Class11 Biology Half Yearly Model Paper

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Class11 Biology Half Yearly Model Paper

Model Question Paper: 11th Biology

SECTION A: Very Short Answer Questions (1 Mark Each)

Answer the following questions in one word or one sentence.

  1. What is the lowest category in the taxonomic hierarchy for organisms in the plant and animal kingdoms?
  2. Identify the correctly written scientific name of Mango from the options below: Mangifera Indica / Mangifera indica.
  3. Name the organisms that completely lack a cell wall and are the smallest living cells known.
  4. In Annelids and Arthropods, what pattern of body organisation is exhibited where organs associate to form functional systems?
  5. What unique feature distinguishes the skin of mammals from other vertebrates?
  6. The body of Aschelminthes is commonly referred to by what name, derived from its cross-section shape?
  7. What kind of venation (arrangement of veins) is characteristic of most monocotyledonous leaves?
  8. Which layer in the dicotyledonous stem is also referred to as the starch sheath?
  9. Which scientist proposed that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula)?
  10. Name the most abundant chemical component found in living organisms.
  11. What is the approximate Tidal Volume (TV) for a healthy human during a normal respiration?
  12. In the Calvin cycle, what is the name of the 5-carbon ketose sugar that acts as the primary acceptor of $\text{CO}_2$?

SECTION B: Short Answer Type I (2 Marks Each)

  1. Differentiate between Reticulate and Parallel venation. Give one example for a plant exhibiting each type.
  2. Distinguish cytokinesis from karyokinesis.
  3. Explain how viruses, while inert outside a specific host cell, are considered obligate parasites. Briefly mention their composition.
  4. Describe the characteristics of the Phylum Platyhelminthes related to their body symmetry and germ layers.
  5. What are the two major components of $\text{ATP}$ synthase (Complex V) in oxidative phosphorylation, and what are their respective locations/functions?

SECTION C: Short Answer Type II (3 Marks Each)

  1. Explain the basis of classification used by R.H. Whittaker in his Five Kingdom classification system.
  2. Describe the key differences in reproduction, in terms of spores and gametes, between Brown Algae and Red Algae.
  3. Define the three types of vascular bundles based on the arrangement of xylem and phloem, particularly noting the difference between open and closed bundles.
  4. What are Plant Growth Regulators (PGRs)? Briefly explain the discoveries associated with Auxins.
  5. Explain the three main steps that occur during the catalytic action of an enzyme on a substrate.
  6. The partial pressures of $\text{O}_2$ and $\text{CO}_2$ are vital for gaseous exchange. Using the data from the sources, specify the partial pressures of $\text{O}_2$ and $\text{CO}_2$ in the alveolar air and in the deoxygenated blood, and comment on the direction of diffusion.

SECTION D: Long Answer Questions (5 Marks Each)

  1. Justify the statement: “All vertebrates are chordates but all chordates are not vertebrates.” Your answer should refer to the fundamental characteristics of Chordates and the divisions of the phylum.
  2. The respiratory pathway is considered an amphibolic pathway. (i) Define catabolism and anabolism. (ii) How does the respiratory pathway function in both catabolism (breakdown) and anabolism (synthesis), using fatty acids as an example? (iii) What is the theoretical net gain of $\text{ATP}$ molecules during aerobic respiration of one glucose molecule?
  3. Compare the characteristics of $\text{C}_3$ Plants and $\text{C}_4$ Plants by completing the table below:
Characteristics$\text{C}_3$ Plants$\text{C}_4$ Plants
Cell type where the Calvin cycle takes place(i)(ii)
Primary $\text{CO}_2$ acceptor molecule(iii)(iv)
Number of carbons in the primary $\text{CO}_2$ fixation product(v)(vi)
Presence of Kranz Anatomy(vii)(viii)
$\text{CO}_2$ fixation rate under high light conditions(ix)(x)
  1. Describe the structure of a eukaryotic cell membrane according to the widely accepted Fluid Mosaic Model. (i) What are the main components of the membrane structure? (ii) Explain the arrangement of lipids within the membrane bilayer. (iii) How are proteins classified based on their ease of extraction and location within the membrane? (iv) What property of the lipid bilayer allows for the lateral movement of proteins?

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With Answers

SECTION A: Very Short Answer Questions (1 Mark Each)

Answer the following questions in one word or one sentence.

