Explanation:
Catalase test demonstrate the presence of an enzyme called catalase, that catalyses the release of oxygen from hydrogen peroxide. It is used to tell the difference between the non-catalase producing bacteria from those bacteria that produces an enzyme catalase. Catalase is produced by the bacteria that respire using oxygen. If an organism produces catalase, bubbles of oxygen are produced when hydrogen peroxide is added to it.
I'm pretty sure it's D, because I had something like this last week. but I'm sorry if it's wrong..
The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
I think its because so the plants can absorb more nutrients from the soil while being sturdy and wide so when the plant gets snowed on it doesn't break<span />
It is transplanted routinely to treat a variety of blood and bone marrow diseases, blood cancers, and immune disorders. More recently, stem cells from the blood stream (called peripheral blood stem cells) and umbilical cord stem cells have been used to treat some of the same blood-based diseases