Factors Affecting Growth & Development: Heredity MCQs Quiz | Class 9
This is an online MCQ quiz for Class IX Home Science (Code 064), Unit II: Human Growth & Development – I. The topic covered is Genetic influences on growth/development. Attempt all questions and click ‘Submit Quiz’ to see your score. You can download a PDF of your answers after finishing.
Understanding Heredity and Its Influence on Growth
Heredity is the process by which physical and mental characteristics are passed down from parents to their children. These characteristics are carried by tiny units called genes, which are located on structures called chromosomes. Understanding heredity is crucial in Home Science as it helps us appreciate the biological foundation of human growth and development.
Key Concepts in Heredity
- Genes: These are the basic units of heredity. They are like a blueprint that determines various traits such as eye color, hair color, height, and even certain aspects of personality and health.
- Chromosomes: Genes are arranged on thread-like structures called chromosomes. Humans have 23 pairs of chromosomes in each cell, for a total of 46. You inherit one set of 23 from your mother and another set of 23 from your father.
- DNA (Deoxyribonucleic Acid): Chromosomes are made of a long molecule called DNA. DNA contains the genetic code or instructions for building and maintaining an organism.
- Dominant and Recessive Genes: For many traits, you inherit two genes, one from each parent. A dominant gene is one that will express its trait even if only one copy is present. A recessive gene will only express its trait if two copies are present. For example, the gene for brown eyes is dominant over the gene for blue eyes.
How Heredity Affects Growth and Development
Heredity sets the potential for an individual’s growth. It influences several aspects:
- Physical Growth: Your potential height, body structure, the color of your eyes and hair, and even the timing of puberty are strongly influenced by the genes you inherit.
- Health: Some individuals may inherit a predisposition to certain health conditions like diabetes, heart disease, or allergies.
- Intellectual Abilities: While environment plays a huge role, genetic factors can also influence a person’s natural aptitude for certain skills and their overall intellectual potential.
Examples of Inherited Traits
| Trait | Dominant Example | Recessive Example |
|---|---|---|
| Eye Color | Brown / Black | Blue / Grey |
| Hair Type | Curly / Wavy Hair | Straight Hair |
| Earlobe | Detached Earlobe | Attached Earlobe |
| Dimples | Presence of Dimples | Absence of Dimples |
Quick Revision Points
- Heredity is the passing of traits from parents to offspring.
- Genes are the fundamental units of heredity.
- Humans have 23 pairs of chromosomes (46 total).
- DNA is the molecule that carries genetic information.
- A dominant gene’s trait shows up even with one copy, while a recessive gene needs two copies.
- Heredity provides the blueprint for development, but the environment (nutrition, education, etc.) helps in realizing that potential.
Extra Practice Questions
- Explain in your own words why two brown-eyed parents can have a blue-eyed child.
- What is the difference between a gene and a chromosome?
- How does heredity influence the physical development of a teenager?
- Besides physical traits, what other characteristics can be influenced by heredity?
- Why is it said that heredity sets the limits, but environment determines the final outcome?
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