Step-by-step ICSE solutions and marking scheme for The Nervous System & Sense Organs from Selina Concise Biology (Class 10) - Chapters 10 & 11 and 5 generated practice problem sets.

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Biology Chapter 8 1 Textbook + 5 Generated Exercises 14 - 16 Marks in ICSE Board Exam

The Nervous System & Sense Organs — Solved Textbook & 5 Practice Sets

Prescribed Reference Textbook: Selina Concise Biology (Class 10) - Chapters 10 & 11

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📘 Prescribed Textbook Solved Exercise (Selina Concise Biology (Class 10))

Primary Curriculum Benchmark

Direct solution to core textbook review exercise with complete CISCE marking scheme breakdown.

Textbook Exercise 8 - Review Questions Q.5 Selina Concise Biology (Class 10) - Chapters 10 & 11 - End-of-Chapter Review

3 Marks Allotted

With reference to The Nervous System & Sense Organs: (i) Define the biological process of Brain Parts & Functions. (ii) State its exact location and physiological significance in the living organism.

Step-by-Step ICSE Evaluator Marking Key

Step 1: Scientific Definition with Technical Keywords

Define Brain Parts & Functions incorporating mandatory ICSE terminology: Cerebrum: Intelligence, memory, voluntary thought, Cerebellum: Muscular coordination and balance, Medulla: Involuntary vital centers (heartbeat/respiration).

1 Mark

Step 2: Anatomical / Cellular Location

State the precise anatomical site or organelle where this biological process occurs.

1 Mark

Step 3: Biological Significance / Function

Explain the physiological necessity of this process for organismal survival, homeostasis, or reproduction.

1 Mark

Final Verified Answer: Precise scientific definition, exact organ/organelle location, and physiological function (Key Units: Biological Nomenclature)

💡 Examiner Directive: Underline key technical terms in biological definitions. CISCE examiners specifically look for mandatory keywords.

🎯 5 Generated Practice Exercises with Step-Marking

CISCE Syllabus Graded Set

Graded from fundamental 2-mark definitions and 3-mark numerical applications to 4-mark structured and High-Order Thinking (HOTS) questions.

Generated Practice Set 1 - Core Concept (2 Marks) Difficulty: Easy

2 Marks Total

Define "Brain Parts & Functions" in the context of ICSE Class 10 Biology. State its primary characteristic or SI unit/standard symbol.

Step-by-Step Marking Breakdown

Step 1: Precise Technical Definition

1. Cerebrum: Largest part; seat of consciousness, intelligence, memory, voluntary actions. 2. Cerebellum: Coordinates muscular movement and maintains body equilibrium/balance. 3. M...

1 Mark

Step 2: Mandatory Technical Criteria

Ensure the definition contains mandatory keywords: Cerebrum: Intelligence, memory, voluntary thought, Cerebellum: Muscular coordination and balance, Medulla: Involuntary vital centers (heartbeat/respiration).

1 Mark

Final Answer: Accurate scientific/scholarly definition containing all mandatory ICSE evaluation keywords. (Units: Theoretical definition)

💡 Examiner Directive: Avoid colloquial explanations. Use the exact technical definition given in prescribed CISCE curriculum.

Generated Practice Set 2 - Method & Application (3 Marks) Difficulty: Medium

3 Marks Total

Explain the procedural method or practical demonstration used to verify "Eye Defects: Myopia vs Hypermetropia". State the working apparatus/setup and key precautions.

Step-by-Step Marking Breakdown

Step 1: State the Formula / Conceptual Principle

State the fundamental principle governing Eye Defects: Myopia vs Hypermetropia.

1 Mark

Step 2: Mathematical / Procedural Deduction

Describe the experimental procedure with step-by-step observational recording.

1 Mark

Step 3: Concluding Result & Interpretation

Express the final outcome clearly with proper units or scientific deduction.

1 Mark

Final Answer: Verified procedural conclusion for Eye Defects: Myopia vs Hypermetropia (Units: Procedural steps)

💡 Examiner Directive: In derivation and numerical questions, every intermediate mathematical step carries fractional credit.

Generated Practice Set 3 - Comparative Analysis (3 Marks) Difficulty: Medium

3 Marks Total

Differentiate between "Brain Parts & Functions" and "Eye Defects: Myopia vs Hypermetropia" on the basis of: (i) Fundamental definition/mechanism, (ii) Key working condition or formula, (iii) Real-world practical example or application.

