Biology Class 11 SEE Model Paper 1 2025-26 (Outstanding Success)

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Biology Class 11 SEE Model Paper 1 2025-26

Section – A

  1. The scientific name of Lion is:
  1. Felis Leo
  2. Panthera tigris
  3. Panthera Leo
  4. Panthera Pardus.

Answer: (C) Panthera Leo

  1. No. of cranial nerves present in frogs is-
  1. 15
  2. 20
  3. 10
  4. Infinite

Answer: (C) 10

  1. Name the complication which arises when a Rh+ foetus is developing the womb of a Rh- mother.
  1. Angina
  2. Erythroblastosis foetalis
  3. Cardiac arrest
  4. None

Answer: (B) Erythroblastosis foetalis

  1. What will happen if CO₂ level increases in blood?
  1. The body accelerates breathing to fulfil oxygen needs.
  2. Chemo sensitive area adjacent to respiratory rhythm centre gets activated.
  3. The respiratory rhythm centre in the medulla regulates breathing rate.
  4. All of the above.

Answer: (D) All of the above.

Biology Class 11 SEE Model Paper 1 2025-26

  1. During tubular secretion, which ions are secreted in the filtrate: –
  1. H⁺ ions
  2. K⁺ ions
  3. Ammonia⁺ ion
  4. All of the above

Answer: (D) All of the above.

  1. Pick the mismatched pair
  1. Cycas- Dioecious
  2. Equisetum-Homosporous
  3. Salvinia- Heterosporous
  4. Pinus – Dioecious

Answer: (D) Pinus – Dioecious

  1. Arrangement of Ovules within the Ovary is known as-
  1. Aestivation
  2. Placentation
  3. Both A & B
  4. None

Answer: (B) Placentation

  1. What is the first stable product of the Hatch Slack pathway?
  1. 3- phosphoglycerate
  2. Pyruvate
  3. Oxaloacetic acid
  4. Malate

Answer: (C) Oxaloacetic acid

  1. What is the function of the enzyme ACC synthase in ethylene biosynthesis?
  1. Converts ACC to ethylene
  2. Inhibits ethylene production
  3. Promotes cell division
  4. Catalyzes the formation of ACC

Answer: (D) Catalyzes the formation of ACC

  1. Which of the following is not correct about sternum?
  1. It is a flat bone.
  2. It is located on the ventral midline of the thorax.
  3. It is 2 in number.
  4. It is commonly called breast bone.

Answer: (C) It is 2 in number. 

  1. Match List I with List II and select the correct option-
List I (Plasma Protein)List II (Functions)
iFibrinogenaDefence mechanism
iiGlobulinsbOsmotic Balance
iiiAlbuminscCoagulation of Blood
  1. I-C,II-A,III-B
  2. I-A,II-C,III-B
  3. I-C,II-B,III-A
  4. I-B,II-A,III-C

Answer: (A) I- C, II- A, III- B

Biology Class 11 SEE Model Paper 1 2025-26

  1. The two halves ( left and right) cerebral hemispheres are connected by a tract of nerve fibres called:
  1. Association areas
  2. Corpus callosum
  3. Hypothalamus
  4. None of the above.

Answer: (B) Corpus callosum

For questions 13 through 16, two statements are provided: Assertion (A) and Reason (R).

  1. Both A and R are factually correct, and R provides the precise logical explanation for A.
  2. A is true and R is also true, but R does not logically justify or clarify A.
  3. Assertion A holds true; however, the reason given in R is factually incorrect.
  4. Assertion A is not valid, but the statement in Reason R is accurate.

Assertion (A): Sponges exhibit cellular level of organisation.

 Reason (R): In sponges, cells are arranged as loose cell aggregates.

Answer: (A). Both A and R are factually correct, and R provides the precise logical explanation for A.

Assertion(A): Amino acid is amphoteric in nature.

Reason (R): Essential amino acids must be obtained through diet, as the body cannot produce them.

Answer: (C) Assertion A holds true; however, the reason given in R is factually incorrect.

