The right answer is The first image (the left one).
An atrium is an upper cavity of the heart, delimited by a thin wall, receiving blood from the bloodstream. There are two in the human heart, they allow the passage of blood from the veins (cellars and lungs) to the ventricles (right and left).
In its upper part (near the entrance of the superior vena cava) is located the sinus node, microscopic structure from which the electrical impulse which ensures the contraction of the heart (especially atrium) ...
The depolarization of the action potential is conducted step by step in the cells of the right and left atria, accompanied by a contraction of the muscle fibers.
Magnetic reversals C. PROVIDE STRONG EVIDENCE FOR SEAFLOOR SPREADING.
Magnetic reversal is evident when the <span>change in the Earth's magnetic </span><span>field results in the magnetic </span><span>north being aligned with the geographic south, and the magnetic </span><span>south being aligned with the geographic north. It is also called geomagnetic reversal</span><span>.</span>
Magnetic reversals can occur in less than 100 years. It led to extinction events during the pre-historic times. Because the magnetic field is rapidly weakening, magnetic reversal may cause biblical floods.
Answer:
Speciation occurs at terminal population groups
Explanation:
A ring species represents a group of organism that has moved beyond a geographic barrier to produce a ring shaped distribution. This population is contiguous and there exists no barrier to gene flow anywhere in the ring except at the terminal populations.
Speciation is demonstrated in the terminal population has become sympatric and it does not interbreed even if they are connected by chain of intergrading or interbreeding populations
Answer:
I think that 4 is the answer, sorry if I am wrong
