Cell Size, Presence of other cells, and Chemical Stimulators
Ventricular systole is when the ventricles of the heart as the result of electrical activity which helps to pump blood. During ventricular systole oxygenated blood is pumped from the left ventricle through the aortic valve and aorta. Simultaneously deoxygenated blood is pumped from the right ventricle through the pulmonic valve and pulmonary artery to the lungs. Using this explanation blood enters the aorta and pulmonary artery during ventricular systole. <span />
The bell shaped curve indicates polygenic traits. A polygenic trait is controlled by multiple alleles. Hope this makes sense :)
There's been a lot of bad news for polar bears recently. In 2007, for example, scientists reported that if global warming continues unabated, the population could drop two-thirds by 2050.