Human Biology and Environmental Science

Salyut 1, launched by the Soviet Union on April 19, 1971, was the world's first space station. It preceded both Mir (1986) and the International Space Station (1998). 'Freedom' was an early American space station proposal that was never built as initially conceived.

The ozone layer (90% of atmospheric ozone) is in the stratosphere (10-50 km), formed when UV radiation splits oxygen molecules into atomic oxygen which then combines with O2 to form O3. Ozone is NOT produced only at ground level, and 90% is NOT in the troposphere. This process is fundamental atmospheric chemistry.

Ozone levels are measured in Dobson Units (DU), representing the thickness of the ozone layer in a column compressed to standard temperature and pressure. 300 DU = 3mm thick layer. Chapman unit is not used for ozone measurement. Ground UV or oxygen measurements don't directly quantify ozone. This is standard atmospheric science.

CFCs/HCFCs from refrigeration and climate change affecting stratospheric temperatures both cause ozone depletion. Dumping old refrigerators releases CFCs. Volcanic HCl DOES cause depletion but the question asks what does NOT cause depletion - this is a double negative trick question. All options except volcanic eruptions are anthropogenic, but volcanoes ARE natural ozone-depleting agents.

Ozone depletion increases UV-B reaching earth, causing skin cancer, cataracts, immune damage (A), reduces phytoplankton (B), and damages plants worsening climate change (D). However, it does NOT directly cause storms/floods - those are separate climate phenomena. This tests understanding of ozone depletion's actual impacts versus speculative effects.

'Ozone is good up high but bad nearby' correctly states that stratospheric ozone protects from UV (A), while ground-level ozone from NOx emissions worsens respiratory diseases (B, D). Option C is INCORRECT because high-altitude ozone does NOT create favorable air movement for travel - it absorbs UV, affecting atmospheric circulation but not specifically 'air travel'. This tests which statement doesn't fit the science.

The Montreal Protocol (1987) is the international treaty specifically designed to phase out ozone-depleting substances like CFCs. Kyoto Protocol (1997) targets greenhouse gases, Basel Convention (1989) controls hazardous waste transport, and Ramsar Convention (1971) protects wetlands. Montreal Protocol is considered the most successful environmental treaty. This is standard environmental GK.

Red blood corpuscles (RBCs) are formed in the bone marrow through a process called erythropoiesis. In adults, this primarily occurs in flat bones like the sternum, pelvis, and ribs. The liver produces RBCs during fetal development, while kidneys produce the hormone erythropoiesis-stimulating erythropoietin but not the actual cells.

The tibia (shin bone) is found in the leg - it's the larger of the two lower leg bones connecting the knee to the ankle. The skull contains cranial and facial bones, the arm contains humerus, radius and ulna, and the face has various smaller bones. The tibia is exclusively a leg bone.

The pancreas is a dual-function organ that produces both digestive enzymes and hormones like insulin. Insulin regulates blood sugar levels by allowing cells to take in glucose. Bile juice is produced by the liver, and peptic juice refers to gastric secretions from the stomach lining.

The cerebrum is the largest part of the human brain, making up about 85% of the brain's weight. It's responsible for higher cognitive functions like thinking, reasoning, memory, and decision-making. The medulla controls vital autonomic functions, while the cerebellum coordinates movement and balance.

Calcium phosphate (specifically hydroxyapatite) is the primary mineral component of bones and teeth, providing hardness and structural strength. Calcium carbonate is found in seashells and eggshells, while calcium sulphate and nitrate are not major components of skeletal tissue.

Hemoglobin contains iron in the form of heme groups, which bind oxygen molecules for transport throughout the body. Each hemoglobin molecule contains four iron atoms. This is why iron deficiency leads to anemia - not enough iron to make functional hemoglobin.

The pituitary gland is called the 'master gland' because it secretes hormones that regulate other endocrine glands, including the thyroid, adrenals, and reproductive glands. The pancreas produces insulin and digestive enzymes, the thyroid regulates metabolism, and the spleen is part of the immune system.

Malaria primarily affects the spleen, causing it to enlarge (splenomegaly) as it filters out infected red blood cells. The Plasmodium parasite infects and destroys red blood cells, which the spleen then removes. While malaria affects the whole body, the spleen bears the brunt of the damage.

Most food digestion and nutrient absorption occurs in the small intestine, particularly the duodenum and jejunum. The stomach mainly breaks down proteins with acid and enzymes, while the large intestine primarily absorbs water and electrolytes. The liver produces bile but doesn't digest food directly.

Iron is a ferromagnetic material, meaning it is strongly attracted to magnets. This property is due to the alignment of magnetic domains within the metal when exposed to a magnetic field. This fundamental property of iron is why it's widely used in electromagnets and magnetic applications.

The focus is the point where parallel light rays (from infinity) converge after passing through a lens. This is a fundamental principle in geometric optics. The center is the middle of the lens, infinity is a theoretical distance, and parabola is a type of curve.