BCHET 149 key facts at a glance
- Course code: BCHET 149
- Course title: Molecules of Life
- Programme: Bachelor of Science (General), BSCG
- Course type: Discipline Specific Elective in Chemistry
- Credits: 4 (the BCHEL 150 lab carries 2 more)
- Blocks and units: 5 blocks, 17 units
- Maximum marks: 50
- Duration: 2 hours
- Questions in the paper: 8 questions (18 answer parts), answer any five
- Samples on this page: 2 (Q2(b) and Q8(a)); all 18 parts in the full file
- Assignment weightage: 30 per cent (TMA)
BCHET 149 Solved Question Paper for June 2026 gives you complete, exam-length answers to all 8 questions (18 answer parts) of the IGNOU Molecules of Life paper. Two answers are open on this page so you can check the quality first. The other 16 sit in the full file, which you get by messaging us on WhatsApp 9899436384.
1. What the June 2026 Paper Covers
BCHET 149 Molecules of Life is a 4-credit chemistry Discipline Specific Elective in the IGNOU Bachelor of Science (General), or BSCG, that studies the biomolecules cells are built from and the energy that runs them.
The June 2026 paper moved across all five blocks. It opened with waxes and lipid functions, went into bioenergetics through the first law of thermodynamics and ATP, then asked short notes on tRNA, paper chromatography and sugars. Cell biology returned through peroxisomes, catalase and the cytoskeleton.
The last three questions covered DNA replication, three-letter amino acid symbols, how enzymes lower activation energy, polysaccharide classification, haemoglobin and allosteric regulation. With choices that wide, picking your five questions well matters as much as writing them well.
Our file answers each of the 18 parts at the length its marks deserve, with the reactions, values and named examples a chemistry examiner looks for.
2. Two Answers Solved in Full, Sixteen Held Back
Two answers from the June 2026 paper are printed in full below, Q2(b) on ATP and Q8(a) on haemoglobin, while the remaining 16 parts appear only as question text.
We chose one topic IGNOU has asked again and again and one that was new this session. Both answers were written by our team, as the question paper itself carries no answers.
ATP as the energy currency of living cells
Question: Why is ATP considered the energy currency of living cells? Explain.
Adenosine triphosphate (ATP) is a nucleotide made of the base adenine, the sugar ribose and a chain of three phosphate groups, labelled α, β and γ. The links between α and β and between β and γ are phosphoanhydride bonds, and breaking the terminal one releases a large amount of free energy:
ATP + H2O → ADP + Pi ΔG°′ = −30.5 kJ mol−1 (about −7.3 kcal mol−1)
Why this hydrolysis gives out so much energy
- Charge repulsion: at pH 7 ATP carries about four negative charges packed close together. Removing one phosphate relieves this electrostatic strain.
- Resonance stabilisation: released inorganic phosphate has more resonance forms than the same group held inside ATP, so the products are more stable.
- Better hydration: ADP and Pi are surrounded by water molecules more easily than ATP is.
Why ATP works like a currency
- Common intermediate: ATP sits midway on the phosphoryl transfer scale. Phosphoenolpyruvate (−61.9 kJ mol−1), 1,3-bisphosphoglycerate (−49.3) and creatine phosphate (−43.0) can hand a phosphate to ADP, while ATP can phosphorylate low-energy acceptors such as glucose, whose product glucose 6-phosphate releases only −13.8 kJ mol−1. Energy is earned in one reaction and spent in another, just like money.
- Energy coupling: glucose + Pi → glucose 6-phosphate has ΔG°′ = +13.8 kJ mol−1 and will not go forward alone. Coupled with ATP hydrolysis by hexokinase, the overall change becomes −16.7 kJ mol−1, so the reaction proceeds.
- Earned through several routes: substrate-level phosphorylation in glycolysis and the TCA cycle, oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts all make ATP from ADP.
- Spent on every kind of work: mechanical work in muscle contraction through myosin ATPase, transport work such as the Na+/K+ ATPase moving 3 Na+ out and 2 K+ in, and chemical work in making proteins, nucleic acids and lipids.