  1. What is the lowest category in the taxonomic hierarchy for organisms in the plant and animal kingdoms?
    • Answer: Species.
  2. Identify the correctly written scientific name of Mango from the options below: Mangifera Indica / Mangifera indica.
    • Answer: Mangifera indica. The specific epithet (indica) must start with a small letter.
  3. Name the organisms that completely lack a cell wall and are the smallest living cells known.
    • Answer: PPLO (Pleuro Pneumonia-Like Organisms) (They are about 0.1 $\mu$m in size).
  4. In Annelids and Arthropods, what pattern of body organisation is exhibited where organs associate to form functional systems?
    • Answer: Organ-system level of body organisation.
  5. What unique feature distinguishes the skin of mammals from other vertebrates?
    • Answer: The skin of mammals is unique in possessing hair.
  6. The body of Aschelminthes is commonly referred to by what name, derived from its cross-section shape?
    • Answer: Roundworm (Example: Ascaris).
  7. What kind of venation (arrangement of veins) is characteristic of most monocotyledonous leaves?
    • Answer: Parallel venation.
  8. Which layer in the dicotyledonous stem is sometimes referred to as the starch sheath?
    • Answer: Endodermis (This is the innermost layer of the cortex).
  9. Which scientist proposed that cells divide and new cells are formed from pre-existing cells (Omnis cellula-e cellula)?
    • Answer: Rudolf Virchow (1855).
  10. Name the most abundant chemical component found in living organisms.
    • Answer: Water (70-90% of the total cellular mass).
  11. What is the approximate Tidal Volume (TV) for a healthy human during a normal respiration?
    • Answer: Approx. 500 mL.
  12. In the Calvin cycle, what is the name of the 5-carbon ketose sugar that acts as the primary acceptor of $\text{CO}_2$?
    • Answer: Ribulose bisphosphate (RuBP).

SECTION B: Short Answer Type I (2 Marks Each)

  1. Differentiate between Reticulate and Parallel venation. Give one example for a plant exhibiting each type.
    • Reticulate Venation: The veinlets form a network. This type is characteristic of dicotyledonous plants. Example: Mustard or Dicotyledonous plants generally.
    • Parallel Venation: The veins run parallel to each other within the leaf lamina. This type is characteristic of most monocotyledons. Example: Wheat or Monocotyledons generally.
  2. Distinguish cytokinesis from karyokinesis.
    • Karyokinesis refers to the nuclear division, which in mitosis involves the stages of Prophase, Metaphase, Anaphase, and Telophase.
    • Cytokinesis refers to the division of the cytoplasm.
    • Karyokinesis (nuclear division) is generally followed by cytokinesis (cytoplasmic division).
  3. Explain how viruses, while inert outside a specific host cell, are considered obligate parasites. Briefly mention their composition.
    • Viruses are considered obligate parasites because they are inert outside their specific host cell. They lack the ability to replicate on their own and only become “active” when they enter and utilize the machinery of a host cell, killing it as they replicate.
    • Viruses are fundamentally nucleoproteins. They consist of a protein coat (capsid/crystals) and contain genetic material that is either RNA or DNA, but never both.
  4. Describe the characteristics of the Phylum Platyhelminthes related to their body symmetry and germ layers.
    • Symmetry: Flatworms (Platyhelminthes) are bilaterally symmetrical.
    • Germ Layers: They are triploblastic (possessing three germ layers, inferred from their phylogenetic position among animals).
    • Body Cavity: They are acoelomates (lacking a body cavity/coelom).
  5. What are the two major components of $\text{ATP}$ synthase (Complex V) in oxidative phosphorylation, and what are their respective locations/functions?
    • The $\text{ATP}$ synthase complex consists of two major components: $\mathbf{F_1}$ and $\mathbf{F_0}$.
    • $\mathbf{F_1}$ Component: This is a peripheral membrane protein complex located on the inner mitochondrial membrane (facing the matrix). It contains the site for the synthesis of $\text{ATP}$ from $\text{ADP}$ and inorganic phosphate ($\text{P}_i$).
    • $\mathbf{F_0}$ Component: This is an integral membrane protein complex that forms a channel through which protons ($\text{H}^+$) cross the inner membrane, driving the synthesis of $\text{ATP}$ by coupling the proton passage to the $\text{F}_1$ catalytic site.

