Answer:
Many scientists favor the RNA world hypothesis, in which RNA, not DNA, was the first genetic molecule of life on Earth. Other ideas include the pre-RNA world hypothesis and the metabolism-first hypothesis. Organic compounds could have been delivered to early Earth by meteorites and other celestial objects
The given is incomplete as the options are missing. The correct options for the given question are as follows-
(A) cultivation of agricultural land inhibits the decomposition of organic matter
(B) nitrogen-fixing bacteria are not as plentiful in agricultural soils because of the use of pesticides
(C) land that is available for agriculture tends to be nutrient-poor
(D) the nutrients that become the biomass of plants are not cycled back to the soil on lands where they are harvested
Answer:
Option (D)
Explanation:
In order to carry out agricultural practices, the soil must be rich in essential nutrients for the growth of crops. The soil fertility is a key role in the production of crops.
This agricultural land often requires a large amount of these nutrients and minerals because some of the nutrient minerals are converted into plant biomass which is then used up to produce energy in other sectors. So, the nutrients that were present in the soil are taken away and not transferred back into the soil. This means that the nutrient cycle gets affected. Due to this reason, there requires a constant supply of nutrients into the agricultural fields.
Thus, the correct answer is option (D).
Here is a hint, mitosis is the division of cells.
Answer:
Variola virus.
Explanation:
Smallpox is caused by a virus named as Variola virus.
