RRB NTPC GK Questions 2026

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.

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.

An ion-exchange resin or zeolite swaps the calcium and magnesium ions that cause permanent hardness for sodium or hydrogen ions.

Smooth muscle is a muscular tissue, one of the four basic animal tissues, not a connective tissue. Animal tissues are of four kinds: epithelial, connective, muscular and nervous.

Copper in the +1 state is reduced to metal, so it is the oxidant; sulphur of Cu2S is oxidised, so it is the reductant.

The two hemispheres always have opposite seasons, so one hemisphere's summer solstice is the other's winter solstice. On about 21 June the Sun is overhead at the Tropic of Cancer; the northern hemisphere has its longest day and summer begins there, while the southern hemisphere has its shortest day.

The RER is studded with ribosomes, the actual sites where amino acids are joined into proteins. Ribosomes read the message carried by mRNA and link amino acids in the right order.

A medium more concentrated than the cell is hypertonic, so water leaves the cell by osmosis. In osmosis water moves across a selectively permeable membrane from the side with fewer dissolved particles to the side with more.