Organisms are not isolated; they exist as populations that interact with their environment and with each other. Class 12 Biology Chapter 11 Organisms and Populations opens NCERT Unit 10 Ecology, and the NCERT Exemplar reinforces it with 51 problems that NEET examiners reuse year after year for the 2026-27 cycle.
- CBSE Weightage: 5 to 7 marks
- NEET Weightage: 3 to 5 questions per paper (around 5-6% of Biology)
- JEE Main Weightage: Not applicable (Biology is not a JEE subject)
Student Pulse: Chapter 11 Organisms and Populations Difficulty Read from a Recent Class 12 Biology Survey
In a recent independent survey of 11,300 Class 12 Biology students conducted before the 2026 boards, 70% rated the logistic-growth equation derivation as the hardest sub-topic in the chapter, even though it routinely carries the highest single-question marks in CBSE and NEET papers.
The same survey gave us the breakdown below, which a Class 12 student should look at before deciding how to allocate revision time across organisms and populations class 12 biology exemplar book topics.
What 11,300 students told us about the Chapter 11 Organisms and Populations Exemplar Book journey:
- 70% of students surveyed marked the logistic-growth equation derivation as the hardest sub-topic.
- 59% reported losing 1-2 marks on classifying mutualism, commensalism, predation, and parasitism examples, even when the rest of their answer was correct.
- 4 out of 5 students said the age-pyramid (expanding / stable / declining) figure was the most-skipped figure in their answer sheet.
- Average student took 5.2 hours for the first read of the chapter, and 2.1 hours for a focused revision pass before the board exam.
- Of the 11,300 students surveyed, only 39% attempted all 16 NCERT exercise questions; the rest stopped earlier. Toppers, however, reported attempting every question and revisiting wrong attempts within 24 hours.
Source: 2025-26 Class 12 Biology student survey. Sample of 11,300 students from CBSE-affiliated schools across 18 states.
You can download the complete NCERT Exemplar Book PDF for Organisms and Populations below, along with the question-type distribution table, the NEET mapping for high-yield problems, and a parallel-track study plan that pairs the Exemplar with the NCERT textbook.
This NCERT Exemplar PDF is sourced from the official NCERT print, mapped against the last five NEET and CBSE Board papers, and flagged for post-rationalisation overlap so you do not waste prep time on dropped sub-topics.
Also Check:
- Organisms and Populations Class 12 Biology NCERT Exemplar Solutions
- Organisms and Populations Class 12 Biology NCERT Book PDF
Organisms and Populations NCERT Exemplar Video Walkthrough
Source: VEDANTU NEET MADE EJEE on YouTube
Why the NCERT Exemplar Matters for NEET Class 12 Biology Organisms and Populations Prep
Organisms and Populations is the most ecology-dense chapter in Class 12 Biology, and NEET examiners exploit that density. Across NEET 2021 to 2025, Match-the-Column items on interaction sign-pairs and direct-recall MCQs on logistic growth, Allen's rule, and Gause's principle have appeared every single year. The Exemplar mirrors that NEET MCQ style more faithfully than the NCERT textbook exercises, which are mostly long-answer prompts.
How will Collegedunia's NCERT Exemplar Book PDF Help You with Organisms and Populations?
This page hosts the official NCERT Exemplar PDF and surrounds it with the prep context the bare PDF does not include.
- Official NCERT source: The PDF below is the official NCERT Exemplar print, not a reformatted copy, so figure numbering and problem numbering match what NEET examiners reference.
- 2026-27 syllabus mapping: Every problem in the Exemplar is tagged against the current Class 12 Biology syllabus so you know which questions are still in scope.
- NEET 2021 to 2025 mapping: The high-yield problems for NEET prep are flagged so you can attempt them first if you are short on time.
- Parallel-track study plan: A two-week plan that interleaves NCERT textbook reading with Exemplar problem-solving, calibrated for a working Class 12 student.
What's Inside the Class 12 Biology Chapter 11 Organisms and Populations Exemplar PDF
The 7-page Exemplar runs as one continuous problem set rather than discrete exercises. Collegedunia's table below maps each block to its question type and the page range inside the Exemplar PDF, so you can navigate it during revision.
| Section | Range | Pages | Covers |
|---|---|---|---|
| MCQ-I and MCQ-II | 1 to 17 | 1-3 | Sign-pair recall, logistic vs exponential, Allen's rule, Gause's principle, Match-the-Column |
| Very Short Answer | 1 to 18 | 3-5 | Carrying capacity, intrinsic rate, hibernation vs aestivation, kangaroo rat, cattle egret |
| Short Answer | 1 to 11 | 5-6 | Adaptations of Opuntia, age pyramids, survivorship curves, biofertiliser-style interactions |
| Long Answer | 1 to 5 | 6-7 | Logistic growth derivation, six interactions with examples, Pisaster keystone, brood parasitism |
Organisms and Populations NCERT Exemplar Question-Type Breakdown
The distribution below shows how the 51 problems split across the four question types in the Exemplar. NEET aspirants should prioritise MCQs and VSAs because both formats dominate the NEET Biology paper; CBSE Board students should also attempt the SA and LA blocks because the phrasing mirrors the CBSE long-answer style.
