Grade XI Biology under the New Course splits into Botany and Zoology, and this Set 1 paper (Code 2011) makes that split immediately obvious — Section I covers Botany with its own MCQs, short answers, and a single long-answer question, while Section II covers Zoology with its own separate MCQs, short answers, and two long-answer questions. Combined, the two sections add up to 75 marks, but the way marks are distributed is genuinely lopsided: Botany’s Group C carries just one 8-mark question, while Zoology’s long-answer section carries two 8-mark questions (16 marks total). If you’re budgeting revision time evenly between the two sections without accounting for this difference, you may be under-preparing for Zoology’s heavier long-answer load.

This particular paper leans heavily on classification, comparative biology, and “justify this statement” reasoning. The Botany section asks students to identify floral families from petal structure (Q1), recall which botanical groups belong to Bryophytes (Q3), and — in one of the more demanding OR options — justify why gymnosperms are considered more advanced than pteridophytes using actual examples (Q8 OR). The Zoology section is similarly comparison-driven: distinguishing histology from physiology and morphology (Q1), identifying which duct in vertebrates serves both excretory and reproductive functions (Q3), and crediting the correct scientist for the “ontogeny recapitulates phylogeny” concept (Q5) — a detail that’s easy to get wrong if you’ve only half-memorized the names associated with evolutionary biology’s major ideas.

Diagram-based questions also carry real weight here. Q9 in Botany shows three flower diagrams and asks students to identify the condition represented — almost certainly testing knowledge of floral symmetry or aestivation patterns. In Zoology, Q8 presents an unlabeled figure (likely a planarian or flatworm cross-section, based on the structures shown) requiring four-part labeling and functional descriptions, while Q11 requires a fully labeled diagram of the amphibian heart’s internal structure. If your revision has been mostly text-based, this paper is a strong signal to dedicate real practice time to drawing and labeling.

Below, you’ll find the complete MCQ answer key for both sections with explanations, a breakdown of the topics this paper draws from, a curated list of important questions for your final exam, FAQs with detailed explanations for the trickier and more ambiguous questions, and the complete downloadable question paper. Whether you’re balancing Botany and Zoology revision, working on diagram-based answers, or trying to nail down classification and comparative biology details that are easy to mix up, this guide should give you a solid foundation.

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• Download Full Question Paper (PDF)
• MCQ Answer Key — Botany and Zoology
• Topics Covered in This Paper
• Important Questions for Your Final Exam
• FAQs with Detailed Explanations
• How to Use This Paper Effectively

View the Full Question Paper

Get the complete NEB Grade XI Biology Set 1 (New Course) paper as a PDF — includes the three-flower diagram (Q9, Botany) and the unlabeled figure for Q8 (Zoology) referenced in the questions below.

MCQ Answer Key — NEB Biology Grade XI, Set 1

Botany contributes 5 marks (Q1-5) and Zoology contributes 6 marks (Q1-6, numbered separately within their own section), all 1 mark each, for a combined 11 marks of objective questions.

Quick explanations: Botany Q1 — a “claw” (narrow stalk-like base) and “limb” (broad upper portion) describe the structure of individual petals in a papilionaceous (butterfly-shaped) corolla, which is the diagnostic petal arrangement of the Fabaceae (pea/legume family) — consisting of a large standard petal, two wing petals, and two fused keel petals, each with a distinct claw and limb. Botany Q2 — DNA replication (the S phase, “S” for synthesis) occurs during interphase, before the cell enters the visible stages of mitotic division (prophase, metaphase, anaphase, telophase). Botany Q3 — Bryophytes is the group encompassing mosses and liverworts (and hornworts), all non-vascular land plants; ferns belong to Pteridophytes, a separate (vascular) group. Botany Q4 — “syn-” means “together,” so synecology studies groups of organisms (communities) together with their environment, as opposed to autecology, which studies individual organisms or species in relation to their environment. Botany Q5 — ribosomes are the site of protein synthesis (translation), earning them the nickname “protein factories” of the cell. Zoology Q1 — physiology is specifically the study of how body systems function (internal mechanisms), as distinct from anatomy (structure), histology (tissue-level structure), and morphology (external form). Zoology Q2 — the malarial parasite Plasmodium causes periodic fever as infected red blood cells rupture in synchronized cycles; for Plasmodium vivax and P. ovale, this cycle is approximately 48 hours (tertian malaria). Zoology Q3 — Bidder’s canal is a structure found in male frogs/toads, an anterior extension of the kidney associated with Bidder’s organ, that can serve as a pathway for both excretory products and, under certain conditions, reproductive cells — making it the structure that serves “both excretory and reproductive” functions among the listed options. Zoology Q5 — Ernst Haeckel proposed the recapitulation theory, summarized as “ontogeny recapitulates phylogeny” — the idea that the embryonic development of an organism (ontogeny) reflects the evolutionary history of its species (phylogeny). Zoology Q6 — anadromous fish (like salmon) migrate from the sea into fresh water (typically to spawn); the reverse — fresh water to sea — is called catadromous (like eels).

