General Science Mixed Quiz: Set 163

On a banked road the normal reaction is tilted, its vertical component balances the weight and its horizontal component supplies the centripetal force; dividing one equation by the other leaves the tangent of the banking angle equal to the square of the speed divided by the radius multiplied by the…

Mycology is the study of fungi, the group that includes moulds, yeasts, mushrooms and the rusts and smuts that attack crops, and a specialist in it is called a mycologist.

By this sub-stage the homologous chromosomes have already paired in zygotene and are held together as bivalents or tetrads, each made of four chromatids.

Heavy water, in which the hydrogen of ordinary water is replaced by deuterium, slows the fast neutrons released in fission to low speeds at which they are far more likely to split further uranium nuclei, and it absorbs very few neutrons in doing so, which is why Indian pressurised heavy…

A shaft turning directly inside a sleeve slides against it, and sliding friction is large; placing hard steel balls between the shaft and its housing makes the surfaces roll over one another instead, and rolling friction is a small fraction of sliding friction, so less energy is wasted and the…

The base of a transistor is made very thin and only lightly doped so that most of the carriers injected by the emitter pass straight through it to the collector instead of recombining in it.

In the zygotene sub-stage of prophase I the two members of each pair of homologous chromosomes come to lie side by side along their whole length, matching point for point, and the structure that forms between them and holds them together is called the synaptonemal complex.

Galena is lead sulphide, with the formula PbS, and is the principal ore from which lead is extracted; being a sulphide, it is concentrated by froth flotation and then roasted to the oxide before reduction.

To move along a curve a body needs a force directed towards the centre of that curve.

Arthropoda is the largest phylum of the animal kingdom, holding more described species than all the others together, because it contains the insects along with the crustaceans, spiders, scorpions and centipedes; its members have a chitinous exoskeleton and jointed legs.

This single difference is the reason meiosis I is called the reduction division. In anaphase I the two homologous chromosomes of each bivalent are pulled to opposite poles, but each of them still consists of two sister chromatids joined at an undivided centromere.

All of them are attached behind to the thoracic vertebrae. In front, the first seven pairs join the sternum directly and are called true or vertebrosternal ribs; the next three pairs join the seventh rib through cartilage and are called false or vertebrochondral ribs; and the last two pairs have…

In uniform circular motion the magnitude of the velocity does not change, so the acceleration can have no component along the direction of motion; the whole of it is perpendicular to the velocity and points to the centre, which is why it is called centripetal, meaning centre seeking, and its…

It is secreted by the trophoblast of the implanted blastocyst and then by the placenta, appears in the blood and urine within a few weeks of conception, and is unique to pregnancy, so test kits use antibodies against it.

Interphase occupies more than ninety-five per cent of the duration of the cell cycle, because in it the cell must grow to a sufficient size, synthesise proteins and RNA, duplicate its entire DNA and prepare the structures needed for division.

Landsteiner and Wiener found the antigen in 1940 while working with the blood of the rhesus monkey, and the first two letters of rhesus gave the factor its name; a person with the D antigen on the red cells is Rh positive and one without it is Rh negative.

In uniform circular motion the speed stays the same but the direction keeps turning, and that change needs an acceleration pointing to the centre.

His detailed drawings of the stages are the basis of the account still given in textbooks.

If gametes carried the full chromosome number, fertilisation would double it in every generation. Meiosis halves the number when gametes are formed, so that the union of two gametes restores the original diploid number and keeps it constant from one generation to the next.

The primary spermatocyte is the diploid cell that enters meiosis I and splits into two haploid secondary spermatocytes. Spermatogenesis takes place in the seminiferous tubules of the testes.