Which statement best describes the availability of nonrenewable energy resources? their supplies will be completely used up within ten years. they are readily available in all countries. their exact amounts are not currently known. they are stored in primary forests around the world.

The correct answer would be "Their exact amounts are not currently known".

Non-renewable sources of energy are those which are present in limited quantity in an ecosystem. For example, petrol, diesel, coal et cetera.

They are also termed as exhaustible resources as they would deplete sooner or later.

It is because the pace of their replenishment or replacement by natural means is way too slower than the pace of consumption by human beings.

The exact amount of these resources is not known however, it is believed that they are going to be depleted in the next 50 years or so if they are being consumed at the current rates.

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products