The right answer is D (less responsive to antigens)
It is proven that, after puberty, thymus activity (an organ that is included in the lymphatic system, producing T cells that pick up antigens) decreases and that in adult and aged people the thymus has no role. Work done in humans indicate that in fact the cellularity begins to decline from birth in favor of lymphocyte perivascular spaces and connective and adipose tissue, which leads to a decrease in the capture of antigens.
Answer:
....I think you should give us the scenarios first so that we can help you.
Answer:
A model in which oak has a positive transition rate to the invasive and the invasive has a positive transition to oak.
Explanation:
An invasive species is the one which is non-native to the given ecosystem. Its growth hampers balanced ecological parameters and disturbs food web as well as normal flora.The overall effect of invasive species is decreasing biodiversity in selected ecosystem. As the ecologist needs to understand effect of this invasive species, firstly it is important to understand the transition of oak tress to invasive form. The transition rate is one of the deciding factor to introduce diversity in ecosystem. Also if the invasive form has the ability to revert back to original oak tress it would restore the original ecosystem. Thus a model in which oak has a positive transition rate to invasive and the invasive has a position transition to oak can be selected for the analysis. In other models, the final trnasition to grass would introduce lot of biodiversity in selected ecosystem which would be of little importance to understand transition rate.
I would say that two products of the earth are coal and petroleum and when they are burned say in a car or a power generating facility they can be converted to fossil fuels.The burning of these fossil fuels are causing too much greenhouse gases and making the earth's temperature rise and resulting in more extreme weather so fossil fuels need to be phased out so the earth will remain inhabitable for humans.
