BZYCT-135 Solved Question Paper June 2026 covers every question of the term-end paper for Physiology and Biochemistry, a zoology core course in IGNOU's Bachelor of Science (General). Two complete answers are open on this page — Q4(i) on the Loop of Henle and Q7(i) on haemostasis; the other 14 parts come in the full file on WhatsApp 9899436384.
BZYCT-135 Physiology and Biochemistry key facts for the June 2026 solved question paper
- Course code: BZYCT-135
- Course title: Physiology and Biochemistry
- Programmes: Bachelor of Science (General), BSCG — Discipline Specific Core, Zoology, Semester III; also listed for Bachelor of Science (Multidisciplinary), BSCM
- Credits: 4, theory; taken with its 2-credit companion lab BZYCL-136, so the pair comes to 6 credits
- Blocks and units: 4 blocks, 17 units — Animal Physiology-I (1–4), Animal Physiology-II (5–8), Essential Molecules of Biochemistry (9–13) and Metabolism (14–17)
- Maximum marks: 50 (Term-End Examination)
- Duration: 2 hours
- Paper code: C-3856
- Structure of the June 2026 paper: Question 1 compulsory for 10 marks, then any four of Questions 2 to 7 at 10 marks each
- Answerable parts: 16
- Mark values used: 1, 2½, 3, 5 and 7 — Question 7 splits 7 + 3, the only uneven split on the paper
- Paper language: bilingual — English on pages 1 to 5, Hindi on pages 6 to 10
- Assignment weightage: 30 per cent of the final result
- Samples shown on this page: 2 (Q4(i) Loop of Henle, Q7(i) haemostasis)
- Questions in the paid file: all 16 parts; 14 are not shown on this page
What the BZYCT-135 solved question paper June 2026 covers
The June 2026 paper is a two-hour, 50-mark paper with 7 questions. Question 1 is compulsory and you attempt any four of Questions 2 to 7. Split into its parts, the paper has 16 answerable items, from fill-in-the-blanks on collagen synthesis and anaerobic glycolysis to a 7-mark answer on haemostasis.
The paper mixes physiology and biochemistry almost evenly. Kidney function, blood, respiration and nerve signalling sit beside enzymes, antioxidants and carbohydrate metabolism.
Three things on this paper are worth knowing before you plan. First, Question 1 is the best-value ten marks on the paper — ten one-mark items, each needing a single word or a single pairing. Section 5 works out just how much more efficient it is than a long question. Second, the paper's units are loaded very unevenly: Block 1 supplied six of the sixteen parts and Block 4 only two, from the same number of units, and section 7 shows that this is exactly where the December gaps sit. Third, we have corrected the answer lengths this page originally gave, because the figures were around half again too long for a two-hour paper.
Two complete answers are open below so you can judge the depth and structure before you ask for the file. The other 14 parts are listed exactly as printed.
BZYCT-135 sample solved questions from June 2026
Question 4(i) on the Loop of Henle and Question 7(i) on haemostasis are shown in full below. Both come from repeat areas of the course — kidney physiology and blood clotting — and each follows the length its marks deserve.
Question 4(i) Any 4 of Q2 to Q7 Block 1, Unit 4 5 marks sketch helps Kidney questions in 3 of 6 earlier papers — reworded every time
4. (i) Explain the role of Loop of Henle in urine formation. 5
The Loop of Henle is the U-shaped part of the nephron that lies between the proximal convoluted tubule and the distal convoluted tubule. It dips from the cortex into the medulla and has three parts: a thin descending limb, a thin ascending limb and a thick ascending limb. Its main role in urine formation is to build a salt gradient in the medulla, so that the kidney can make urine more concentrated than blood.
- Descending limb. This limb is freely permeable to water but only slightly permeable to Na+ and Cl−. As the filtrate flows down into the salty medulla, water leaves by osmosis. The filtrate becomes more concentrated, rising from about 300 mOsm/L in the cortex to about 1200 mOsm/L at the tip of the loop in humans.
- Thin ascending limb. This part is impermeable to water. Na+ and Cl− diffuse out passively because the filtrate is now more concentrated than the surrounding tissue fluid.
- Thick ascending limb. This limb is also impermeable to water, but it actively pumps Na+, K+ and 2Cl− out of the filtrate through the Na+-K+-2Cl− co-transporter, powered by the Na+/K+ ATPase. Salt leaves without water, so the filtrate leaving the loop is dilute, about 100 mOsm/L. For this reason it is called the diluting segment.
- Countercurrent multiplier. Fluid flows in opposite directions in the two limbs, and salt pumped out of the ascending limb draws water out of the descending limb. Repeated along the loop, this small difference is multiplied into a large vertical gradient. Urea recycled from the inner medullary collecting duct adds to it.
