"AKC SCIENCE CLASSES"
CLASS 10 TH (CBSE AND MP BOARD)
CHAPTER 15
OUR ENVIRONMENT
INTEXT QUESTIONS ANSWERS
NCERT INTEXT QUESTIONS (PAGE NO. 257)
Q.01:- Why are some substances biodegradable and some non-biodegradable?
Ans:- Substances which can be broken down by the help of enzymes secreted by the bacteria and other saprophytes over a period of time are biodegradable. These substances have short molecular organisation and can be assimilated by the saprophytes. Non-biodegradable substances cannot be acted upon by the enzymes in nature as they consist of polymers which are strongly bonded with each other.
Q.02:- Give any two ways in which biodegradable substances would affect the environment.
Ans:- (ⅰ) Biodegradable substances in large quantities would contribute to the pollution of the environment and
(ⅱ) They serve breeding to flies which are carrier of many diseases such as cholera.
Q.03:- Give any two ways in which non-biodegradable substances would affect the environment.
Ans:- (ⅰ) Non-biodegradable substances cannot degrade and return the minerals to the environment. Instead of a cycle, these materials follow a linear path. They are produced in a factory and then end up in the soil. They pile up and cause harm to various members of the eco-system.
ⅱ) They may cause bio-magnification in the food chain and end up in humans. For example, pesticides like DDT enter the food chain, bio-magnify and affect human being and other organism.
NCERT INTEXT QUESTIONS (PAGE NO. 261)
Q.01:- What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Ans:- Trophic level is the functional level occupied by an organism in a food chain. Trophic literally means feeding, so trophic levels are the levels or positions at which species feed. Examples of trophic levels include 'herbivores' and 'decomposers'. An example of a food chain depicting various trophic levels is as follows :-
Ans:- Without decomposers, the remains of the other organisms in a community would accumulate. Eventually the world would run out of carbon dioxide or nitrate or phosphate or other inorganic material essential for life. The decomposers breakdown the organic waste products and dead remains of organisms into the inorganic substances needed by the producers (plants). Most decomposition is carried out by saprophytic fungi, by bacteria and by invertebrates.
NCERT INTEXT QUESTIONS (PAGE NO. 264)
Q.01:- What is ozone and how does it affect any eco-system?
Ans:- Ozone (O₃) a molecule formed by three atoms of oxygen. It is a deadly poisonous gas. However, at the higher level of atmosphere, it performs an essential function. It shields surface of earth from ultraviolet radiation (UV) of solar radiations. This radiation is highly damaging to organisms, it is known to cause skin cancer, cataract in human beings.
Q.02:- How can you help in reducing the problem of waste disposal? Give any two methods.
Ans:- We can help in reducing the problem of waste disposal by adopting the following methods :-
- Minimizing the use of non-biodegradable wastes.
- Recycling the non-biodegradable wastes like plastic.
- Production of compost, biogas from biodegradable wastes.
- Reducing the volume of wastes by burning them incinerator.