Assertion(A): Carbohydrates are used first by most cells in respiration.

Reason(R): Lipids are used in respiration.

Answer: (B) A is true and R is also true, but R does not logically justify or clarify A.

16.

Assertion(A): The chemicals stored in the synaptic vesicles are termed as neurotransmitters.

Reason(R): These chemicals are released by synaptic vesicles into the synaptic cleft.

Answer: (A). Both A and R are factually correct, and R provides the precise logical explanation for A.

Biology Class 11 SEE Model Paper 1 2025-26

Section – B

  1. Differentiate between primary and secondary metabolites.

Answer:

  • Primary Metabolites: These are directly involved in normal growth, development, and reproduction of an organism. They perform physiological functions. Examples: carbohydrates, proteins, lipids, nucleic acids.
  • Secondary Metabolites: These are not directly involved in normal growth and development but often play a role in ecological functions like defence, attraction, etc. They are derived from primary metabolites. Examples: alkaloids (morphine), tannins, antibiotics, pigments.
  1. Differentiate between myelinated and non- myelinated axons.

Answer:

  • Myelinated axons: Have a myelin sheath (a fatty insulating layer) formed by Schwann cells (in PNS) or oligodendrocytes (in CNS). They have nodes of Ranvier. Conduction of nerve impulses is faster (saltatory conduction).
  • Non-myelinated axons: Lack a myelin sheath. The axon is simply enveloped by Schwann cells without myelin winding. Conduction of nerve impulses is slower.

OR

Distinguish between efferent and afferent neurons.

Answer:

  • Afferent Neurons (Sensory Neurons): Transmit nerve impulses from sensory receptors (in sense organs, skin, etc.) towards the central nervous system (brain and spinal cord).
  • Efferent Neurons (Motor Neurons): Transmit nerve impulses from the central nervous system to effector organs like muscles and glands.
  1. Identify the structure responsible for bacterial movement.
  2. Name two surface extensions that are not concerned with motility of bacterial cells

Answer:

(i) Structure for motility in bacterial cells: Flagella (or bacterial flagella).
(ii) Surface extensions not concerned with motility: Pili and Fimbriae.

  1. A virus is considered as a living organism and an obligate parasite when inside a host cell. Why are viruses classified separately from bacteria and fungi, and what non-living traits do they exhibit?

Answer:

Characteristics of viruses similar to non-living objects:

  1. They are acellular, consisting only of genetic material (DNA or RNA) surrounded by a protein coat.
  2. They lack their own metabolism and can be crystallized.
  3. They cannot reproduce (multiply) outside a living host cell. They are inert in their extracellular state.

Biology Class 11 SEE Model Paper 1 2025-26

  1. Cellulose, starch, chitin, glycogen are polysaccharides found among the following. Select the correct option and write it beside each item.
  1. Peeled potato -_ _ _ _ _ _ _ _ _
  2. Exoskeleton of cockroach -_ _ _ _ _ _ _ _ _
  3. Liver -_ _ _ _ _ _ _ _ _
  4. Cotton fibre – _ _ _ _ _ _ _ _

Answer:

(A) Peeled potato: Starch.

(B) Exoskeleton of cockroach: Chitin.

(C) Liver: Glycogen.

(D) Cotton fibre: Cellulose

Biology Class 11 SEE Model Paper 1 2025-26

Section – C

  1. Provide one example for each category listed.
  1. An organ, which regulates buoyancy.
  2. A fish possessing a poison string.
  3. Name an animal that displays alternation of generations.
  4. A fish possessing an electric organ
  5. Identify an organism with a water vascular system.
  6. Name one flightless bird.

Answer:

  1. An organ which regulates buoyancy: Swim bladder (in bony fishes)
  2. A fish possessing a poison string: Trygon (Stingray)
  3. An animal which exhibits alternation of generation: Obelia (a type of cnidarian)
  4. A fish possessing an electric organ: Torpedo (Electric ray)
  5. An organism possessing a water vascular system: Asterias (Starfish)
  6. Name one flightless bird: Ostrich
  1. How are gibberellins useful in agriculture to improve productivity?