- Rapid turnover, not storage: a cell keeps only a small ATP pool and recycles it constantly through the ATP and ADP cycle. A resting adult turns over roughly his or her own body weight of ATP in a day.
Conclusion: ATP links energy-releasing catabolic reactions with energy-using anabolic ones, is made and used in every cell, and delivers energy in usable, moderate packets. That is why it is called the energy currency of living cells.
Structure and function of haemoglobin
Question: Describe in brief the structure and function of haemoglobin.
Haemoglobin (Hb) is the oxygen-carrying protein of red blood cells. It is a conjugated protein made of globin (protein part) and haem (non-protein prosthetic group), with a molecular mass of about 64,500 Da.
Structure
- Quaternary structure: Hb is a tetramer of four polypeptide chains. Adult haemoglobin (HbA) is α2β2. Each α chain has 141 amino acids and each β chain has 146, folded mainly into α-helices (the globin fold, helices A to H).
- Haem group: each chain carries one haem, a protoporphyrin IX ring with a ferrous ion (Fe2+) held by four pyrrole nitrogens. So one Hb molecule binds four O2 molecules.
- Iron coordination: the fifth bond of iron goes to the proximal histidine (F8). Oxygen binds at the sixth position, where the distal histidine (E7) stabilises it. Oxidised iron (Fe3+) gives methaemoglobin, which cannot carry oxygen.
- T and R states: deoxy-Hb is in the tense (T) state, held by salt bridges between subunits. Oxygen binding pulls iron into the plane of the ring, shifts helix F, breaks salt bridges and moves Hb to the relaxed (R) state with higher affinity.
Functions
- Oxygen transport: Hb loads O2 in the lungs and releases it in tissues. Binding is cooperative, so the oxygen dissociation curve is sigmoidal, with a P50 of about 26 mm Hg.
- Bohr effect: higher H+ and CO2 in active tissues lower oxygen affinity, so more O2 is released where it is needed.
- Regulation by 2,3-bisphosphoglycerate: 2,3-BPG binds the central cavity between the β chains of deoxy-Hb and lowers affinity, which helps at high altitude. Foetal Hb (α2γ2) binds 2,3-BPG weakly, so it takes O2 from maternal blood.
- CO2 transport and buffering: Hb carries part of the CO2 as carbamino-haemoglobin and buffers H+ through its histidine residues.
Clinical link: in sickle cell anaemia a single change, glutamate to valine at position 6 of the β chain, makes deoxy-Hb polymerise. Carbon monoxide binds haem more than 200 times more strongly than oxygen, which is why it is poisonous.
3. Questions Answered Only in the Full File
These 16 parts are listed exactly as printed in the June 2026 paper. Their answers are in the full file only.
- Q1 (a) Fill in the blanks. (i) The enzyme … unwinds the DNA by breaking the hydrogen bonds between the nitrogenous base pairs. (ii) In vertebrates, waxes are secreted by … glands. (iii) The … fatty acids are found in fried foods. (iv) Waxes are … of long chain saturated and unsaturated fatty acid chains. (v) Waxes are formed when a fatty acid undergoes … with a monohydric alcohol.
- Q1 (b) Describe the important functions of lipids in the human body.
- Q2 (a) Explain the first law of thermodynamics. How does it relate to the energy changes in a system?
- Q3 (i) Briefly explain with a suitable example: Glucogenesis.
- Q3 (ii) Briefly explain with a suitable example: Transfer RNA (tRNA).
- Q3 (iii) Briefly explain with a suitable example: Paper chromatography.
- Q3 (iv) Briefly explain with a suitable example: Reducing and non-reducing sugars.
- Q4 (a) Describe the three stages of the metabolic breakdown of carbohydrates, fats and proteins.
- Q4 (b) What is the role of phosphofructokinase (PFK) in regulating glycolysis? How does its activity influence the overall rate of glycolysis?
- Q5 (a) What is the role of peroxisomes in cells? How does catalase help protect the cell from hydrogen peroxide?
- Q5 (b) What is the cytoskeleton? How do microfilaments, microtubules and intermediate filaments help the cell maintain its shape and movement?
