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.
If all the waste we generate is biodegradable, will this have no impact on 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
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?
What is an homologous series? Explain with an example.
What criteria do we use to decide whether something is alive?
Metallic oxides of zinc, magnesium and copper were heated with the following metals.
Metal | Zinc | Magnesium | Copper |
---|---|---|---|
Zinc oxide | |||
Magnesium oxide | |||
Cooper oxide |
In which cases will you find displacement reactions taking place?
Why is DNA copying an essential part of the process of reproduction?
What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Where do plants get each of the raw materials required for photosynthesis?
We saw in this chapter that there are four main stakeholders when it comes to forests and wildlife. Which among these should have the authority to decide the management of forest produce? Why do you think so?
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
What are the advantages and disadvantages of using a solar cooker? Are there places where solar cookers would have limited utility?