General Science · Practice test 3

Correct answer: Oxygen

Photosynthesis takes in carbon dioxide and water and, using light, produces sugar and oxygen. Respiration runs the other way, consuming oxygen and giving off carbon dioxide.

Go to the question and method

Correct answer: The medulla

The medulla, at the base of the brainstem, controls involuntary processes like heartbeat and breathing rate without any conscious effort. The cerebrum handles thought and voluntary movement.

Go to the question and method

Correct answer: a herbivore

Herbivores eat plants, carnivores eat animals, and omnivores eat both. Decomposers feed on dead material rather than living organisms.

Go to the question and method

Correct answer: oesophagus

The oesophagus is the muscular tube connecting the throat to the stomach; rhythmic contractions called peristalsis push food along it. The trachea is a separate tube that carries air, not food.

Go to the question and method

Correct answer: amperes

Current, the flow of electric charge, is measured in amperes. Volts measure electrical pressure and ohms measure resistance to that flow.

Go to the question and method

Correct answer: difficulty seeing in dim light

Vitamin A is needed to make the light-sensitive pigment in the eye's rod cells, so a deficiency first shows up as trouble seeing in low light, known as night blindness.

Go to the question and method

Correct answer: 46

Human cells carry 46 chromosomes arranged in 23 pairs, one member of each pair inherited from each parent. Sex cells carry only 23, the unpaired half.

Go to the question and method

Correct answer: ureters

Each kidney connects to the bladder by a ureter, which carries newly formed urine down for storage. The urethra is the separate tube that later carries urine out of the body.

Go to the question and method

Correct answer: commensalism

In commensalism only one side gains, as when a bird nests in a tree. Mutualism benefits both, and parasitism benefits one at the other's expense.

Go to the question and method

Correct answer: transpiration

Water drawn up by the roots escapes as vapour through pores in the leaves, a process called transpiration. It is the plant's contribution to the water cycle and is what pulls water upward through the stem.

Go to the question and method

Correct answer: elastic potential energy

Stretching or compressing a spring stores energy in its deformation, ready to be released. Kinetic energy is the energy of motion, which the spring only has once it is moving.

Go to the question and method

Correct answer: keep material moving through the digestive tract

Fibre is a carbohydrate the body cannot digest, so it passes through adding bulk and keeping the gut moving. Because it is not absorbed, it supplies almost no energy.

Go to the question and method

Correct answer: sublimation

Sublimation skips the liquid stage entirely, as dry ice does when it turns straight into carbon dioxide gas. Evaporation is liquid to gas, and condensation is gas to liquid.

Go to the question and method

Correct answer: igneous

Igneous rock crystallises from molten material, as granite and basalt do. Sedimentary rock forms from settled particles and metamorphic rock from existing rock reshaped by heat and pressure.

Go to the question and method

Correct answer: evaporation

Evaporation is the change from liquid to gas, which can happen at any temperature below boiling as faster-moving molecules escape the surface. Condensation is the reverse change, gas back to liquid.

Go to the question and method

Correct answer: conduction

Conduction moves heat through direct contact, particle to particle within a solid. Convection carries heat in a moving fluid and radiation crosses empty space, as sunlight does.

Go to the question and method

Correct answer: Cell wall

A rigid cell wall of cellulose surrounds the plant cell outside its membrane and gives the plant its structure. Chloroplasts and a large central vacuole are also plant-only; the other three choices appear in both.

Go to the question and method

Correct answer: provide a baseline for comparison

The control group is treated identically except for the one variable being tested, so any difference in outcome can be traced to that variable. Without it there is nothing to compare the result against.

Go to the question and method

Correct answer: an enlarged thyroid gland, or goitre

Iodine is required to make thyroid hormone; without enough, the thyroid gland swells as it works harder to compensate, producing a goitre.

Go to the question and method

Correct answer: an omnivore

Omnivores, such as bears and humans, eat a mixed diet of plant and animal material, unlike carnivores, which eat only animals, or herbivores, which eat only plants.

Go to the question and method

Correct answer: Mercury

The order outward is Mercury, Venus, Earth, Mars. Venus is the hottest planet despite being second, because of its thick carbon dioxide atmosphere.

Go to the question and method

Correct answer: mutation

A mutation alters the genetic code. Most have no visible effect, some are harmful, and a few are beneficial, which is what supplies the variation natural selection acts on.

Go to the question and method

Correct answer: pituitary gland

The pituitary gland, at the base of the brain, releases hormones that regulate growth and control other endocrine glands such as the thyroid and adrenal glands.

Go to the question and method

Correct answer: a compound

In a compound the elements are joined chemically and the result has new properties, so it takes a reaction to separate them. In a mixture the parts keep their own properties and can be separated physically.

Go to the question and method

Correct answer: liquid volume

A graduated cylinder has marked lines along its side for reading off the volume of a liquid poured into it, offering a more precise reading than most beakers.

Go to the question and method