Basic genetics refresher: which cellular structures carry the thousands of genes that enable animal and plant cells to transmit inherited characteristics?

Introduction / Context:
Hereditary information is encoded in DNA and packaged within specialized cellular structures. Recognizing the correct term is fundamental for learners across biology, biotechnology, and medicine.

Given Data / Assumptions:

• Genes reside on long DNA molecules.
• These DNA molecules are organized with proteins to form discrete bodies in the nucleus (or nucleoid in prokaryotes).
• Terminology can be confused with similarly named laboratory techniques.

Concept / Approach:
Chromosomes are the cellular entities that package DNA and carry genes. Chromatograms and chromatography relate to analytical chemistry; chromium is a chemical element unrelated to genetic information; chloroplast thylakoids perform photosynthesis, not genetic inheritance per se.

Step-by-Step Solution:

Verification / Alternative check:
Introductory genetics texts detail the chromosomal theory of inheritance connecting genes to chromosome behavior during meiosis.

Why Other Options Are Wrong:

• B/C: Analytical outputs and methods, not heritable structures.
• D: Chemical element; irrelevant to genetic carriage.
• E: Photosynthetic membranes; while chloroplasts have DNA, the question asks about structures that carry thousands of genes in general across plants and animals, which are nuclear chromosomes.

Common Pitfalls:
Confusing etymologically similar words starting with “chroma-”.

Final Answer:
Chromosomes