29 April RAS Mains Answer Writing

Ras mains answer writing practice

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Subject – General Science

Topic – Control and Coordination, Reproductive, Excretory, Respiratory, Circulatory and Digestive systems in Human beings

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Click on the question to see the model answer. Submit your answers below and complete the 90-day challenge for RAS Mains answer writing

Q1 What is the role of hemoglobin in transporting gases in the body?


Haemoglobin acts as a carrier molecule for both oxygen and carbon dioxide, facilitating their transport between the lungs and various tissues and organs in the body.

  • Transport of Oxygen: Oxygen binds reversibly to haemoglobin in the blood, forming oxyhemoglobin. It binds to haemoglobin in the lungs and dissociates in the tissues.
  • Transport of Carbon Dioxide: In addition to oxygen, hemoglobin also carries about 20-25% of carbon dioxide as carbaminohemoglobin. Carbon dioxide dissociates from carbaminohemoglobin formed in the tissues and is released in the alveoli.

Q2 What are plant growth regulators? Explain their different types with one example of each.(5M)


 Plant growth regulators (PGRs) are small, simple molecules with diverse chemical compositions that regulate various aspects of plant growth and development. These regulators can be broadly divided into two groups based on their functions within a living plant body.

Q3 Answer the following parts of  the question
a.How does a nephron contribute to the process of urine formation and waste excretion?
b.What are the main functions of the liver?


The nephron is the functional unit of the kidney responsible for filtering blood and forming urine. It consists of a renal corpuscle and a renal tubule 

Urine formation and waste excretion:

  • Filtration : afferent arteriole brings blood into the glomerulus, where filtration occurs, allowing small molecules and ions to pass into the Bowman’s capsule.
  • Reabsorption: Proximal Convoluted Tubule (PCT) reabsorbs most filtered water, ions, and essential nutrients back into the bloodstream. Descending limb of the Loop of Henle allows passive water reabsorption, while the ascending limb actively pumps out sodium and chloride ions.
  • Secretion: Distal Convoluted Tubule (DCT) secretes additional ions such as potassium and hydrogen ions into the tubule lumen, regulating ion balance and pH.
  • Adjustment and Concentration: The collecting duct receives urine from multiple nephrons and adjusts its final composition based on the body’s hydration status and electrolyte balance.

Main functions of the liver:

The liver is the largest gland located in the upper right part of the abdomen, just beneath the diaphragm and above the stomach.Given its crucial role in various physiological processes, the liver is Often described as the body’s chemical factory. 


  • Metabolism: carbohydrate metabolism (glycogenesis, glycogenolysis, gluconeogenesis), lipid metabolism (synthesis and breakdown of fats), and protein metabolism (synthesis of plasma proteins, conversion of ammonia to urea).
  • Detoxification: The liver removes toxins, drugs, and harmful substances from the bloodstream, making them less harmful and easier to excrete.
  • Synthesis: It synthesizes important proteins such as albumin, which helps maintain osmotic pressure in the blood, and clotting factors, which are essential for blood coagulation.
  • Storage: The liver stores vitamins (such as A, D, E, K, and B12), minerals (such as iron and copper), and glycogen, which serves as a readily available source of glucose.
  • Bile production: The liver produces bile, which is necessary for the digestion and absorption of fats in the small intestine.
  • Immune function: contains specialized immune cells called Kupffer cells, which help remove pathogens, bacteria, and foreign particles from the bloodstream.
  • Regulation of Blood Glucose: by balancing the processes of glycogenolysis (breakdown of glycogen into glucose), gluconeogenesis (synthesis of glucose from non-carbohydrate sources), and glycogenesis (storage of excess glucose as glycogen). It responds to hormonal signals, such as insulin and glucagon, to regulate blood sugar levels.
  • Regulation of cholesterol and hormones: The liver regulates cholesterol levels and metabolizes hormones, helping to maintain hormonal balance in the body.
  • Blood filtration: The liver filters and processes blood from the digestive system before it is distributed to the rest of the body.
  • Forms blood in embryo.

Q4 निम्नाकिंत अनुच्छेद का हिन्दी में अनुवाद कीजिएः  [RAS Mains 2021]

A language is something infinitely greater than grammar and philology. It is the poetic testament of the genius of a race and a culture and the living embodiment of the thoughts and fancies that have moulded them. Words change their meaning from age to age and old ideas transform themselves into new, often keeping their attire. It is difficult to capture the meaning; much less the spirit, of an old word or phrase. 


भाषा, व्याकरण और भाषाशास्त्र से असीम रूप से बड़ी चीज़ है। यह एक जाति और संस्कृति की प्रतिभा का काव्यात्मक वसीयतनामा है और उन विचारों और कल्पनाओं का जीवंत अवतार है जिन्होंने उसे बनाया है। शब्द अपने अर्थ को समय के अनुसार बदलते हैं और पुराने विचार स्वयं ही नए में बदल जाते हैं किंतु अक्सर अपना मूल भाव बनाये रखते हैं। एक पुराने शब्द या वाक्यांश के अर्थ को पकड़ना मुश्किल एवं भावना को समझना तो अति मुश्किल है। 

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