GK (Science)

A thermos flask prevents heat loss through conduction and convection using vacuum, and through radiation using silver coating on inner walls. The vacuum between the walls stops heat transfer by conduction and convection since both require matter. The silver coating reflects infrared radiation back into the flask, keeping contents hot or cold.

The medulla oblongata, located at the base of the brainstem, contains the respiratory center that controls breathing rate and rhythm automatically. It continuously monitors blood CO2 and pH levels to adjust breathing as needed. The cerebrum handles conscious thought, cerebellum coordinates movement, and hypothalamus regulates hormones - none control breathing.

Fertilization occurs in the fallopian tubes, where sperm meets the egg after ovulation. The fertilized egg (zygote) then travels to the uterus for implantation. The follicle releases the egg in the ovary, the vagina is the birth canal, and testis is a male reproductive organ.

Chicken eggs require approximately 21 days (3 weeks) of incubation to hatch. The embryo develops all necessary structures during this period. One or two weeks is insufficient for development, while four weeks is excessive - eggs that don't hatch by day 22 typically won't hatch at all.

Alcohol fermentation by yeast converts pyruvate to ethanol and releases CO2 as a byproduct. This process creates carbonation in bread and beverages. Glycolysis produces pyruvate without releasing CO2, lactic acid fermentation converts pyruvate to lactate without CO2, and glycogen hydrolysis only breaks glycogen into glucose units.

Sedimentary rocks form from layers of sediment that accumulate and compress, creating ideal conditions for fossil preservation. Organisms get buried in sediment before hardening into rock. Metamorphic rocks undergo intense heat and pressure that destroy fossils, while igneous rocks like granite form from molten material that would burn organic remains.

Convex mirrors provide a wider field of view than flat or concave mirrors, allowing drivers to see more area and detect approaching vehicles from the sides. The curved surface creates a slightly reduced image but covers a much larger viewing area, which is crucial for safety. Concave mirrors magnify but have narrow fields.

Animals store glucose as glycogen in liver and muscle tissue for short-term energy needs. The liver maintains blood glucose levels for the whole body, while muscles keep glycogen for their own use during exercise. Plants store energy as starch, and while fat is also an energy reserve, glycogen is the primary storage form in liver and muscles.

Gonadal sexual differentiation begins during the 7th week of embryonic development. The bipotential gonad develops into either testes or ovaries based on genetic and hormonal signals. Earlier stages (5th week) have undifferentiated gonads, while 9th and 11th weeks are too late - differentiation is typically complete or well underway.

Carbon monoxide is a primary product of incomplete combustion in automobile engines and is the most distinctive component of automobile exhaust among the options.

Monotremes (egg-laying mammals like the platypus and echidna) are endemic only to Australia and New Guinea, making this the correct answer.

In orbit, objects experience weightlessness due to continuous free-fall, but mass is an intrinsic property that remains constant regardless of location or motion.

Hybridization involves crossing different plant varieties, which can result in branches producing different types of fruits on the same tree.

Deforestation removes trees that anchor soil and regulate water cycles, leading to soil erosion, reduced rainfall, and increased flooding.

Pisciculture is the correct term for artificial fish rearing, derived from the Latin word 'piscis' meaning fish.

In earthworms, the ovaries are located in the 13th segment, which is part of their reproductive anatomy.

India's low crop yields are primarily due to underdeveloped agricultural technology and poor management practices rather than soil or weather conditions.

Gold is a noble metal, meaning it is resistant to corrosion and oxidation. Diamond is not a metal, and steel is an alloy of iron.

Agriculture contributes significantly to India's GDP (around half in historical context), making it economically crucial. Option C captures the economic rationale.