🧬 Biological Sciences & Public Health
Complete Question Bank with Answers — Sections A • B • C • D • E
📘 Section A – Multiple Choice Questions
1 mark each
1 Mark
1. According to the bulletin board, what is one of the leading risk factors for health?
✔ Answer: (b) Air pollution
1 Mark
2. A person complains of body ache, sore throat, and nasal congestion. Based on the symptoms described in the chapter, which disease is the person most likely suffering from?
✔ Answer: (c) Common cold and influenza
1 Mark
3. You visit a new city and notice a high Air Quality Index (AQI). Based on the chapter, what would you infer about the air quality?
✔ Answer: (c) The air has high levels of pollutants from vehicles and factories.
1 Mark
4. According to the chapter, what is one of the leading causes of diabetes?
✔ Answer: (a) Fast food
1 Mark
5. Which of the following is an example of a sign of illness?
✔ Answer: (c) Rash
1 Mark
6. A disease is a condition that affects the normal working of the body or mind, and can happen when:
✔ Answer: (a) One or more organs stop functioning properly.
1 Mark
7. What is the main function of the immune system?
✔ Answer: (c) To fight against diseases
1 Mark
8. Who discovered the first antibiotic, Penicillin?
✔ Answer: (d) Alexander Fleming
1 Mark
9. Assertion (A): Antibiotics are effective against viral infections. Reasoning (R): They are designed to kill bacteria by targeting specific parts of bacterial cells.
✔ Answer: (d) A is false but R is true.
1 Mark
10. Assertion (A): The number of people with diabetes has increased in India. Reasoning (R): This is due to a combination of factors like unhealthy eating habits and lack of physical activity.
✔ Answer: (a) Both A and R are true and R is the correct explanation of A.
1 Mark
11. A student observes a microorganism from a pond water sample under a microscope. The student notes that the organism is green and moves using specialized structures. Based on the description in the textbook, which category of microorganism is the student most likely observing?
✔ Answer: (c) Algae
1 Mark
12. Which of the following statements about plant and animal cells is correct, based on the chapter?
✔ Answer: (c) Plant cells have chloroplasts and a cell wall, which animal cells lack.
1 Mark
13. If a laboratory has only a foldscope, what is its primary limitation when studying microorganisms compared to a high-powered laboratory microscope?
✔ Answer: (b) It does not provide the same level of detail as a high-powered microscope.
1 Mark
14. A farmer observes that his crop yield is consistently low. Based on the chapter, which microorganism, when grown with his legume crops, can help improve the soil naturally without chemical fertilizers?
✔ Answer: (b) Rhizobium
1 Mark
15. A group of scientists is studying a newly discovered organism. They find that its cells are prokaryotic, meaning they lack a well-defined nucleus with a nuclear membrane. According to the textbook, which of the following is most likely this organism?
✔ Answer: (d) Bacteria
1 Mark
16. You have a piece of dough that you want to make soft and fluffy for baking. Based on the activity in the chapter, which ingredient is essential for this purpose and why?
✔ Answer: (c) Yeast, because it releases carbon dioxide gas which forms bubbles.
1 Mark
17. Which of the following best describes the function of a cell wall in a plant cell?
✔ Answer: (b) It provides rigidity and strength to the plant.
1 Mark
18. Based on the levels of organization described in the chapter, what is the correct hierarchy from the simplest to the most complex level?
✔ Answer: (d) Cell → Tissue → Organ → Organ System → Organism
1 Mark
19. Assertion (A): The ostrich egg is considered the largest single cell in the living world. Reason (R): All complex living organisms, whether plants or animals, begin their life as a single cell.
✔ Answer: (b) Both A and R are true but R is not the correct explanation of A.
1 Mark
20. Assertion (A): Robert Hooke's invention of a microscope, which could magnify objects 200 to 300 times, was a groundbreaking scientific discovery. Reason (R): This tool enabled him to observe and name the basic unit of life, the 'cell', for the first time.
✔ Answer: (a) Both A and R are true and R is the correct explanation of A.
1 Mark
21. You find a powdery, white growth on a forgotten lemon. Based on the chapter, which microorganism is most likely responsible for this growth?
✔ Answer: (d) Fungi
1 Mark
22. According to the chapter, what is the primary function of the cytoplasm in a cell?
✔ Answer: (d) Most life processes take place within it.
1 Mark
23. Which of the following is an example of a unicellular fungus?
✔ Answer: (c) Yeast
1 Mark
24. A botanist discovers a new plant species. When observing its cells under a microscope, which component would confirm that it is a plant cell and not an animal cell?
✔ Answer: (d) Cell wall
1 Mark
25. A group of cells work together to perform a specific function, such as protecting the inner lining of the cheek. According to the levels of organization, what do these cells form?
✔ Answer: (b) A tissue
1 Mark
26. Which scientist is known as the "Father of Microbiology" for being the first to clearly see and describe tiny living things like bacteria?
✔ Answer: (b) Antonie van Leeuwenhoek
1 Mark
27. What is a key characteristic that distinguishes bacteria from other microorganisms like yeast, protozoa, and algae?
✔ Answer: (c) They lack a well-defined nucleus and nuclear membrane.
1 Mark
28. Which of the following is a non-cellular material present in an ostrich egg that helps in its continued development?
✔ Answer: (b) The shell and white liquid
1 Mark
29. Assertion (A): The use of glycerin is important when preparing a slide of onion peel. Reason (R): Glycerin prevents the cells from drying out and improves the clarity for better visualization of the cells.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
30. Assertion (A): The elongated and branched structure of a nerve cell is a key feature that helps it perform its function. Reason (R): Cells are found in different shapes and sizes because their unique structure helps them carry out specific functions.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
31. Which of the following is an example of a unicellular microorganism mentioned in the chapter?
✔ Answer: (c) Amoeba
1 Mark
32. In the activity to observe onion peel cells, why is a red-colored stain like safranin used?
✔ Answer: (b) To give a pinkish color to the cells for clearer visibility.