SECTION C: Short Answer Type II (3 Marks Each)

  1. Explain the basis of classification used by R.H. Whittaker in his Five Kingdom classification system.
    • R.H. Whittaker proposed the Five Kingdom classification (Monera, Protista, Fungi, Plantae, and Animalia) in 1969.
    • The classification was based on several main criteria:
      1. Cell structure (e.g., prokaryotic vs. eukaryotic).
      2. Body organisation (e.g., cellular, tissue, organ-system level).
      3. Mode of nutrition (e.g., autotrophic, heterotrophic).
      4. Reproduction.
      5. Phylogenetic relationships.
  2. Describe the key differences in reproduction, in terms of spores and gametes, between Red Algae and Brown Algae.
    • Red Algae (Rhodophyceae):
      • Vegetative reproduction occurs by fragmentation.
      • They reproduce asexually by non-motile spores.
      • They reproduce sexually by non-motile gametes.
    • Brown Algae (Phaeophyceae):
      • While Brown Algae are a defined class, the specific characteristics of their spore and gamete motility used for direct comparison are not detailed in the provided sources. We know they are distinct from Red Algae (which have non-motile spores/gametes).
  3. Define the three types of vascular bundles based on the arrangement of xylem and phloem, particularly noting the difference between open and closed bundles.
    • Three Types of Vascular Bundles:
      1. Radial: Xylem and phloem are arranged on different radii (typical in roots).
      2. Conjoint: Xylem and phloem are situated along the same radius. This type is subdivided based on cambium presence:
        • Conjoint Open: Cambium is present between the xylem and phloem. The presence of cambium allows the vascular bundle to form secondary xylem and phloem, enabling secondary growth. This is typical of dicotyledonous stems.
        • Conjoint Closed: Cambium is absent. Because cambium is absent, these bundles cannot form secondary tissues, and thus secondary growth does not occur. This is typical of monocotyledonous plants.
  4. What are Plant Growth Regulators (PGRs)? Briefly explain the discoveries associated with Auxins.
    • PGR Definition: Plant Growth Regulators (PGRs) are chemical factors internal to the plant (intracellular or intercellular) that control the processes of growth and development. They represent one of the two types of intrinsic factors regulating plant development.
    • Discovery of Auxins:
      1. Darwin and Francis Darwin: They first observed that the coleoptiles of canary grass displayed a bending response (phototropism) towards unilateral light. They concluded that the tip of the coleoptile generated a transmittable influence responsible for this bending.
      2. F.W. Went: He successfully isolated Auxin from the tips of coleoptiles of oat seedlings.
  5. Explain the three main steps that occur during the catalytic action of an enzyme on a substrate.
    • The sources describe general enzyme function and inhibition but do not explicitly list the three classical steps (E+S binding, transition state, E+P dissociation). However, the general mechanism involves converting a substrate into a product at an active site.
    • Based on the properties described in the sources, the following catalytic actions occur:
      1. Binding/Affinity: The enzyme must encounter the substrate, and the substrate must bind to the enzyme’s active site. This binding is specific.
      2. Catalysis (Chemical Change): The enzyme facilitates the chemical conversion of the substrate (S) into a product (P), such as the hydrolysis of starch into glucose. During this transformation, chemical bonds are broken and/or new bonds are formed.
      3. Inhibition/Competition: The effectiveness of the enzyme can be influenced by other molecules, such as a competitive inhibitor that closely resembles the substrate. This inhibitor competes for the substrate-binding site, demonstrating the necessity of the correct substrate binding for the catalytic action to proceed.
  6. The partial pressures of $\text{O}_2$ and $\text{CO}_2$ are vital for gaseous exchange. Using the data from the sources, specify the partial pressures of $\text{O}_2$ and $\text{CO}_2$ in the alveolar air and in the deoxygenated blood, and comment on the direction of diffusion.
    • Partial Pressures (P) in mm Hg: | Respiratory Gas | Alveoli | Deoxygenated Blood | | :— | :— | :— | | $\text{O}_2$ | 104 | 40 | | $\text{CO}_2$ | 40 | 45 |
    • Direction of Diffusion Across Alveolar Membrane: Diffusion of gases relies on the concentration gradient.
      1. Oxygen ($\text{O}_2$): Since the partial pressure of $\text{O}_2$ in the alveoli (104 mm Hg) is significantly higher than in the deoxygenated blood (40 mm Hg), oxygen diffuses from the alveoli into the blood.
      2. Carbon Dioxide ($\text{CO}_2$): Since the partial pressure of $\text{CO}_2$ in the deoxygenated blood (45 mm Hg) is slightly higher than in the alveoli (40 mm Hg), carbon dioxide diffuses from the blood into the alveoli.

