1. What is Friction? Why Do We Need It?
Friction is the resistance encountered when one surface moves or attempts to move over another. It plays a crucial role in our daily lives.
- Essential for Movement: Friction allows us to walk without slipping.
- Enables Control: It helps vehicles brake and steer effectively.
- Facilitates Gripping: It is essential for holding objects securely.
2. Advantages and Disadvantages of Friction
Friction has both benefits and drawbacks.
- Advantages:
- Provides traction for vehicles and pedestrians.
- Allows for the operation of machines (e.g., gears).
- Helps in writing (friction between pen and paper).
- Disadvantages:
- Causes wear and tear on materials.
- Generates heat, leading to energy loss.
- Can cause accidents due to slipping.
3. Explain the Nitrogen Cycle
The nitrogen cycle is a process through which nitrogen moves between the atmosphere, soil, and living organisms.
- Fixation: Nitrogen gas (N₂) is converted into ammonia (NH₃) by bacteria.
- Nitrification: Ammonia is transformed into nitrites (NO₂) and then nitrates (NO₃) by soil bacteria.
- Assimilation: Plants absorb nitrates and incorporate nitrogen into their tissues.
- Ammonification: Decomposing organisms convert organic nitrogen back to ammonia.
- Dentrification: Nitrates are converted back to nitrogen gas, completing the cycle.
4. Explain the Formation of Petroleum
Petroleum forms over millions of years from the remains of ancient marine organisms.
- Accumulation: Organic matter settles on the ocean floor.
- Burial: Layers of sediment cover the organic matter, increasing pressure and temperature.
- Transformation: Heat and pressure convert the remains into hydrocarbons, forming crude oil.
5. How Does Food Get Spoiled?
Food spoilage occurs due to microbial activity, enzyme action, and environmental factors.
- Microorganisms: Bacteria, yeasts, and molds can grow on food, leading to decay.
- Enzymatic Reactions: Natural enzymes in food can break down nutrients.
- Environmental Factors: Temperature, humidity, and exposure to air can accelerate spoilage.
6. Microorganisms and Diseases Caused by Them
Microorganisms can cause various diseases.
- Bacteria:
- *Salmonella*: Causes food poisoning.
- *Streptococcus*: Can lead to throat infections.
- Viruses:
- *Influenza*: Causes the flu.
- *HIV*: Leads to AIDS.
- Fungi:
- *Candida*: Causes yeast infections.
- *Aspergillus*: Can lead to respiratory issues.
Understanding these microorganisms helps in prevention and treatment of diseases.