- Vasa recta. These U-shaped capillaries run beside the loop and act as a countercurrent exchanger. They carry away reabsorbed water and solutes without washing out the medullary gradient.
- Final concentration. When antidiuretic hormone (ADH) is present, the collecting duct becomes permeable to water, which moves out into the hypertonic medulla, and concentrated urine is formed. Without ADH, dilute urine is passed. Overall the loop reabsorbs about 25 per cent of the filtered NaCl and about 15 per cent of the filtered water.
Conclusion. Mammals and birds are the only vertebrates with a Loop of Henle. Juxtamedullary nephrons have long loops, and desert mammals such as the kangaroo rat have very long loops, which lets them produce highly concentrated urine and save water.
At five marks this needs about 150 words plus a sketch, not six developed paragraphs. Draw the loop with the three limbs and mark the osmolarity at each level — 300 at the top, 1200 at the tip, 100 leaving — and those three numbers carry the whole mechanism. If you are short of time, keep the two permeability contrasts (water out of the descending limb, salt out of the ascending) and the phrase countercurrent multiplier; the vasa recta and the kangaroo rat are the first things to drop.
Question 7(i) Any 4 of Q2 to Q7 Block 1, Unit 3 7 marks the paper's only 7-mark part Set in 2 of 3 June papers and none of the 3 December papers
7. (i) Define the term haemostasis. Describe any one of the haemostatic mechanisms. 7
Definition. Haemostasis is the set of processes that stops bleeding from a damaged blood vessel while keeping blood fluid in the rest of the circulation. It works in three overlapping steps: vascular spasm, formation of a platelet plug, and blood coagulation. These are followed by clot retraction and, once the vessel heals, fibrinolysis. The mechanism described here is blood coagulation.
Clotting factors. Coagulation depends on clotting factors numbered I to XIII. Most are plasma proteins made in the liver. Calcium ions act as factor IV, and vitamin K is needed by the liver to make factors II, VII, IX and X. The factors activate one another in a chain, so a small trigger is amplified into a large response.
- Extrinsic pathway, fast, seconds. Damaged tissue releases tissue factor (factor III). It combines with factor VII in the presence of Ca2+, and this complex activates factor X.
- Intrinsic pathway, slower, minutes. Factor XII is activated when blood touches exposed collagen or another negatively charged surface. Activated XII activates XI, which activates IX. Factor IXa, with factor VIIIa, Ca2+ and platelet phospholipid, then activates factor X.
- Common pathway. Activated factor X joins factor Va, Ca2+ and phospholipid to form prothrombinase. This converts prothrombin (factor II) into thrombin. Thrombin changes soluble fibrinogen (factor I) into insoluble fibrin threads, and factor XIIIa cross-links these threads into a stable mesh that traps red blood cells and platelets. Thrombin also activates factors V, VIII and XI and more platelets, a positive feedback that speeds up clotting.
- Clot retraction and removal. Platelets in the clot contract, squeezing out serum and pulling the edges of the wound together. Natural anticoagulants such as antithrombin, protein C and heparin keep the clot local. Later, tissue plasminogen activator turns plasminogen into plasmin, which digests fibrin and dissolves the clot.
Flowchart of coagulation
- Tissue factor + VII (extrinsic), or XII → XI → IX + VIII (intrinsic)
- Factor X → Xa
- Xa + Va + Ca2+ + phospholipid = prothrombinase
- Prothrombin (II) → thrombin
- Fibrinogen (I) → fibrin → cross-linked by XIIIa → stable clot
Conclusion. Coagulation is a tightly controlled enzyme cascade. A missing factor shows how important each step is: lack of factor VIII causes haemophilia A, lack of factor IX causes haemophilia B, and vitamin K deficiency delays clotting because factors II, VII, IX and X are not made properly.
Seven marks is about 210 words, and the five-step flowchart is the single most efficient thing you can write — it shows the whole cascade in five lines where prose would take a page. Build the answer as definition, factor list, flowchart, then one line each on the two pathways. The haemophilia A and B examples at the end are cheap marks: two facts, one sentence, and they show you know what the cascade is for.
Questions answered only in the full file
The remaining 14 parts are printed below exactly as they appear in the June 2026 paper. Their answers are in the full solved file only.
1. (a) Fill in the blanks with suitable terms: 5 × 1 = 5
(i) Vitamin .............. is crucial for the synthesis of collagen.
(ii) ..................... is a metalloprotein and is also known as respiratory pigment.
