General Science GK Questions with Answers – Page 66

A salamander is an amphibian, and amphibians have a heart with two atria and one ventricle. Heart chambers increase along the vertebrate groups.

Electric power is voltage multiplied by current, and 110 V × 0.2 A = 22 W. Power is the rate at which electrical energy is used.

The cell membrane is flexible, and this lets a cell fold it around food and other material and take it in.

Chlorophyll absorbs light energy, which is used to split water and then to reduce carbon dioxide to sugar. In the light reactions, energy trapped by chlorophyll splits water molecules (photolysis), releasing oxygen, hydrogen ions and electrons and producing ATP and NADPH.

Wet straw or gunny bags keep the fresh concrete moist, so water does not evaporate before the cement has hydrated properly.

Sodium is so reactive that carbon cannot reduce its compounds, so it is obtained by passing electricity through molten sodium chloride.

Resistivity is a property of the material itself, so it stays the same when the length of the wire is changed.

Massive giant stars burn their fuel so fast that they live much shorter lives than dwarf stars, so Statement I is false and Statement II is true.

The oyster feeds by drawing water over its gills and straining out plankton and organic particles, which is filter feeding.

RTGs power spacecraft using heat from the natural decay of plutonium-238; they are not reactors and involve no fission. In an RTG, a radioactive isotope gives off heat as it decays on its own.

Of the three, only red sanders is native to India; cashew and papaya were brought from the Americas. Red sanders (Pterocarpus santalinus) is endemic to the southern Eastern Ghats, mainly the Seshachalam and nearby hills of Andhra Pradesh.

Each of the three groups includes species that carry toxins in their bodies to deter predators. Butterflies: the Monarch butterfly feeds as a caterpillar on milkweed and stores its bitter cardiac glycosides, so birds that eat it fall sick; its bright orange colour is a warning.

An anemometer measures how fast the wind is blowing; its name comes from the Greek word anemos, meaning wind.

Light that enters a cut diamond is reflected again and again inside it before it escapes, which makes the stone sparkle.

Sound is a mechanical wave that needs a medium to travel, while the other three are electromagnetic waves. Sound travels as a longitudinal wave of compressions and rarefactions in air, water or solids, which is why it cannot pass through a vacuum.

Electromagnetic waves are transverse, not longitudinal, so this statement is false. In an electromagnetic wave the electric field and the magnetic field oscillate at right angles to each other and both at right angles to the direction in which the wave travels.

The normal human ear hears sound from about 20 hertz to 20,000 hertz, the audible range. Frequency, measured in hertz, is the number of vibrations per second, and it decides the pitch of a sound: the higher the frequency, the shriller the note.

Ultrasound is sound with a frequency above 20,000 Hz, the upper limit of human hearing. Humans hear sound between about 20 Hz and 20 kHz.

Propane is a light gaseous hydrocarbon that burns completely with a blue flame, leaving no smoke, soot or ash. A clean fuel burns completely, gives high heat and releases few pollutants.

Soft soaps are potassium salts of fatty acids, while ordinary hard bar soaps are sodium salts. Soap is made by saponification, heating an oil or fat with an alkali.