What is the most abundant mineral in our body?

A. Four hours is longer than the recommended safe time for perishable foods to remain at temperatures where bacteria can grow. Even with cool weather, bacteria multiply rapidly in the “danger zone” (40°F–140°F).

B. Perishable foods, including cooked meats, salads with mayonnaise, eggs, and cut fruits, should not be left out at room temperature for more than 2 hours (or 1 hour if the ambient temperature is above 90°F). Keeping foods on ice helps slow bacterial growth, but 2 hours is the generally accepted limit to prevent foodborne illness. After this period, foods should be discarded to ensure safety.

C. Thirty minutes is unnecessarily conservative for most outdoor temperatures. While shorter exposure is safer, perishable foods can remain safe for up to 2 hours under controlled conditions with ice.

D. Six hours far exceeds the safe limit. Perishable foods left out this long, even on ice, are at high risk for bacterial contamination and could cause foodborne illness.

A. Plasma is the straw-colored liquid portion of blood that makes up about 55% of total blood volume. It serves as a medium for transporting nutrients, hormones, electrolytes, and waste products throughout the body. While plasma is crucial for circulation and maintaining blood pressure, it does not carry oxygen directly to tissues. Oxygen transport requires specialized cells and proteins.

B. Platelets, or thrombocytes, are small cell fragments that play a vital role in blood clotting and the repair of damaged blood vessels. While essential for hemostasis, they do not participate in oxygen transport or nutrient delivery to cells.

C. Erythrocytes, also known as red blood cells, are specialized cells whose primary function is the transport of oxygen. Each erythrocyte contains hemoglobin, an iron-containing protein that binds oxygen molecules in the lungs and releases them in tissues where oxygen is needed. Hemoglobin also helps carry carbon dioxide, a metabolic waste product, from tissues back to the lungs for exhalation. The biconcave shape of erythrocytes increases surface area for gas exchange, while their flexibility allows them to navigate through narrow capillaries. Low erythrocyte count or inadequate hemoglobin leads to conditions such as anemia, resulting in fatigue, weakness, and impaired tissue oxygenation.

D. Leukocytes, or white blood cells, are part of the immune system. They defend the body against infections, remove damaged cells, and participate in inflammatory responses. While they are vital for health, they do not transport oxygen to body tissues.