curves because speed on the approach is too great.

Epithelial tissue is made of layers of cells that cover the surfaces of the body that come into contact with the exterior world, line internal cavities, and form glands.

The four types of tissue in the body are epithelial, connective, muscle, and nervous. 

Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment.

Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. This removes material that will either float or readily settle out by gravity. It includes the physical processes of screening, comminution, grit removal, and sedimentation.

Secondary treatment removes the soluble organic matter that escapes primary treatment. It also removes more of the suspended solids. Removal is usually accomplished by biological processes in which microbes consume the organic impurities as food, converting them into carbon dioxide, water, and energy for their own growth and reproduction.

Tertiary treatment includes removal of nutrients such as phosphorus and nitrogen and practically all suspended and organic matter from waste water.

By whom was the food burned?

Single selled organisms are also known as Unicellular organisms in which they have only one cell.

Examples are :: Fungi, Algae, Amaeba, Paramaecium,...

Hence, all the above given options are single selled organisms.

The correct order of evolutionary history from the above given options is jellyfish, reptiles, mammals.

Tomatoes