General Science GK Questions with Answers – Page 124

Anabaena is a cyanobacterium, a prokaryote with no true nucleus, and all prokaryotes are placed in Monera. In R.H.

Nitrogen is an unreactive gas, so it drives the oxygen out of the packet and stops the oil in the chips from getting oxidised.

Violet has the shortest wavelength in visible light, so glass slows it the most and bends it the most. White light is a mix of seven colours, remembered as VIBGYOR.

Each metal here is paired with one of its best-known ores. Bauxite is hydrated aluminium oxide; alumina is refined from it and then broken down by electrolysis in the Hall-Héroult process.

The number 235 is the mass number and uranium's atomic number is 92, so the nucleus holds 235 minus 92, that is 143 neutrons.

At great heights the air is thin, so the atmospheric pressure acting on the body is much lower than at sea level.

Bronze is made by melting copper and tin together, with copper as the main metal. It is harder than pure copper and does not corrode easily, so it has been used for statues, bells, medals and utensils for thousands of years.

All three are needed by plants only in very small amounts, which makes them micronutrients. Plants need macronutrients in large amounts: nitrogen, phosphorus and potassium as primary nutrients, and calcium, magnesium and sulphur as secondary ones.

Of the three, only citrus canker is caused by bacteria; rust of wheat is caused by a fungus and yellow vein mosaic of bhindi by a virus.

The pituitary gland sends out hormones that order the thyroid and the adrenal glands to release their own hormones. The pituitary is a pea-sized gland attached to the base of the brain, and it is called the master gland because it controls several other endocrine glands.

The rough strip of a safety matchbox is coated with powdered glass and a little red phosphorus, while the head of the matchstick carries antimony trisulphide and potassium chlorate.

Veins usually carry blood low in oxygen back to the heart, but the pulmonary veins are the exception. After blood picks up oxygen in the lungs, four pulmonary veins, two from each lung, bring this oxygen-rich blood to the left atrium of the heart.

The pancreas is both an exocrine gland, pouring digestive enzymes into the intestine, and an endocrine gland. Its endocrine part is made of small clusters of cells called the islets of Langerhans.

The liver needs vitamin K to make several clotting factors, including prothrombin, which help blood form a clot and seal a wound.

When light travels from a denser medium to a rarer one and strikes the boundary at an angle greater than the critical angle, it does not pass out at all but is reflected completely back.

The liver needs vitamin K to make prothrombin and other clotting factors, so without it blood takes much longer to clot.

Milk contains very little vitamin C, and what little there is gets destroyed further when milk is boiled. Milk is otherwise called a nearly complete food: it gives calcium and phosphorus for bones and teeth, good-quality protein, mainly casein, the sugar lactose, fat, and vitamins A, B2 and B12.

Each stoma is surrounded by two guard cells, and the pore opens or closes as these cells gain or lose water.

Aluminium oxide and zinc oxide behave like a base with acids and like an acid with bases, so both are amphoteric.

Magnification is a ratio of two lengths, so the units cancel and it is a pure number. For a mirror or a lens, magnification m equals the height of the image divided by the height of the object (h′/h).