(b) Microbial fixation
Microbial fixation is the process by which microbes fix nitrogen and carbon dioxide:
Nitrogen fixation: Microbes fix nitrogen by oxidizing organic molecules and requiring 16 moles of adenosine triphosphate (ATP) to reduce each mole of nitrogen. Nitrogen is a macronutrient that is part of proteins and nucleic acids. Microbes that fix nitrogen include Azotobacter, Bacillus, Clostridium, and Klebsiella.
Carbon dioxide fixation: Microbial fixation of carbon dioxide involves metabolic routes, genetic manipulations, and engineering of microbial hosts.

(c) A is true but R is false
Nitrogen is present in soil in the form of nitrates or nitrites, which plants can’t directly absorb. Nitrogen deficiency can cause yellowing and stunted growth. Soils in India are deficient in nitrogen.
Rocks contain varying concentrations of nitrogen, much of it in forms that organisms can use. Nitrogen in rock can come from organically bound nitrogen associated with sediment, or in thermal waters.

(c) Coconut + Black pepper
The major plantation crops are coconut, arecanut, oil palm with or without intercultivation of pineapple, tapioca and pepper. In the coastal and mountain valley rice is grown during monsoon season.

(d) Photosynthesis and carbohydrate metabolism
Magnesium deficiency can affect photosynthesis in plants. Magnesium deficiency can also cause other issues, including: Carbohydrate accumulation, reduced root growth, altered chloroplast ultrastructure, reduced plasmodesmata, and Decreased CO assimilation and transpiration rate.

(c) Both 1 and 2
Researchers have linked hydroxychloroquine — an antimalarial drug that was briefly promoted by former US President Donald Trump and others as a “miracle” medicine for COVID-19 — to an increased mortality rate of up to 11%.
Hydroxychloroquine has been used to treat malaria for several decades. It serves to alleviate pain and inflammation. It is typically ingested for a brief time until the condition is resolved. Hence, statement 1 is correct.
The drug is also used to treat autoimmune disorders, such as lupus. Hence, statement 2 is correct.
Its anti-inflammatory properties have reduced the need for higher doses of other lupus treatments.
Most people do not experience side effects, but it sometimes causes stomach pain, digestive problems, such as nausea or diarrhoea, dryness of skin or damage to the eyes after prolonged use.