Answer:

  • Increasing fruit size: Spraying gibberellins on grapes leads to elongation of the stalks and larger fruits (e.g., seedless grapes).
  • Breaking dormancy: They help in breaking the dormancy of seeds and buds, promoting germination and growth.
  • Bolting: They stimulate internode elongation in plants like cabbage, causing them to “bolt” (flower) before harvesting.
  • Parthenocarpy: enables the formation of seedless fruits.

OR

Answer the following:

  1. Name a hormone which is gaseous in nature.
  2. Name a hormone which induces femaleness in the flower of cucumber.
  3. Name a hormone which induce parthenocarpy.

Answer:

  1. Name a hormone which is gaseous in nature. Ethylene
  2. Name a hormone which induces femaleness in the flower of cucumber.Ethylene
  3. Name a hormone which induce parthenocarpy. Auxin

Biology Class 11 SEE Model Paper 1 2025-26

  1. Name the organism, the figure of which is given below.
  2. Classify the organism given below according to the label shown.
  3. Why are they called protochordates?
Biology Class 11 SEE Model Paper 1 2025-26

Answer:

  1. Organism: A typical Chordate (e.g., Branchiostoma or Amphioxus).
  2. Labels: Because of the presence of dorsal hollow nerve chord, a notochord, gill slits and host anal part the organism shown will be classified as A typical Chordate.
  3. Protochordates: They are called so because they possess a notochord but lack a true vertebral column.
    Chloroplast (https://gyanpankh.com/)
    1. Observe the diagram and identify parts A and B.
    2. Identify the picture shown below.
    3. Give the function of each.

    Answer:

    1. Labels: A = Stroma, B = Grana (Thylakoid stack).
    2. Picture: Chloroplast.
    3. Functions: Grana is the site for light-dependent reactions (ATP production); Stroma is the site for dark reactions (CO2 fixation).
    1. Imagine you have been provided the transverse section of the young stem of a plant from your school garden. After observation, how would you ascertain whether it is a dicot stem or a monocot stem? Give reasons.

    Answer:

    Dicot Stem: Vascular bundles are arranged in a ring; a distinct pith is present.

    Monocot Stem: Vascular bundles are scattered throughout the ground tissue; no distinct pith.

    Biology Class 11 SEE Model Paper 1 2025-26

    1. represent schematically the pathway of TCA cycle.

    Answer:

    citric acid cycle
    1. In which plant type is Kranz anatomy found, and what adaptations does it confer? How are these plants better adapted than the plants, which lack this anatomy?

    Answer:

    Found in C4 plants (e.g., Maize, Sugarcane).

    Adaptation: Better adapted to high light intensities and high temperatures.

    Advantage: They lack photorespiration, making them more efficient at carbon fixation than C3 plants.

    Biology Class 11 SEE Model Paper 1 2025-26

    Section – D

    1. Review the passage and respond to the questions:

    Pancreas is a composite gland which acts both exocrine and endocrine gland. Islets of Langerhans constitute the pancreatic endocrine tissue. The two main types of cells in the Islets of Langerhans are called Alpha cells & Beta cells. The Alpha cells secrete a hormone called glucagon while beta cells secrete insulin.

    1. What is the role of insulin in controlling the level of glucose in blood?
    2. Which endocrine gland and its part is involved in the secretion of insulin?
    3. What is hypo glycaemia?

    Answer:

    Role of Insulin: It lowers blood glucose levels by stimulating cellular glucose uptake and conversion to glycogen.

    Gland/Part: Pancreas; Beta cells of the Islets of Langerhans.

    Hypoglycaemia: A condition where blood glucose levels are abnormally low.

    1. Read the given passage and answer the questions:

    The sporophyte of pteridophytes features true roots, stems, and leaves with well-developed vascular tissue.

    1. What are sporophylls?
    2. List two heterosporous pteridophyte species.
    3. Identify the male and female reproductive structures in pteridophytes.

    Answer:

    Sporophylls: Leaf-like structures that bear sporangia.