Step-by-Step Marking Breakdown

Point 1: Conceptual Difference

Contrast the primary mechanisms: Brain Parts & Functions focuses on Cerebrum: Intelligence, memory, voluntary thought, whereas Eye Defects: Myopia vs Hypermetropia emphasizes Myopia: Image forms IN FRONT of retina, corrected by concave lens.

1 Mark

Point 2: Quantitative / Operational Difference

Highlight differences in formulas, governing laws, operating environments, or physical behavior.

1 Mark

Point 3: Exemplary Differentiation

Provide one clear, unambiguous textbook example illustrating each concept under everyday conditions.

1 Mark

Final Answer: Three-point structured comparative table with clear opposing criteria. (Units: Tabular points)

💡 Examiner Directive: Always construct a comparative answer in a two-column table with an explicit "Point of Difference" header column.

Generated Practice Set 4 - Board Standard Structured (4 Marks) Difficulty: Board Expected

4 Marks Total

A comprehensive ICSE examination question based on "The Nervous System & Sense Organs":
(i) State the fundamental law or rule governing "Brain Parts & Functions". [1 Mark]
(ii) How does this concept change with temperature / pressure / time / scale? [1 Mark]
(iii) State one common mistake students make in this chapter and provide the correct scientific reasoning. [2 Marks]

Step-by-Step Marking Breakdown

Part (i): Statement of the Law

State the formal principle verbatim as recognized by CISCE syllabus committees.

1 Mark

Part (ii): Dependency Analysis

Explain the direct or inverse variation of the target variable with respect to environmental or operational factors.

1 Mark

Part (iii): Error Analysis & Correct Resolution

Identify the frequent pitfall: Students often confuse Cerebrum: Intelligence, memory, voluntary thought with related quantities. The correct understanding requires strict application of Eye Defects: Myopia vs Hypermetropia.

2 Marks

Final Answer: Structured 4-mark solution completely addressing parts (i), (ii), and (iii). (Units: Multi-part breakdown)

💡 Examiner Directive: Notice the mark distribution in multi-part questions; allocate your answering time and detail strictly in proportion to allotted marks.

Generated Practice Set 5 - Higher Order Thinking (HOTS) (4 Marks) Difficulty: Hard

4 Marks Total

A critical scenario-based problem in "The Nervous System & Sense Organs": An experiment is performed under non-ideal conditions involving "Brain Parts & Functions" and "Eye Defects: Myopia vs Hypermetropia".
(a) Predict what happens to the expected outcome if the boundary condition fails.
(b) Give complete scientific justification.
(c) State the critical safeguard or correction formula to rectify the error.

Step-by-Step Marking Breakdown

Part (a): Prediction of Anomalous Outcome

Accurately predict the deviation from theoretical expectations when standard assumptions are violated.

1 Mark

Part (b): Scientific Justification

Provide a rigorous scientific explanation using first principles and mandatory keywords: Cerebrum: Intelligence, memory, voluntary thought, Cerebellum: Muscular coordination and balance, Medulla: Involuntary vital centers (heartbeat/respiration), Reflex arc pathway (Sensory -> Motor -> Effector).

2 Marks

Part (c): Correction Protocol & Mathematical Remedy

State the exact rectification formula or procedural calibration necessary to restore accuracy.

1 Mark

Final Answer: Full scenario analysis with anomaly prediction, first-principles justification, and correction method. (Units: HOTS Analytical Reasoning)

💡 Examiner Directive: HOTS questions in ICSE evaluate depth of conceptual understanding. Avoid superficial guessing; reason backward from core laws.

🔑 Mandatory ICSE Examiner Technical Keywords Required in Solutions

Required for Step-Marking Credit

CISCE evaluators check for the explicit usage of mandatory technical terminology when scoring reasoning questions and step derivations. The table below outlines each key term, its technical description, the examiner marking directive, and the exact model answer phrasing expected in ICSE board examination solutions.

Mandatory Keyword #1 Core Definition Chapter Concept: Brain Parts & Functions

1 Mark (Structural Location / Physiological Function)

"Cerebrum: Intelligence, memory, voluntary thought"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Cerebrum: Intelligence, memory, voluntary thought" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Cerebrum: Intelligence, memory, voluntary thought".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Brain Parts & Functions is characterized by "Cerebrum: Intelligence, memory, voluntary thought", ensuring proper structural and functional regulation."

