Our Environment- 1 - Free MCQ Practice Test with solutions, Class 3 Science

Chewing or mastication is the process by which food is crushed and ground by teeth. It is the first step of digestion, and it increases the surface area of foods to allow a more efficient break down by enzymes.

Germs are microorganisms. This means that they can be seen only through a microscope. They can be found everywhere - in the air, soil, and water.

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable. In 2019, there were an estimated 229 million cases of malaria worldwide. 

Malaria and dengue are among the main dangers of stagnant water, which can become a breeding ground for the mosquitoes that transmit these diseases. Stagnant water can be dangerous for drinking because it provides a better incubator than running water for many kinds of bacteria and parasites. 

The destruction of pupae and larvae of mosquitoes can be achieved chemically and biologically. The spraying of some oils such as kerosene oil, petroleum, paraffin oil, crude oil, etc. on the surface does not allow larvae to breathe and consequently, they die due to suffocation.
Cultivation of larvivorous fishes like Gambusia is another important control measure for mosquitoes. These fishes eat their larvae and pupae.
Application of mustard oil or citronella oil or some repellent cream on uncovered body parts of the body keeps mosquitoes away.

This method is useful for the disposal of biodegradable waste. The part of the garbage which can rot in nature to form harmless substances is called biodegradable (plants and animal waste). Different biodegradable waste can be dumped in a pit. Here, it can be allowed to decompose after which the garbage will convert into useful manure. This is known as composting.

It is unwanted materials and objects that people have thrown away. It is often also called trash, garbage, rubbish, or junk. Garbage is the waste we produce daily in our homes, including old or unwanted food, chemical substances, paper, broken furniture, used containers, and other things.

The diseases that flies can transmit include enteric infections (such as dysen- tery, diarrhoea, typhoid, cholera and certain helminth infections), eye infections (such as trachoma and epidemic conjunctivitis)

Spitting in public is an offence under municipal laws in various cities, but it is hardly taken seriously by the people in the country. Spitting in public places could enhance the spread of the virus.

Your passion for gardening may also be the reason for excess water usage in your home. You must have noticed how some water flows down drainage holes at the bottom of pots. Instead of letting the excess water go to waste, you can collect it and reuse it to water your plants. Do this especially while watering larger plants so that the smaller ones can be watered using the wastewater collected from drainage holes.