- Q6 (a) Describe briefly the process of DNA replication.
- Q6 (b) Write the three-letter symbol representation of the following amino acids: (i) Valine (ii) Leucine (iii) Tyrosine (iv) Isoleucine (v) Alanine.
- Q7 (a) Explain how enzymes lower the activation energy of a reaction.
- Q7 (b) How is the classification of polysaccharides related to their composition and function?
- Q8 (b) Describe briefly about allosteric regulation.
4. Molecules of Life Block and Unit Map
BCHET 149 is taught through 5 blocks and 17 units, running from cell structure and carbohydrates in Block 1 to bioenergetics and metabolism in Block 5.
The unit titles below follow the course listing on eGyanKosh, the official IGNOU study material repository. The topics column names what each unit teaches and what IGNOU has actually drawn from it in past papers.
| Block | Unit | Key topics |
|---|---|---|
| Block 1: Cell Structure and Carbohydrates | Unit 1: Cell Structure and Function | Prokaryotic and eukaryotic cells, fluid mosaic model, mitochondria, Golgi bodies and lysosomes |
| Block 1: Cell Structure and Carbohydrates | Unit 2: Carbohydrates: Monosaccharides | Aldoses and ketoses, D and L configuration, anomers and mutarotation |
| Block 1: Cell Structure and Carbohydrates | Unit 3: Carbohydrates: Disaccharides and Polysaccharides | Maltose, lactose and sucrose, reducing versus non-reducing sugars, starch, glycogen and cellulose |
| Block 2: Amino Acids, Peptides and Proteins | Unit 4: Amino Acids | Classification by R group, zwitterion and isoelectric point, stereochemistry of amino acids |
| Block 2: Amino Acids, Peptides and Proteins | Unit 5: Peptides | Formation and geometry of the peptide bond, methods of amino acid sequencing |
| Block 2: Amino Acids, Peptides and Proteins | Unit 6: Proteins | Primary to quaternary structure, classification by biological function, fibrous and globular proteins |
| Block 3: Enzymes | Unit 7: Enzymes: Nature and Classification | Systematic and trivial names, apoenzyme, coenzyme and holoenzyme, induced fit |
| Block 3: Enzymes | Unit 8: Enzymes: Activation and Inhibition | Effect of pH and temperature, competitive inhibition, isoenzymes |
| Block 3: Enzymes | Unit 9: Enzymes: Drug and Action | Drug receptor theory, structure activity relationship (SAR), enzymes as drug targets |
| Block 4: Lipids and Nucleic Acids | Unit 10: Lipids I | Fatty acids and essential fatty acids, fats, oils and waxes, saponification and rancidity |
| Block 4: Lipids and Nucleic Acids | Unit 11: Lipids II | Phospholipids, lipoproteins, eicosanoids such as prostaglandins |
| Block 4: Lipids and Nucleic Acids | Unit 12: Nucleic Acids | Nucleosides and nucleotides, DNA double helix and its stabilising forces, types of RNA |
| Block 4: Lipids and Nucleic Acids | Unit 13: Replication and Transcription | Role of DNA polymerase, replication compared with transcription |
| Block 5: Bioenergetics and Metabolism | Unit 14: Bioenergetics | Laws of thermodynamics and free energy, ATP and other high-energy phosphates |
| Block 5: Bioenergetics and Metabolism | Unit 15: Carbohydrate Metabolism | Reactions of glycolysis, alcoholic and lactic fermentation, gluconeogenesis |
| Block 5: Bioenergetics and Metabolism | Unit 16: Kreb's Cycle and its Metabolic Role | TCA cycle reactions, its amphibolic nature, electron transport chain |
| Block 5: Bioenergetics and Metabolism | Unit 17: Metabolism of Lipids and Proteins | Fatty acid activation to acyl-CoA, ketone bodies, urea cycle |
If you have not opened the books yet, start with our BCHET 149 Study Material and read Blocks 1 and 5 first. In June 2026 they fed Q2, Q4 and Q5 between them, which is three of the five questions you need.
