General Science

A sphygmomanometer is the medical device used to measure blood pressure. It consists of an inflatable cuff to collapse the artery and a mercury or aneroid manometer to measure the pressure.

The enzyme is called carbonic anhydrase, not 'carbonic anhydrous'. Carbonic anhydrase is found in red blood cells (RBCs) and catalyzes the conversion of CO2 and water to bicarbonate and protons, essential for CO2 transport.

The SA node (sinoatrial node) is the heart's natural pacemaker, located in the right atrium. It spontaneously generates electrical impulses that initiate each heartbeat. These impulses then spread to the AV node, Bundle of His, and Purkinje fibres to coordinate the cardiac cycle.

Hemophilia A is caused by deficiency of Factor VIII (antihemophilic factor), a clotting protein essential for the coagulation cascade. Without sufficient Factor VIII, blood cannot clot properly, leading to prolonged bleeding. Factor IX deficiency causes Hemophilia B, but Factor VIII is the most common form.

Macrophages are the major phagocytic cells of the immune system, derived from monocytes. They engulf and digest pathogens, dead cells, and debris through phagocytosis. Lymphocytes are involved in adaptive immunity, mast cells in allergic responses, and plasma cells produce antibodies.

Coronary veins drain deoxygenated blood from the heart muscle (myocardium). Coronary arteries supply oxygenated blood TO the heart. Pulmonary veins carry oxygenated blood from lungs to heart, while pulmonary arteries carry deoxygenated blood to lungs.

Sodium citrate is the standard anticoagulant used in blood banks because it chelates calcium ions, which are essential for the clotting cascade. Heparin is also an anticoagulant but not typically used for blood storage. Sodium glycocholate and taurocholate are bile salts unrelated to coagulation.

Prawns have an open circulatory system where hemolymph (not true blood) is pumped by the heart into body cavities (sinuses). The heart receives and pumps mixed hemolymph containing both oxygenated and deoxygenated components, as there's no complete separation like in closed circulatory systems.

The sun's energy is produced by nuclear fusion - hydrogen nuclei combine to form helium, releasing enormous energy. This occurs in the sun's core under extreme temperature and pressure. Chemical reactions and combustion are surface processes; nuclear fission is not the sun's energy source.

After 40 days (which is 4 half-lives of 10 days each), the remaining mass = 2g × (1/2)^4 = 2g × 1/16 = 0.125g. Each half-life reduces the quantity by half, so after n half-lives, remaining = initial × (1/2)^n.

When the bus stops suddenly, passengers continue moving forward due to inertia of motion - the tendency of moving objects to remain in motion. No force pushes them from behind; rather, their bodies maintain their state of motion while the bus decelerates. This is Newton's first law.

Isobars are atoms with the same mass number (total nucleons) but different atomic numbers (different numbers of protons). Isotopes have the same atomic number but different mass numbers. Isotones have the same number of neutrons. Isochores relate to constant volume in thermodynamics.

Arterial blood pH is normally 7.35-7.45, with 7.4 being the standard value. This slightly alkaline pH is tightly regulated by buffer systems (bicarbonate, hemoglobin, phosphate) and respiratory/kidney mechanisms. pH 7.0 is neutral, 6.0 is acidic, and 7.1 is too low for arterial blood.

Insects have an open circulatory system where hemolymph (blood) is pumped into body cavities called hemocoel, directly bathing the organs. Unlike closed systems, the blood is not confined to vessels throughout most of the body. Reptiles have closed circulation, man has a closed circulatory system, and 'animals' is too broad since most vertebrates have closed systems.

Myoglobin is an oxygen-binding protein found predominantly in red muscle fibers (slow-twitch fibers), which are specialized for sustained aerobic activity and endurance. These fibers appear red due to high myoglobin content and mitochondrial density. White muscle fibers (fast-twitch) rely on glycogen and have little myoglobin as they're meant for quick, anaerobic bursts.

The nucleus contains protons and neutrons (collectively called nucleons), which account for over 99.9% of an atom's mass. Electrons orbit the nucleus and have negligible mass (about 1/1836 of a proton). Therefore, the nucleus is both the most massive and solid (densest) part of the atom.

The atomic nucleus is composed of protons (positively charged) and neutrons (neutral), collectively called nucleons. These particles are bound together by the strong nuclear force. Electrons orbit the nucleus in electron shells and are not part of the nucleus itself.

The photoelectric effect occurs when photons of sufficient energy (above a threshold frequency) strike a metal surface and eject electrons. This phenomenon provided key evidence for quantum theory, showing light behaves as discrete packets of energy (photons). It is not about producing radioactive particles (alpha, beta, or gamma rays).

Gamma globulins (γ-globulins) are the class of plasma proteins that include immunoglobulins (antibodies). Antibodies are produced by plasma B cells and are essential for the adaptive immune response. Albumins transport substances, while alpha and beta globulins have other functions like transport and enzyme inhibition.

Crocodilians are unique among reptiles in having a four-chambered heart (two atria, two ventricles), similar to birds and mammals. This prevents mixing of oxygenated and deoxygenated blood, supporting their active predatory lifestyle. Most reptiles have three-chambered hearts.

Blood group AB individuals are called universal recipients because they lack both anti-A and anti-B antibodies in their plasma, allowing them to receive blood from any ABO group (A, B, AB, or O). Group O individuals are universal donors (have no A or B antigens), while A and B can only receive from specific compatible types.

Radioactive dating (also called radiometric dating) calculates the age of rocks, fossils, or archaeological materials by measuring the ratio of a radioactive isotope to its decay product. This relies on known half-lives - not the time for complete decay (which takes infinite time). It's different from radiation detection methods.

Diapedesis is the key characteristic of leucocytes (white blood cells) - the ability to squeeze through capillary walls and migrate into tissues to fight infection or inflammation. WBCs are nucleated (unlike RBCs), many are granular (not agranular), and they're typically colorless (stains are used to see them).