(iii) Identify the missing component in the given reaction: H2CO3 → (Carbonic anhydrase, Low pCO2) → ? + CO2
(iv) The animals that excrete uric acid are ................
(v) ................ is the end product of anerobic [anaerobic] glycolysis.1. (b) Match the following: 5 × 1 = 5
Column I: (A) Dopamine (B) Kidney (C) Ligases (D) Thyroid (E) Niacin
Column II: I. Calcitonin · II. Pellagra · III. Angiotensin-II · IV. Parkinson's Disease · V. Synthesis2. Write short notes on the following: 2 × 5 = 10
(i) Neurotransmitters
(ii) Isoenzymes3. Write the differences between the following pairs: 4 × 2½ = 10
(i) Homo- and Hetero-polysaccharides
(ii) Arteries and Veins
(iii) Amoeboid and Ciliary Movements
(iv) Action Potential and Membrane Potential4. (ii) Illustrate citric acid cycle and discuss its significance in glucose metabolism. 5
5. (i) What are the proteolytic enzymes? Describe their two categories with suitable examples. 5
(ii) What is Blood Plasma? List any four blood plasma components and their functions. 56. (i) Define the term antioxidants. Explain the importance of any two antioxidant enzymes with suitable examples. 5
(ii) With the help of a diagram explain the exchange of gases in alveoli. 57. (ii) Compare and contrast between glycogenesis and glycogenolysis. 3
BZYCT-135 Physiology and Biochemistry block-wise syllabus
BZYCT-135 has 4 blocks and 17 units: Animal Physiology-I, Animal Physiology-II, Essential Molecules of Biochemistry, and Metabolism. The course is listed on the official eGyanKosh page for BZYCT-135, where the Block 3 unit titles match those below. The fourth column shows real questions from official papers, linked to units by our team.
| Block | Unit | Unit title | Topics asked in papers (our mapping) | June 2026 |
|---|---|---|---|---|
| Block 1: Animal Physiology-I | 1 | Nutrition and Digestion | Proteolytic enzymes; carbohydrate digestion by salivary and pancreatic amylase (Dec 2022, Dec 2025) | Q5(i) |
| 2 | Respiration | Gas exchange in alveoli (Jun 2025); Bohr effect (Jun 2022); O2 dissociation curve (Dec 2023) | Q6(ii) | |
| 3 | Circulation | Haemostasis (Jun 2022, Jun 2025); blood plasma; cardiac cycle (Dec 2023) | Q3(ii), Q5(ii), Q7(i) | |
| 4 | Osmoregulation and Excretion | Loop of Henle (Jun 2022); juxtaglomerular apparatus (Jun 2025); green glands (Dec 2025) | Q4(i) | |
| Block 2: Animal Physiology-II | 5 | Movements | A and I bands (Dec 2022, Jun 2023); calcium in muscle contraction (Dec 2023) | Q3(iii) |
| 6 | Communication: Nerve Cells | Neurotransmitters (Jun 2025); synaptic transmission (Jun 2023) | Q2(i), Q3(iv) | |
| 7 | Communication: Chemical Signalling | Cyclic AMP as second messenger (Jun 2025); pancreatic hormones (Jun 2022); chemical nature of hormones (Jun 2023) | None | |
| 8 | Reproduction | Oogenesis (Dec 2022); menstrual cycle (Jun 2023); hormonal regulation of the ovary (Dec 2023) | None | |
| Block 3: Essential Molecules of Biochemistry | 9 | Biomolecules | Mono-, di- and polysaccharides (Jun 2025); levels of protein structure (Dec 2022) | Q3(i) |
| 10 | Enzymes: Specificity and Mechanism of Action | Hydrolases vs lyases (Dec 2023); effect of temperature and pH on enzymes (Dec 2022) | Q1(b), ligases | |
| 11 | Enzyme Kinetics and Regulation | Isoenzymes (Jun 2022, Dec 2025); Km and Vmax (Jun 2022, Dec 2023); enzyme regulation (Jun 2023) | Q2(ii) | |
| 12 | Vitamins | Fat-soluble vitamins (Jun 2022, Jun 2023, Dec 2025); B-complex vitamins (Jun 2025) | Q1(a)(i), vitamin C only | |
| 13 | Free Radicals and Antioxidants | Antioxidants with examples (Dec 2025); free radical sources (Jun 2022) | Q6(i) | |
| Block 4: Metabolism | 14 | Carbohydrate Metabolism-I | Citric acid cycle (Dec 2022); fate of pyruvate (Jun 2023); electron transport chain (Dec 2022, Dec 2023) | Q4(ii), citric acid cycle only |
| 15 | Carbohydrate Metabolism-II | Glycogenesis vs glycogenolysis (Jun 2022, Jun 2025); HMP shunt (Jun 2025) | Q7(ii) | |
| 16 | Lipid Metabolism | Beta-oxidation of fatty acids (Jun 2022, Jun 2023, Dec 2025); fatty acid synthesis regulation (Dec 2022, Dec 2023) | None | |
| 17 | Protein Metabolism | Urea cycle (five sessions, Jun 2022 to Jun 2025); transamination vs deamination (Dec 2025) | None |
June 2026 drew its 16 parts from 13 of the 17 units · the four that fed nothing are Units 7, 8, 16 and 17 · block split Block 1: 6 parts · Block 2: 3 · Block 3: 3 · Block 4: 2, plus the two mixed items of Question 1
Block 1 and Block 4 have four units each, and Block 1 produced three times as many parts. All four Block 1 units were examined, two of them more than once — Unit 3 on circulation alone fed three parts, the arteries-and-veins difference, blood plasma and the seven-mark haemostasis question. Block 4 gave two parts from two units and left its other two silent.
