Blood pressure is generated byA. Valves in the heart B. Contractions of the heart muscle C. Veins D. Contractions of the diaphragm muscle

The answer is B, contractions of the heart muscle.

Explanation:

Basically blood pressure is the pressure in which your blood is pushed away from the heart to the other parts of your body.  So the force in which the heart has to use to pump that blood is the blood pressure.  This is called the systolic pressure.  The harder your heart has to work to pump the blood, the higher your pressure will be.  There's a secondary pressure is called diastolic pressure.  This is the second force where your heart rests between pumps.  So you will have 2 numbers for blood pressure, the systolic and the diastolic.  You want your heart to work as little as possible to pump the blood through your body.

humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell. the only human cells that do not contain pairs of chromosomes are reproductive cells, or gametes, which carry just one copy of each chromosome.

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.