1 Mark
33. Which part of a plant cell provides rigidity and strength?
✔ Answer: (d) Cell wall
1 Mark
34. A muscle cell is described as being "spindle-shaped". How does this shape help it perform its function?
✔ Answer: (b) It allows the cell to contract and relax in a wave-like manner.
1 Mark
35. What is the primary function of the cell membrane?
✔ Answer: (b) To enclose the cytoplasm and nucleus and allow the entry/exit of materials.
1 Mark
36. What is the largest known single cell in the living world?
✔ Answer: (b) Ostrich egg
1 Mark
37. Which of the following is a key function of the nucleus?
✔ Answer: (c) It regulates growth and all activities that occur within the cell.
1 Mark
38. Which of the following is not a microorganism mentioned in the chapter?
✔ Answer: (d) Worms
1 Mark
39. Assertion (A): The body of a living organism is organized in a complex way, starting from a single cell. Reason (R): A group of similar cells forms a tissue, different tissues form an organ, and several organs form an organ system.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
40. Assertion (A): Plant cells can have a large vacuole, but animal cells usually do not. Reason (R): The vacuole in a plant cell helps to store substances and maintain the cell's shape and strength.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
41. According to the bulletin board, which of the following practices is most effective at reducing infection by 50%?
✔ Answer: (a) Regular handwashing
1 Mark
42. You see a news clipping that says 'Air pollution is a public health emergency'. Based on the chapter, what is the most likely reason for this declaration?
✔ Answer: (b) Air pollution is a leading risk factor for health issues.
1 Mark
43. A student reads that dinacharya and ritucharya are important for maintaining health. This concept is derived from which traditional system?
✔ Answer: (c) Ayurveda
1 Mark
44. What is the World Health Organization (WHO)'s definition of health?
✔ Answer: (c) A state of complete physical, mental, and social well-being.
1 Mark
45. Which of the following is an example of a symptom?
✔ Answer: (d) Dizziness
1 Mark
46. A disease that is not caused by pathogens and does not spread from person to person is classified as:
✔ Answer: (d) A non-communicable disease
1 Mark
47. Which of the following diseases is transmitted by an insect vector?
✔ Answer: (c) Dengue fever
1 Mark
48. What is the traditional Indian practice of creating a mild smallpox infection to build immunity called?
✔ Answer: (b) Variolation
1 Mark
49. Assertion (A): Vaccines are preventive, not curative. Reasoning (R): They train the immune system to recognize and fight germs before a person gets sick.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
50. Assertion (A): The ability of the body to fight diseases is called immunity. Reasoning (R): The immune system protects us against harmful pathogens.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
1 Mark
51. You notice a headline that states '28.6% Indians are obese'. According to the chapter, what is one of the health risks associated with obesity?
✔ Answer: (b) Increased risk of diabetes and heart attack
1 Mark
52. A student learns that the arrival of the monsoon season often leads to an increase in malaria and dengue cases. Which of the following is the most effective way to prevent the spread of these diseases, based on the chapter?
✔ Answer: (b) Using mosquito nets and repellents
1 Mark
53. A person is advised to follow a 'Diet mantra: Reduce the amount of oil and sugar in diet.' Based on the chapter's content, what is the most likely reason for this advice?
✔ Answer: (b) To prevent non-communicable diseases.
1 Mark
54. What is the definition of a parasite as given in the chapter?
✔ Answer: (c) An organism that lives in or on another living being and feeds on nutrients.
1 Mark
55. Which of the following is a communicable disease?
✔ Answer: (d) Typhoid
1 Mark
56. What is the full form of NCDs?
✔ Answer: (a) Non-Communicable Diseases
1 Mark
57. Who was the Indian scientist who played a key role in developing the Rotavirus vaccine?
✔ Answer: (d) Dr. Maharaj Kishan Bhan
1 Mark
58. Which of the following is a component of complete well-being as per the WHO definition of health?
✔ Answer: (d) All of the above
1 Mark
59. Assertion (A): Dr. Maharaj Kishan Bhan developed the Rotavirus vaccine. Reasoning (R): He believed in using research to create affordable healthcare.
✔ Answer: (b) Both A and R are true, but R is not the correct explanation of A.
1 Mark
60. Assertion (A): The indiscriminate use of antibiotics can lead to a decline in their effectiveness. Reasoning (R): This is because bacteria can develop resistance and survive despite antibiotic treatment.
✔ Answer: (a) Both A and R are true, and R is the correct explanation of A.
📗 Section B – Short Answer Questions
2 marks each
2 Marks
Q. Explain how the shape and structure of a nerve cell are specifically adapted to its function in the human body.
✔ Answer: The elongated and branched structure of a nerve cell is a key feature that helps it perform its specific function of carrying out signals in the body.
2 Marks
Q. A person prepares a pickle by adding a high concentration of salt to vegetables. Explain, based on the information in the chapter, why this method prevents microbial growth and spoilage.
✔ Answer: A high concentration of salt acts as a preservative. It creates an environment that is not conducive to microbial growth because it draws out water from the cells of the microorganisms, essentially dehydrating them and preventing their multiplication.
2 Marks
Q. Explain the difference between unicellular and multicellular organisms with examples mentioned in the chapter.
✔ Answer: Unicellular organisms are composed of just a single cell, and all the functions necessary for survival are carried out by that one cell, such as in Amoeba. Multicellular organisms are made up of many cells with specialized functions that work together to ensure survival, such as plants and animals.