SECTION D: Long Answer Questions (5 Marks Each)

  1. Justify the statement: “All vertebrates are chordates but all chordates are not vertebrates.” Your answer should refer to the fundamental characteristics of Chordates and the divisions of the phylum.
    • Chordate Characteristics (Inclusion): All animals in Phylum Chordata are characterized by the presence of three fundamental features:
      1. A notochord.
      2. A dorsal hollow nerve cord.
      3. Paired pharyngeal gill slits.
    • Vertebrate Characteristics (Divisions and Distinction): The Phylum Chordata is divided into three subphyla: Urochordata (Tunicata), Cephalochordata, and Vertebrata.
      • All vertebrates are chordates because the subphylum Vertebrata is a division within Chordata, meaning all vertebrates possess the notochord, dorsal hollow nerve cord, and pharyngeal gill slits (at some stage). Vertebrates also possess additional features like a ventral muscular heart and kidneys for osmoregulation.
      • All chordates are not vertebrates because the subphyla Urochordata and Cephalochordata are chordates that do not fall under the Vertebrata class. These non-vertebrate chordates are collectively referred to as Protochordates. Therefore, a Urochordate possesses chordate characteristics but is explicitly not a vertebrate, justifying the statement.
  2. The respiratory pathway is considered an amphibolic pathway. (i) Define catabolism and anabolism. (ii) How does the respiratory pathway function in both catabolism (breakdown) and anabolism (synthesis), using fatty acids as an example? (iii) What is the theoretical net gain of $\text{ATP}$ molecules during aerobic respiration of one glucose molecule?
    • (i) Defining Catabolism and Anabolism:
      • Catabolism: This refers to the breakdown component of metabolism. In respiration, catabolic reactions involve the utilization of $\text{O}_2$ to break down simple molecules like glucose, amino acids, or fatty acids to derive energy and release $\text{CO}_2$.
      • Anabolism: This refers to the synthesis component of metabolism. The respiratory pathway provides intermediary compounds, such as the carbon skeleton, that are used as precursors for the biosynthesis of other molecules needed by the cell.
    • (ii) Amphibolic Function (using Fatty Acids): The respiratory pathway is considered amphibolic because it is involved in both breakdown (catabolism) and synthesis (anabolism).
      • Catabolism (Breakdown): If fatty acids are used as respiratory substrates, they must first be broken down into glycerol and fatty acids. The fatty acids are subsequently degraded to acetyl $\text{CoA}$ before they can enter the respiratory pathway (specifically the Krebs’/TCA cycle).
      • Anabolism (Synthesis): Conversely, if the organism requires to synthesize fatty acids, the precursor molecule, acetyl $\text{CoA}$, is withdrawn from the respiratory pathway.
    • (iii) Theoretical Net $\text{ATP}$ Gain: The theoretical maximum net gain of $\text{ATP}$ molecules during aerobic respiration of one molecule of glucose is 38 $\text{ATP}$ molecules.
  3. Compare the characteristics of $\text{C}_3$ Plants and $\text{C}_4$ Plants by completing the table below:
Characteristics$\text{C}_3$ Plants$\text{C}_4$ Plants
Cell type where the Calvin cycle takes place(i) Mesophyll(ii) Bundle sheath
Primary $\text{CO}_2$ acceptor molecule(iii) RuBP (Ribulose bisphosphate)(iv) PEP (Phosphoenol pyruvate)
Number of carbons in the primary $\text{CO}_2$ fixation product(v) 3 (3-phosphoglyceric acid, PGA)(vi) 4 (Oxaloacetic acid, OAA)
Presence of Kranz Anatomy(vii) No (Kranz anatomy is characteristic of C4 plants)(viii) Yes (Presence of particularly large bundle sheath cells forming a ‘wreath’)
$\text{CO}_2$ fixation rate under high light conditions(ix) Low(x) High
  1. Describe the structure of a eukaryotic cell membrane according to the widely accepted Fluid Mosaic Model. (i) What are the main components of the membrane structure? (ii) Explain the arrangement of lipids within the membrane bilayer. (iii) How are proteins classified based on their ease of extraction and location within the membrane? (iv) What property of the lipid bilayer allows for the lateral movement of proteins?
    • (i) Main Components: The widely accepted Fluid Mosaic Model proposed by Singer and Nicolson (1972) depicts the cell membrane as primarily composed of: Phospholipid bilayer, Proteins (Integral and Peripheral), Cholesterol, and Sugar moieties.
    • (ii) Arrangement of Lipids: The foundation of the membrane is the phospholipid bilayer.
    • (iii) Protein Classification and Location: Proteins are classified based on their position:
      • Integral Proteins: These are typically embedded within the membrane structure.
      • Peripheral Proteins: These proteins reside on the membrane surface.
    • (iv) Property Allowing Movement: The model is termed “Fluid Mosaic” because the quasi-fluid nature of the lipid allows for the lateral movement of proteins within the overall bilayer structure. This characteristic fluidity is crucial for essential cell functions like cell growth, secretion, and cell division.
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