Topics Covered in This Paper

This Set 1 paper draws from across both the Botany and Zoology portions of the Grade XI New Course syllabus. Here’s the breakdown:

• Plant Taxonomy and Classification (Q1, Q9, Q10 Botany): floral characteristics of families like Fabaceae and Solanaceae, floral formulas and floral diagrams, identifying floral conditions from diagrams (likely aestivation or symmetry patterns).
• Cell Biology and Cell Division (Q2 Botany, Q8 Botany, Q12 Zoology OR): DNA replication timing in the cell cycle, mitochondria as the “powerhouse of the cell,” reductional division (meiosis) and prophase I.
• Plant Diversity — Lower Plant Groups (Q3 Botany): Bryophytes (mosses and liverworts) vs. Pteridophytes (ferns).
• Ecology (Q4 Botany, Q10 Botany OR, Q9 Zoology OR, Q10 Zoology): synecology vs. autecology, ecological imbalance, greenhouse effect (consequences and control measures), pollution (water pollution causes and controls), levels of biodiversity, causes of wildlife extinction.
• Cell Organelles (Q5 Botany, Q8 Botany): ribosomes (protein synthesis), mitochondria (cellular respiration/ATP production) and its functions.
• Fungi (Mycota) (Q6 Botany): definition and general characteristics of Mycota with examples.
• Microbial Biotechnology (Q7 Botany): applications of microbial biotechnology in medicine.
• Plant Groups — Comparative Evolution (Q8 Botany OR): comparing Gymnosperms and Pteridophytes in terms of evolutionary advancement.
• Long Answer Botany Topics (Q10 Botany): family Solanaceae — diagnostic floral characters, floral formula, floral diagram, medicinally/edibly important plants from this family.
• Physiology and Anatomy Terminology (Q1 Zoology): distinguishing histology, anatomy, physiology, and morphology.
• Parasitology (Q2 Zoology): malaria — Plasmodium life cycle and fever periodicity.
• Comparative Anatomy — Excretory and Reproductive Systems (Q3 Zoology): structures like Bidder’s canal, vasa efferentia, vasa deferentia.
• Wildlife Conservation (Q4 Zoology): objectives of conservation — protection, propagation, and management.
• Evolutionary Biology (Q5 Zoology, Q7 Zoology, Q12 Zoology): recapitulation theory (Haeckel), vestigial organs, Darwin’s theory of natural selection, human evolution.
• Fish Biology / Migration (Q6 Zoology): anadromous, catadromous, potamodromous, and oceanodromous migration patterns.
• Excretory System (Q7 Zoology OR): porphyrin, septal nephridium (likely referring to earthworm excretory structures).
• Invertebrate Anatomy (Q8 Zoology): labeling and functional description of structures in an unlabeled diagram (likely a flatworm/planarian based on typical Grade XI syllabus figures).
• Animal Adaptations (Q9 Zoology): volant (flight) adaptations with examples.
• Comparative Cardiovascular Anatomy (Q11 Zoology): internal structure of the amphibian heart and blood circulation mechanism.

Important Questions for Your Final Exam

These topics from Set 1 are high-value because they combine definitions with examples, diagrams, or comparative reasoning — the combination NEB Grade XI Biology consistently rewards.

