Heredity — العلوم – الصف 10 (CBSE) بشرح مبسّط

ما ستتعلّمه

1. 1

   الدرس 1: Variation and the First Rules of Inheritance

   6 دقائق
   • Similar, but Subtly Different
   • Follow Diversity Through Generations
   • Small Differences During Asexual Reproduction
   • When a Variation Helps Survival
   • Inherited Traits: Observe Earlobes
   • A Trait Can Be Influenced by Both Parents
   • Mendel Combines Observation and Countingغير مُقيَّم
   • The First Generation Is All Tall
2. 2

   الدرس 2: Reading Mendel’s Crosses

   6 دقائق
   • Short Plants Reappear in F₂
   • Dominant and Recessive Traits
   • A Visible Trait Does Not Reveal Every Combination
   • Infer Dominance from Flower Colour
   • Two Traits Can Be Inherited Independently
   • Seed Shape and Colour: Parents to F₁
   • Read the F₂ Grid One Cell at a Time
   • Count the Four Seed Combinations
3. 3

   الدرس 3: How Genes Work and How Sex Is Determined

   8 دقائق
   • A Gene Provides Information for a Protein
   • How a Gene Can Affect Plant Height
   • Two Gene Sets in the Plant, One in Each Germ Cell
   • Chromosomes Organise Inheritance
   • Different Species Use Different Strategies
   • Human Sex Chromosomes: X and Y
   • Trace the Paternal X or Y
   • Explain What the Evidence Shows
   • Prepare Your Exercise Strategy
   • Recap: Connect Inheritance, Expression and Survival

المفاهيم الأساسية

Reproduction and variation

Quite distinct variations are visible among different individuals. Some variation also arises during asexual reproduction.

Variation in asexual reproduction

The differences are minor, while the common body design remains.

The F₂ evidence

Shortness reappears even though every F₁ plant is tall.

Dominant and recessive traits

Dominant describes which trait is expressed when the copies differ. It does not mean the other copy disappears.

Chromosomes and inheritance

The mechanism explains Mendel's results and is used by sexually reproducing organisms. Asexually reproducing organisms also follow similar inheritance rules.

Human sex chromosomes

Most human chromosomes have a maternal copy and a paternal copy.

تركيز الامتحان

Board exam

CBSE assesses this chapter in the 2026-27 year-end board examination.

Syllabus

Heredity: Heredity; Mendel's contribution- Laws for inheritance of traits: Sex determination: brief introduction.

Not assessed

These parts go beyond the 2026-27 syllabus and are taught for understanding only: Mendel Combines Observation and Counting.

Exam note

Evolution is formative-only this session and is not part of this textbook chapter.

Paper pattern

80 marks, 3 hours, 39 questions in three sections (A Biology, B Chemistry, C Physics); internal assessment 20. Units: I Chemical Substances 25, II World of Living 25, III Natural Phenomena 12, IV Effects of Current 13, V Natural Resources 5.

Question style

About 50% of board questions are competency-focused: case-based, source-based, integrated, data interpretation, situational and application-oriented.

Practice in the app

79 board-pattern questions with marking schemes: 20 multiple choice (1 mark), 11 assertion–reason (1 mark), 17 very short answer (2 marks), 17 short answer (3 marks), 3 long answer (5 marks) and 11 case-based (4 marks).

أسئلة نموذجية مع نقاط التصحيح

أسئلة بنمط امتحان المجلس من مجموعة تدريبات AI Lessons لهذا الفصل. توضّح نقاط التصحيح ما يبحث عنه المصحّح؛ والإجابات النموذجية الكاملة في التطبيق.

1. Very short answerدرجتان

   For the cross RR yy x rr YY, write the gamete contributed by each parent and give the gene combination and appearance of the F₁ seeds.

   نقاط التصحيح

   • The RR yy parent contributes Ry.0.5
   • The rr YY parent contributes rY.0.5
   • The F₁ gene combination is Rr Yy.0.5
   • The F₁ seeds are round and yellow.0.5

2. Short answer3 درجات

   During a heat wave, a student argues that all bacterial variants should survive equally well because they belong to the same species. Evaluate this claim and explain how variation can promote survival.

   نقاط التصحيح

   • Rejects equal survival and explains that advantages depend on the nature of variations and environmental conditions.1
   • Bacteria able to withstand heat survive better during a heat wave.1
   • Variation can promote survival because some individuals possess advantageous differences under the prevailing conditions.1

3. Long answer5 درجات

   (a) Explain how an alteration in a gene can result in a short pea plant through its effect on an enzyme and a growth-triggering hormone. (3 marks) (b) Explain how germ cells and chromosomes ensure equal genetic contribution from both parents while maintaining the normal chromosome number. (2 marks)

   نقاط التصحيح

   • A gene is a section of DNA providing information for one protein.1
   • An alteration in the gene for the hormone-production enzyme may make the enzyme less efficient.1
   • Lower enzyme efficiency reduces growth-triggering hormone production, resulting in a short plant.1
   • Each germ cell carries one gene set and takes one chromosome from each pair.1
   • Combination of germ cells restores the normal chromosome number, with one chromosome of each pair contributed by each parent.1

الأسئلة الشائعة

فصول أخرى في العلوم – الصف 10

• الفصل 9Light - Reflection and Refractionالدروس: 4 · الدقائق: 24→
• الفصل 10The Human Eye and the Colourful Worldالدروس: 4 · الدقائق: 21→
• الفصل 11Electricityالدروس: 4 · الدقائق: 24→
• الفصل 12Magnetic Effects of Electric Currentالدروس: 4 · الدقائق: 21→

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