Chromosomes (Basic Structure) MCQs Quiz | Class 9
Class IX Science (Code 086), Unit II: Organization in the Living World. This quiz covers the concept of chromosomes, their basic structure, chemical composition, and their role in heredity. Attempt these 10 MCQs to test your understanding, then submit to check your score and download the answer PDF.
Understanding Chromosomes
Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA). Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.
1. Basic Structure
Chromosomes are not always visible in the cell. They become visible as rod-shaped structures only when the cell is about to divide.
- Chromatids: During cell division, a chromosome consists of two identical strands called sister chromatids.
- Centromere: These two chromatids are joined together at a specific point known as the centromere.
- Chromatin: In a non-dividing cell, DNA is present as part of chromatin material, which looks like an entangled mass of thread-like structures.
2. Chemical Composition
Chromosomes consist principally of two components:
- DNA (Deoxyribonucleic Acid): This molecule carries genetic information. Functional segments of DNA are called genes.
- Proteins: These help package the DNA into a compact shape that fits inside the nucleus.
3. Functions of Chromosomes
The primary function of chromosomes is to carry hereditary information in the form of genes from parents to the next generation. This ensures the continuity of life and the transmission of traits (like eye color, height, etc.).
Quick Summary
| Component | Description |
|---|---|
| Gene | The basic physical and functional unit of heredity; a segment of DNA. |
| DNA | The chemical molecule containing genetic instructions. |
| Chromosome | The organized structure containing DNA and proteins visible during division. |
Practice Questions
- What is the difference between chromatin and chromosomes?
- Define a gene. Where is it located?
- Why are chromosomes called “hereditary vehicles”?
- Draw a schematic diagram of a chromosome showing sister chromatids and the centromere.
- Name the two chemical components of a chromosome.
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