General Science Mixed Quiz: Set 126

The oesophagus, like the mouth, is lined by flat squamous epithelium that protects it from wear as food passes. Epithelial tissue covers body surfaces and lines organs, and its cells are named by shape.

The adult human skeleton has 206 bones, of which 80 belong to the axial skeleton, that is the skull, vertebral column and chest, and 126 to the appendicular skeleton of the limbs and girdles.

Fungal cell walls are built mainly of chitin, whereas plant cell walls are built of cellulose. Chitin is a tough polysaccharide made of units of N-acetylglucosamine, a sugar that carries nitrogen.

The 2011 FSSAI labelling rules made the list of ingredients, nutrition information and the vegetarian or non-vegetarian mark compulsory, but not medical advice on allergies.

Sphagnum is a bog moss, a bryophyte, whose dead cells hold many times their own weight of water; in waterlogged and acidic bogs its remains decay only partly and pile up as peat, which is cut, dried and burnt as fuel and is also used in nurseries to keep soil…

Meiosis halves them in the gametes, and fertilisation restores them in the offspring. Each parent makes gametes by meiosis, so a human egg or sperm carries 23 chromosomes instead of 46.

Chlorine released from chlorofluorocarbons destroys ozone fastest where polar stratospheric clouds form in the extreme cold of winter, because those ice clouds hold the chlorine compounds that sunlight then breaks up; the thinning is therefore deepest over Antarctica, where it is called the ozone hole, and is seen over the…

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

The liver weighs about one and a half kilograms and is both the largest gland and the largest internal organ of the body; it secretes bile, stores glycogen, iron and vitamin A, converts ammonia into urea and detoxifies drugs and poisons.

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.

Ultraviolet photons carry more energy than visible light, not less, so this statement is wrong. The energy of a photon is E = hc/λ, so a shorter wavelength means higher energy.

Levers are grouped by where the fulcrum, the load and the effort sit. In a second class lever the load lies between the fulcrum and the effort.

Boiling removes only temporary hardness; permanent hardness comes from salts that do not break down on heating. Temporary hardness is caused by the bicarbonates of calcium and magnesium.

A light year is the distance that light, moving at about three lakh kilometres per second, covers in one year, which works out to roughly 9.46 trillion kilometres.

In water plants, parenchyma cells enclose large air cavities; this special form is called aerenchyma, and it helps the plants float.

A microphone is a transducer: sound waves strike a thin diaphragm, the diaphragm vibrates, and that mechanical vibration is turned into a varying electric signal.

Yeast is a single-celled fungus, placed in kingdom Fungi in Whittaker's five-kingdom system. Yeast cells are eukaryotic, have a cell wall containing chitin and do not make their own food, which are the marks of fungi.

Mosses and liverworts have no xylem or phloem, so water moves through them cell to cell. Bryophytes, such as Funaria (a moss) and Marchantia (a liverwort), are called the amphibians of the plant kingdom because they live on land but need water for fertilisation.

It is called laughing gas because it produces a feeling of elation when inhaled in small quantities, and it is used as a mild anaesthetic in dentistry and minor surgery and as the propellant in whipped cream; it is also a greenhouse gas.

The sino-atrial node is a small patch of specialised muscle tissue in the wall of the right atrium near the opening of the superior vena cava, and it generates the impulse that sets the rate of each heartbeat without any outside stimulus, which is why it is called the pacemaker.