Answer:
The two major pancreatic enzymes that digest proteins in the small intestine are chymotrypsin and trypsin. Trypsin activates other protein-digesting enzymes called proteases, and together, these enzymes break proteins down to tripeptides, dipeptides, and individual amino acids.
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.
Answer:
We can predict or comment about reactivity of elements by taking into consideration their electronic configuration that imparts stability or un-stability to an atom.
Explanation:
Reactivity : It refers to the affinity of a substance to combine with other substance .
Elements are mainly of two types :
In terms of metals or non metals it can be defined as tendency to loose or gain electrons .
- On the basis of it ,we can easily make out or comment about the reactivity of element (metal or non metal ) .Like ,if an element has completely filled outermost shell or we can say have stable electronic configuration then it is already stable .Therefore , it won't react with any other element .
- But, if its outer shell isn't complete then in order to attain stability it will combine or react with other .Hence , we can say it will be quite reactive .
