The primary succession takes a long time to be done. the secondary succesion takes 200-500 years for completion. the secondary succession occurs in an area which has been denuded recently and lately inhabited. soil is present at the beginning of the secondary succession with some organisms. thank you for this question.
In the heart, the valves are located between atria and ventricles and between ventricles and arteries (option D).
<h3>What are valves in the heart?</h3>
Valves are membranous partitions which permit the passage of the contents of a vessel or cavity in one direction, but stop or control the flow in the opposite direction.
Valves in the heart enforce a one-way blood flow through the heart and separate atria from ventricles, and ventricles from the large arteries that leave them.
The four valves in the heart and their location is as follows:
- tricuspid valve: located between the right atrium and the right ventricle
- pulmonary valve: located between the right ventricle and the pulmonary artery
- mitral valve: located between the left atrium and the left ventricle
- aortic valve: located between the left ventricle and the aorta.
The valves between the atria and ventricles are called atrioventricular valves or cuspid valves while those at the bases of the large vessels leaving the ventricles are called semilunar valves.
Therefore, it can be said that the valves of the heart are located between atria and ventricles and between ventricles and arteries.
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Cancers are said to be caused by genetics, meaning the disease originated from the DNA structure. There are viruses that affect the DNA. Examples are hepatitis B virus, Epstein-Barr virus, herpes virus-8 and human papilloma virus. These are the DNA viruses that could cause cancer.
Meninges are membranes that cover and protect the brain and spinal cord.
There are three layers of meninges: Dura mater (closest to the bone), Arachnoid loosely around the brain, Pia mater is closely attached to the brain and spinal cord surface.