5. Paper Pattern and Marks Split in June 2026
The June 2026 paper had 8 questions of 10 marks each, and you had to answer any five in 2 hours for a maximum of 50 marks.
The BCHET 149 Question Paper for June 2026 runs to 10 printed pages, English first and Hindi after. There is no compulsory question and no section split, so the whole choice is yours.
| Question | Format | Marks split | Topic area |
|---|---|---|---|
| Q1 | Five one-mark blanks plus one descriptive part | 5 × 1 + 5 | Waxes, trans fats, helicase, lipid functions |
| Q2 | Two descriptive parts | 5 + 5 | First law of thermodynamics and ATP |
| Q3 | Four short explanations with examples | 2.5 × 4 | Glucogenesis, tRNA, paper chromatography, sugars |
| Q4 | Two descriptive parts | 5 + 5 | Stages of catabolism and PFK control |
| Q5 | Two descriptive parts on cell biology | 5 + 5 | Peroxisomes, catalase and the cytoskeleton |
| Q6 | One descriptive part plus five symbols | 5 + 5 × 1 | DNA replication and amino acid codes |
| Q7 | Two descriptive parts | 5 + 5 | Enzyme catalysis and polysaccharide classes |
| Q8 | Two descriptive parts on proteins | 5 + 5 | Haemoglobin and allosteric regulation |
The instructions have changed slightly over time. Papers up to December 2023 said only to answer any five questions, while June 2024 onwards add that all questions carry equal marks. June 2025 even set a single 10-mark question on prokaryotic and eukaryotic cells, so do not assume every question splits in two.
If you are sitting more than one chemistry elective this term, our BSCG Question Paper pages follow the same question-by-question layout, so you can plan all your papers in one sitting.
6. Topics That Keep Returning in BCHET 149
Six topics were each asked in 4 of the 6 official BCHET 149 papers we checked, and five of them came back in June 2026.
We counted from six official IGNOU papers: June 2022, December 2022, June 2023, December 2023, June 2024 and June 2025. December 2024 and December 2025 are not in the count because we could not open those two papers from the IGNOU site, so read every count as out of six.
| Topic | Sessions asked | Count (of 6) | In June 2026 |
|---|---|---|---|
| ATP and biological energy transfer | June 2022, June 2023, December 2023, June 2024 | 4 | Q2(b), Sample 1 above |
| Carbohydrate and polysaccharide classification | June 2022, June 2023, December 2023, June 2024 | 4 | Q7(b) |
| Cell organelles (mitochondria, Golgi bodies, lysosomes) | December 2022, June 2023, June 2024, June 2025 | 4 | Q5(a), now peroxisomes |
| Amino acid structure, zwitterions and stereochemistry | June 2022, June 2023, June 2024, June 2025 | 4 | Q6(b), three-letter symbols |
| Types of RNA and their role in protein synthesis | December 2022, June 2023, December 2023, June 2024 | 4 | Q3(ii), tRNA note |
| Membrane structure and fluid mosaic model | June 2022, June 2023, June 2024, June 2025 | 4 | Not asked in June 2026 |
| How enzymes catalyse reactions | June 2022, December 2022, June 2023 | 3 | Q7(a) |
| Reactions of glycolysis | June 2022, June 2023, December 2023 | 3 | Q4(b), regulation by PFK |
| Reducing and non-reducing sugars | December 2022, December 2023, June 2025 | 3 | Q3(iv) |
| Gluconeogenesis | December 2022, June 2023, June 2025 | 3 | Q3(i) is the closest match |
| Link between carbohydrate, fat and protein metabolism | December 2022, June 2024 | 2 | Q4(a) |
| Functions of lipids | June 2022, June 2023 | 2 | Q1(b) |
| DNA replication | June 2022, December 2023 | 2 | Q6(a) |
| Fats, oils and waxes | June 2024 | 1 | Q1(a) |
| First law, cytoskeleton, PFK, paper chromatography, haemoglobin, allosteric control | Not in any of the six papers | 0 | New in June 2026 (haemoglobin is Sample 2 above) |
Two patterns stand out. The fluid mosaic model was asked four times and then skipped in June 2026, which makes it a strong bet for December 2026. And several June 2026 topics, including haemoglobin and allosteric regulation, had never appeared before, so a paper built only on old questions would have missed them.
