According to Mendel, "factors" or "genes"

Options

A. are the units of inheritance
B. contain information that is required to express a particular trait
C. Both 1 and 2
D. None of the above

Answer

### Step-by-Step Text Solution:

1. **Understanding Mendel's Concept of Factors/Genes**:
- According to Gregor Mendel, the "factors" or "genes" are the basic units of inheritance. They are responsible for the transmission of traits from parents to offspring.

2. **Definition of Genes**:
- Mendel described these genes as discrete particles that carry the information necessary to express specific traits. This means that genes are not just random sequences but have a defined role in determining characteristics.

3. **Location of Genes**:
- Genes are located on chromosomes. Each gene occupies a specific position, known as a locus, on a chromosome.

4. **Alleles**:
- Each gene can have different forms called alleles. For example, in the case of a trait like plant height, there can be a dominant allele (represented as a capital letter, e.g., T) and a recessive allele (represented as a lowercase letter, e.g., t).

5. **Dominant and Recessive Alleles**:
- The dominant allele will express the trait when present, while the recessive allele will only express the trait when the dominant allele is absent. For instance, a plant with the genotype Tt (one dominant and one recessive allele) will be tall because the dominant allele T masks the effect of the recessive allele t.

6. **Homologous Chromosomes**:
- In diploid organisms, chromosomes come in pairs known as homologous chromosomes. Each pair contains one chromosome from each parent, and the alleles for a gene are located at the same locus on each chromosome of the pair.

7. **Conclusion**:
- Therefore, according to Mendel, factors or genes are the units of inheritance that contain the information required to express particular traits. The correct answer to the question is that these factors are the units of inheritance and contain the necessary information for trait expression.