2 Marks
Q. How do some microorganisms, like bacteria and fungi, act as "key players in cleaning the environment"?
✔ Answer: Microorganisms like fungi and bacteria act on dead plant and animal waste. They break down these complex materials into simpler, nutrient-rich substances which return to the soil to help new plants grow, thus acting as natural decomposers to clean the environment.
2 Marks
Q. A student notices that the letters on a book appear larger when viewed through a flask filled with water. Explain why this happens, based on the chapter.
✔ Answer: This happens because the round-bottom flask filled with water acts as a magnifying glass. The curved surface of the flask and the water inside bend light in a way that makes the letters on the book appear larger than they are, allowing them to be seen more clearly.
2 Marks
Q. Explain the function of plastids in plant cells and name the specific type of plastid responsible for the green color of plants.
✔ Answer: Plastids are tiny rod-shaped structures found in all parts of a plant, and in non-green parts, they help in the storage of substances. The specific type of plastid responsible for the green color of plants is the chloroplast, which contains chlorophyll and helps in the process of photosynthesis.
2 Marks
Q. What is a foldscope, and what is its main advantage over a traditional laboratory microscope?
✔ Answer: A foldscope is a low-cost, foldable paper microscope. Its main advantage is that it makes the microscopic world accessible to many people because it is affordable and portable.
2 Marks
Q. Why are microorganisms, like bacteria and fungi, unable to grow on food items that have a high concentration of salt or sugar, such as pickles and murabbas?
✔ Answer: Microorganisms cannot grow on foods with a high concentration of salt or sugar because these substances act as preservatives. A high concentration of salt or sugar creates an environment that is not conducive for microbial growth by drawing out water from the cells of the microorganisms, essentially dehydrating them and preventing their multiplication.
2 Marks
Q. A foldscope can be used to observe microorganisms. Explain what a foldscope is and why it is a useful tool.
✔ Answer: A foldscope is a low-cost, foldable paper microscope. It is a useful tool because it makes the fascinating microscopic world accessible to many people who may not have access to expensive, high-powered laboratory microscopes.
2 Marks
Q. Explain the function of the cell membrane and how it helps in the maintenance of life processes.
✔ Answer: The cell membrane is the thin outer layer of a cell that encloses the cytoplasm and nucleus. It is porous, which means it allows the entry of essential materials and the exit of waste materials, making it vital for the maintenance of life processes as it controls what substances go in and out of the cell.
2 Marks
Q. What are the two types of organisms that can be seen in the digestive system? What are their functions?
✔ Answer: The human intestine has many bacteria that help in digestion. Additionally, the stomach has different types of cells (such as muscle cells and other inner lining cells) that perform functions like churning food and producing digestive juices and acid.
2 Marks
Q. What is the significance of the word "cell" and who coined this term?
✔ Answer: The word "cell" is significant because it was the first term used to describe the basic unit of life. This term was coined by the scientist Robert Hooke in 1665 after he observed small, empty compartments in a thin slice of cork that reminded him of a honeycomb.
2 Marks
Q. Differentiate between a sign and a symptom with examples from the chapter.
✔ Answer: A symptom is what we feel when we are unwell, such as pain or dizziness. A sign is something that can be seen or measured by others, such as a fever or a rash.
2 Marks
Q. Based on the chapter, list two common bad habits that are not good for health.
✔ Answer: Two common bad habits mentioned are: (i) Spending too much time on mobile phones or other digital screens, and (ii) Eating fast food and other junk food every day.
2 Marks
Q. Give two reasons why non-communicable diseases are becoming more common in India.
✔ Answer: Non-communicable diseases are becoming more common in India due to: (i) Changes in people's lifestyle, such as eating more processed food and getting less exercise, and (ii) People living longer lives, which increases the likelihood of developing these diseases.
2 Marks
Q. How does a vaccine work to provide acquired immunity?
✔ Answer: A vaccine provides acquired immunity by training the immune system to recognize and attack harmful germs. It does this by using weakened or dead pathogens, or harmless parts of a pathogen, to stimulate a protective response without causing the actual disease.
2 Marks
Q. What is the difference between a communicable and a non-communicable disease? Give one example of each.
✔ Answer: Communicable diseases are caused by pathogens and can spread from one person to another, like typhoid. Non-communicable diseases are not caused by pathogens and do not spread from person to person, such as cancer or diabetes.
2 Marks
Q. Based on the chapter, what two things are important for staying healthy?
✔ Answer: Two important things for staying healthy are: (i) Maintaining a healthy lifestyle, which includes eating nutritious food and exercising regularly, and (ii) Keeping the environment clean, including the air and water, to prevent illness.
2 Marks
Q. How can staying at home when unwell help the body recover and also prevent the spread of disease?
✔ Answer: Staying at home when unwell allows the body to rest and recover, which is important for healing. It also helps to minimize the spread of the disease to other people.
2 Marks
Q. How does the body's immune response change when it encounters the same pathogen for the second time?
✔ Answer: When the body is exposed to the same pathogen for the second time, the immune response is much more effective and stronger compared to the first exposure.
2 Marks
Q. What is the difference between a chronic disease and a short-term disease? Give an example of a chronic disease from the chapter.
✔ Answer: A chronic disease is a disease that persists for a long time (more than 3 months), while a short-term disease lasts for a short time. An example of a chronic disease is diabetes.
2 Marks
Q. Why is it important to spend time with friends and family?
✔ Answer: Spending time with friends and family, talking, laughing, and having fun are important because they help keep our minds healthy. It addresses the mental and social aspects of health.
2 Marks
Q. What is a balanced diet, and why is it important for a healthy lifestyle?
✔ Answer: A balanced diet consists of plenty of fruits, vegetables, and whole grains. It is important for a healthy lifestyle because it provides the body with the necessary nutrients and helps prevent non-communicable diseases.