Two units were examined only in half. Unit 14 covers both the citric acid cycle and the electron transport chain, and June 2026 took the citric acid cycle and left the ETC. Unit 12 covers fat-soluble vitamins and vitamin C, and the paper took only vitamin C, inside a one-mark fill-in-the-blank. Both unexamined halves have a repeat record of their own, which puts them on the December list in section 7.
For unit-wise reading alongside the paper, see our BZYCT-135 study material.
BZYCT-135 question paper pattern and marks distribution
The paper carries 50 marks in 2 hours: Question 1 for 10 marks is compulsory, and you answer any four of Questions 2 to 7 at 10 marks each.
| Question | What it asked in June 2026 | Marks | Choice |
|---|---|---|---|
| Q1(a) | Fill in the blanks, 5 items — collagen, respiratory pigment, carbonic anhydrase, uric acid, glycolysis | 5 × 1 = 5 | Compulsory |
| Q1(b) | Match the following, 5 pairs — dopamine, kidney, ligases, thyroid, niacin | 5 × 1 = 5 | Compulsory |
| Q2 | Short notes: neurotransmitters; isoenzymes | 2 × 5 = 10 | Any four of Q2 to Q7 |
| Q3 | Differences: polysaccharides; arteries and veins; amoeboid and ciliary movement; action and membrane potential | 4 × 2½ = 10 | |
| Q4 | Loop of Henle; citric acid cycle (illustrate) | 5 + 5 = 10 | |
| Q5 | Proteolytic enzymes; blood plasma | 5 + 5 = 10 | |
| Q6 | Antioxidant enzymes; gas exchange in alveoli (diagram) | 5 + 5 = 10 | |
| Q7 | Haemostasis; glycogenesis versus glycogenolysis | 7 + 3 = 10 |
Q1 (10) + six questions of 10 in Q2 to Q7 = 70 marks printed, 50 attempted · five distinct mark values: 1, 2½, 3, 5 and 7 · Q7's 7 + 3 is the paper's only uneven split · 120 minutes for 50 marks = 2.4 minutes a mark
Question 1 is the best-value ten marks on this paper, and the arithmetic is worth seeing. Its ten items each need one word or one pairing — no definitions, no explanation, no diagram. If you know them, the whole question takes eight to ten minutes. That is roughly one mark a minute. A ten-mark long question, written properly in the twenty-seven minutes you can spare for it, earns about 0.36 marks a minute. Question 1 is nearly three times more efficient than anything else on the paper.
The practical consequence: answer Question 1 first, quickly, and do not linger over an item you cannot recall — no amount of staring produces the word. Then give the remaining 110 minutes to your four long questions, about 27 minutes each.
On answer length, we have corrected what this page previously said. It gave 200 to 250 words for a 5-mark part and 350 to 400 for a 7-mark part, which is 45 to 54 words a mark. Four ten-mark questions at that rate is about 1,800 words in under two hours, before any diagram — around 16 words a minute, where a person writing by hand sustains 11 to 12. The realistic figures are:
| Part | Marks | Roughly how many words | Roughly how many minutes | Best form |
|---|---|---|---|---|
| Fill-in-the-blank or matching pair | 1 | One word or one pairing | Under a minute | Nothing added |
| A "differences between" pair | 2½ | 70 to 80 | 7 | A three- or four-row two-column table |
| Compare and contrast (Q7(ii)) | 3 | 90 | 8 | A short table of points |
| A five-mark part | 5 | 140 to 160 | 13 to 14 | Numbered points, plus a sketch where asked |
| The seven-mark part (Q7(i)) | 7 | 200 to 220 | 19 | Definition, then a flowchart |
That works out to about 30 words a mark, dropping nearer 25 if you choose both diagram questions, Q4(ii) on the citric acid cycle and Q6(ii) on alveolar gas exchange, since a labelled figure replaces prose and earns marks faster than describing it would. For comparison, IGNOU prints 30 words a mark on its own psychology papers and 20 on its sociology papers — so 25 to 30 on a science paper with figures is in line with what the university itself asks elsewhere.