    Heterosporous species: Selaginella and Salvinia.

    Sex organs: Male: Antheridia; Female: Archegonia.

    Biology Class 11 SEE Model Paper 1 2025-26

    Section – E

    1. Inspiratory muscles and expiratory muscles play a very important role in the Respiratory process. Explain.
    2. Cigarette smoking causes emphysema. Give reason.

    Answer:

    (a) Muscles: Inspiration is initiated by the contraction of the diaphragm and external intercostal muscles, increasing thoracic volume. Expiration occurs when these muscles relax, decreasing volume and forcing air out.

    (b) Emphysema: Cigarette smoking damages the alveolar walls, significantly reducing the surface area for gas exchange

    OR

    Explain how red blood cells facilitate oxygen and carbon dioxide transport.

    Answer:

    Role of RBCs: Haemoglobin in RBCs binds with oxygen to form oxyhaemoglobin for transport to tissues; it also carries about 20-25% of carbon dioxide as carbamino-haemoglobin.

    1. Why is mitosis called equational division?
    2. Comment on the statement -Telophase is the reverse of prophase.

    Answer:

    (a) Mitosis: Called equational division because the number of chromosomes in daughter cells remains the same as in the parent cell.

    (b) Telophase/Prophase: Telophase is the reverse because chromosomes decondense, the nuclear envelope reforms, and the nucleolus reappears—all events that are undone during prophase.

    OR

    List the stages of meiotic prophase I in order? Enumerate the chromosomal events during each stage?

    Answer:

    Meiotic Prophase I stages:

    1. Leptotene: Chromosomes become visible.
    2. Zygotene: Pairing of homologous chromosomes (synapsis).
    3. Pachytene: Crossing over occurs.
    4. Diplotene: Dissolution of the synaptonemal complex; chiasmata formation.
    5. Diakinesis: Terminalisation of chiasmata.

    Biology Class 11 SEE Model Paper 1 2025-26

    1. the diagram given below represents a kind of Aestivation.
    Biology Class 11 SEE Model Paper 1 2025-26
    1. define Aestivation.
    2. Identify the type of Aestivation.
    3. Provide a plant example that demonstrates this characteristic.
    4. Differentiate between actinomorphic and zygomorphic.

    Answer:

    (A) Definition: The mode of arrangement of sepals or petals in the floral bud with respect to other members of the same whorl.

    (B) Type (from diagram): Valvate

    (C) Example: Calotropis.

    (D) Difference: Actinomorphic flowers have radial symmetry (can be divided into two equal halves in any radial plane) Example: Mustard, China rose.

    Zygomorphic flowers have bilateral symmetry (can be divided into two equal halves in only one vertical plane). Example: Pea, Gulmohar.

    OR

    Draw and label a detailed diagram showing the internal anatomy of a dorsiventral leaf.

    Answer:

    dorsiventral leaf

    1. Epidermis

    • Upper (Adaxial) & Lower (Abaxial) Epidermis: Covers both surfaces of the leaf and is usually covered by a thick cuticle to prevent water loss.
    • Stomata: In a dorsiventral leaf, stomata are generally more numerous on the lower epidermis than on the upper epidermis; sometimes the upper epidermis may even lack them.

    2. Mesophyll

    Mesophyll refers to the tissue layer situated between the upper and lower epidermis. It contains chloroplasts for photosynthesis and is differentiated into two types of cells:

    • Palisade Parenchyma: Located adaxially (towards the top), consisting of vertically elongated cells arranged parallel to each other.
    • Spongy Parenchyma: Located below the palisade cells and extends to the lower epidermis. These cells are oval or round, loosely arranged, and have large intercellular spaces or air cavities.

    3. Vascular System

    • Vascular Bundles: These are found in the veins and the midrib. The size of the vascular bundles is dependent on the size of the veins.
    • Bundle Sheath: Each vascular bundle is surrounded by a layer of thick-walled cells called bundle sheath cells.
    • Xylem and Phloem: Xylem is typically located towards the upper epidermis (adaxial), while phloem is located towards the lower epidermis (abaxial).

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