Class 8 Science Holiday Homework – The Invisible World & Health – The Ultimate Treasure
Class 8 Science Holiday Homework.
Section A: The Invisible World
1. Bread Mould Activity
Aim
To observe the growth of bread mould on a slice of bread.
Observation
I kept a slice of bread in a warm and moist place for five days.
- On the first day, the bread looked normal.
- After a few days, small green and black spots appeared.
- These spots gradually spread over the bread.
- The mould looked soft and cotton-like.
- Bread mould is a type of fungus that grows on moist food.
Diagram provided below.
2. Types of Microorganisms
A. Bacteria
Uses:
- Used in making curd.
- Improve soil fertility.
- Help in the production of medicines.
Harms:
- Cause diseases such as cholera and typhoid.
Diagram provided below.
B. Virus
Uses:
- Used in scientific research.
- Help in the development of vaccines.
Harms:
- Cause diseases such as COVID-19, polio, and influenza.
Diagram provided below.
C. Fungi
Uses:
- Yeast is used in making bread and cakes.
- Used in the production of medicines like penicillin.
Harms:
- Spoil food.
- Cause skin infections.
D. Protozoa
Uses:
- Play an important role in aquatic food chains.
Harms:
- Cause diseases such as malaria and amoebic dysentery.
Diagram provided below.
3. Uses of Microorganisms
In Curd Making
Lactobacillus bacteria convert milk into curd.
In Bread Making
Yeast produces carbon dioxide gas, which makes the dough rise and become soft.
In Medicines
Some microorganisms are used to produce antibiotics that help cure diseases.
4. Thinking Questions
Why are viruses considered non-living outside the body?
Viruses cannot perform life processes on their own. They become active only inside the living cells of a host organism. Therefore, they are considered non-living outside the body.
How do diseases spread?
Diseases spread through air, water, contaminated food, direct contact with infected persons, and through carriers such as mosquitoes.
Section B: Health – The Ultimate Treasure
5. Weekly Balanced Diet Chart
| Day | Breakfast | Lunch | Dinner |
|---|---|---|---|
| Monday | Milk and fruits | Dal, rice, salad | Roti and vegetables |
| Tuesday | Sprouts and milk | Rajma and rice | Roti and dal |
| Wednesday | Poha and milk | Roti and vegetables | Khichdi |
| Thursday | Fruits and milk | Dal and rice | Roti and paneer |
| Friday | Upma | Roti and vegetables | Dal and rice |
| Saturday | Paratha and curd | Rice and dal | Roti and vegetables |
| Sunday | Fruits and milk | Vegetable pulao and raita | Roti and dal |
6. My Daily Routine
I wake up at 6:00 a.m. every day. After freshening up, I do some exercise and have breakfast. I go to school and attend my classes. After returning home, I complete my homework and spend some time playing outdoor games. In the evening, I revise my lessons. I have dinner with my family and go to bed by 10:00 p.m.
Suggested Improvements
- Drink more water daily.
- Reduce screen time.
- Exercise regularly.
- Sleep on time.
7. Communicable and Non-Communicable Diseases
| Type | Examples | Cause | Prevention |
|---|---|---|---|
| Communicable Diseases | Dengue, COVID-19 | Germs | Hygiene, Vaccination |
| Non-Communicable Diseases | Diabetes | Unhealthy Lifestyle | Healthy Habits |
8. Poster
CLEANLINESS IS THE KEY TO GOOD HEALTH
- Wash your hands regularly.
- Drink clean water.
- Eat healthy food.
- Keep your surroundings clean.
- Throw garbage in dustbins.
"Healthy Habits, Healthy Life"
9. Case Study: Effects of Junk Food
Junk food contains high amounts of oil, sugar, and salt. Eating junk food regularly can lead to obesity, diabetes, heart problems, and digestive disorders. It does not provide enough nutrients required for healthy growth. Therefore, we should eat fresh fruits, vegetables, and balanced meals instead of junk food.
Section C: Short Questions
1. What are Microorganisms?
Microorganisms are very tiny living organisms that can be seen only with the help of a microscope.
2. What is Vaccination?
Vaccination is the process of giving vaccines to protect the body from diseases.
3. What is a Balanced Diet?
A balanced diet is a diet that contains all the essential nutrients in the right amounts for healthy growth and development.
4. What are Deficiency Diseases?
Deficiency diseases are diseases caused by a lack of essential nutrients in the diet.
Creative Writing
How to Stay Healthy During Holidays
Holidays are a time to relax and enjoy, but it is also important to stay healthy. We should eat a balanced diet that includes fruits, vegetables, milk, and whole grains. Drinking plenty of water helps keep our body hydrated. Regular exercise and outdoor games keep us active and fit. We should avoid eating too much junk food and limit screen time. Getting enough sleep and maintaining personal hygiene are also important. By following healthy habits, we can enjoy our holidays while staying physically and mentally healthy.
Diagrams
Bread Mould
Bacteria
Virus
Fungi
Protozoa
Disease Spread
Balanced Diet Chart
Daily Routine
Cleanliness Poster
Effects of Junk Food
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