Heredity

Step-by-Step Solution

Step 1: Identify dominance

All progeny have violet flowers ⇒ Violet colour is dominant (W) over white (w).

Step 2: Analyze flower colour inheritance

Since one parent is white (ww), and all offspring are violet, the other parent must supply dominant allele W in every case.

This is possible only if tall parent has genotype: \[ Ww \text{ or } WW \]

Step 3: Analyze height inheritance

Short parent genotype = tt
Almost half offspring are short ⇒ ratio ≈ 1:1

This occurs only when: \[ Tt \times tt \]

Gametes from tall parent: \[ T, t \]

Offspring: \[ Tt \; (\text{tall}), \quad tt \; (\text{short}) \]

Step 4: Combine both traits

Height genotype of tall parent = Tt
Flower colour must include dominant W but may carry w ⇒ Ww

Therefore, genotype of tall parent: \[ TtWw \]

Step 5: Match with options

Correct answer is:
(d) TtWw

Step-by-Step Solution

Step 1: Given Observation

Children with light-coloured eyes have parents with light-coloured eyes.

Step 2: Case 1 — Assume light eye colour is dominant

Let dominant allele = L (light), recessive = l (dark)

Possible genotypes of parents: \[ LL \text{ or } Ll \]

Such parents can produce: \[ LL, Ll, \text{ or } ll \]

Hence, even dominant parents can have children with different traits. But they can also have light-eyed children.

Step 3: Case 2 — Assume light eye colour is recessive

Let recessive allele = l (light), dominant = L (dark)

Parents must be: \[ ll \]

Cross: \[ ll \times ll \Rightarrow ll \]

All children will have light eyes.

Step 4: Compare both cases

• Dominant case → light-eyed children possible
• Recessive case → light-eyed children also possible

Thus, both genetic models explain the observation.

Step 5: Final Conclusion

We cannot determine whether light eye colour is dominant or recessive based only on this information. Additional data such as:

• Cross-breeding results
• Pedigree analysis over generations
• Cases where parents and offspring differ

would be required.

Step-by-Step Project Outline

Step 1: Objective

To determine which coat colour in dogs is dominant using inheritance patterns.

Step 2: Selection of Dog Population

Select dogs with clearly distinguishable coat colours such as black, brown, white, etc. Ensure parentage records are available.

Step 3: Collection of Data

Record coat colour of:

• Parent dogs (P generation)
• Offspring (F1 generation)
• If available, previous generations

Step 4: Perform Controlled Crosses

Example cross:

Black dog × Brown dog

Repeat with multiple pairs to ensure reliability.

Step 5: Record F1 Generation

Observe coat colour of all offspring.

• If all offspring show same colour → that trait is likely dominant.

Step 6: Perform F1 × F1 Cross (Second Generation)

Cross two F1 individuals:

\[ F1 \times F1 \]

Step 7: Analyze F2 Generation

Count number of each coat colour.

If ratio is approximately: \[ 3:1 \] then dominant and recessive traits are confirmed.

Step 8: Test Cross (Optional but Strong Evidence)

Cross F1 individual with recessive parent:

\[ F1 \times rr \]

• 1:1 ratio confirms heterozygous dominant individual.

Step 9: Identify Dominant Trait

The coat colour that:

• Appears in all F1 offspring
• Appears in majority in F2 (3:1 ratio)

is the dominant coat colour.

Step 10: Conclusion and Report

Compile observations, ratios, and genetic interpretation to conclude dominance.

Step-by-Step Solution

Step 1: Chromosome Number in Parents

In humans (and most organisms), body cells are diploid: \[ 2n \] This means chromosomes exist in pairs—one from mother and one from father.

Step 2: Formation of Gametes (Meiosis)

During gamete formation:

• Male produces sperm
• Female produces eggs (ova)

Meiosis reduces chromosome number: \[ 2n \rightarrow n \]

Thus, each gamete carries only half the genetic material.

Step 3: Equal Contribution at Gamete Level

Each parent contributes: \[ n \text{ chromosomes} \]

Step 4: Fertilization

Fusion of gametes: \[ n + n \rightarrow 2n \]

This forms a zygote with complete chromosome set.

Step 5: Genetic Contribution

Since:

• Half chromosomes come from sperm (father)
• Half chromosomes come from egg (mother)

Therefore, genetic contribution is: \[ 50\% \text{ from father} + 50\% \text{ from mother} \]

Final Conclusion

Equal genetic contribution is ensured by:

• Formation of haploid gametes through meiosis
• Fusion of gametes during fertilization

This guarantees that offspring inherit equal genetic material from both parents.