NDA GK Questions 2026

Bony fishes of the class Osteichthyes fill or empty a gas-filled air bladder and so hover at any depth without effort.

These are fine blind tubules that float in the body fluid of an insect and open into the gut, where they take up nitrogenous waste and pass it out as nearly dry uric acid, so that very little water is lost.

It belongs to the phylum Mollusca and the class Cephalopoda, so it is a relative of the squid and the cuttlefish rather than of any fish, and the common name devil fish came from its appearance and its eight arms with suckers.

Each cnidoblast holds a capsule called a nematocyst with a coiled thread that shoots out and injects a toxin when touched, and it is found in Hydra, the sea anemone, the jellyfish and the corals.

In sponges the cells are arranged loosely and work with a good deal of independence, with collar cells driving water through a canal system and other cells digesting the food particles, so the body never rises to the level of a true tissue.

Flame cells, also called solenocytes, are specialised cells with a tuft of beating cilia that drives waste fluid into a system of tubules, and they handle both the removal of nitrogenous waste and the balance of water in animals such as Planaria, Taenia and Fasciola.

Starfishes, sea urchins, sea cucumbers, brittle stars and sea lilies are found only in the sea, and their water vascular system, which works by taking in sea water, is one reason they never colonised fresh water or land.

More than three-fourths of all described animal species are arthropods, that is insects, spiders, scorpions, centipedes, crabs and prawns. A hard chitinous exoskeleton, jointed appendages, small body size and, in insects, the power of flight allowed the group to spread into almost every habitat on earth.

A large central vacuole filled with sap presses the cytoplasm against the cell wall, keeping the cell firm, or turgid.

Annelids such as the earthworm, leech and Nereis are the first coelomates in the usual sequence: their body cavity is lined on all sides by mesoderm.

No pathway of respiration in living cells turns glucose into methanol. Glucose is first split in the cytoplasm into two molecules of pyruvate; this step, glycolysis, is common to all cells.

Of the four options, oxygen is by far the most plentiful element; it makes up about 46% of the Earth's crust by mass.

The melting point is the minimum temperature at which a solid melts to become a liquid at atmospheric pressure, not the maximum.

For small swings the time period is T = 2π√(L/g), which contains the length and gravity but neither the mass nor the amplitude.

Apical meristem sits at the growing tips of stems and roots, and its dividing cells make them longer. Meristems are groups of cells that keep dividing throughout a plant's life.

Polyaromatic hydrocarbons are soot-related pollutants from incomplete burning; they are not among the gases that make up photochemical smog. Photochemical smog forms on warm, sunny days in cities with heavy traffic.

HIV spreads through body fluids such as blood, semen, vaginal fluid and breast milk, not through droplets from coughing, sneezing or talking.

The operations fall in 1965, 1971, 1984 and 1999, in that order: Riddle, Cactus Lily, Meghdoot, Safed Sagar. Operation Riddle was the Indian Army's thrust towards Lahore in September 1965, during the second India–Pakistan war.

Moving a substance from low to high concentration is uphill work, and the cell pays for it with ATP.

Ribosomes stuck on the outer surface of the endoplasmic reticulum give it a grainy, rough look under the electron microscope.