General Science Previous Year Questions (PYQ) with Answers – Page 9

The pituitary releases FSH and LH, and the ovary responds with estrogen and progesterone; together these hormones run the cycle.

Rearranging Newton's law of gravitation gives G = F r² / (m₁ m₂), so its unit is newton × metre² ÷ kilogram².

The thyroid gland needs iodine to make thyroxine, so iodized salt keeps this hormone in supply. Thyroxine (T4) contains four iodine atoms in each molecule, and the thyroid cannot make it without iodine from food.

Using v² = u² + 2as with u = 12 m/s, v = 0 and s = 45 m gives a = −144 ÷ 90 = −1.6 m/s².

The human brain has three main parts: the fore-brain, the mid-brain and the hind-brain. The hind-brain consists of the pons, the medulla and the cerebellum.

It reverses the facts: the pulmonary arteries carry deoxygenated blood and the pulmonary veins carry oxygenated blood. Arteries and veins are named by the direction of flow, not by the oxygen they carry.

With the same voltage, heat varies inversely as resistance, and the parallel resistance is one-fourth of the series resistance. The two wires are identical, so each has the same resistance R. In series the total resistance is R + R = 2R; in parallel it is R/2.

Tidal volume is the volume of air breathed in or out in one normal, quiet breath, about 500 mL in a healthy adult.

Potential difference is the work done per unit charge, so V = W/Q = 24 J ÷ 2 C = 12 V. The potential difference between two points is the work needed to move one coulomb of charge from one point to the other.

Pepsin works in the strongly acidic stomach, while trypsin works in the mildly alkaline small intestine. Pepsin is secreted by the chief cells of the stomach as inactive pepsinogen, which hydrochloric acid from the parietal cells turns into pepsin.

The blind spot is the place where the optic nerve leaves the eye, and it has no rods or cones, so light falling there is not seen.

For any position of a real object in front of a convex mirror, the image forms behind the mirror between P and F. A convex mirror bulges outward, and its focus and centre of curvature lie behind it.

Pyruvate, the ion of pyruvic acid (CH3COCOOH), is a three-carbon molecule. It is formed at the end of glycolysis, the first stage of respiration, which takes place in the cytoplasm of every living cell.

Isoenzymes, also called isozymes, are different molecular forms of an enzyme that speed up the same chemical reaction but differ in their amino acid sequence.

Lactose, the sugar of milk, is a disaccharide formed when one molecule of glucose joins one molecule of galactose. Disaccharides are sugars made of two simple sugar units, or monosaccharides, linked by a glycosidic bond.

Sponges are the members of phylum Porifera, a name that means "pore bearers", because their bodies are full of tiny pores called ostia.

Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury.

Thyroxine is an animal hormone, made by the thyroid gland in the neck, and it controls the rate of metabolism in the human body.

The endoplasmic reticulum (ER) is a network of membrane tubes and sacs inside the cell. Part of it is studded on the outside with tiny granules called ribosomes, which give it a dotted, rough look under an electron microscope; this part is the rough ER.

A person with myopia sees nearby objects clearly but finds distant objects blurred, which is why the defect is called near-sightedness or short-sightedness.