Answer:
The correct answer is option - a virus.
Explanation:
Viruses are the infectious agents that are neither considered living nor nonliving organisms. The viruses possess the genetic material enclosed in the capsid made up of the proteins.
Genetic material or the genome of the viruses could be the DNA or the RNA as single or double-stranded forms. The viruses with RNA as genetic material termed as the adenoviruses such as tobacco mosaic viruses and HIV and others.
Thus, the correct answer is option - a virus.
Answer:
What sends oxygenated blood back to the heart from the lungs?
Oxygen-rich blood flows from the lungs back into the left atrium (LA), or the left upper chamber of the heart, through four pulmonary veins. Oxygen-rich blood then flows through the mitral valve (MV) into the left ventricle (LV), or the left lower chamber.
Explanation:
Answer:
<em>Food and shelter are the most likely limiting factors in this case.</em>
Explanation:
In a forest, the huge trees act as a source of shelter for the animals that live in that habitat. It protects the animals from the heat of the Sun and extreme cold conditions.
The tress in the forest are the primary source of food for almost all the organisms that live in the forest. Cutting down trees will lead to food scarcity for the animals which inhabit that forest. As a result, the animals will either have to migrate or they will become die due to lack of food.
Hence, food and shelter are the limiting factors in this case.
Nitrogen is the major nutrient required by grass and is used to
stimulate high growth rates and is key to achieving high yields, however
if too much nitrogen is applied this can have a negative effects on
quality.
High rates of nitrogen can also cause problems with silage
fermentation due to excess nitrate having a negative impact on the
fermentation process and will produce silage that is less palatable and
the animals will be less keen to eat it.
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Nitrate is generally taken up by grasses quicker than it is
incorporated into proteins and until used this excess known as luxury
uptake is stored in the leaves. Excess nitrate will be present if
insufficient time is allowed between application and mowing and can also
occur under conditions of poor growth eg low light levels, cool
temperatures. It is also a problem if there is a dry spell after
application, when nitrate cannot be taken up by the roots, followed by a
period of wet weather that results in luxury uptake. The plant cannot
convert it to protein quickly enough so it accumulates in the plant.
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High rates of nitrogen may cause a reduction in crop sugars as they
are used to provide energy for the increased rate of plant growth and
for the manufacture of plant proteins and this increased growth rate may
in turn lead to lower crop dry matter content although in practice this
is often not significant.
Excess nitrate can be avoided by following the Grassland Rule to apply nitrogen at the rate of no more than 2.5 kg N/ha/day.
Answer:
C. Synthesis of organic molecules
Explanation:
According to chemical evolution theory, life originated from inorganic molecules by the mode of chemical evolution. In primitive conditions of earth, only inorganic molecules were present. These molecules reacted under lightning, UV radiation and other environmental conditions to give rise to complex organic molecules like amino acids, sugars, lipids etc. They formed the basis for proteins, RNA and other molecules which ultimately led to the formation of cellular structures.