For shortlists across other IGNOU science electives, our IGNOU Important Questions page groups the topics that return most often, course by course.
7. How the Answers Were Written and Checked
Every answer was written by our chemistry team from the BCHET 149 course blocks, sized to the marks printed against it, and reviewed before the file was closed.
We read each question against its unit so the answer uses the course book's own terms, such as phosphoanhydride bond, holoenzyme, and T and R states. Examiners mark against the book, so using its vocabulary is the quickest way for an answer to look complete.
The team also went through the six earlier papers listed above, which you can open in our IGNOU Previous Year Question Paper section. Where a topic had been asked in a different form before, the answer is written so it still works if IGNOU turns the question around.
Numbers were checked twice. Free energy values, chain lengths and molecular masses match standard biochemistry references, with units written in full. Where a question asks for examples, the answer names at least one, not just a class.
Length follows the marks. A 5-mark part gets about 250 to 300 words, a 2.5-mark note about 120 to 150, and each blank in Q1(a) gets the exact term with a one-line reason so it sticks.
8. BCHEL 150 Lab Work and the Solved File Index
BCHET 149 has a separate 2-credit lab course, BCHEL 150 Molecules of Life: Laboratory, and the index below shows where each of the 18 June 2026 parts sits in the theory units.
The BCHEL 150 manual opens with separating a mixture of amino acids by paper chromatography, the same technique the theory paper asks about in Q3(iii). If you have done that experiment, your lab record is already half your revision for that note.
| Part | Topic | Course unit | Where to read it |
|---|---|---|---|
| Q1 (a) | Waxes, trans fats and DNA helicase blanks | Units 10 and 13 | Full file |
| Q1 (b) | Functions of lipids in the body | Units 10 and 11 | Full file |
| Q2 (a) | First law and energy change in a system | Unit 14 | Full file |
| Q2 (b) | ATP as energy currency | Unit 14 | Sample 1 above |
| Q3 (i) | Glucose-forming pathway note | Unit 15 | Full file |
| Q3 (ii) | tRNA structure and role | Unit 12 | Full file |
| Q3 (iii) | Separation by paper chromatography | Unit 4 | Full file |
| Q3 (iv) | Reducing versus non-reducing sugars | Unit 3 | Full file |
| Q4 (a) | Three stages of catabolism | Units 15 to 17 | Full file |
| Q4 (b) | PFK as the glycolysis control point | Unit 15 | Full file |
| Q5 (a) | Peroxisomes and catalase | Unit 1 | Full file |
| Q5 (b) | Three cytoskeletal filaments | Unit 1 | Full file |
| Q6 (a) | Steps of DNA replication | Unit 13 | Full file |
| Q6 (b) | Three-letter amino acid codes | Unit 4 | Full file |
| Q7 (a) | Enzymes and activation energy | Unit 7 | Full file |
| Q7 (b) | Homo and heteropolysaccharides by role | Unit 3 | Full file |
| Q8 (a) | Haemoglobin structure and function | Unit 6 | Sample 2 above |
| Q8 (b) | Allosteric regulation of enzymes | Unit 8 | Full file |
That is 18 parts in all: 2 on this page and 16 in the full file. The unit mapping is ours, made by reading each question against the unit titles, so use it to find the right chapter fast.
9. Programmes That Carry BCHET 149
BCHET 149 is offered in the IGNOU Bachelor of Science (General), programme code BSCG, as a chemistry Discipline Specific Elective paired with the BCHEL 150 lab.
Under the Bachelor of Science (General) scheme, students who pick BCHET 149 take BCHEL 150 as its matching lab. The other chemistry electives in the same slot include BCHET 141 Analytical Methods in Chemistry and BCHET 147, which covers organometallics and bioinorganic chemistry.
The June 2026 paper itself is printed for BSCG only. The IGNOU assignment booklet gives the tutor-marked assignment a 30 per cent weightage, asks for 35 per cent to pass it, and says you cannot fill the exam form for BCHET 149 until the assignment is in.
