The majority of life on the planet is based on a food chain which revolves around sunlight, as plants make food via photosynthesis.. Chemosynthesis occurs in bacteria and other organisms and involves the use of energy released by inorganic chemical reactions to produce food
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The gene/genes which was applied for the molecular clock determination may have evolved at a slow pace in these two taxa when compared to species used to calibrate the clock; this will lead to the clock underestimating the time of divergence of the two taxa apart from each other.
You seem to have forgotten to include the statements we are supposed to select from. However I still wish you good luck !
Answer: Hi (warning change the wording or you may get charged for plagiarism!)
The idea of the atom is dated back way back to Aristotle's day as you know. But you may not have known that there were many ideas about what the atom would be. some believed that there was only 1 fundamental particle, others however believed that there was no atom at all and that you could just keep cutting the cake forever and never stop. Aristotle's four elements (fire earth air and water) where believed to be fundamental units that everything was made of. Different things such as would and glass would be a combination of earth fire and air perhaps. You may see now how different this idea is from the atom nowadays. there are magnitudes of different types of atoms. the 118 elements you know of are only a fraction of the thousands of isotopes (an isotope is an atom with slightly more or less nuetrons than the normal one with as many nuatrons as protons).
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Defense against a particular antigen is provided by adaptive immunity which is also called specific immunity. In adaptive immunity immunological memory is created which is used by immune cells to destroy that particular pathogen when it again comes in the body.
Adaptive immunity involves T cells and B cells. T cells generate cell mediated immune response and B cells generate a humoral immune response. These responses by T and B cells are specific to a particular pathogen which results in the killing of the pathogen by their phagocytosis enhanced by antibodies or by direct killing of pathogen.
Therefore adaptive immunity provides defense to the body against a particular pathogen by generating immunological memory.