2 Marks
Q. How does air pollution from vehicles and factories affect human health?
✔ Answer: Air pollution from vehicles and factories can cause health problems like coughing and asthma. It also makes it hard for people to breathe, indicating that clean air is crucial for health.
📙 Section C – Long Answer Questions
3 marks each
3 Marks
Q15. Describe the three basic parts of a cell and briefly explain the function of each part.
✔ Answer: The three basic parts of a cell are the cell membrane, cytoplasm, and nucleus. The cell membrane is porous and allows the entry of essential materials and the exit of waste materials. Most of the life processes take place within the cytoplasm. The nucleus regulates growth and all activities that occur within the cell.
3 Marks
Q16. A student observes a microscopic slide of a plant cell and an animal cell side-by-side. Based on the chapter, list three key differences the student would observe between the two cells.
✔ Answer: First, plant cells have an extra outer layer called the cell wall, which animal cells lack. Second, plant cells have a large central vacuole that helps store substances, but animal cells usually do not. Third, plant cells have chloroplasts (plastids) that contain chlorophyll, which are not found in animal cells.
3 Marks
Q17. The process of curdling milk into curd is a common household phenomenon. Explain the role of the microorganism responsible for this process, including the specific conditions required for it to thrive.
✔ Answer: The microorganism responsible for turning milk into curd is a bacterium called Lactobacillus. It feeds on the sugar in milk and converts it into lactic acid, which causes the milk to curdle through a process called fermentation. The specific condition required for this bacterium to thrive and multiply effectively is a lukewarm temperature.
3 Marks
Q15. Describe the experiment mentioned in the chapter to observe human cheek cells. What are the key steps involved and what does a student observe?
✔ Answer: To observe human cheek cells, a student must first rinse their mouth with clean water. Then, using the blunt end of a clean toothpick, they gently scrape the inside of their cheek to collect material. This scraped material is placed in a drop of water on a clean glass slide and spread evenly. A drop of methylene blue stain is added to improve visibility and contrast, followed by a drop of glycerin to prevent the cells from drying. Finally, a coverslip is carefully placed over the material, and the slide is observed under a microscope. A student would observe polygon-shaped structures, which are the cheek cells.
3 Marks
Q16. Explain the significance of the invention of the microscope. How did the contributions of both Robert Hooke and Antonie van Leeuwenhoek advance our understanding of the invisible living world?
✔ Answer: The invention of the microscope was a major scientific discovery as it opened up a hidden world of tiny living creatures that were previously invisible to the naked eye. Robert Hooke's microscope, which could magnify objects 200 to 300 times, allowed him to see and name the 'cell' for the first time by observing a thin slice of cork. Antonie van Leeuwenhoek improved lenses to build more useful microscopes, allowing him to be the first person to clearly see and describe tiny living organisms like bacteria and blood cells, earning him the title of the "Father of Microbiology". Together, their contributions advanced our understanding of the fundamental unit of life.
3 Marks
Q17. Explain how microorganisms help to recycle nutrients in nature. Give an example of this process.
✔ Answer: Microorganisms play a vital role in recycling nutrients in nature by acting as decomposers. They break down dead plant and animal waste into simpler, nutrient-rich substances, which are then returned to the soil to help new plants grow better. A specific example of this is the process of manure formation, where microorganisms like fungi and bacteria slowly break down plant waste (e.g., fruit and vegetable peels) into natural manure, increasing soil fertility.
3 Marks
Q15. A student is preparing a microscope slide of a microorganism from a water sample. Explain the importance of using a coverslip and blotting paper in this process.
✔ Answer: A coverslip is a small, thin piece of glass used to cover the specimen on a microscope slide. Its purpose is to flatten the material and protect it, while also preventing air bubbles from getting trapped, which could obstruct the view. Blotting paper is used to gently wipe off any excess liquid, such as glycerin or stain, from the edges of the coverslip. This ensures that the slide is clean and the cells are in focus for clear observation.
3 Marks
Q16. Compare and contrast unicellular and multicellular organisms based on their cell number and how they perform life functions. Give one example of each from the text.
✔ Answer: Unicellular organisms are composed of just a single cell, and all the functions necessary for survival, such as respiration, digestion, and excretion, are carried out by that one cell. An example of a unicellular organism is Amoeba. Multicellular organisms are made up of many cells where different cells have specialized functions and work together to ensure survival. Plants and animals are examples of multicellular organisms.
3 Marks
Q17. Explain how different types of cells work together to perform the complex function of digestion in the stomach.
✔ Answer: The stomach performs digestion through the cooperation of different types of cells. Muscle cells in the stomach wall help to churn the food, which is crucial for breaking it down mechanically. Concurrently, other specialized cells in the inner lining of the stomach produce digestive juices and acid, which are essential for the chemical breakdown of food. The combined effort of these different types of cells makes the overall process of digestion possible.
3 Marks
Q15. Explain how a clean environment is crucial for both physical and mental well-being, as described in the chapter.
✔ Answer: A clean environment is important for physical health as it prevents us from falling sick more often. It is also crucial for mental well-being because even if we are physically healthy, we may not feel good if our surroundings are polluted or messy. A cleaner environment helps us feel better and stay healthy overall.
3 Marks
Q16. Ayurveda teaches true health is a balance of body, mind, and surroundings. How does dinacharya (daily routine) and ritucharya (seasonal routine) help achieve this balance?
✔ Answer: Dinacharya (daily routine) and ritucharya (seasonal routine) help maintain the balance of body, mind, and surroundings as taught in Ayurveda. Following these routines ensures practices like eating fresh, wholesome food, getting restful sleep, exercising regularly, and maintaining a calm mind, all of which are essential for overall well-being.
3 Marks
Q17. What are vectors? How are they responsible for the spread of some communicable diseases? Give an example.
✔ Answer: Vectors are insects, like mosquitoes and houseflies, that spread pathogens from an infected person to a healthy person. For example, mosquitoes act as vectors by transmitting the virus causing dengue fever, and the protozoa causing malaria, to humans.
3 Marks
Q15. What are pathogens, and through what three ways can they enter the human body?
✔ Answer: Pathogens are disease-causing organisms like bacteria, viruses, fungi, and protozoa. They can enter our body through the air we breathe, by consuming contaminated food or water, or through direct or indirect contact with an infected person.
3 Marks
Q16. Explain the concept of parasites, giving an example of a disease they cause. How do these parasites typically spread?
✔ Answer: Parasites are organisms that live in or on another living being and feed on nutrients. Some infectious diseases are caused by worms that act as parasites and live inside our bodies, especially in the digestive system. These worms typically spread through contaminated food, water, soil, or contact with infected people or animals.
3 Marks
Q17. What are the key contributions of Dr. Kamal Ranadive to biomedical research as highlighted in the chapter?
✔ Answer: Dr. Kamal Ranadive was a pioneering biomedical researcher whose work established a link between hormones and certain viruses with cancer. She also showed how lifestyle factors like tobacco, diet, and pollution can increase the risk of cancer, emphasizing the importance of a healthy lifestyle.
3 Marks
Q15. Explain how a disease is defined in the chapter. What are the two main groups of diseases based on their causes and spread?
✔ Answer: A disease is defined as a condition that affects the normal working of the body or mind, and can occur when one or more organs stop functioning properly. The two major types of diseases based on their causes and spread are communicable diseases and non-communicable diseases.
3 Marks
Q16. Some non-communicable diseases are deficiency diseases. Explain this with an example.
✔ Answer: Deficiency diseases are a type of non-communicable disease caused by a lack of specific nutrients in the diet. An example is scurvy, which is caused by a lack of Vitamin C. Anemia and goitre are other examples of deficiency diseases.
3 Marks
Q17. What are the different ways a communicable disease can spread from one person to another, as mentioned in the chapter?
✔ Answer: A communicable disease can spread from one person to another through the air (when an infected person coughs or sneezes), through direct contact (like shaking hands), or through indirect contact (by sharing personal items like towels). They can also spread through contaminated food or water, and through vectors like mosquitoes and houseflies.
📕 Section D – Extended Response Questions
5 marks each
5 Marks
Q18. What are the key components of a healthy lifestyle? Explain how each of these components contributes to overall well-being.
✔ Answer: Several key components of a healthy lifestyle include:
- Eat a balanced diet: Eating plenty of fruits, vegetables, and whole grains while avoiding processed, fatty, or sugary foods is essential for good physical health and preventing diseases like diabetes and obesity.
- Stay physically active: Regular physical activity like playing outdoors, walking, or exercising helps in taking care of our body and mind.
- Limit screen time: Spending too much time on digital screens is a bad habit that can lead to health problems like dry eye disease, obesity, sleep disorders, and anxiety.
- Get enough sleep: Proper sleep helps the body and mind rest and recover, which is crucial for overall well-being.
- Practice yoga or breathing exercises: These practices support a calm mind, reduce anxiety, and increase concentration.
- Say 'NO' to harmful substances: Avoiding things like tobacco, alcohol, and addictive drugs is vital to prevent serious health risks.
5 Marks
Q18. Imagine you are a scientist trying to find a new way to deal with waste from a local farm. Based on the chapter, explain how you could use microorganisms to help solve this problem. Detail the process, the microorganisms involved, and the potential products that could be created from this process.
✔ Answer: Microorganisms act as natural environmental cleaners and decomposers. To deal with waste from a local farm, I would use a composting technique utilizing bacteria and fungi present in the soil.
The Process: The dead plant and animal waste from the farm (like vegetable peels, crop residue, or animal dung) is collected in containers or pits. The microorganisms act on these complex waste materials and slowly break them down into simpler, nutrient-rich substances.
Microorganisms Involved: Fungi and bacteria are the primary microorganisms responsible for this decomposition process.
Potential Products: This natural recycling process creates a dark-colored, nutrient-rich product called manure (or compost). This natural manure can be returned to the farm's soil to increase its fertility and help new plants grow better, effectively recycling the waste without the need for chemical fertilizers.
The Process: The dead plant and animal waste from the farm (like vegetable peels, crop residue, or animal dung) is collected in containers or pits. The microorganisms act on these complex waste materials and slowly break them down into simpler, nutrient-rich substances.
Microorganisms Involved: Fungi and bacteria are the primary microorganisms responsible for this decomposition process.
Potential Products: This natural recycling process creates a dark-colored, nutrient-rich product called manure (or compost). This natural manure can be returned to the farm's soil to increase its fertility and help new plants grow better, effectively recycling the waste without the need for chemical fertilizers.
5 Marks
Q18. In the chapter a cell is compared to a brick and an organism to a complete building. Using this analogy and the levels of organization described, elaborate on how different cells in an organism work together to perform complex functions, using the digestive system as a specific example.
✔ Answer: The analogy of a cell as a brick and an organism as a building helps to understand the levels of organization in a living being. Just as a group of bricks forms a wall, a group of similar cells forms a tissue. Different tissues then organize to form an organ, and several organs working together form an organ system, which finally makes up a complete organism.
The digestive system is an excellent example of this organization:
The digestive system is an excellent example of this organization:
- Cells to Tissue: A group of muscle cells in the food pipe, for instance, forms a tissue. These cells are thin, flexible, and spindle-shaped, allowing them to contract and relax in a wave-like manner to push food down to the stomach.
- Tissue to Organ: The stomach itself is an organ composed of different tissues. One type of muscle tissue in the stomach wall helps to churn the food. Another tissue, composed of different types of cells in the inner lining, produces digestive juices and acid to break down the food chemically.
- Organ to Organ System: The stomach, along with other organs like the food pipe and intestines, works together to form the digestive system. All these cells, tissues, and organs cooperate to ensure digestion is possible, highlighting how simple building blocks (cells) come together to perform a complex function.
5 Marks
Q18. Imagine you are a teacher explaining the importance of microorganisms to your class. Based on the chapter, explain two different ways microorganisms are beneficial to humans or the environment, providing a detailed example for each.
✔ Answer: Microorganisms are beneficial in several ways:
- Microbes as Environmental Cleaners: Microorganisms are vital for cleaning the environment through the process of decomposition. An excellent example is the breakdown of waste on Earth. Microorganisms like fungi and bacteria act on dead plant and animal waste. They break down these complex materials into simpler, nutrient-rich substances. These substances return to the soil, where they help new plants grow. This recycling of nutrients is a natural process that keeps the environment clean and maintains the health of the soil without human intervention or chemical fertilizers.
- Microbes in Food Production: Microorganisms also play a crucial role in our kitchens and in the production of various food items. A prime example is the production of curd. A bacterium called Lactobacillus is responsible for turning milk into curd. This bacterium feeds on the sugar in milk and converts it into lactic acid, which causes the milk to curdle and gives curd its characteristic sour taste. This process, known as fermentation, is an important application of microbes in our daily lives.
5 Marks
Q18. Explain the concept of antibiotic resistance. What are the two key precautions mentioned in the chapter that can be taken to reduce its development and spread?
✔ Answer: Antibiotic resistance is a phenomenon where bacteria that were previously killed by a given antibiotic learn to survive and multiply despite treatment. This makes common infections harder to treat and increases the risk of complications, prolonged illness, or even death.
The two key precautions to reduce antibiotic resistance are:
The two key precautions to reduce antibiotic resistance are:
- Use antibiotics wisely: Antibiotics should only be taken when prescribed by a doctor, in the correct dose, and for the right duration.
- Avoid unnecessary use: Avoiding the unnecessary use of antibiotics helps prevent the rise of resistant bacteria and keeps the drugs effective for future generations.
5 Marks
Q18. Explain the discovery of the first antibiotic, Penicillin, by Alexander Fleming. How did this chance discovery benefit humanity, and what is the biggest challenge associated with its use today?
✔ Answer: In 1928, bacteriologist Alexander Fleming noticed that a mould growing on a discarded petri dish had stopped the growth of harmful bacteria. He realized that the mould was releasing a substance that was killing the bacteria. This chance discovery led to the development of Penicillin, the first antibiotic, which has since saved millions of lives by treating bacterial infections.
The biggest challenge today is antibiotic resistance, where bacteria are becoming immune to antibiotics, making common infections harder to treat and increasing the risk of death.
The biggest challenge today is antibiotic resistance, where bacteria are becoming immune to antibiotics, making common infections harder to treat and increasing the risk of death.
📘 Section E – Case Study Based Questions
4 marks each
Case Study 1: Lifestyle and Non-Communicable Diseases
A Grade 8 student surveyed her neighborhood and noticed that many people were suffering from diseases like diabetes and high blood pressure. She spoke to a family member who worked as a doctor and learned that these diseases were linked to lifestyle choices. The doctor explained that eating processed food, not exercising, and being overweight are significant factors. She then created a health chart to track her family's eating habits and physical activity to prevent such diseases.
(a) What type of diseases did the student observe in her neighborhood?
Answer: The student observed non-communicable diseases in her neighborhood.
(b) What were the three lifestyle-related factors identified by the doctor?
Answer: The three lifestyle-related factors identified were: eating processed food, not exercising, and being overweight.
(c) How can the student's initiative help her family prevent these diseases?
Answer: The student's initiative can help her family by encouraging them to make positive changes to their lifestyle, such as eating a balanced diet and exercising regularly, which can prevent and manage these diseases.
(d) What is one symptom of diabetes mentioned in the chapter?
Answer: One symptom of diabetes mentioned in the chapter is frequent urination, excessive thirst, weight loss, or tiredness.
Case Study 2: The Discovery of the First Vaccine
Dr. Edward Jenner, an English doctor in the late 1700s, observed that milkmaids who had a milder disease called cowpox did not get smallpox, a deadly disease. He hypothesized that the content from the cowpox blisters protected people from smallpox. He then conducted an experiment where he injected cowpox sap into a boy. The boy later showed no illness when exposed to smallpox. This led to the invention of the first vaccine, which eventually helped eradicate smallpox worldwide.
(a) What was Dr. Jenner's initial observation that led to his hypothesis?
Answer: Dr. Jenner's initial observation was that milkmaids who had cowpox did not get smallpox.
(b) How did his experiment prove his hypothesis?
Answer: He proved his hypothesis by injecting cowpox sap into a boy. The boy's later resistance to smallpox proved that exposure to cowpox provided protection.
(c) What is a key difference between vaccines and antibiotics, as mentioned in the chapter?
Answer: The key difference is that vaccines are preventive, while antibiotics are curative. Vaccines prevent diseases by training the immune system beforehand, whereas antibiotics treat an existing bacterial infection.
(d) How did this discovery benefit the world in the long run?
Answer: The discovery led to the mass vaccination of people, which eventually helped eradicate smallpox worldwide.
Case Study 3: The Tiny Food Factory
Rohit, a young chef, was fascinated by the fermentation process. He learned that many of his favorite foods, from bread to idli, rely on tiny, invisible organisms. He decided to experiment with making his own sourdough bread, which requires a starter culture of microorganisms. Rohit knew that these microbes need specific conditions to work their magic. He prepared a dough by mixing flour, water, and a pinch of sugar, and then added a small amount of yeast. He kept the bowl in a warm corner of his kitchen, away from drafts. To his delight, after a few hours, the dough had risen, become fluffy, and had a distinctive smell.
(a) What is the function of the sugar and warm water in Rohit's dough preparation?
Answer: Sugar acts as a food source for the yeast to grow, while the warm water provides the optimal lukewarm temperature for the yeast to multiply effectively.
(b) How did the yeast make the dough rise and become fluffy?
Answer: As the yeast consumed the sugar, it released carbon dioxide gas. The gas bubbles got trapped in the dough, causing it to rise and become soft and fluffy.
(c) What is the name of the process by which the yeast broke down the sugar?
Answer: The process is called fermentation.
(d) Besides yeast, name another microorganism mentioned in the chapter that helps in the fermentation of food items.
Answer: Lactobacillus (a bacterium responsible for turning milk into curd).
Case Study 4: The Ocean's Unseen Powerhouse
A marine biologist, Dr. Anya, was studying the health of a coral reef. She explained to her team that the ocean's ecosystem is heavily dependent on microscopic plant-like organisms. These tiny organisms are so abundant that they produce a significant portion of the Earth's oxygen supply. She highlighted their importance not just for oxygen production but also as a food source for aquatic life and even for humans as a health supplement. Dr. Anya also warned that their existence is threatened by human activities like pollution.
(a) What are the microscopic organisms that Dr. Anya is referring to?
Answer: Microalgae.
(b) How do these organisms produce oxygen?
Answer: Since they are plant-like organisms with chloroplasts, they produce oxygen through the process of photosynthesis.
(c) Name two other uses of these organisms mentioned in the chapter.
Answer: Two other uses are cleaning water and making biofuel (or serving as a nutrient-rich health supplement like Spirulina).
(d) Why is it important to conserve these tiny organisms?
Answer: They must be conserved because they produce a massive amount of the Earth's oxygen, are foundational to aquatic food webs, and help maintain a balanced global ecosystem.
Case Study 5: The Soil's Secret Helpers
A school science club was running an experiment to learn about composting. They took two identical containers. Container A was filled with garden soil, and Container B was filled with garden soil and a mix of kitchen waste like fruit and vegetable peels. They covered both containers and left them in a corner of the school garden. After a few weeks, they noticed that the contents of Container B had turned into a dark-coloured, nutrient-rich material, while the contents of Container A remained unchanged. The science teacher explained that tiny living beings in the soil were responsible for this transformation. She also mentioned that some gardeners in the neighbourhood use a similar technique.
(a) What is the dark-coloured material in Container B called, and what is its significance?
Answer: The dark-coloured material in Container B is called manure. Its significance is that it is rich in nutrients and helps to increase the fertility of the soil, making it beneficial for plant growth.
(b) What type of microorganisms are responsible for the change in Container B?
Answer: The microorganisms responsible for the change are fungi and bacteria. They act on the plant waste and slowly break it down into simpler substances.
(c) Why did the contents of Container A remain unchanged?
Answer: The contents of Container A remained unchanged because it contained only soil and no biodegradable organic waste like fruit and vegetable peels. The microorganisms in the soil had nothing to decompose, so no manure was formed.
(d) How does this process help the environment?
Answer: This process helps the environment by recycling waste and returning important nutrients to nature. It reduces the amount of waste that would otherwise go to landfills and provides a natural way to enrich the soil without using chemical fertilizers.
Case Study 6: A Scientist's Innovative Solution
Dr. Ananda, a brilliant scientist, was deeply concerned about the environmental damage caused by oil spills in the oceans. He knew that conventional methods were often slow and ineffective. He decided to find an alternative solution. After years of research, in 1971, he successfully engineered a special bacterium that had the unique ability to break down oil. This discovery was so significant that it was granted a patent in 1980, ensuring that no one could copy his invention without permission. His work demonstrated a novel way to use microorganisms to tackle major environmental problems.
(a) What was the main environmental problem Dr. Ananda aimed to solve?
Answer: The main environmental problem Dr. Ananda aimed to solve was the pollution caused by oil spills in the ocean.
(b) What special ability did the bacterium he developed have?
Answer: The special ability of the bacterium he developed was that it could break down oil spills.
(c) What is a 'patent' and why was it important for Dr. Ananda's discovery?
Answer: A patent is a legal copyright given to a person so that no one else can copy, use, or sell their invention without permission. It was important for Dr. Ananda's discovery because it protected his intellectual property and ensured that his unique solution could not be exploited without his consent.
(d) How did Dr. Ananda's work expand our understanding of microorganisms?
Answer: Dr. Ananda's work showed that microorganisms are not just for basic life processes or decomposition but can also be used to solve complex environmental problems like pollution. It expanded our understanding of the potential and versatility of microbes beyond their traditionally known roles.
Case Study 7: The Curd Mystery
Priya was learning about microorganisms in her science class and decided to perform a small experiment at home to make curd. She took two bowls, A and B. She poured lukewarm milk into bowl A and cold milk into bowl B. She then added a small spoon of curd from a previous batch to both bowls. After a few hours, she was surprised to find that the milk in bowl A had transformed into a firm, sour curd, while the milk in bowl B remained mostly liquid, just a little sour. Her mother explained that the temperature made all the difference.
(a) What is the microorganism responsible for turning milk into curd?
Answer: The microorganism responsible for turning milk into curd is a bacterium called Lactobacillus.
(b) What is the substance produced by this microorganism that makes the curd sour?
Answer: The substance produced by this microorganism that makes the curd sour is lactic acid.
(c) Why did the milk in bowl A turn into curd, but not in bowl B?
Answer: The milk in bowl A turned into curd because it was kept in lukewarm conditions, which is the optimal temperature for the bacteria to grow and multiply. In contrast, bowl B had cold milk, where the bacteria could not grow effectively, so the milk did not curdle.
(d) What is the process of turning milk into curd called?
Answer: The process of turning milk into curd is called fermentation.