• Floral characteristics of major families — Fabaceae, Solanaceae, Cruciferae, Liliaceae — with floral formulas and diagrams
• DNA replication and the phases of the cell cycle (interphase, S phase)
• Bryophytes vs. Pteridophytes — distinguishing features and examples
• Synecology vs. autecology — definitions and scope
• Mitochondria — structure, “powerhouse of the cell” reasoning, and at least three functions
• Ribosomes — structure and role in protein synthesis
• General characteristics of Mycota (fungi) with examples
• Applications of microbial biotechnology in medicine — at least five examples
• Comparative advancement of Gymnosperms over Pteridophytes — with named examples of each group
• Identifying floral conditions from diagrams (aestivation patterns: valvate, twisted, imbricate, etc.)
• Ecological imbalance, greenhouse effect — causes, consequences, and control measures
• Histology, anatomy, physiology, morphology — precise definitions and distinctions
• Malaria — Plasmodium life cycle, periodicity of fever, and transmission
• Comparative excretory/reproductive ducts in vertebrates (Bidder’s canal, vasa efferentia, vasa deferentia)
• Objectives and methods of wildlife conservation
• Recapitulation theory (Haeckel) and its significance in evolutionary biology
• Vestigial organs — definition and examples in humans
• Darwin’s theory of natural selection — key postulates (“monumentals”)
• Anadromous, catadromous, potamodromous, oceanodromous fish migration — definitions and examples
• Porphyrin and septal nephridium — structure and function (earthworm excretory system)
• Volant (flight) adaptations in animals — examples across different groups
• Pollution — types, causes of water pollution, and control measures
• Levels of biodiversity (genetic, species, ecosystem) and causes of wildlife extinction
• Internal structure of the amphibian (frog) heart and the mechanism of blood circulation
• Human evolution — major stages and hominid species
• Meiosis — why it’s called reductional division, prophase I in detail, and significance of reduction division

Frequently Asked Questions

What does “claw and limb” mean in the context of petal structure (Q1 Botany)?

In certain flowers, individual petals are differentiated into two distinct regions: the claw (or “unguis”) is the narrow, stalk-like basal portion of the petal that attaches to the receptacle, while the limb (or “lamina”) is the broader, expanded upper portion of the petal that’s typically visible and colorful. This differentiation is characteristic of the papilionaceous corolla found in Fabaceae (the pea/bean family), where the standard, wing, and keel petals each show this claw-limb structure, giving the flower its distinctive butterfly-like appearance.

Why is mitochondria the answer for “power house of the cell” in Q8, and what are its key functions?

Mitochondria are called the “power house of the cell” because they are the primary site of aerobic cellular respiration, where glucose and other organic molecules are broken down through the Krebs cycle and the electron transport chain to produce ATP (adenosine triphosphate), the cell’s main energy currency. Three key functions of mitochondria: (1) ATP production through oxidative phosphorylation — the electron transport chain located on the inner mitochondrial membrane generates the majority of a cell’s ATP; (2) site of the Krebs cycle (citric acid cycle) — occurs in the mitochondrial matrix, oxidizing acetyl-CoA derived from pyruvate and producing NADH and FADH2 for the electron transport chain; (3) regulation of cellular metabolism and apoptosis — mitochondria play roles in calcium signaling, heat production (in brown fat), and triggering programmed cell death when a cell is damaged beyond repair.

How would you justify “Gymnosperms are advanced group than Pteridophytes” in Q8 (OR)?

Several features place Gymnosperms ahead of Pteridophytes on the evolutionary scale: (1) Seed habit — Gymnosperms (e.g., Pinus, Cycas) produce true seeds, which provide protection, nutrition, and dormancy capability for the embryo, allowing survival through unfavorable conditions; Pteridophytes (e.g., Pteris, Selaginella) reproduce via spores, which lack this protective and nutritive advantage. (2) Heterospory and pollination — most Gymnosperms produce two types of spores (microspores and megaspores) and have evolved pollination mechanisms (often wind pollination) that don’t require water for fertilization; many Pteridophytes (especially homosporous ones) still depend on water for the motile sperm to reach the egg. (3) Reduced dependence on water for fertilization — Gymnosperm pollen tubes deliver sperm directly to the egg without needing a film of water, whereas Pteridophyte fertilization typically requires water for sperm motility (a holdover from their algal ancestry). (4) Vascular tissue organization — Gymnosperms have more developed vascular tissue (including tracheids with bordered pits) compared to the simpler vascular arrangements in many Pteridophytes. Together, these adaptations represent a progressive reduction in dependence on water for reproduction and improved survival of offspring — hallmarks of evolutionary advancement toward the seed plants (Gymnosperms and Angiosperms).

What floral condition might Q9’s three-flower diagram be testing?

