General Science Previous Year Questions (PYQ) with Answers – Page 61

The liver needs vitamin K to make several clotting factors, including prothrombin, which help blood form a clot and seal a wound.

The liver needs vitamin K to make prothrombin and other clotting factors, so without it blood takes much longer to clot.

Milk contains very little vitamin C, and what little there is gets destroyed further when milk is boiled. Milk is otherwise called a nearly complete food: it gives calcium and phosphorus for bones and teeth, good-quality protein, mainly casein, the sugar lactose, fat, and vitamins A, B2 and B12.

Luminous intensity is the amount of visible light a source sends out in a given direction per unit solid angle, and its SI base unit is the candela (cd), roughly the light of one ordinary candle.

The torr is a unit of pressure named after Evangelista Torricelli, the Italian scientist who invented the mercury barometer in 1643.

Beriberi is caused by a lack of thiamine, which is vitamin B1. Thiamine helps the body turn carbohydrates into energy and keeps nerves and the heart working, so its shortage weakens muscles and nerves (dry beriberi) or causes swelling and heart failure (wet beriberi).

A person with AB positive blood can receive red cells from every ABO and Rh group, so AB+ is called the universal recipient.

Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.

Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.

It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.

They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.

Hooke's law says stress is directly proportional to strain, and that holds only up to the proportional limit, where the curve is a straight line.

A constellation is a group of stars that appears to form a shape when seen from the earth, but its stars usually lie at very different distances from us.

In an ideal gas the molecules move with a whole range of speeds, so this statement is false. The kinetic theory treats an ideal gas as a large number of tiny molecules in random motion that collide elastically with one another and with the walls.

The peacock is a bird and the camel is a mammal, and these are the only two groups of animals that are warm-blooded.

Nereis, the clamworm, is an annelid, and annelids are bilaterally symmetrical: only one plane divides the body into identical left and right halves.

Agaricus is a mushroom, a fungus that feeds on dead and decaying organic matter, which is the saprophytic mode of nutrition.

Lateral meristems divide along the sides of the stem and root and add new cells that make them thicker. Meristems are groups of cells that keep dividing.

Lysosomes are small membrane-bound sacs filled with digestive enzymes, which is why they are called the storehouse of digestive enzymes.

Proteins are made on ribosomes, and the smooth endoplasmic reticulum has no ribosomes on its surface. The endoplasmic reticulum is a network of membrane tubes and sacs in the cytoplasm.