Answer:
Aaa It is the heterogeneous mixture and particles settle down if left undesrbied
The food chain is very important to ecosystems.
The following statements accurately reflect the beliefs on Earth's early history:
B. Scientists believe the early atmosphere lacked the oxygen necessary to support modern human life.
The following statements are incorrect:
A. Scientists believe that DNA may have existed before RNA - Scientists actually believe the opposite - RNA may have existed before DNA.
C. Scientists believe that microspheres nearly prevented the development of early life.
D. Scientists believe that oxygen was plentiful in the early atmosphere - again, scientists believed the opposite
Answer:
A genetic factor for a trait that is always expressed when it is present is best described as dominant.
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Answer:
Ligand-receptor interaction is the first interaction that triggers cell signalling.
Ligands are the hormones, drugs or neurotransmitters that specifically bind with receptors present in cell surface to initiate cell signalling. Ligand binding to the receptor is reversible. Binding of the ligand to the receptor can activate or inactivate receptor. Activation may lead to cell signalling pathways. Inside cells, there are secondary molecules which on activation starts a cascade of reactions. which in-turn regulate the function of the ligand molecule.
At first, the activated receptor relates with G proteins molecules in the cell.
before the ultimate physiological effect of the ligand on the cell's behavior is produced Therefore, the cellular signaling starts as soon as the first messenger (the ligand) binds to its receptor.
hope this helps