Based on the description of three similar flowers shown side by side, each appearing to have a central structure surrounded by petal-like parts arranged in a row, this diagram likely illustrates aestivation — the arrangement of sepals or petals in a flower bud relative to one another (before the flower opens). Common aestivation types include valvate (margins just touching, not overlapping), twisted/imbricate (each petal overlaps the next in one direction, like a pinwheel), and imbricate (petals overlap irregularly, with at least one petal fully internal and one fully external). Alternatively, if the three flowers show progressively different arrangements, the diagram may be illustrating the floral whorls (calyx, corolla, androecium, gynoecium) at different developmental stages, or different types of placentation visible in a longitudinal section. Without seeing the exact diagram clearly, we recommend cross-referencing with your textbook’s chapter on floral morphology (aestivation patterns) and comparing the diagram’s petal arrangement to the standard valvate/imbricate/twisted illustrations — this is one of the more commonly tested “identify from diagram” questions in Grade XI Botany.

What is Bidder’s canal, and why does it serve both excretory and reproductive functions (Zoology Q3)?

Bidder’s canal is a longitudinal canal found within Bidder’s organ, a rudimentary structure present at the anterior end of the testis in male frogs and toads (and which can develop into ovarian tissue under certain conditions, making it biologically significant for understanding amphibian sex determination). Bidder’s canal connects to the kidney’s excretory ducts and, in some contexts, can also serve as a pathway related to reproductive cell transport — this dual association with both the urinary (excretory) system and the gonadal (reproductive) system is why it’s identified as serving “both excretory and reproductive” functions, distinguishing it from purely excretory ducts (like the ureter) or purely reproductive ducts (like the vas deferens) in the typical vertebrate body plan.

What is the “recapitulation theory” associated with Haeckel (Zoology Q5)?

Ernst Haeckel’s recapitulation theory, often summarized by the phrase “ontogeny recapitulates phylogeny,” proposes that the embryonic development of an individual organism (its ontogeny) passes through stages that resemble the evolutionary stages (phylogeny) of its ancestors. For example, early human embryos display gill-like structures (pharyngeal arches) reminiscent of fish ancestors, and a tail-like structure that’s later reduced. While the theory in its strict original form has been largely revised by modern evolutionary developmental biology (embryos don’t literally “replay” ancestral adult forms), the broader observation that related organisms often share similar early developmental stages, which diverge as development proceeds, remains an important concept in comparative embryology and evolutionary biology.

What does “septal nephridium” refer to in Zoology Q7 (OR)?

A septal nephridium is a type of excretory organ (nephridium) found in earthworms (Annelida), located on the septa (partition walls) that divide the worm’s body into segments. Each septal nephridium is a coiled tubular structure that filters coelomic fluid and waste products, with one end (the nephrostome, a ciliated funnel) opening into the coelom of the segment in front, and the other end (the nephridiopore) opening to the exterior on the segment behind — meaning each nephridium spans across a septum, hence “septal.” Porphyrin, mentioned in the same question, refers to a class of organic compounds with a characteristic ring structure (the same core structure found in hemoglobin’s heme group and chlorophyll) — in the context of earthworm excretion, porphyrins (or related pigments) can be found in the excretory products and body fluids, and their presence is sometimes discussed in relation to the chloragogen cells and excretory physiology of annelids.

What might the unlabeled figure in Zoology Q8 represent?

Based on the description of an oval/leaf-shaped outline with internal structures including what appears to be eye-spots near the top, a branched central structure, and a tube-like structure toward the bottom, this figure is highly consistent with the typical planarian (flatworm) anatomy diagram commonly used in Grade XI Biology — showing structures such as the eyespots (ocelli, labeled around “a” near the top), the auricles or sensory lobes, the pharynx (the tube-like protrusible structure, often labeled “d”), and the branched gastrovascular cavity (labeled “c”). Given the question asks for characteristics of “a” and functions of “b,” “c,” and “d,” this strongly suggests “a” refers to the eyespots/sensory structures (with characteristics like light sensitivity, simple structure without lenses), “b” might refer to the auricles (function: chemoreception/sensory perception), “c” to the branched intestine/gastrovascular cavity (function: digestion and distribution of nutrients, since flatworms lack a circulatory system), and “d” to the pharynx (function: ingestion of food, extends out of the mouth to capture prey). We strongly recommend viewing the actual figure in the downloaded PDF to confirm these identifications, as flatworm anatomy diagrams vary in which structures are emphasized.

What are “volant adaptations” as asked in Zoology Q9?

