Answer:
C. two tetramers of histone proteins
Explanation:
The nucleosome core particle is responsible for packaging DNA in the chromosomes. The protein components that make up the nucleosome core are two tetramers of histone proteins. One of which is composed of two units each of histones H2A and H2B, while the other one is composed of two units each of histones H3 and H4. Thus making up the entire protein component of the nucleosome core.
Answer:
scavengers, predators, decomposers
Answer:
The correct answer is: β1 adrenergic receptor activation. Increased in cAMP lead to increased amounts of Na influx (though if channels) and calcium influx of pacemaker cells. This increases the frequency of APs of the pacemaker and increases the rate of contraction.
Explanation:
cAMP generated in response to β1 adrenergic receptors,results in excitation contraction coupling by initiating PKA and causing phosphorylation of L type Ca2+ channels and ryanodine receptors. This increases the concentration of intracellular Ca2+ ions in atrial cells, ventricular cells and AV pacemaker cells. This increase in firing rate. As a result rate of contraction increases.
B. are more difficult to control than point sources. This is because A. is wrong (point source), and C. is wrong, because it doesn't necessarily cost less or more to identify the sources. D. may be right, as non point sources are natural, such as snow melts or rain.
