Cytoplasmic inheritance differs from nuclear inheritance in the absence of

Options

A. Similalrity of reciprocal crosses
B. Biparental contribution
C. Effect on backcrossing
D. All the above

Answer

To answer the question regarding how cytoplasmic inheritance differs from nuclear inheritance, let's analyze the options provided step by step.

### Step 1: Understanding Cytoplasmic Inheritance
Cytoplasmic inheritance refers to the transmission of genetic material that is located outside the nucleus, primarily in the cytoplasm of the cell, such as mitochondrial DNA. In contrast, nuclear inheritance involves genes located within the nucleus.

### Step 2: Analyzing the Options
1. **Similarity of Reciprocal Crosses**: In nuclear inheritance, reciprocal crosses do not yield the same results due to the segregation of alleles. However, in cytoplasmic inheritance, reciprocal crosses yield the same results because the cytoplasmic traits are inherited from the mother. Therefore, this option is not a difference; it is a similarity in cytoplasmic inheritance.

2. **Bi-parental Contribution**: In nuclear inheritance, traits can be inherited from both parents (bi-parental contribution). In cytoplasmic inheritance, traits are typically inherited only from the mother, as the cytoplasm of the egg contributes the majority of the cytoplasmic material. Thus, this option highlights a difference.

3. **Effect of Back-Crossing**: Back-crossing is a method used in genetics to determine the genotype of an organism. In nuclear inheritance, back-crossing can reveal the genotype of offspring based on the phenotypes of the parents. However, in cytoplasmic inheritance, back-crossing does not have the same effect because the traits are not influenced by the paternal contribution. Therefore, this option also indicates a difference.

### Step 3: Conclusion
Based on the analysis, we can conclude that cytoplasmic inheritance differs from nuclear inheritance in the absence of:
- Similarity of reciprocal crosses (present in cytoplasmic inheritance)
- Bi-parental contribution (absent in cytoplasmic inheritance)
- Effect of back-crossing (absent in cytoplasmic inheritance)

Since all the options presented highlight differences between cytoplasmic and nuclear inheritance, the correct answer is **"all of the above."**

### Final Answer
The correct option is **"all of the above."**

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