Case Study 8: The Superfood Revolution
In a small village, a group of entrepreneurs started a project to farm a microscopic organism for a sustainable livelihood. They learned that this organism, a type of microalga, is rich in protein and Vitamin B12 and is considered a "superfood." They set up clear glass tanks in a place with moderate temperature and filled them with pond water. They added a starter culture of the organism, stirred it regularly, and after a few weeks, harvested a nutrient-rich substance by filtering it through a fine cloth. The villagers were excited to see how this tiny organism could provide a new source of income and nutrition.
(a) What is the name of the microalga that is called a superfood in the chapter?
Answer: The microalga that is called a superfood in the chapter is Spirulina.
(b) What makes this organism a "superfood"? Name two nutrients it provides.
Answer: Spirulina is considered a superfood because it is rich in nutrients. Two nutrients it provides are protein (more than 60% of its body weight) and Vitamin B12.
(c) Why was it important for them to keep the tanks at a moderate temperature and stir the culture regularly?
Answer: It was important for them to keep the tanks at a moderate temperature and stir the culture because these conditions are conducive to the growth of Spirulina. The stirring ensures that the nutrients are evenly distributed and the culture gets proper access to sunlight for photosynthesis.
(d) Besides being a food source, how else can this microalga be useful?
Answer: Besides being a food source, the chapter also mentions that microalgae can be used to clean water and to make biofuel.
Case Study 9: The Impact of Screen Time and Social Health
Rahul, a Grade 8 student, moved to a new city. In his new school, he struggled to make friends and felt lonely as his parents were very busy. To cope with this feeling, he spent a lot of time on his phone and social media, which made him feel even worse. He started having frequent headaches, lost weight, and had trouble sleeping. A doctor advised him to cut down on screen time and meet with a counsellor. His school counsellor arranged for support to help him make friends.
(a) What kind of well-being was Rahul lacking in his new environment?
Answer: Rahul was lacking in social well-being, as he had no friends in his new environment and felt lonely.
(b) How did his attempt to cope affect his physical health?
Answer: His attempt to cope by spending more time on his phone led to physical health problems like headaches, weight loss, and an inability to sleep well.
(c) According to the chapter, why is spending time with friends and family important for health?
Answer: Spending time with friends and family, talking, laughing, and having fun helps keep our minds healthy.
(d) What two aspects of a healthy person's life, as per the chapter, were being affected by Rahul's situation?
Answer: The two aspects of a healthy person's life being affected were his mental and social well-being.
Case Study 10: Sanitation and Communicable Diseases
A community in the Bhadrak district of Odisha launched a sanitation campaign to encourage people to build and use toilets. This initiative significantly reduced open defecation, leading to fewer cases of diarrhoea and other infections among children. The campaign demonstrated that simple steps like good sanitation can play a huge role in preventing the spread of diseases.
(a) What type of diseases was the sanitation campaign most likely trying to prevent?
Answer: The sanitation campaign was most likely trying to prevent communicable diseases, which are caused by pathogens and spread from person to person.
(b) How did the campaign directly improve the health of children?
Answer: The campaign directly improved the health of children by reducing cases of diarrhoea and other infections, which were likely caused by poor sanitation and open defecation.
(c) The chapter mentions a disease that is transmitted through contaminated water and food. What is one such disease mentioned in the table?
Answer: The table in the chapter lists Cholera and Hepatitis A as diseases spread through contaminated water and food.
(d) What is the main inference from this case study about the prevention of diseases?
Answer: The main inference is that simple, community-led steps like good sanitation can significantly reduce the spread of communicable diseases.
Case Study 11: Hygiene and Disease Prevention Campaign
A community health worker is conducting a campaign to educate people on the importance of hygiene. She explains that diseases like Hepatitis A and Typhoid spread through contaminated water and food. She stresses the importance of washing hands frequently, maintaining personal hygiene, and consuming properly cooked food and boiled drinking water. She also mentions that during the monsoon season, there is an increase in diseases like malaria and dengue, which are transmitted by insects like mosquitoes.
(a) What type of diseases is the health worker focusing on in her campaign?
Answer: The health worker is focusing on communicable diseases because they are caused by pathogens and can spread from person to person through various means, including contaminated water and insect vectors.
(b) What are two diseases transmitted through contaminated food or water, as mentioned in the case study?
Answer: The two diseases mentioned are Hepatitis A and Typhoid.
(c) What are the insects that spread diseases like malaria and dengue called?
Answer: The insects that spread diseases like malaria and dengue are called vectors.
(d) How can the community control the spread of malaria and dengue during the monsoon season?
Answer: The community can control the spread of these diseases by using mosquito nets and repellents, wearing long-sleeved clothes, and controlling mosquito breeding by avoiding areas with still water.
Case Study 12: Understanding Vaccines
A young boy named Aditya is advised to get a tetanus shot after an injury. He learns that the shot is a vaccine that contains an inactivated bacterial toxin. This helps his immune system develop protection without causing the disease. He is also told that vaccines are one of the most effective ways to protect people against serious diseases and that they are preventive, not curative.
(a) What type of disease is the tetanus shot protecting Aditya against?
Answer: The tetanus shot is protecting Aditya against an infection caused by tetanus-causing bacteria.
(b) What is a key purpose of the inactivated bacterial toxin in the vaccine?
Answer: The purpose of the inactivated bacterial toxin is to help the immune system develop protection without causing the disease itself.
(c) According to the chapter, why is a tetanus shot considered a preventive measure?
Answer: A tetanus shot is considered a preventive measure because it trains the immune system to recognize and fight the harmful germs before an infection can take hold. Vaccines are preventive, not curative.
(d) What is the main principle behind how a vaccine works?
Answer: The main principle is that a vaccine helps our body fight a disease by training the immune system to recognize and attack harmful germs.
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