Biology

The average weight of a man's brain is approximately 4.8 ounces, while the average weight of a woman's brain is slightly less, around 4.4 ounces. This difference is well-documented in anatomical studies.

Adrenalin (also called epinephrine) is the hormone responsible for increasing heart rate and blood pressure, especially during stress or shock. It prepares the body for 'fight or flight' responses by stimulating the heart and constricting blood vessels.

ATP (adenosine triphosphate) is known as the energy currency of body cells because it stores and provides energy for many cellular processes. The other options (ADP, DNA, RNA) do not serve this function.

Animals do not directly use atmospheric nitrogen gas (N2) or nitrites. Instead, they obtain nitrogen by consuming plants or other organisms that have incorporated nitrogen in the form of organic compounds derived from nitrates and ammonium absorbed by plants. Nitrates (NO3-) are a primary form of nitrogen absorbed by plants from the soil, which then enter the food chain. Nitrites (NO2-) are intermediate compounds in the nitrogen cycle and are generally not directly used by animals. Therefore, among the given options, 'Nitrates' is the correct answer as animals indirectly use nitrogen in this form through their diet.

White blood cells are also known as leukocytes, which are part of the immune system and help fight infections. Erythrocytes are red blood cells, and thrombocytes are platelets, so they are not correct.

Bubo bubo is the scientific name of the Eurasian eagle-owl, which is a species of owl. Therefore, option D (Owl) is correct.

Platelets are also known as thrombocytes, which are small blood components involved in clotting. Erythrocytes are red blood cells, and leukocytes are white blood cells, so option C is correct.

Gastric juice contains hydrochloric acid, making it highly acidic with a low pH around 1-3, which is lower than the pH of hepatic bile, saliva, and pancreatic juice. Therefore, gastric juice has the lowest pH among the options.

Red blood cells are also known as erythrocytes because they contain the pigment hemoglobin which gives them their red color and allows them to transport oxygen.

The Rafflesia is known as the largest flower in the world, with some species producing flowers over 1 meter in diameter. The other options (Conifer, Fern, Horsetail) are not flowers but types of plants or plant groups.