Biology Questions and Answers

Answer: C

Both 1 and 2 are correct.

Taeniasis is an intestinal infection with adult tapeworms of three species: Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm) and Taenia asiatica. It is caught by eating undercooked infected meat (1).

When a person swallows the eggs of T. solium, the larvae can form cysts in tissues; cysts in the brain cause neurocysticercosis, a leading cause of acquired epilepsy in India (2). So both statements are true.

Answer: C

The ones that are not tastes are 4 and 7: spicy and pungent.

The tongue's taste receptors detect five basic tastes: sweet, bitter, salty, sour and umami (the savoury taste of glutamate). Spiciness, the burn of chilli, and pungency, the sharpness of mustard or garlic, are not tastes; they are sensations of heat and irritation carried by pain and touch nerves.

Every other option includes at least one of the five true tastes, such as bitter, umami, sweet or salty.

Answer: C

The correct pairs are Only 3 and 4.

Dyspnoea is shortness of breath or difficulty in breathing (3), and anosmia is partial or complete loss of the sense of smell (4), a symptom widely reported with COVID-19.

The first two pairs are swapped. Anorexia (anorexia nervosa) is an eating disorder marked by self-starvation, and insomnia is a sleep disorder, difficulty in falling or staying asleep. So options including 1 or 2 are wrong.

Answer: A

The answer is by introducing a harmless piece of SARS-CoV-2 virus.

Most COVID-19 vaccines present the immune system with a harmless part of the virus, usually the spike protein or the genetic instructions for making it (as in mRNA and viral-vector vaccines). The body makes antibodies and T cells against it, and is then ready if the real virus enters.

No COVID vaccine introduces a real, live virus that can cause disease, and live attenuated vaccines were not the approach used. Introducing ready-made antibodies is passive immunisation, as in monoclonal antibody therapy, not vaccination.

Answer: A

The double helix was discovered by James Watson and Francis Crick.

Watson and Crick proposed the double-helix model of DNA in Nature in April 1953, and shared the 1962 Nobel Prize in Physiology or Medicine with Maurice Wilkins. Their model relied on X-ray diffraction images of DNA, notably Photo 51, made in Rosalind Franklin's work at King's College London.

Franklin and Wilkins supplied crucial evidence but did not propose the structure. Linus Pauling proposed an incorrect triple-helix model, and Gregor Mendel founded genetics in the 1860s, long before DNA's structure was studied.

Answer: C

Vector vaccines work by placing the virus in a modified version of a different virus.

A viral vector vaccine uses a harmless virus, such as a modified chimpanzee adenovirus in Covishield (Oxford-AstraZeneca), as a carrier. A gene from the target virus, for COVID-19 the gene for the spike protein, is placed in the vector, which delivers it to human cells; the cells make the protein and the immune system learns to recognise it.

Introducing a weakened or inactivated virus describes attenuated and inactivated vaccines. Vaccines do not attack pathogens directly; the immune system does. Entering cells to make spike proteins describes the effect of mRNA vaccines rather than the defining mechanism of a vector vaccine.

Answer: A

mRNA stands for Messenger Ribonucleic Acid.

Messenger RNA carries the genetic instructions from DNA in the nucleus to the ribosomes, where they are translated into proteins. mRNA vaccines against COVID-19, such as those of Pfizer-BioNTech and Moderna, deliver mRNA that tells cells to make the virus's spike protein, prompting an immune response.

'Mutant', 'Modified' and 'Mnemonic' ribonucleic acid are not what the 'm' stands for; the molecule is named for its role as a messenger.

Answer: B

Input and output nerves meet at the central nervous system.

Sensory (input, afferent) nerves carry signals from receptors to the brain and spinal cord, and motor (output, efferent) nerves carry commands from them to muscles and glands. The brain and spinal cord, the central nervous system, are where these meet and where information is processed, as in a reflex arc through the spinal cord.

The liver and heart are organs that receive nerves but do not process nervous signals.

Answer: C

The macronutrient is protein.

Macronutrients are nutrients the body needs in large amounts: carbohydrates, proteins and fats, which supply energy and build tissue.

Zinc and iron are minerals and vitamin D is a vitamin; all three are micronutrients, needed in only small quantities.

Micronutrient deficiencies still matter greatly, as with iron-deficiency anaemia, but the amounts needed are measured in milligrams or micrograms, not grams.

Answer: D

The acid in gastric juice is hydrochloric acid.

The parietal (oxyntic) cells of the stomach lining secrete hydrochloric acid. It makes the stomach strongly acidic, kills many microbes and activates pepsinogen into pepsin, which begins protein digestion.

Acetic acid is the acid of vinegar, ascorbic acid is vitamin C, and citric acid is found in citrus fruits; none is secreted by the stomach.