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Answer: Disinfectant is a chemical formulation which may include biological components used to reduce the population of a microbe from a living or dead surface.
Explanation:
The plant tissue is treated with a disinfectant before culturing it and growing new plants. This is done to remove dirt, dust, foreign particles like pollen, microbes from the plant tissue surface or from plant part. This help in growth of disease free and contamination free plants. The culture can be utilized for different cycles of plant growth as it remains free from any kind of contamination.
The thymus becomes smaller with age as well as decreased immune system function.
The process of shrinking of the thymus is known as involution. This process occurs with any tissue that is not in frequent use. Before an individual reaches adulthood, the immune system has produced most of its T-cells. Therefore, new T-cells do not need to be produced, so the tissue of the thymus gland is replaced by adipose tissue.