NDA GK Questions 2026

Photosynthetic bacteria have no chloroplasts; their pigments sit on infoldings of the cell membrane that form vesicles or sacs, often called chromatophores.

Adipose tissue is a loose connective tissue whose cells, called adipocytes, are built to store fat. Each cell holds a large droplet of fat that pushes the nucleus and cytoplasm to one side.

Germanium is a metalloid, an element whose properties lie between those of metals and non-metals. It is a hard, shiny, grey-white solid like a metal, yet it is brittle and conducts electricity far less well than a metal, which makes it a semiconductor.

This statement is wrong because every photon, whatever its energy, travels in vacuum at the same speed of light, about 3 × 10^8 metres per second.

Temporary hardness is caused by the bicarbonates of magnesium and calcium, Mg(HCO3)2 and Ca(HCO3)2. It is called temporary because simple boiling removes it: on heating, the soluble bicarbonates break down into insoluble carbonate or hydroxide, carbon dioxide and water, and the solid settles out.

The gap between an object and its real image is smallest when the object is placed at 2F, twice the focal length from the lens.

These are four of the twelve soil orders in the USDA Soil Taxonomy, the classification also used by Indian soil scientists.

Rutherford's gold foil experiment showed that an atom has a tiny, dense, positively charged centre, which he called the nucleus.

By weight, calcium is the smallest of the four and oxygen the largest, so the ascending order is calcium, aluminium, silicon, oxygen.

A rod standing upright on one end falls over at the slightest push, because its centre of gravity is high and its base is tiny.

Physiological density divides the total population of a region by the area of its cultivable or arable land, so it measures the pressure of all the people on the land that can actually grow food, and it is far higher than ordinary density in countries such as Egypt, where most…

Push factors are the unfavourable conditions of the place a person leaves, such as unemployment, poverty, crop failure, drought, flood, epidemic and political unrest; they push people out.

Natural growth is the increase that comes from the balance of births over deaths alone, so it is births minus deaths in the period, and it is negative when deaths exceed births.

Asia holds roughly three-fifths of all the people in the world, mainly in the two great clusters of East Asia and South Asia, which include the two most populous countries on earth.

The width of each bar in a population pyramid shows the share of that age group, so a broad base means that children form a very large part of the population, which happens where the birth rate is high; the narrow top shows that few people survive to old age.

In the first stage of the demographic transition the society is rural and agrarian, life expectancy is low, medical facilities are poor and literacy is low, so both the birth rate and the death rate are high and they roughly cancel each other, leaving population almost stationary.

Replacement level fertility is the total fertility rate at which a generation of women exactly replaces itself in the next generation.

The United Nations marked 15 November 2022 as the Day of Eight Billion, the date on which the world population was estimated to have reached eight thousand million.

In this essay of 1798 Malthus argued that population tends to increase in a geometric progression while the means of subsistence can increase only in an arithmetic progression, so growth must be restrained either by positive checks such as famine, disease and war, or by preventive checks such as late…

Density of population is a ratio between the number of people and the area they occupy, and the standard unit is the number of persons living in one square kilometre; it is the simplest way of measuring the pressure of people on land.