What is one difference between primary and secondary succession? Primary succession can start from bare rock; secondary succession starts from organic soils. Primary succession occurs in habitats with rich organic soil; secondary succession does not. Primary succession is always caused by human disturbances; secondary succession is not. Trees are often the first colonizing species in primary succession, but trees are never the first species in secondary succession.

Primary succession can start from bare rock; secondary succession starts from organic soils.

Explanation:

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.