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:
the answer is D :)
Explanation:
Active transport uses energy molecules to move particles like sodium, against their concentration gradients, from areas of low concentration to areas of high concentration.
Antagonistic is the term for the phenomenon that occurs when two hormones present together to produce effects that are weaker than the effects of either one acting alone.
An antagonism, in ecology is an association between the organisms in which one benefits at the expense of the other. In Biology, it can be defined as A biological response to the exposure to multiple substances which is very less than would be predicted if the known effects of the individual substances were added together. For example, Your little sister or brother benefiting by disturbing you while you study.
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Answer: they are specific in action
Explanation: The similarity between cell receptors and antibodies is that both are specific in action. They bind to their specific targets.
These targets can be determined by the shape of the receptor or the antibody. shape of a protein has a profound effect on its functions
Answer:
The cells of living things also get energy by "burning." They "burn" glucose in the process called cellular respiration. Inside every cell of all living things, energy is needed to carry out life processes. Energy is required to break down and build up molecules and to transport many molecules across plasma membranes.
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Explanation:
