COMBINED REVISIONS:

Revision-1 (Conservation of Plants and Animals) :

Fill in the Blanks: Conservation of Plants and Animals (Class 8)

Instructions: Fill in the blanks with the appropriate term.

1. A place where animals are protected in their natural habitat is called a __________ sanctuary.
2. Species found only in a particular area are known as __________ species.
3. Migratory birds fly to faraway places because of __________ changes. (e.g., temperature, food availability)
4. The gradual destruction of natural forests and woodlands is called __________ .
5. The practice of planting trees where they have been cut down is called __________ .
6. A place where plants and animals are protected by law is called a __________ park.
7. The __________ Data Book is a record of plant and animal species facing endangerment of extinction.
8. We should conserve plants and animals because they play a vital role in maintaining a healthy __________ .
9. Using __________ resources like solar energy can help reduce our dependence on resources that harm the environment.
10. By __________ paper, plastic, and other materials, we can minimize waste and conserve resources.

MCQ for Conservation of Plants and Animals (Class 8 Science)

Instructions: Choose the best answer for each question. (1 mark each)

1. Which of the following is NOT a major threat to the survival of plants and animals?

• a) Deforestation
• b) Increased rainfall
• c) Pollution
• d) Overexploitation

The act of planting trees where there were once forests is called:

• a) Afforestation
• b) Reforestation
• c) Deforestation
• d) Habitat destruction

Animals and plants that are found only in a particular area are called:

• a) Endangered species
• b) Extinct species
• c) Endemic species
• d) Migratory species

National parks are protected areas where:

• a) Limited human activity is allowed for recreation.
• b) Any kind of human activity is prohibited.
• c) Animals are bred in captivity for commercial purposes.
• d) Plants are grown for agricultural purposes.

The Red Data Book contains information on:

• a) All known species of plants and animals.
• b) Plants and animals with a high economic value.
• c) Only the most beautiful plants and animals.
• d) Only domesticated plants and animals.

Which of the following practices helps in conserving water?

• a) Leaving the tap running while brushing teeth.
• b) Watering plants during the hottest part of the day.
• c) Using a washing machine for even small loads of clothes.
• d) Taking shorter showers.

Recycling paper helps in conserving:

• a) Water
• b) Soil fertility
• c) Electricity
• d) All of the above

Which of the following statements about migration is FALSE?

• a) Migration is a seasonal movement of animals from one place to another.
• b) Animals migrate in search of food, water, and breeding grounds.
• c) All animals migrate long distances.
• d) Birds are a common example of migrating animals.

True or False

True or False (1 mark each)

1. Deforestation is the planting of new trees. (True/False)
2. Biodiversity refers to the variety of plant and animal life in a particular habitat. (True/ False)
3. Biosphere reserves are protected areas that allow some human activity. (True/ False)
4. Endangered species are animals with stable populations. (True/False)
5. Using paper bags instead of plastic bags is an example of a sustainable practice. (True/ False)
6. The burning of fossil fuels contributes to climate change, which can harm plant and animal life. (True/ False)
7. We should avoid using pesticides in agriculture to protect beneficial insects. (True/ False)
8. National parks are areas with stricter protection compared to wildlife sanctuaries. (True/ False)
9. It's okay to keep wild animals as pets. (True/False)
10. Recycling paper helps to conserve trees. (True)

 

REVISION-2 (Friction) :

True or False Questions on Friction (Class 8)

Instructions: Write "True" or "False" for each statement.

1. Friction is a force that always helps objects move faster.
2. Rough surfaces create less friction than smooth surfaces.
3. Lubricants like oil or grease increase friction between surfaces.
4. The weight of an object has no effect on the amount of friction it experiences.
5. Streamlined shapes, like those of fish, are designed to reduce drag (a type of fluid friction).
6. Friction is always a negative force, making it difficult to do things.
7. Applying oil to a bicycle chain reduces friction, making it easier to pedal.
8. Static friction is the force that keeps a book lying on a table from sliding off.
9. Sliding friction is always greater than static friction for the same two surfaces.
10. Air resistance is a type of fluid friction that affects objects moving through air.

Fill-in-the-Blanks Questions on Friction (Class 8)

Instructions: Fill in the blanks with the most appropriate words. (1 mark each)

1. Friction is the force that __________ the relative motion between surfaces in contact.
2. __________ friction is the force that acts between an object at rest and the surface it is on.
3. __________ friction is the force that acts between an object already in motion and the surface it is moving on.
4. __________ friction is the force that acts between an object and a fluid (liquid or gas).
5. The roughness of the surfaces in contact, the weight of the object, and the __________ of the contact area all affect friction.
6. Lubricants like oil or grease work by creating a thin film between surfaces, there by __________ friction.
7. Streamlined shapes, like those of fish or airplanes, experience __________ drag (a type of fluid friction) compared to blunt shapes.
8. __________ friction helps us walk, run, and grip objects.
9. __________ friction is responsible for the wear and tear of shoes and car tires.
10. Understanding _________ is important for designing airplanes that fly efficiently and ships that move smoothly through water.

Friction MCQs for Class 8 Science (Choose the best answer)

1. Which of the following is NOT a factor affecting friction?

• a) The roughness of the surfaces in contact
• b) The weight of the object
• c) The color of the surfaces
• d) The area of contact between surfaces

Friction is a force that:

• a) Increases the speed of an object.
• b) Opposes the relative motion between surfaces in contact.
• c) Makes objects heavier.
• d) Creates a pulling force.

Which of these has the highest friction?

• a) A smooth, polished surface.
• b) A rough, sandpapered surface.
• c) A wet, soapy surface.
• d) An oiled metal surface.

Walking on a wet floor is slippery because:

• a) Water increases friction.
• b) Water reduces friction between your shoes and the floor.
• c) Water makes the floor heavier.
• d) Water changes the color of the floor.

Lubricants like oil or grease reduce friction by:

• a) Increasing the roughness between surfaces.
• b) Creating a thin film between surfaces, reducing contact.
• c) Making objects heavier.
• d) Changing the color of the surfaces.

 

 

 

REVISION-3 (FORCE AND PRESSURE)

MCQs on Force and Pressure

1. What is a force?
2. a) A push or a pull
3. b) Energy
4. c) Speed
5. d) Mass
6. Which of the following is a unit of force?
7. a) Meter (m)
8. b) Newton (N)
9. c) Kilogram (kg)
10. d) Second (s)
11. A balanced force will:
12. a) Change the object's state of motion
13. b) Keep the object at rest or in constant motion
14. c) Increase the pressure on the object
15. d) Decrease the object's mass
16. Which of the following is a contact force?
17. a) Gravitational force
18. b) Magnetic force
19. c) Frictional force
20. d) Electrostatic force
21. Pressure is defined as:
22. a) Force acting on an object
23. b) Force per unit area
24. c) Mass of an object
25. d) Speed of an object
26. A sharp knife cuts a tomato easily because:
27. a) The force applied is large.
28. b) The pressure exerted is high due to the small contact area.
29. c) The tomato is soft.
30. d) All of the above.
31. Why are wide straps preferred for carrying heavy loads?
32. a) To distribute the weight evenly
33. b) To reduce the force required
34. c) To increase the pressure on the shoulders
35. d) None of the above
36. Which of the following statements about pressure is INCORRECT?
37. a) Pressure is directly proportional to the force applied.
38. b) Pressure is inversely proportional to the area of contact.
39. c) Liquids and gases exert pressure in all directions.
40. d) Pressure can be created without applying any force.
41. A balloon inflates when filled with air because:
42. a) The air molecules exert pressure on the balloon walls.
43. b) The weight of the air increases.
44. c) The balloon becomes lighter.
45. d) The air molecules lose energy.
46. Which of the following can be used to measure pressure?
47. a) Ruler
48. b) Spring balance
49. c) Barometer
50. d) Stop watch

Answer Key (Please don't peek unless you've tried your best!)

1. (a)
2. (b)
3. (b)
4. (c)
5. (b)
6. (b)
7. (a)
8. (d)
9. (a)
10. (c)

 

Fill in the blanks

1. Force is a __________ that can change the state of motion or shape of an object.
2. The SI unit of force is __________.
3. The force applied per unit area is called __________.
4. The formula to calculate pressure is __________.
5. Air pressure __________ as we go higher up in the atmosphere.
6. A force applied in the same direction as the motion of an object __________ its speed.
7. The pressure exerted by a liquid depends on its __________ and __________.
8. A force applied perpendicular to the surface of an object creates __________.
9. Pascal's law states that __________ applied to a confined fluid is transmitted undiminished to every point of the fluid and to the walls of its container.
10. The pressure exerted by a liquid depends on its __________ and the __________ of the liquid column above it.

Answers:

1. vector quantity
2. Newton (N)
3. pressure
4. Pressure = Force / Area
5. decreases
6. increases
7. density, depth
8. pressure
9. pressure
10. density, height

TRUE OR FALSE

1. True or False: Pressure is the force exerted by an object against another object.
2. True or False: A force can only change the shape of an object, not its state of motion.
3. True or False: The SI unit of pressure is Pascal (Pa).
4. True or False: Pressure exerted by a liquid depends on the density of the liquid and the area of the surface it acts upon.
5. True or False: Pascal's law states that pressure applied to a confined fluid is transmitted only to the adjacent point of the fluid.
6. True or False: The pressure exerted by a liquid increases with depth.
7. True or False: Friction always decreases the pressure between two surfaces in contact.
8. True or False: Force and pressure are scalar quantities.
9. True or False: A force applied perpendicular to the surface of an object creates pressure.
10. True or False: Air pressure decreases with increasing altitude.

Answers:

1. False
2. False
3. True
4. True
5. False
6. True
7. False
8. False
9. True
10. True

 

PLT

Friction, Force, and Pressure:

1. Which of the following is a force that opposes motion between two surfaces in contact?
2. a) Gravitational force
3. b) Frictional force
4. c) Magnetic force
5. d) Electrostatic force
6. Which type of friction occurs when an object moves through a fluid?
7. a) Static friction
8. b) Rolling friction
9. c) Fluid friction
10. d) Kinetic friction
11. Which factor does NOT affect the force of friction between two surfaces?
12. a) The roughness of the surfaces
13. b) The force pressing the surfaces together
14. c) The color of the surfaces
15. d) The type of material of the surfaces
16. Pressure is defined as:
17. a) Force per unit area
18. b) Force acting perpendicular to the surface
19. c) Force acting parallel to the surface
20. d) Force acting tangentially to the surface
21. Which of the following will increase pressure?
22. a) Increasing the force applied
23. b) Increasing the area over which the force is applied
24. c) Decreasing the force applied
25. d) Decreasing the area over which the force is applied

Conservation of Plants and Animals:

1. Which of the following is NOT a reason for the conservation of plants and animals?
2. a) Maintaining biodiversity
3. b) Preserving natural habitats
4. c) Accelerating climate change
5. d) Protecting endangered species
6. Which practice helps conserve plant species?
7. a) Deforestation
8. b) Overfishing
9. c) Afforestation
10. d) Habitat destruction
11. Which of the following is a threat to animal conservation?
12. a) Sustainable farming practices
13. b) Pollution of natural habitats
14. c) Protection of wildlife reserves
15. d) Promoting ecotourism
16. Which conservation strategy involves breeding species in captivity and reintroducing them into the wild?
17. a) Ex situ conservation
18. b) In situ conservation
19. c) Biodiversity hotspot preservation
20. d) Habitat restoration
21. What is the main goal of conservation biology?
22. a) To exploit natural resources sustainably
23. b) To reduce human population growth
24. c) To preserve genetic diversity
25. d) To maximize agricultural productivity

Revision for Case study’s

Q1. Case Study: Protecting the Endangered Red Panda Habitat

In the mountainous regions of the Eastern Himalayas, a small community nestled within dense forests is facing a conservation challenge. The community depends on the forest for their livelihoods, but the habitat of the endangered red panda is under threat due to human activities such as logging, grazing, and agricultural expansion.

Background Information:

• The red panda (Ailurus fulgens) is a small, arboreal mammal native to the Himalayas and southwestern China.
• Red pandas are classified as endangered by the International Union for Conservation of Nature (IUCN) due to habitat loss and fragmentation, poaching, and climate change.
• The forests where red pandas live are also home to many other plant and animal species, making them biodiversity hotspots.

Investigation:

• Local conservationists, in collaboration with scientists and government agencies, conducted surveys to assess the population and habitat of red pandas in the area.
• They found that the red panda population was declining rapidly due to habitat destruction and fragmentation caused by human activities.
• The loss of forests not only threatened the red pandas but also endangered other species, including rare plants and animals unique to the region.

 

 

 

Questions for Discussion:

1. What are the main threats to the habitat of red pandas in the Eastern Himalayas?
2. Why is it important to conserve the habitat of red pandas and other species in the region?
3. What are the consequences of habitat loss and fragmentation for biodiversity?
4. What conservation strategies can be implemented to protect the habitat of red pandas and other species?
5. How can local communities be involved in conservation efforts?

Possible Answers:

1. Main threats to the habitat of red pandas include:

• Deforestation: Logging for timber and clearing land for agriculture reduces the available habitat for red pandas.
• Grazing: Livestock grazing in forested areas can degrade habitat and reduce food sources for red pandas.
• Agricultural expansion: Conversion of forests into agricultural land leads to habitat loss and fragmentation.
• Human development: Infrastructure projects such as roads and settlements further fragment red panda habitat.

Importance of conserving red panda habitat:

• Red pandas are keystone species, meaning they play a crucial role in maintaining the structure and function of their ecosystems.
• Conservation of red panda habitat helps protect biodiversity and ecosystem services, such as clean water and air.
• Red pandas are also culturally significant and serve as flagship species for conservation efforts in the region.

Consequences of habitat loss and fragmentation:

• Loss of biodiversity: Habitat destruction leads to the decline or extinction of plant and animal species.
• Fragmentation disrupts ecological processes such as migration and genetic exchange, making species more vulnerable to extinction.
• Reduced ecosystem resilience: Fragmented habitats are less able to withstand environmental disturbances such as climate change.

Conservation strategies:

• Establishing protected areas and wildlife corridors to connect fragmented habitats and facilitate species movement.
• Implementing sustainable land use practices, such as agroforestry and community-based natural resource management.
• Engaging local communities in conservation planning and decision-making processes.
• Conducting outreach and education programs to raise awareness about the importance of biodiversity conservation.

Involvement of local communities:

• Empowering local communities to participate in conservation initiatives can lead to more effective and sustainable outcomes.
• Providing alternative livelihood options that are compatible with conservation goals, such as eco-tourism or sustainable agriculture.
• Collaborating with local stakeholders to develop and implement conservation plans that reflect their needs and priorities.

This case study highlights the complex interactions between humans and the environment and underscores the importance of conservation efforts in protecting biodiversity and ecosystem services. It encourages students to think critically about the impacts of human activities on natural habitats and explore potential solutions to conservation challenges.

Q2. **Case Study: The Mystery of the Slipping Shoes**

In a bustling city, Sarah, a student in class 8, was walking to school when she slipped and fell on the pavement. She noticed that her shoes seemed to lose their grip on the ground more easily, especially when it rained. Concerned about her safety and curious about what caused her shoes to slip, Sarah decided to investigate.

**Background Information:**

- Friction is the force that opposes the motion of objects in contact with each other.

- The amount of friction between two surfaces depends on factors such as the nature of the surfaces and the force pressing them together.

- Friction plays a crucial role in everyday activities, such as walking, driving, and playing sports.

 

**Investigation:**

- Sarah conducted experiments to compare the friction between different types of shoe soles and the pavement.- She observed that shoes with worn-out or smooth soles had less grip on the ground compared to shoes with newer or textured soles.

- Sarah also tested the effect of moisture on friction by wetting the pavement and measuring how it affected the slipperiness of her shoes.

**Questions for Discussion:**

1. **What is friction, and why is it important in our daily lives?**
2. **How does the surface texture of shoe soles affect friction?**
3. **Why do shoes tend to slip more easily on wet surfaces?**
4. **What are some ways to increase friction between shoes and the ground?**
5. **Can friction be both helpful and harmful? Give examples.**

**Possible Answers:**

1. **Friction is the force that opposes the motion of objects in contact with each other.**

   - It is important in our daily lives because it allows us to walk, drive, and grip objects.

   - Friction helps prevent objects from sliding or slipping uncontrollably.