Volant adaptations are anatomical and physiological features that enable an organism to fly (volant = “flying” or “capable of flight”). Examples across different animal groups include: in birds, lightweight but strong bones (often hollow/pneumatic with internal struts), feathers providing both lift and insulation, a keeled sternum for flight muscle attachment, and an efficient respiratory system with air sacs; in bats (the only flying mammals), a patagium (wing membrane) stretched between elongated finger bones, the forearm, and the body, along with echolocation for navigation; in insects (like butterflies and dragonflies), wings derived from cuticular extensions of the exoskeleton, powered by either direct or indirect flight muscles attached to the thorax. Across all these examples, common themes include weight reduction, surface area maximization for lift generation, and powerful musculature dedicated to wing movement.

What’s the structure of the amphibian (frog) heart, as asked in Zoology Q11?

The frog heart has three chambers: two atria (left and right) and a single ventricle, plus a structure called the sinus venosus (a thin-walled chamber that receives deoxygenated blood from the body and oxygenated blood doesn’t pass through it directly — it feeds into the right atrium) and the truncus arteriosus (which leads blood out of the ventricle and contains a spiral valve that helps direct blood flow). The right atrium receives deoxygenated blood from the body via the sinus venosus, while the left atrium receives oxygenated blood from the lungs via the pulmonary veins. Both atria empty into the single ventricle, where some mixing of oxygenated and deoxygenated blood occurs (though the spiral valve in the truncus arteriosus and the timing of contractions minimize this mixing). From the ventricle, blood is pumped through the truncus arteriosus, which branches into vessels supplying the lungs/skin (pulmocutaneous circuit, carrying less oxygenated blood) and the rest of the body (systemic circuit, carrying more oxygenated blood). This arrangement — a single ventricle with partial separation of oxygenated and deoxygenated blood flows — is characteristic of amphibians and represents an intermediate stage between the fully separated double circulation of mammals/birds and the simpler single-circuit hearts of fish.

Why is meiosis called “reductional division” and what’s the significance (Zoology Q12 OR)?

Meiosis is called reductional division specifically referring to Meiosis I, because it reduces the chromosome number from diploid (2n) to haploid (n) — the resulting daughter cells have half the number of chromosomes as the parent cell. This occurs because, unlike mitosis (where chromosomes are duplicated and then separated, maintaining the chromosome number), in Meiosis I, homologous chromosome pairs separate from each other (without prior duplication between Meiosis I and II), halving the chromosome number. Prophase I is the longest and most complex phase, divided into substages: leptotene (chromosomes begin condensing, appearing as thin threads), zygotene (homologous chromosomes pair up via synapsis, forming bivalents/tetrads), pachytene (crossing over occurs between homologous chromosomes, exchanging genetic material), diplotene (homologous chromosomes begin to separate but remain connected at chiasmata), and diakinesis (chromosomes reach maximum condensation, nuclear envelope breaks down). The significance of reductional division: it ensures that when gametes (with n chromosomes) fuse during fertilization, the resulting zygote has the correct diploid (2n) chromosome number for the species — without this reduction, chromosome numbers would double with each generation. Additionally, the crossing over that occurs during prophase I generates new combinations of alleles, contributing significantly to genetic variation among offspring.

How to Use This Paper Effectively

Given the mark distribution in this paper — Botany’s Group C is worth only 8 marks while Zoology’s long-answer section is worth 16 marks — allocate your practice and revision time proportionally. If you’ve been splitting Botany and Zoology revision 50/50, this paper is a reminder that Zoology’s long-answer topics (comparative anatomy, evolution, cell division) often carry more weight in the overall mark scheme and deserve correspondingly more practice time.

The “justify this statement” and “discuss” style questions (Q8 Botany OR, Q10 Botany OR, Q10 Zoology) reward structured, point-by-point answers rather than flowing prose. When practicing these, draft your answer as a numbered or clearly segmented list of distinct points (each with a brief explanation), since this format both helps you cover enough distinct points to earn full marks and makes your answer easier for examiners to credit completely.

For the diagram-based questions (Q9 Botany, Q8 Zoology, Q11 Zoology), don’t just look at the diagrams passively — redraw each one from memory multiple times, labeling every part, until you can reproduce it without referring to your notes. NEB Biology consistently allocates marks for diagram accuracy and correct labeling independent of the written explanation, so a strong diagram with a weaker explanation often scores better than a strong explanation with a missing or incorrect diagram.