One point on Question 3. Four "differences between" pairs for 2½ marks each is the most fragmented question on the paper, and it rewards a two-column table far more than paragraphs. Three or four contrasting rows per pair is a complete answer; a paragraph of prose for each takes twice as long and reads as less organised.
The paper has kept this one-compulsory-plus-any-four structure since June 2022, though the item types inside Question 1 change: June 2022 used matching and definitions, while papers from December 2022 onward pair fill-in-the-blanks with matching.
Papers from other courses in the same programme are collected on our BSCG question paper page.
Most repeated BZYCT-135 topics
We counted topics in the official BZYCT-135 papers for June 2022, December 2022, June 2023, December 2023, June 2025 and December 2025, taken from ignou.ac.in and webservices.ignou.ac.in. The June 2024 and December 2024 files are scanned images we could not read reliably, so they are left out. The count column covers those six earlier papers, with June 2026 shown separately.
| Topic | Unit | Sessions asked earlier | Papers (of 6) | In June 2026? |
|---|---|---|---|---|
| Transport and exchange of respiratory gases | 2 | Jun 2022, Dec 2022, Jun 2023, Dec 2023, Jun 2025 | 5 | Yes — Q6(ii) |
| Urea cycle and its regulation | 17 | Jun 2022, Dec 2022, Jun 2023, Dec 2023, Jun 2025 | 5 | No |
| Ammonotelic, ureotelic and uricotelic animals | 4 | Dec 2022, Jun 2023, Dec 2023, Jun 2025 | 4 | Yes — Q1(a)(iv) |
| Neurotransmitters and synaptic transmission | 6 | Jun 2023, Dec 2023, Jun 2025, Dec 2025 | 4 | Yes — Q2(i) |
| Beta-oxidation of fatty acids | 16 | Jun 2022, Jun 2023, Dec 2023, Dec 2025 | 4 | No |
| Urine formation in the nephron and Loop of Henle | 4 | Jun 2022, Jun 2023, Dec 2023 | 3 | Yes — Q4(i) |
| Electron transport chain | 14 | Jun 2022, Dec 2022, Dec 2023 | 3 | No |
| Fat-soluble vitamins | 12 | Jun 2022, Jun 2023, Dec 2025 | 3 | No |
| Chemical signalling and hormones | 7 | Jun 2022, Jun 2023, Jun 2025 | 3 | No |
| Reproduction: oogenesis, ovarian cycle | 8 | Dec 2022, Jun 2023, Dec 2023 | 3 | No |
| Glycogenesis versus glycogenolysis | 15 | Jun 2022, Jun 2025 | 2 | Yes — Q7(ii) |
| Isoenzymes | 11 | Jun 2022, Dec 2025 | 2 | Yes — Q2(ii) |
| Antioxidants and free radicals | 13 | Jun 2022, Dec 2025 | 2 | Yes — Q6(i) |
| Haemostasis and blood clotting | 3 | Jun 2022, Jun 2025 | 2 | Yes — Q7(i) |
14 recurring topics tracked · only 8 of the 14 appeared again in June 2026 · a reuse rate of 57 per cent, the lowest we have measured on any course · six topics were skipped, and three of the six are in Block 4
Two of those rows are additions we made, and the reason matters. The repeat table this page originally carried listed twelve topics, all of them taken from what June 2026 happened to ask. That meant two whole units with a clear exam history — Unit 7 on chemical signalling and Unit 8 on reproduction — had no row at all, simply because the June 2026 paper did not ask about them. Their counts above are drawn from the syllabus mapping in section 4: hormones in June 2022, June 2023 and June 2025; oogenesis, the menstrual cycle and ovarian regulation in December 2022, June 2023 and December 2023. Adding them changes the reuse rate from 67 per cent to 57, and it changes the December shortlist.
Kidney questions keep returning in new forms, which is worth noticing: the Loop of Henle in June 2022, urine production in the nephron in June 2023, dilute and concentrated urine in December 2023, the juxtaglomerular apparatus in June 2025, and the Loop of Henle again in June 2026. The topic is constant; the wording is not. Prepare the nephron as a whole rather than memorising one question.
