General Science Mixed Quiz: Set 161

Sunlight takes about 8 minutes and 20 seconds, roughly 500 seconds, to travel from the Sun to the Earth. The average distance between the Sun and the Earth is about 150 million kilometres, a distance called one astronomical unit.

Herpetology is the study of reptiles such as snakes, lizards, crocodiles and turtles, together with amphibians such as frogs, toads and salamanders, and in India it includes the work on snake venom and antivenom at institutions that maintain snake parks.

A drupe is a fleshy fruit with a thin epicarp, a mesocarp that may be pulpy as in the mango or fibrous as in the coconut, and a hard, stony endocarp enclosing a single seed; the coconut's shell is that endocarp and the white kernel is the seed.

DNA copies itself from loosened chromatin, and chromatin condenses into chromosomes before division, but prokaryotes divide differently from eukaryotes. In a non-dividing eukaryotic cell, DNA lies in the nucleus as a loose network called chromatin.

Friction is defined as the force that opposes the relative motion, or the tendency of relative motion, between two surfaces in contact; it acts along the surfaces and always against the direction of motion.

Charles’s law says that at constant pressure the volume of a fixed mass of gas is directly proportional to its absolute temperature, so V by T stays constant.

During this phase the DNA of the cell is copied so that the amount of DNA in the nucleus doubles, while the number of chromosomes remains unchanged because each chromosome now simply consists of two identical sister chromatids joined at the centromere.

Crown gall is caused by the bacterium Agrobacterium tumefaciens, which enters through a wound near the base, or crown, of the stem and makes the plant grow rough tumour-like swellings there.

When light of a suitable frequency falls on a metal and knocks electrons out of it, the process is called photoelectric emission.

In 1905 Einstein explained the photoelectric effect by treating light as made of packets of energy, later called photons, and he received the 1921 Nobel Prize in Physics for this work.

Clay is a plastic material: it deforms permanently under even a small force, so its stress is not proportional to its strain.

Four grams of hydrogen gas is two moles, so it contains 2 × 6.022 × 10²³, about 1.2 × 10²⁴ molecules, not 6.022 × 10²³.

This is the defining condition of simple harmonic motion, written F = −kx, where k is the force constant and the minus sign shows that the force always points back towards the mean position.

In a dicot leaf most stomata are on the lower surface, so coating that surface blocks most of the water loss and the leaf stays fresh the longest.

The pea's ovary is made of one carpel whose two margins fuse to form a ridge, and the ovules are arranged in two rows along that ridge; this is marginal placentation, and it is why the pod opens to show a single row of seeds on each side.

When a wire is stretched its volume stays the same, so the length must grow in the same ratio as the cross-sectional area shrinks.

The coefficient of friction is the ratio of the limiting or kinetic frictional force to the normal reaction, and since both are forces the ratio is a pure number; the same reasoning applies to other ratios such as the refractive index and relative density.

In mitosis each centromere splits in anaphase and one chromatid of every chromosome goes to each pole, so the two daughter cells receive exactly the same number of chromosomes as the parent cell had, and exactly the same genetic information.

The nucellus is the diploid tissue of the ovule itself, while the synergids, the egg and the antipodals are haploid cells of the embryo sac.

When a body rolls, the surfaces in contact change continuously and the irregularities have no time to interlock deeply, so rolling friction is very much smaller than sliding friction; this single fact is the reason the wheel was invented and the reason a ball bearing is fitted wherever a shaft…