Heredity — Class 10 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 10 Biology chapter "Heredity" — 7 important questions with detailed answers for CBSE board exam preparation.
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TL;DR: Free step-by-step NCERT solutions for Class 10 Biology chapter "Heredity" — 7 important questions with detailed answers for CBSE board exam preparatio…
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Key Questions Covered:
- What is heredity? Define the terms gene, allele, and trait.
- Who was Gregor Mendel? What are Mendel's laws of inheritance?
- What is a monohybrid cross? Explain Mendel's monohybrid cross with a Punnett …
- What is sex determination? Explain how sex is determined in humans.
- Explain the difference between dominant and recessive traits with examples.
- What is the difference between homozygous and heterozygous organisms? Give ex…
- + 1 more questions in the full chapter
Solutions Summary:
| Question | Status |
|---|---|
| What is heredity? Define the terms gene, allele, and trait. | ✓ Solved |
| Who was Gregor Mendel? What are Mendel's laws of inherita… | ✓ Solved |
| What is a monohybrid cross? Explain Mendel's monohybrid c… | ✓ Solved |
| What is sex determination? Explain how sex is determined … | ✓ Solved |
| Explain the difference between dominant and recessive tra… | ✓ Solved |
| What is the difference between homozygous and heterozygou… | ✓ Solved |
Showing 6 of 7 questions
Q1: What is heredity? Define the terms gene, allele, and trait.
Heredity is the passing of characteristics from parents to offspring through genes. It is the basis of inheritance.
Key definitions:
1. Gene:
- A unit of heredity
- A segment of DNA that codes for a specific protein
- Responsible for a particular trait
- Located on chromosomes
- Humans have about 20,000-25,000 genes
2. Allele:
- Different forms or variants of a gene
- Example: For eye color gene, alleles might be for brown eyes or blue eyes
- Each organism has two alle...
Q2: Who was Gregor Mendel? What are Mendel's laws of inheritance?
Gregor Mendel (1822-1884):
- Augustinian friar and scientist
- Conducted experiments with pea plants in monastery garden
- Discovered fundamental laws of inheritance
- Work was ignored in his lifetime; rediscovered in 1900
- Now called the "Father of Genetics"
Mendel's Laws of Inheritance:
1. Law of Segregation:
- During gamete formation, alleles of a gene separate so each gamete receives only one allele
- During fertilization, pairs of alleles are restored
- Each offspring ...
Q3: What is a monohybrid cross? Explain Mendel's monohybrid cross with a Punnett square.
A monohybrid cross is a cross between two organisms that differ in only one trait, controlled by one gene with two alleles.
Example: Cross between tall pea plant (TT) and short pea plant (tt)
Setup:
- TT plant produces gametes: all T
- tt plant produces gametes: all t
- Cross: TT × tt
Punnett square:
Gametes of tt parent
t t
T | Tt | Tt |
T | Tt | Tt |
Gametes of TT parent
F1 Generation Results:
- Genotype: All Tt (100% heterozygous)
- Phenotype: A...
Q4: What is sex determination? Explain how sex is determined in humans.
Sex determination is the biological process that determines whether an organism develops as male or female.
In humans, sex is determined by chromosomes:
Chromosome system:
- Humans have 23 pairs of chromosomes (46 total)
- 22 pairs are autosomes (non-sex chromosomes)
- 1 pair is sex chromosomes: XX or XY
Sex chromosomes:
- Females: XX (two X chromosomes)
- Each parent contributes one X
- Homozygous for X chromosome
- Males: XY (one X and one Y chromosome)
- Mother contributes X
- Fath...
Q5: Explain the difference between dominant and recessive traits with examples.
Dominant and Recessive Traits:
Dominant trait:
- The trait that appears in the organism's phenotype when at least one dominant allele is present
- Represented by capital letter (e.g., A, T, B)
- Expressed in both homozygous (AA) and heterozygous (Aa) genotypes
- Dominant allele: stronger or masks the recessive allele
- Example: Brown eyes (B) is dominant over blue eyes (b)
- BB person: brown eyes
- Bb person: brown eyes (blue is hidden)
Recessive trait:
- The trait that appears only when t...
Q6: What is the difference between homozygous and heterozygous organisms? Give examples.
Homozygous:
- An organism having two identical alleles for a particular gene
- Both alleles are the same (either both dominant or both recessive)
- Represented as: AA (homozygous dominant) or aa (homozygous recessive)
- Homozygous organisms are called pure breeds
- Produce only one type of gamete for that gene
- Example: TT (both alleles for tallness) or tt (both alleles for shortness)
Heterozygous:
- An organism having two different alleles for a particular gene
- One dominant allele and one r...
Showing 6 of 7 questions. Visit the full page for complete solutions.