What June 2026 left out, and what to prepare next
The six earlier papers divide into exactly three June sessions (June 2022, 2023 and 2025) and three December ones (December 2022, 2023 and 2025), so a session comparison is meaningful even on a small window. Combining the plain counts with the session pattern reorders the shortlist, so both are given below.
| Topic | Unit | June papers (of 3) | December papers (of 3) | In June 2026? |
|---|---|---|---|---|
| Chemical signalling and hormones | 7 | 3 | 0 | No |
| Haemostasis and blood clotting | 3 | 2 | 0 | Yes |
| Glycogenesis versus glycogenolysis | 15 | 2 | 0 | Yes |
| Electron transport chain | 14 | 1 | 2 | No |
| Reproduction: oogenesis, ovarian cycle | 8 | 1 | 2 | No |
Three topics have never been set in a December paper on this evidence: hormones and chemical signalling, haemostasis, and the glycogen comparison. Two lean the other way: the electron transport chain and reproduction. Note what that means for the samples published above — haemostasis is a June-only topic and the Loop of Henle is June-leaning, so both of this page's open answers serve a June attempt better than a December one.
Putting the counts and the session pattern together, the ranked additions for December 2026 are:
- Urea cycle (Block 4, Unit 17). Joint-highest count on the table at five of six papers, set in five sessions running from June 2022 to June 2025, then skipped — and Unit 17 fed nothing at all. The count and the dead unit agree, which is the strongest combination on this page.
- Beta-oxidation of fatty acids (Block 4, Unit 16). Four of six, skipped, and Unit 16 also fed nothing. Session-neutral, so it is as likely in December as in June.
- Electron transport chain (Block 4, Unit 14). Three of six, skipped, and December-leaning at two of three December papers against one of three June. It is also the unexamined half of a unit whose citric-acid-cycle half was asked, so you are extending a chapter rather than opening a new one.
- Reproduction (Block 2, Unit 8). Three of six, a dead unit, and December-leaning at two of three. Oogenesis, the menstrual cycle and hormonal regulation of the ovary.
- Fat-soluble vitamins (Block 3, Unit 12). Three of six, skipped — the paper took only vitamin C, as a one-mark blank. Vitamins A, D, E and K are still due.
- Chemical signalling and hormones (Block 2, Unit 7). Three of six and a dead unit, but set in all three June papers and none of the three December ones, which pushes it down a December list even though its count is the same as the two above.
Block 4 is where the gaps are concentrated. It has four units, produced only two of the paper's sixteen parts, and three of the six skipped topics belong to it. If you are revising for December with limited time, metabolism is where to start — and it is the half of this course students most often leave until last.
Two caveats. June 2024 and December 2024 are scans we could not read, so the window has a two-session hole between December 2023 and June 2025. And three papers a side is a small balanced window: it is enough to notice a topic that has never appeared in one session type, not enough to treat that as a rule.
If you revise from a shortlist, our IGNOU Solved Guess Paper collection groups such repeat topics by course.
How our BZYCT-135 answers are written and checked
Every answer is written by our science team from the official June 2026 paper and reviewed before release. The solved paper series is led by Prateek Talwar, Academic Head of Unnati Educations, and Sheetal Kirola reviews each file for structure, accuracy and length before it goes out to students.
For this course the checks are subject-specific: figures such as about 1200 mOsm/L at the tip of the human Loop of Henle, the clotting factor numbers and the enzyme names are cross-checked, and the parts that ask for a figure — the citric acid cycle and gas exchange in the alveoli — are answered with labelled diagrams.
Answers were planned after studying the earlier papers, which is why this page can tell you which topics are overdue rather than only which were asked. The two samples above are written a little longer than we advise you to write in the hall, because a revision page should give you more points than you need; the notes inside each sample say what to keep when the clock is the constraint.
You can read the older papers on our IGNOU Previous Year Question Paper page.
BZYCT-135 solved file index for June 2026
The solved file answers all 16 parts; 2 are open on this page and 14 are in the full file only.
