The hereditary characters in plants and animals are located on the

1. Analyze the question The question asks where hereditary characters (traits passed from parents to offspring) are located. The key word is "located on", so we need the structure that physically carries the hereditary material.

2. Explain the concept

• Cell: the basic unit of life. It contains the nucleus, but it is too general.
• Nucleus: the control center of the cell. It contains the chromosomes.
• Chromosome: a thread-like structure made of DNA and protein, found in the nucleus. It carries the genes in a linear order.
• Gene: a short section of DNA that codes for a particular trait. Genes are the units of heredity.

The hierarchy runs from big to small: Cell → Nucleus → Chromosome → Gene.

3. Solution Genes are the actual units of heredity, but they do not float freely in the cell. They are arranged along chromosomes, so we say genes are located on chromosomes. Hereditary characters are therefore located on the chromosomes.

• A (gene): hereditary characters are determined by genes, but genes themselves are located on chromosomes.
• B (nucleus): the nucleus is the organelle that houses the chromosomes, so it is too broad.
• C (chromosome): correct. It is the carrier of the genes.
• D (cell): too general.

4. Answer The correct option is C. chromosome.

5. Exam tip Remember the phrase "genes sit ON chromosomes, chromosomes sit IN the nucleus." If a question says "located on", think chromosome. If it says "units of heredity" or "determine a trait", think gene.