What is species ? how are new species formed ?

The image shows ekgs of a person with normal heart waves and of a person having tachycardia. based on this image, what kind of condition is tachycardia? a. the heart beats abnormally fast. b. the heart beats abnormally slow. c. the right atrium of the heart stops working. d. the left ventricle pumps less blood to the aorta.

Compare the depth of field when focusing with low power and high power. which power has the greater depth of field?

The transport tubes for food coming down the plants are called?