Heating is still done largely by burning fuels, like it has been in the past, although people now have central heating to circulate the warm air throughout the house. Some people use electric heaters and people used to use cool water to cool their houses. Now people use electric air conditioners.
Answer:
The cell membrane is selectively permeable, which controls the movement of materials in and out of the cell by passive and active transport.
Explanation:
According to this question, animal cells are made up of the following contents: 90% water and 10% protein, carbohydrates, nucleic acid, lipids and other molecules. The cell regulates this internal composition in a stable way via a process called HOMEOSTASIS.
The animal cell is able to regulate or maintain a stable internal composition by the possession of a selective permeable membrane called CELL MEMBRANE. The cell membrane is semi-permeable in the sense that it allows the entry of some molecules into and out of the cell and blocks others.
Some molecules are allowed by the cell membrane without the need for energy input in a transport called PASSIVE TRANSPORT while some requires energy input in a transport called ACTIVE TRANSPORT.
Mutations. Definition. A Mutationoccurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed
The bear's usually travel alone, but will tolerate each other and travel in groups, you never see them in groups cause they are independent and can survive on their on, and mainly because they don't like sharing their food..:D