Mandatory Keyword #2 Core Definition Chapter Concept: Brain Parts & Functions

1 Mark (Structural Location / Physiological Function)

"Cerebellum: Muscular coordination and balance"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Cerebellum: Muscular coordination and balance" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Cerebellum: Muscular coordination and balance".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Brain Parts & Functions is characterized by "Cerebellum: Muscular coordination and balance", ensuring proper structural and functional regulation."

Mandatory Keyword #3 Experimental Precaution Chapter Concept: Brain Parts & Functions

1 Mark (Structural Location / Physiological Function)

"Medulla: Involuntary vital centers (heartbeat/respiration)"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Medulla: Involuntary vital centers (heartbeat/respiration)" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Medulla: Involuntary vital centers (heartbeat/respiration)".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Brain Parts & Functions is characterized by "Medulla: Involuntary vital centers (heartbeat/respiration)", ensuring proper structural and functional regulation."

Mandatory Keyword #4 Core Definition Chapter Concept: Brain Parts & Functions

1 Mark (Structural Location / Physiological Function)

"Reflex arc pathway (Sensory -> Motor -> Effector)"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Reflex arc pathway (Sensory -> Motor -> Effector)" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Reflex arc pathway (Sensory -> Motor -> Effector)".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Brain Parts & Functions is characterized by "Reflex arc pathway (Sensory -> Motor -> Effector)", ensuring proper structural and functional regulation."

Mandatory Keyword #5 Core Definition Chapter Concept: Eye Defects: Myopia vs Hypermetropia

1 Mark (Structural Location / Physiological Function)

"Myopia: Image forms IN FRONT of retina, corrected by concave lens"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Myopia: Image forms IN FRONT of retina, corrected by concave lens" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Myopia: Image forms IN FRONT of retina, corrected by concave lens".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Eye Defects: Myopia vs Hypermetropia is characterized by "Myopia: Image forms IN FRONT of retina, corrected by concave lens", ensuring proper structural and functional regulation."

Mandatory Keyword #6 Core Definition Chapter Concept: Eye Defects: Myopia vs Hypermetropia

1 Mark (Structural Location / Physiological Function)

"Hypermetropia: Image forms BEHIND retina, corrected by convex lens"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Hypermetropia: Image forms BEHIND retina, corrected by convex lens" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Hypermetropia: Image forms BEHIND retina, corrected by convex lens".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Eye Defects: Myopia vs Hypermetropia is characterized by "Hypermetropia: Image forms BEHIND retina, corrected by convex lens", ensuring proper structural and functional regulation."

Mandatory Keyword #7 Core Definition Chapter Concept: Eye Defects: Myopia vs Hypermetropia

1 Mark (Structural Location / Physiological Function)

"Accommodation of eye by ciliary muscles"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Accommodation of eye by ciliary muscles" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Accommodation of eye by ciliary muscles".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Eye Defects: Myopia vs Hypermetropia is characterized by "Accommodation of eye by ciliary muscles", ensuring proper structural and functional regulation."

Mandatory Keyword #8 Core Definition Chapter Concept: Eye Defects: Myopia vs Hypermetropia

1 Mark (Structural Location / Physiological Function)

"Fovea / Yellow spot has highest visual acuity"

📘 Technical Definition & Detailed Description:

In ICSE Class 10 Biology (The Nervous System & Sense Organs), "Fovea / Yellow spot has highest visual acuity" is an indispensable physiological term, anatomical structure, or biological process defined in the prescribed ICSE syllabus.

⚠️ CISCE Examiner Directive & Marking Rubric:

CISCE biology evaluators deduct marks for incorrect phonetic spelling or vague layperson descriptions. Candidates must use exact biological terminology: "Fovea / Yellow spot has highest visual acuity".

📝 Model Answer Application (Exact Phrasing for Board Solutions):

"The physiological role of Eye Defects: Myopia vs Hypermetropia is characterized by "Fovea / Yellow spot has highest visual acuity", ensuring proper structural and functional regulation."

⚖️ CISCE Evaluation Directives for Biology

Step-Mark Allocation: Every sub-step, formula statement, and intermediate substitution carries independent marks. Writing final answers without formula yields zero in Section B numericals.

Mandatory SI Units: In ICSE Science and Mathematics, omitting SI units or writing incorrect unit exponents causes automatic 1/2 mark deduction per problem.

Examiner Technical Vocabulary: CISCE evaluators look for exact prescribed terms in definitions and reasoning questions. General paraphrasing often loses full credit.

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