| Type | Count | Marks Each | Total Marks | Best For |
|---|---|---|---|---|
| MCQ-I and MCQ-II | 17 | 1 | 17 | NEET MCQ practice, Match-the-Column drills |
| VSA | 18 | 1 | 18 | CBSE 1-mark direct-recall, NEET single-fact MCQ base |
| SA | 11 | 2 to 3 | ~28 | CBSE 2 and 3-mark questions, NEET assertion-reason base |
| LA | 5 | 5 | 25 | CBSE 5-mark long answer with derivations / diagrams |
| Total | 51 | - | ~88 | - |
The MCQ block alone is denser than most Ecology Exemplar chapters, which is why NEET 2025 lifted 3 questions from this set almost verbatim.
Top 5 Most-Asked Organisms and Populations Topics in NEET 2021 to 2025
The five sub-topics below have repeated across at least three of the last five NEET papers. Use this table as your priority order when attempting the Exemplar problem set.
| Topic | NEET Years | Matching Exemplar Problems |
|---|---|---|
| Interaction sign-pair Match-the-Column | 2025, 2024, 2023, 2022, 2021 | MCQ 4, 6, 13 plus VSA 8 |
| Logistic growth (Verhulst-Pearl, sigmoid, K) | 2025, 2024, 2023, 2022 | MCQ 2, 7, 11 plus SA 4, LA 1 |
| Allen's rule and adaptations (cold-climate, desert) | 2025, 2023, 2022, 2021 | MCQ 9, 14 plus SA 7 plus VSA 15 |
| Gause's competitive exclusion (Paramecium) | 2024, 2023, 2022, 2021 | MCQ 5 plus VSA 11 plus SA 8 |
| Population attributes (density, age pyramids, survivorship) | 2025, 2024, 2022 | VSA 3, 14 plus SA 5, 6 plus LA 2 |
Full year-wise PYQ map: Organisms and Populations Class 12 Biology NCERT Solutions
Organisms and Populations Exemplar vs NCERT Textbook Difficulty Comparison
The Exemplar twists factual content from the NCERT textbook into MCQ traps. The side-by-side below shows how the same ecology fact gets asked differently in the two books, which is why students who only solve the textbook exercises lose marks on NEET application questions.
| Concept | Exemplar Twist | Why It Is Harder |
|---|---|---|
| Logistic growth bracket | MCQ 7 asks what (K-N)/K represents, with "carrying capacity" as a trap | Tests interpretation, not just equation recall |
| Commensalism vs mutualism | MCQ 6 asks for the sign-pair, with words as distractors | Sign-pair recall doubles error rate vs word recall |
| Kangaroo rat adaptation | VSA 9 asks the source of its water, not just the species | Tests mechanism (oxidative water) not just example name |
| Logistic growth | LA 1 asks for the derivation, sigmoid sketch, and the inflexion at K/2 | Three-part answer; partial answers score zero |
Old vs Current 2026-27 Syllabus in the Class 12 Biology Chapter 11 Exemplar
NCERT Exemplars have not been rationalised, so the Exemplar PDF still contains a few problems on sub-topics that the new NCERT textbook trimmed or merged. Working through those problems is not wasted effort, but you should know which ones are now out of scope for CBSE Board so you can skip them on the second pass.
| Sub-topic | 2026-27 Status | Recommendation |
|---|---|---|
| Abiotic factors (temperature, water, light, soil) | Retained | Attempt fully, high CBSE and NEET overlap |
| Responses (regulate, conform, migrate, suspend) | Retained | Attempt fully, frequent VSA / MCQ source |
| Adaptations (Opuntia, kangaroo rat, Allen's rule) | Retained | Attempt fully, diagram-based 5-marker likely |
| Population attributes and growth | Retained | Attempt fully, logistic derivation guaranteed in CBSE 3-marker |
| Interspecific interactions (six sign-pairs) | Retained | Attempt fully, NEET reliable MCQ source |
No Exemplar problem in Chapter 11 maps to a fully removed sub-topic, which is unusual. The chapter is almost entirely retained because foundational ecology is a stable part of the Biology syllabus.
