The phenotype of an individual may be affected in the modified allele produces
(a) No enzyme at all
(b) The normal enzyme
(c) A non-functional enzyme

Options

A. Only a is correct
B. a and c are correct
C. b and c are correct
D. Only c is correct

Answer

To solve the question regarding how the phenotype of an individual may be affected by a modified allele, we can break it down into the following steps:

### Step 1: Understand the Role of Alleles
Alleles are different forms of a gene that can produce variations in traits. A modified allele can lead to different outcomes in terms of enzyme production.

**Hint:** Consider how changes in genes can lead to different types of proteins or enzymes being produced.

### Step 2: Analyze the Three Conditions
The question presents three scenarios regarding the effect of a modified allele on enzyme production:
1. No enzyme at all.
2. The normal enzyme.
3. A non-functional enzyme.

**Hint:** Think about how each of these scenarios might impact the organism's phenotype.

### Step 3: Evaluate Each Condition
- **Condition (a): No enzyme at all** - If the modified allele does not produce any enzyme, the metabolic processes that depend on that enzyme will be disrupted. This will likely lead to a noticeable change in phenotype, possibly resulting in a genetic disorder.

- **Condition (b): The normal enzyme** - If the modified allele produces the normal enzyme, there will be no effect on the phenotype. The normal physiological processes will continue as they did before the modification.

- **Condition (c): A non-functional enzyme** - If the modified allele produces an enzyme that is non-functional, the metabolic processes will still be affected, leading to a change in phenotype, as the substrate will not be transformed effectively.

**Hint:** Consider how the presence or absence of functional enzymes affects biological processes.

### Step 4: Conclusion
From the analysis:
- Conditions (a) and (c) will lead to an affected phenotype due to the lack of enzyme activity or the presence of a non-functional enzyme.
- Condition (b) will not affect the phenotype since the normal enzyme is still produced.

Thus, the correct answer to the question is that the phenotype of an individual may be affected if the modified allele produces either **(a) No enzyme at all** or **(c) A non-functional enzyme**. However, the option that indicates no effect is **(b) The normal enzyme**.

**Final Answer:** The phenotype of an individual may be affected if the modified allele produces (a) No enzyme at all or (c) A non-functional enzyme. The correct answer is (b) The normal enzyme does not affect the phenotype.