| Part | Topic | Block and unit (our mapping) | Marks | Where to find it |
|---|---|---|---|---|
| Q1(a) | Fill in the blanks: collagen, respiratory pigment, carbonic anhydrase, uric acid, glycolysis | Mixed | 5 | Full file only |
| Q1(b) | Matching: dopamine, kidney, ligases, thyroid, niacin | Mixed | 5 | Full file only |
| Q2(i) | Neurotransmitters | Block 2, Unit 6 | 5 | Full file only |
| Q2(ii) | Isoenzymes | Block 3, Unit 11 | 5 | Full file only |
| Q3(i) | Homo- versus hetero-polysaccharides | Block 3, Unit 9 | 2½ | Full file only |
| Q3(ii) | Arteries versus veins | Block 1, Unit 3 | 2½ | Full file only |
| Q3(iii) | Amoeboid versus ciliary movement | Block 2, Unit 5 | 2½ | Full file only |
| Q3(iv) | Action versus membrane potential | Block 2, Unit 6 | 2½ | Full file only |
| Q4(i) | Loop of Henle in urine formation | Block 1, Unit 4 | 5 | On this page |
| Q4(ii) | Citric acid cycle (illustrate) | Block 4, Unit 14 | 5 | Full file only |
| Q5(i) | Proteolytic enzymes | Block 1, Unit 1 | 5 | Full file only |
| Q5(ii) | Blood plasma components | Block 1, Unit 3 | 5 | Full file only |
| Q6(i) | Antioxidant enzymes | Block 3, Unit 13 | 5 | Full file only |
| Q6(ii) | Gas exchange in alveoli (diagram) | Block 1, Unit 2 | 5 | Full file only |
| Q7(i) | Haemostasis | Block 1, Unit 3 | 7 | On this page |
| Q7(ii) | Glycogenesis versus glycogenolysis | Block 4, Unit 15 | 3 | Full file only |
BZYCT-135 is a theory paper, so the index lists answers rather than practical records — the practical side belongs to the companion lab, BZYCL-136. The two parts of Question 1 draw from several blocks at once, which is why they are marked Mixed: the five blanks alone reach into vitamins, respiration, excretion and carbohydrate metabolism.
Read the index by marks before you choose your four questions. Q3 is the only question split four ways, so it needs four separate structures in the same twenty-seven minutes — easier if you like tables, harder if you do not. Q7 is the only one with an uneven split, and its seven-mark half is a cascade best drawn as a flowchart. Q4 and Q6 are the two that ask for figures. If diagrams are your strength, take Q4 and Q6; if organised comparison is, take Q3 and Q7.
Programmes that include BZYCT-135 Physiology and Biochemistry
BZYCT-135 is a zoology Discipline Specific Core course in IGNOU's Bachelor of Science (General), and it also runs in the Bachelor of Science (Multidisciplinary).
| Programme code | Programme | Evidence |
|---|---|---|
| BSCG | Bachelor of Science (General) | Printed on the June 2026 paper; listed under Zoology DSC on eGyanKosh |
| BSCM | Bachelor of Science (Multidisciplinary) | IGNOU 2025 assignment booklet for BZYCT-135, issued for the BSCM 2024-25 batch |
If you are enrolled in the Bachelor of Science (General), BZYCT-135 sits with the other zoology core papers in Semester III, together with the 2-credit lab course BZYCL-136. BSCM students study the same course content, so the June 2026 answers apply to both groups.
The zoology core runs as theory-and-lab pairs: BZYCT-133 Comparative Anatomy and Developmental Biology with BZYCL-134, and BZYCT-135 Physiology and Biochemistry with BZYCL-136. Each pair is 4 theory credits plus 2 lab credits, and both theory papers use the same 50-mark, two-hour format with a compulsory Question 1 — so preparing one teaches you how to sit the other.
How to get the full BZYCT-135 Solved Question Paper on WhatsApp
The full solved paper for June 2026 has answers to all 16 parts, including the 14 not shown here, and is shared on WhatsApp 9899436384.
Message us with the course code BZYCT 135 and the session June 2026. Our team replies with the file details and how to receive it. The full file answers proteolytic enzymes, blood plasma, antioxidant enzymes, the citric acid cycle and gas exchange in the same style as the two samples above.
BZYCT-135 FAQs
How do I get the complete BZYCT-135 June 2026 solved paper on WhatsApp?
Send a message to WhatsApp 9899436384 with the code BZYCT 135 and the session June 2026. The full file contains answers to all 16 parts of the paper, including the 14 not answered on this page. Our team replies with the file details and how to receive it, so you can start revising the remaining questions straight away.
How many questions are in the BZYCT-135 June 2026 paper?
Seven questions that split into 16 answerable parts. Question 1 is compulsory and carries 10 marks through five fill-in-the-blanks and five matching pairs. You then attempt any four of Questions 2 to 7, each worth 10 marks, for a total of 50 marks in 2 hours. Our solved file covers every part, not only the four you choose.
Why should I answer Question 1 first in BZYCT-135?
Because it is the best-value ten marks on the paper. Its ten items each need one word or one pairing — no explanation, no diagram — so if you know them the whole question takes eight to ten minutes, which is roughly one mark a minute. A ten-mark long question earns about a third of a mark a minute. Answer Question 1 quickly, do not linger over an item you cannot recall, and give the remaining 110 minutes to your four long questions, about 27 minutes each.