 

2. **Surface texture of shoe soles and friction:**

   - Shoes with textured or treaded soles provide more grip on the ground because they increase the contact area and friction between the shoe and the surface.

   - Worn-out or smooth soles have less grip because they reduce the contact area and friction.

3. **Effect of moisture on friction:**

   - Moisture reduces friction by creating a thin layer of water between the shoe sole and the ground, reducing the contact area and increasing slipperiness.

   - This is why shoes tend to slip more easily on wet surfaces, especially if the soles are smooth or worn-out.

4. **Ways to increase friction between shoes and the ground:**

   - Using shoes with textured or treaded soles.

   - Keeping shoe soles clean and free from dirt or debris that can reduce friction.

   - Avoiding walking on wet or slippery surfaces when possible.

5. **Friction can be both helpful and harmful:**

   - Helpful: Friction allows us to walk, run, and grip objects, making many daily activities possible.

   - Harmful: Friction can cause wear and tear on machinery and increase energy consumption in vehicles.

 

By investigating the slipping shoes, Sarah gained a better understanding of the role of friction in her everyday life and learned how to make informed choices to improve her safety and mobility. This case study encourages students to explore the concept of friction through real-life examples and to consider its implications in various contexts.

Q3. Case Study: The Bridge Collapse

In a small town, there was a pedestrian bridge connecting two neighborhoods across a river. One day, while several people were crossing the bridge, it suddenly collapsed, causing injuries to those on it. The town's authorities launched an investigation to determine the cause of the collapse.

Background Information:

• Force is a push or pull acting upon an object as a result of its interaction with another object.
• Pressure is the force applied perpendicular to the surface of an object per unit area.
• Bridges are designed to withstand the forces acting upon them, including the weight of people and vehicles crossing them.

Investigation:

• Engineers and forensic experts examined the wreckage of the collapsed bridge to determine the cause of the collapse.
• They found that the bridge had been under maintenance for several years, but the maintenance records were not up-to-date.
• Analysis of the bridge structure revealed signs of corrosion and metal fatigue, particularly in the support beams and joints.

Questions for Discussion:

1. What are force and pressure, and how are they related?
2. How does the design of a bridge account for the forces and pressures acting upon it?
3. What factors might contribute to the corrosion and metal fatigue of a bridge structure?
4. How can regular maintenance help prevent structural failures in bridges?
5. What are the consequences of a bridge collapse, and how can they be mitigated?

Possible Answers:

1. Force and pressure:

• Force is a push or pull acting upon an object.
• Pressure is the force applied perpendicular to the surface of an object per unit area.
• Pressure is calculated as force divided by the area over which the force is applied (P = F/A).

Bridge design and forces:

• Bridges are designed to distribute the forces acting upon them evenly across their structure.
• Support beams and trusses are strategically placed to bear the weight of the bridge and the loads it carries.
• The design also takes into account factors such as wind, earthquakes, and temperature changes that can exert additional forces on the bridge.

Factors contributing to corrosion and metal fatigue:

• Exposure to moisture and salt from water bodies or road de-icing agents can accelerate corrosion in metal structures.
• Overloading of the bridge beyond its designed capacity can lead to metal fatigue and structural weakening over time.
• Lack of proper maintenance, including inspections and repairs, can allow corrosion and fatigue to go undetected and worsen over time.

Importance of regular maintenance:

• Regular inspections can identify signs of corrosion, metal fatigue, or other structural weaknesses before they lead to catastrophic failures.
• Prompt repairs and maintenance can help extend the lifespan of a bridge and ensure its safety for public use.
• Keeping accurate maintenance records allows engineers to track the condition of the bridge and plan for necessary repairs or upgrades.

Consequences of a bridge collapse and mitigation measures:

• Bridge collapses can result in injuries, loss of life, property damage, and disruption of transportation routes.
• Mitigation measures include implementing stricter inspection and maintenance protocols, investing in infrastructure upgrades, and enhancing emergency response and evacuation plans.

Through the investigation of the bridge collapse, the town's authorities and engineers gained valuable insights into the importance of force and pressure in structural engineering and the need for proactive maintenance to ensure the safety and reliability of infrastructure. This case study prompts students to consider the real-world applications of force and pressure concepts and their implications for public safety and engineering practices.