William Smith and Georges Cuvier
Answer:
a. inhibits cAMP phosphodiesterase, the enzyme that converts cAMP to AMP.
Explanation:
The phosphodiesterases are a group of enzymes that are capable of breaking phosphodiester bonds such as those between nucleotides in nucleic acids. The Cyclic adenosine monophosphate (cAMP) is a second messenger involved in intracellular signaling pathways. This molecule (cAMP) is hydrolyzed by the cAMP-dependent phosphodiesterase, which catalyzes the enzymatic breakdown of phosphodiester bonds (i.e., hydrolyzing cAMP to 5-AMP). The cAMP levels are modulated by the balance between its generation and the degradation via cyclic nucleotide phosphodiesterase.
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.
<span>
<span>
</span>
</span>
<span>
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.
</span>
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:
D) Urethra is the correct answer