How long should BZYCT-135 answers be in the term-end exam?
About 30 words a mark, which works out to roughly 140 to 160 words for a 5-mark part, 200 to 220 for the 7-mark haemostasis question, 90 for the 3-mark comparison and 70 to 80 for each 2½-mark difference. A "differences between" pair is best written as a three- or four-row table rather than prose, and a labelled figure on the citric acid cycle or alveolar gas exchange earns marks faster than describing it in words. Our two sample answers on this page show the structure; in the hall write a little shorter than they run.
Which BZYCT-135 topics repeat most often in IGNOU papers?
Respiratory gas transport and the urea cycle are the strongest repeats, each set in five of the six papers we could read from June 2022 to December 2025. Animal excretory types, neurotransmitters and beta-oxidation of fatty acids follow with four each. June 2024 and December 2024 were scanned files we could not read, so they are not counted.
Which BZYCT-135 topics did June 2026 leave out?
Six, which is unusually many. The urea cycle was the biggest omission — set in five sessions running from June 2022 to June 2025 and then skipped, with its unit, Protein Metabolism, feeding nothing at all. Beta-oxidation of fatty acids, the electron transport chain, fat-soluble vitamins, chemical signalling and hormones, and reproduction were also skipped. Three of the six belong to Block 4, Metabolism, which produced only two of the paper's sixteen parts.
Which BZYCT-135 topics should I add for a December exam?
Start with the urea cycle, then beta-oxidation, then the electron transport chain — all three in Block 4, all three skipped in June 2026, and the ETC additionally set in two of the three December papers against one of three June ones. Add reproduction, which is also December-leaning, and the fat-soluble vitamins, since June 2026 took only vitamin C from that unit. Note that haemostasis and the glycogen comparison, both answered or asked in June 2026, have never appeared in a December paper on our evidence.
Which BZYCT-135 June 2026 questions need a diagram?
Question 4(ii) asks you to illustrate the citric acid cycle and Question 6(ii) asks for a diagram of gas exchange in the alveoli, so both need a labelled figure to score full marks. A flowchart of the clotting cascade also strengthens Question 7(i) on haemostasis, as in our sample answer. The short notes and differences in Questions 2 and 3 are scored on clear points rather than figures.
What does Question 1 of the BZYCT-135 paper test?
Quick recall across the whole course. In June 2026 it had five fill-in-the-blanks on collagen synthesis, a respiratory pigment, the carbonic anhydrase reaction, uric acid excretion and anaerobic glycolysis, plus five matching pairs on dopamine, the kidney, ligases, the thyroid and niacin. Each item carries 1 mark. Because the ten items reach across vitamins, respiration, excretion, enzymes, endocrinology and metabolism, Question 1 is also the one part of the paper you cannot prepare for by choosing a favourite block.
Is BZYCT-135 part of BSCG only, or other IGNOU programmes too?
It is a zoology core course of the Bachelor of Science (General), BSCG, and the June 2026 paper is printed under BSCG. IGNOU also issued the 2025 BZYCT-135 assignment booklet for the Bachelor of Science (Multidisciplinary) 2024-25 batch, so BSCM students take the same course. The solved answers suit both groups.
Is the BZYCT-135 question paper available in Hindi?
Yes. The official June 2026 paper is bilingual, with the English questions on pages 1 to 5 and the Hindi version on pages 6 to 10. Our solved answers are written in English. If you write the exam in Hindi, message WhatsApp 9899436384 to ask whether a Hindi version of the solved file is available.
About the authors
This page was prepared by the academic team at Unnati Educations, which has been helping IGNOU, NIOS, MDU Rohtak and GGSIPU students with solved papers and assignment support for over a decade.
Prateek Talwar, Academic Head, leads the IGNOU solved paper series and built the unit mapping and repeat analysis on this page, including the two repeat-table rows added for Units 7 and 8, the marks-per-minute comparison for Question 1 and the corrected answer-length table. He reads every official paper in a series before a single answer is drafted.
Sheetal Kirola reviewed this page and the solved file against the printed question wording and marks, and verified the physiological detail used — the three limbs of the Loop of Henle and their permeabilities, the 300, 1200 and 100 mOsm/L figures, the Na+-K+-2Cl− co-transporter and the thick ascending limb as the diluting segment, the vasa recta as a countercurrent exchanger, and for Question 7(i) the clotting factor numbering, calcium as factor IV, the vitamin K-dependent factors II, VII, IX and X, the extrinsic, intrinsic and common pathways, and haemophilia A and B as factor VIII and IX deficiencies.