10. How to Get the Full Solved Question Paper
Send a WhatsApp message to 9899436384 with the code BCHET 149 and the session June 2026, and our team shares the complete file with all 18 answer parts.
You have already read 2 of those answers above. The other 16 cover the thermodynamics half of Q2, all four Q3 notes, the metabolism and PFK questions, peroxisomes and the cytoskeleton, DNA replication, the amino acid symbols, enzyme catalysis, polysaccharides and allosteric regulation.
If you are sitting the exam again in December 2026, the full file also works as a revision set, because the repeat table above shows which of these topics IGNOU tends to bring back.
11. BCHET 149 Molecules of Life FAQs
These are the questions BCHET 149 students ask us most often about the June 2026 paper and the solved file.
What is BCHET 149 Molecules of Life in IGNOU?
BCHET 149 Molecules of Life is a 4-credit chemistry Discipline Specific Elective in the IGNOU Bachelor of Science (General), programme code BSCG. It is studied through 5 blocks and 17 units covering cells, carbohydrates, amino acids and proteins, enzymes, lipids and nucleic acids, and bioenergetics with metabolism. It pairs with a separate 2-credit lab course, BCHEL 150, and ends in a 2-hour, 50-mark term-end paper.
How many questions does the June 2026 paper have?
The June 2026 paper has 8 questions of 10 marks each, and you answer any five in 2 hours for 50 marks. Most questions split into two 5-mark parts, Q3 has four 2.5-mark notes and Q1 opens with five one-mark blanks. Counted part by part, the IGNOU BCHET 149 Question Paper has 18 answer parts, and our full file solves every one of them.
How do I get the full solved file on WhatsApp?
Message WhatsApp 9899436384 with the course code BCHET 149 and the session June 2026. Our team replies with the price and how the file reaches you. The full file answers all 8 questions, which is 18 answer parts in total: the 2 sample answers you can read on this page plus 16 more that appear here only as question text.
Which answers can I read before contacting you?
Two answers are open on this page in full. Q2(b) explains why ATP is called the energy currency of living cells, and Q8(a) describes the structure and function of haemoglobin. We picked one topic IGNOU keeps repeating and one that was new in June 2026, so you can judge both kinds of answer before asking for the other 16 parts.
Which Molecules of Life topics repeat most?
In the six official papers we checked, from June 2022 to June 2025, six topics came up four times each: ATP, carbohydrate and polysaccharide classification, cell organelles, amino acid structure, RNA in protein synthesis and the fluid mosaic model. Five of them returned in June 2026. Only the fluid mosaic model was skipped, so keep it ready for December 2026.
Does BCHET 149 have a practical or lab course?
Yes. BCHET 149 carries 4 theory credits and comes with a separate 2-credit lab course, BCHEL 150 Molecules of Life: Laboratory, which BSCG students take alongside it. The lab manual begins with separating a mixture of amino acids by paper chromatography, which is the same technique asked as a short note in Q3(iii) of the June 2026 theory paper.
How long should a 5-mark answer be?
Aim for roughly 250 to 300 words for a 5-mark part. Open with a one-line definition, then give the reaction, value or labelled sketch the question needs, and close with one line that ties it back to the question. The 2.5-mark notes in Q3 need about 120 to 150 words each, with one named example, because the question asks for suitable examples.
Is the question paper printed in Hindi too?
Yes. The June 2026 BCHET 149 Question Paper runs to 10 printed pages, with the English questions on pages 1 to 5 and the same eight questions in Hindi on pages 6 to 10. The question numbers match in both languages, so the solved file lines up with whichever version you read in the exam hall on the day.
12. Who Wrote and Checked the BCHET 149 Answers
The BCHET 149 answers were written by Prateek Talwar and reviewed by Sheetal Kirola at Unnati Educations.
Prateek Talwar builds each solved question paper from the course blocks and the official term-end paper. Sheetal Kirola, Academic Head (M.Ed.), checks every definition, reaction and free-energy value against the IGNOU study material before the file is released.