Consider the following statements : 1. Some mushrooms have medicinal properties. 2. Some mushrooms have psycho-active properties. 3. Some mushrooms have insecticidal properties. 4. Some mushrooms have bioluminescent properties. How many of the above statements are correct?

The correct answer is C, All three. All three statements are correct; microbes called extremophiles live in all these conditions.

Hyperthermophiles, many of them archaea living near deep-sea hydrothermal vents, grow above 100 °C; Methanopyrus kandleri and 'Strain 121' grow at about 120 °C, where high pressure keeps water liquid. Psychrophiles grow below 0 °C in polar ice, permafrost and cold seas, using enzymes that work in the cold and natural antifreeze compounds. Acidophiles thrive at very low pH: Picrophilus can grow near pH 0, and bacteria such as Acidithiobacillus live in acid mine drainage below pH 3. Thermus aquaticus from hot springs gave the Taq polymerase used in PCR.

A is wrong: more than one statement is true.

B is wrong: all three, not just two, are true.

D is wrong: every statement describes a real group of microbes.

Exam tip: thermophile = heat; psychrophile = cold; acidophile = acid; halophile = salt; Taq polymerase comes from Thermus aquaticus.

The correct answer is C, genital herpes. It is caused by a virus that stays latent in the nerve cells for life, so the attacks can be controlled with medicines but the infection cannot be completely cured; hepatitis B and HIV infection fall in the same group. A is wrong because gonorrhoea is a bacterial infection that can be cured with the right antibiotic if it is detected early. B is wrong because syphilis is also bacterial and curable, and untreated cases are dangerous only because the disease is left to advance. D is wrong because chlamydiasis, caused by a bacterium, is curable as well, like trichomoniasis. The lesson examiners want is that early detection matters, and that the viral infections among the sexually transmitted diseases are the ones that stay for life.

The correct answer is A. Colostrum is the thin yellowish milk secreted in the first days after delivery and is rich in antibodies, especially immunoglobulin A, which pass to the baby and protect it from infection at a stage when its own immune system is immature; this protection is called passive immunity. B is wrong because colostrum is not notable for iron, and infants draw mainly on the iron stored before birth. C is wrong because vitamin D is formed in the skin in sunlight and is often given as a supplement; it is not what makes colostrum valuable. D is wrong because colostrum is in fact low in fat and small in quantity, yet rich in protein and protective factors, which is why it should not be discarded as many traditions wrongly advise.

The correct answer is D, 2021. The amendment of 2021 kept termination up to twenty weeks on the opinion of one registered medical practitioner, allowed it between twenty and twenty-four weeks for certain categories of women such as survivors of rape or incest on the opinion of two practitioners, and removed the upper limit where a Medical Board diagnoses substantial foetal abnormality. A is wrong because 1994 is the year of the Pre-natal Diagnostic Techniques Act, which bans sex determination. B is wrong because 2003 is when the rules under that Act were tightened and it became the PCPNDT Act. C is wrong because no amendment of the MTP Act was made in 2017, although courts were deciding individual cases beyond twenty weeks around then. The original Act itself dates from 1971.

The correct answer is A, the Central Drug Research Institute, Lucknow. Saheli contains centchroman and is a non-steroidal pill taken once a week after an initial daily course, which makes it different from the combined hormonal pills that have to be taken daily and carry hormonal side effects. B is wrong because the All India Institute of Medical Sciences is a teaching hospital and research centre but is not credited with this drug. C is wrong because the Indian Institute of Science works mainly in the physical, engineering and basic biological sciences. D is wrong because the National Institute of Nutrition works on diet, nutrient requirements and food safety. The Central Drug Research Institute is a laboratory of the Council of Scientific and Industrial Research, which is why the question also appears in general science.