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DNA.
DNA has a phosphate and deoxyribose sugar backbone.
Answer:
The correct answer will be option-B (purine).
Explanation:
Nucleic acid structure is made up of monomer unit called nucleotide. Each nucleotide is composed of a five-carbon sugar, a phosphate group and five types of nitrogenous bases.
The nitrogenous bases are categorized in two forms the purines (adenine and guanine ) and the pyrimidines (cytosine, thymine and uracil). The "purines" contain double rings in their structure due to which they appear larger in size than pyrimidines which are made up of single rings.
Thus, Option-B is the correct answer.
Answer:
I and III only
Explanation:
Crop rotation is a farm practice that involves cultivating different species of crops on the same land at different seasons. In other words, the different crops are rotated. Crop rotation is done for various reasons including; improvement of soil fertility, pest and disease control etc.
In this case, a crop rotation of various grains and legumes would be an appropriate solution for the following problems:
- The nutrients in the soil on a farm are being depleted: Legumes are known to be rich in nitrogen and hence add nitrogen to the soil due to the nitrogen-fixing microbes in their roots. Hence, rotating between grains and legumes can help return the depleted nutrients (by grains) to the soil.
- A particular kind of pest is infesting the soil on a farm: Most pests are usually crop-specific, hence, planting only one type of crop can make that soil be infested with a particular kind of pest. However, rotating between crops such as grains and legumes can make a particular pests become scarce or less populated.
Pumping water out of the ground faster than it is replenished over the long-term causes similar problems. The volume of groundwater in storage is decreasing in many areas of the United States in response to pumping. Groundwater depletion is primarily caused by sustained groundwater pumping.
