Class 8 General Science Notes: - Unit-3: Variations, Heredity and Cell Division: Solved Exercise (Short Questions and Answers)

(National Book Foundation - New Book/New Syllabus Based on National Curriculum Pakistan 2023-2024 and Onwards)

(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)

B. Short questions 

Q1. Why is meiosis important in organisms that reproduce sexually?

Ans: Importance of Meiosis:

• It produces reproductive cell called gametes that is egg and sperm. For sexually reproducing organisms Zygote is formed by the fusion of sperm with egg. Meiosis is a reduction division that reduces the number of chromosomes to half in the gamete. The Fusion of gametes again restores the number.
• A process of crossing over helps to create variation in the next generation.

Q2. State the importance of mitosis in human life.

Ans: Importance of Meiosis:

1. Growth: An increase in size is called growth. Growth of the human body takes place through mitosis.
2. Development: The development of the human body starts from a single cell called the Zygote, which divides repeatedly by mitosis, and the number of cells increases leading to the formation of tissues, organs, organ systems, and a complete individual.
3. Healing of Wounds: If human skin is cut, new skin comes due to the process of mitosis.
4. Regeneration: The nails and hair of the human body regenerate due to the process of regeneration.

Q3. What is the significance of spindle fibers in cell division?

Ans: 

The spindle fiber plays important role in cell division. They are formed by a protein that helps to divide genetic material (DNA) during cell division. They equally divide chromosomes from the parent cell into two daughter cells.

 

Q4. You never see frogs, snakes, and lizards during extreme winter as they hibernate. What type of adaptation is it? Explain.

Ans:

Hibernation during extreme winter is an example of behavioral adaptation.

Behavioral Adaptation:

It is an adaptation affecting the way an organism responds to its environment.

Examples:

1. Seasonal migration of birds from Siberia to Pakistan to avoid extreme cold.
2. Many plants shed their leaves in winter to prevent water loss.
3. Frogs, snakes, and lizards hibernate during winter.

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Unit-3: Variations, Heredity and Cell Division: Solved Long Questions and Answers

Class 8 General Science Notes

Source: General Science Book (National Book Foundation, Pakistan)

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