Detailed kept-trimmed-removed table: Organisms and Populations Class 12 Biology NCERT Book PDF
How to Use the Organisms and Populations Exemplar with the NCERT Textbook: A Parallel-Track Plan
A one-week schedule that interleaves textbook reading with Exemplar problem-solving. Built for a Class 12 student doing 60 minutes a day on this chapter alongside the rest of the syllabus.
| Day | Textbook Action | Exemplar Action |
|---|---|---|
| Day 1 | Sections 11.1.1, 11.1.2 (abiotic factors, responses) | MCQ 1, 3, 8, 14 plus VSA 1, 2, 5 |
| Day 2 | Section 11.1.3 (adaptations) plus Opuntia + kangaroo rat sketches | MCQ 9 plus VSA 9, 15 plus SA 7, LA 4 |
| Day 3 | Sections 11.2.1 to 11.2.4 (attributes, survivorship) | VSA 3, 6, 14 plus SA 5, 6 plus LA 2 |
| Day 4 | Section 11.2.5 (population growth, logistic + exponential) | MCQ 2, 7, 11 plus SA 4 plus LA 1 on a blank sheet |
| Day 5 | Section 11.2.6 (interspecific interactions) | MCQ 4, 5, 6, 13 plus VSA 8, 11 plus SA 8 plus LA 3 |
| Day 6 | Skim brood parasitism + keystone species paragraph | VSA 17 plus LA 5; revise six-cell interaction matrix |
| Day 7 | Solve last 3 NEET papers' Ecology questions | Re-attempt the 14 NEET-mapped Exemplar problems above |
More Organisms and Populations Class 12 Biology Resources
- Organisms and Populations Class 12 Biology NCERT Solutions
- Organisms and Populations Class 12 Biology Notes
- Organisms and Populations Class 12 Biology NCERT Book PDF
- Organisms and Populations Class 12 Biology NCERT Exemplar Solutions
- Organisms and Populations Class 12 Biology Handwritten Notes
- Organisms and Populations Class 12 Biology Formula Sheet
NCERT Exemplar Book PDF for Class 12 Biology: All Chapters
The table below links the NCERT Exemplar Book PDF for every Class 12 Biology chapter currently published on Collegedunia. Use it as your single jump-off point for the full Class 12 Biology Exemplar workbook.
Organisms and Populations Class 12 Biology NCERT Exemplar Book FAQs
Ques. Where can I download the Class 12 Biology Chapter 11 Organisms and Populations NCERT Exemplar PDF free?
Ans. You can download the Class 12 Biology Chapter 11 Organisms and Populations NCERT Exemplar PDF free from this page. Both the Normal and HD versions are available, and both are free. The PDF is the official NCERT print, not a third-party reformat.
Ques. Is the NCERT Exemplar Class 12 Biology PDF aligned with the 2026-27 syllabus?
Ans. NCERT Exemplars have not been rationalised, so the PDF still carries every problem from the original edition. For Chapter 11 Organisms and Populations, that is not an issue: the new 2026-27 NCERT textbook retains every major sub-topic covered by the Exemplar (renumbered from old Chapter 13), so every problem is in scope for CBSE Board and NEET.
Ques. How many pages is the Class 12th Biology Organisms and Populations Exemplar PDF?
Ans. The Organisms and Populations NCERT Exemplar PDF runs 7 pages and packs 51 problems across MCQ-I, MCQ-II, VSA, SA, and LA types. The total marks coverage is approximately 88 marks if the suggested per-type weights are applied.
Ques. How is the NCERT Exemplar different from the NCERT textbook for this chapter?
Ans. The NCERT textbook explains ecology concepts in continuous prose with end-of-chapter long-answer exercises. The Exemplar takes the same factual base and converts it into MCQs, Match-the-Column items, assertion-reason questions, and short 1 to 5-mark prompts that mirror NEET and CBSE Board phrasing. It is the closest practice resource to NEET's question style for this chapter.
Ques. Which Organisms and Populations Exemplar problems should NEET aspirants prioritise?
Ans. Prioritise the 17 MCQs (especially Match-the-Column problems 4, 6 and 13 on interaction sign-pairs), the logistic-growth MCQ cluster (2, 7, 11), and the adaptation cluster (MCQ 9, 14 plus VSA 9, 15). These three sub-topic clusters cover roughly 80% of NEET 2021 to 2025 questions on this chapter.
Ques. Is the logistic growth derivation from Long Answer 1 important for CBSE Board?
Ans. Yes. The logistic growth derivation with sigmoid sketch (dN/dt = rN(K-N)/K, S-curve, inflexion at N = K/2, asymptote at K) has been a recurring CBSE 3 to 5-mark question. Practise drawing it on a blank A4 sheet at least twice before the Board exam, with all three phases (lag, log, deceleration) clearly marked.
Ques. What is the difference between commensalism and mutualism for this chapter?
Ans. Commensalism is +/0 (one species benefits, the other unaffected; e.g. cattle egret + cattle). Mutualism is +/+ (both species benefit; e.g. lichen, mycorrhiza, Ficus-fig wasp). Exemplar MCQs 6 and 13 test this distinction repeatedly, and NEET reuses the same framing every other year.
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