General Science Mixed Quiz: Set 137

Current multiplied by resistance gives voltage, by Ohm's law, not electrical power. Electrical power is the rate at which electrical energy is used, and its basic formula is P = VI, where V is the potential difference and I is the current.

Melanin absorbs the ultraviolet rays of sunlight and shields the DNA of skin cells from damage. Melanin is made by cells called melanocytes in the lower layer of the epidermis.

In this reaction water accepts a proton (H⁺) from the hydrogen sulphate ion and becomes the hydronium ion, H₃O⁺, and a proton acceptor is a base.

The Food Safety and Standards Authority of India is the statutory body that lays down standards for food and regulates its manufacture, storage, sale and import across India.

This follows the order of these metals in the reactivity series, and hydrochloric acid reacts fastest with the metal highest in it.

The spring constant is force divided by extension, so its SI unit is newton per metre. Hooke's law says that, within the elastic limit, the restoring force of a spring is proportional to how far it is stretched or compressed: F = −kx.

In the sodium-calcium exchanger, Na+ ions enter the cell while Ca2+ ions are pushed out, so the two ions cross the membrane in opposite directions.

A perfectly horizontal rope has no upward component of tension, so no finite tension can hold up the 200 N weight with the rope fully straight.

The coronary arteries carry oxygen-rich blood to the muscle of the heart wall itself. The heart pumps blood to the whole body, but its own thick muscle (the myocardium) needs a separate supply.

The queen can lay both fertilised and unfertilised eggs; the unfertilised ones develop into haploid males called drones, a form of parthenogenesis, while fertilised eggs give rise to diploid females.

Cholesterol is a sterol, a kind of lipid (fat-like substance) that does not dissolve in water. Cholesterol is made mainly in the liver and also comes from animal foods such as eggs, meat and butter; plants do not contain it.

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

Dengue is known for lowering the platelet count, which can lead to bleeding in severe cases. Dengue is a viral disease spread by the bite of the Aedes mosquito, mainly Aedes aegypti, which breeds in clean, stagnant water and bites during the day.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

Alfalfa, chickpea and clover are legumes, and legumes fix nitrogen. Plants of the legume family (Fabaceae) carry root nodules that house Rhizobium bacteria.

The stapedius, only about 1 millimetre long, is the smallest skeletal muscle in the human body. It lies in the middle ear and is attached to the stapes, which is itself the smallest bone of the body.

Natural selection needs variation among members of a species; without variation there is nothing for nature to select, so statement A is the incorrect one.

Pure iron melts at about 1,538°C, so 1,500°C is the only option close to its melting point. Iron is a metal with strong metallic bonds, so a great deal of heat is needed to break up its solid structure.

Cane sugar, or sucrose, is made of carbon, hydrogen and oxygen joined chemically in a fixed ratio, so it is a compound.

Neither beta nor gamma emission changes the total number of protons and neutrons in a nucleus, so the mass number stays the same.