Answer:
B
Explanation:
The spinal cord is part of the central nervous system.
Since pathogens are easily passed from person to person, they need large populations to spread and survive. If they did not have a large population, the pathogens would die out.
Answer:
d. left ventricle
Explanation:
Heart consists of four chambers: left atrium, right atrium, left ventricle and right ventricle. The atria are located above the ventricles and their function is to pump blood to the ventricles.
Right ventricle pumps the deoxygenated blood to the lungs via pulmonary artery. Pulmonary vein brings back oxygenated blood from lungs to the left atrium. From here the blood is sent to left ventricle. Left ventricle pumps blood to the entire body via aorta. Since it has to make blood reach to every part of the body from head to toes, it generates maximum pressure. Therefore, left ventricle also has thickest heart muscles.
Answer: red blood cells
Explanation:
Hemoglobin, iron-containing protein in the blood of many animals—in the red blood cells (erythrocytes) of vertebrates—that transports oxygen to the tissues
