RRB Group D GK Questions 2026

A packet station handles short-distance traffic across a narrow stretch of water, carrying passengers, mail and vehicles rather than bulk cargo.

In the age of coal and later of oil, long ocean voyages had to be broken at fixed points where a ship could take on fuel, fresh water and provisions, and settlements at those points grew into ports.

Rotterdam stands on the delta where the Rhine and the Meuse reach the North Sea, which gives it inland waterway access to the industrial heart of Germany, Switzerland and France.

The Australian Trans-Continental Railway runs for about 4,000 km from Perth on the west coast to Sydney on the east, and on its way it crosses the Nullarbor Plain, a flat treeless limestone surface in the south of the continent.

The Northern Atlantic Sea Route links the north-eastern seaboard of North America with the industrial countries of western Europe, and because the two most developed manufacturing regions of the world face each other across this stretch of ocean it carries more traffic than any other sea route.

It crosses the isthmus of Central America, where the land rises well above sea level, so ships cannot simply be floated through.

The Suez Canal was cut across the Isthmus of Suez in Egypt and opened in 1869.

The line begins in European Russia and runs eastward across the whole of Siberia, and Vladivostok is both its terminus and the principal Russian naval and commercial port on the Pacific.

It runs across Russia from St Petersburg and Moscow in the west to Vladivostok on the Pacific coast, a distance of about 9,289 km from Moscow, and no other single railway line in the world is as long.

The southernmost of India's major ports is V. O. Chidambaranar Port, long known as Tuticorin, which lies on the Gulf of Mannar in the Thoothukudi district of Tamil Nadu.

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.

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

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.

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.

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.

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.

Meiosis begins with a single round of DNA replication and is then followed by two successive nuclear divisions. Meiosis I is the reduction division, in which homologous chromosomes separate and the two cells formed already carry half the parental chromosome number.

An animal cell divides its cytoplasm by a cleavage furrow, in which the plasma membrane is pulled inward around the middle until the cell is pinched into two.

Once the chromosomes are aligned on the metaphase plate and every kinetochore is attached to a spindle fibre, the centromere holding the two sister chromatids together splits.

In this stage the condensed chromosomes, each consisting of two sister chromatids, are moved by the spindle fibres until their centromeres lie in one plane across the middle of the cell, known as the metaphase plate or equatorial plate.