General Science Mixed Quiz: Set 207

For an object between F and P, the image forms behind the mirror, not at infinity. When an object is placed between the pole and the principal focus of a concave mirror, the reflected rays spread out and never meet in front of the mirror.

Biogas is mostly methane, with carbon dioxide as the second gas and only small amounts of nitrogen and others. Biogas forms when cattle dung, kitchen waste or crop residue is broken down by anaerobic bacteria, that is, without air, inside a digester.

A step-up transformer raises an alternating voltage, using more turns in its secondary coil than in its primary. A transformer works on electromagnetic induction and only with alternating current.

Fungi have no chlorophyll, so they cannot make their own food by photosynthesis.

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

Birds and mammals are warm-blooded, which means they keep their body temperature nearly constant whatever the temperature outside, and a pigeon is a bird.

The more a colour is slowed by glass, the higher the refractive index for it and the more it bends.

When muscles run short of oxygen, the pyruvate formed from glucose is converted into lactic acid instead of being broken down fully.

The enzyme breaks the β-lactam ring that gives penicillin its power. Penicillin was discovered by Alexander Fleming in 1928 from the mould Penicillium notatum.

Monkeys are primates, and female primates have a menstrual cycle, not an oestrus cycle.

Once a satellite is placed in orbit with the right speed, the Earth's gravity keeps it going round without any engine.

The deficiency of adenosine deaminase destroys the immune system because the enzyme is needed for the normal working of lymphocytes, and in 1990 lymphocytes of a girl with this disorder were grown outside the body, given a functional gene and returned to her blood; since those cells are not permanent…

Ultraviolet rays have the shortest wavelength of the three, visible light comes next and infrared rays have the longest. The electromagnetic spectrum, in order of increasing wavelength, runs from gamma rays and X-rays to ultraviolet, visible light, infrared, microwaves and radio waves.

Jute is a bast or stem fibre taken from the inner bark of plants of the genus Corchorus, extracted by soaking the cut stems in water, a process called retting, and India and Bangladesh are the main producers.

The cochlea of the inner ear changes the pressure variations of sound into electrical (nerve) signals, which the auditory nerve then carries to the brain.

The American physicist Murray Gell-Mann proposed quarks in 1964 and gave them their name. Gell-Mann, and independently George Zweig, suggested that protons, neutrons and other such particles are built from smaller units.

In uniform circular motion the acceleration points towards the centre of the circle, at right angles to the velocity. In uniform circular motion the speed stays the same, but the direction of motion changes at every point, so the velocity keeps changing and the body is accelerating.

Mitosis keeps the chromosome number unchanged, so it never makes cells haploid; that is the work of meiosis. In mitosis one parent cell divides once and gives two daughter cells that are genetically identical to it.

Movement of ions through protein channels is facilitated diffusion, a passive process that needs no energy from ATP. Active transport moves substances against their concentration gradient, from low to high concentration, using carrier proteins and energy, usually from ATP.

Strain is a ratio of two lengths (or two volumes), so its units cancel and it has no dimensions. When a force deforms a body, strain measures the fractional change in its shape or size.