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Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
Serum cholesterol testing in adults is recommended every 1 to 5 years. People with diabetes and a family history of high cholesterol should be tested even more frequently.
The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.