What is ozone and how does it affect any ecosystem?
Ozone is a clear, blue gas layer which is also known as the layer of protection of the environment. Ozone is the form of oxygen and the molecules of ozone contains three oxygen atoms (O3) It is present in the stratosphere which protects the earth from the ultraviolet (UV) radiations that came from the sun. Stratosphere is present at the altitude of 15-50 km above the earth’s surface and at the lower altitude it has thick sheet of ozone known as ozonosphere. The amount of atmospheric ozone is measured by the Dobson Spectrometer. Reaction:- O2 + O → O3 (Ozone)
Ozone affects the environment in following ways:-
Ozone is very poisonous at the ground level but at the higher altitude it is a layer of protection present in the stratosphere which protects the earth’s surface from the ultraviolet radiations, specially UV- B rays (290- 320 nm). Increase in the amount of UV rays reaches the earth surface when ozone depletion occurs, it can affect the ecosystem like it can cause skin cancer, dimming of the eye sight, herpes and diminishing the functioning of immune system in human beings.
It can cause death (mortality) of the young ones of the human beings and the animals.
It can cause mutation and blindness of the land animals.
All food chains can get disturbed.
The main cause of the ozone depletion is chlorofluorocarbon (CFCs).
What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Give any two ways in which biodegradable substances would affect the environment.
Which of the following constitute a food-chain?
(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat
If all the waste we generate is biodegradable, will this have no impact on the environment?
Why are some substances biodegradable and some non-biodegradable?
Which of the following groups contain only biodegradable items?
(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit-peels, cake and lime-juice
(d) Cake, wood and grass
How can you help in reducing the problem of waste disposal? Give any two methods.
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What is the role of decomposers in the ecosystem?
What will happen if we kill all the organisms in one trophic level?
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Why does distilled water not conduct electricity, whereas rain water does?
Name some devices in which electric motors are used.
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below –
I (amperes) 0.5 1.0 2.0 3.0 4.0
V (volts) 1.6 3.4 6.7 10.2 13.2
Plot a graph between V and I and calculate the resistance of that resistor.
The phenomenon of electromagnetic induction is
(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.
Compare the above system with the probable systems in hilly/mountainous areas or plains or plateau regions.
On the basis of the issues raised in this chapter, what changes would you incorporate in your lifestyle in a move towards a sustainable use of our resources?
Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
Define the principal focus of a concave mirror.
Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.