MCQ Detailed View

Genes are the basic units of heredity that carry the instructions for the development, functioning, and reproduction of all living organisms. In eukaryotic cells, genes are located on chromosomes, which are thread-like structures found in the nucleus of the cell.

Each chromosome is made of DNA (deoxyribonucleic acid) tightly coiled around proteins called histones. DNA contains sequences of nucleotides that form genes, which determine traits such as eye color, blood type, height, and even certain genetic disorders. Humans have 46 chromosomes, arranged in 23 pairs, where each parent contributes one chromosome per pair.

Other options in the question are incorrect:

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  Genetics is the study of genes and heredity, not a cell structure.

  
  


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  Saliva is a digestive fluid and does not contain genes, though it may contain DNA from cells.

  
  


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  Marrow is tissue found in bones and produces blood cells; it contains cells with DNA, but it is not the structure where genes are organized.

  
  

Chromosomes are highly organized and ensure accurate replication and distribution of genetic material during cell division (mitosis and meiosis). During reproduction, genes on chromosomes are passed from parents to offspring, allowing traits to be inherited.

Understanding the role of chromosomes and genes is essential in cell biology, genetics, medicine, and biotechnology. It helps explain inheritance patterns, genetic disorders, and modern techniques like gene therapy and genetic engineering.

In summary, the correct answer is Chromosome, as it is the structure within a cell that contains genes, making it the blueprint for all biological traits and hereditary information.