CHAPTER 15 Our Environment
CHAPTER 15 Our Environment
15.1 ECOSYSTEM — WHAT ARE ITS COMPONENTS?
Question :1 Who interacts with each other in nature and Why ?
Answer :- All organisms such as plants, animals, microorganisms and human beings as well as the physical surroundings interact with each other in nature to maintain a balance in nature.
Question : 2 Who forms an ecosystem ?
Answer :- All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem.
Question : 3 Which kinds of components consist in an ecosystem ?
Answer :- (1) biotic components (2) abiotic components
Question : 4 Name of few biotic components in an ecosystem are ?
Answer :-Animals ,plants ,trees,and human beings.
Question : 5 Name of few abiotic components in an ecosystem are ?
Answer :-Temperature,rainfall,wind,soil and minerals.
Question : 6 By whom the activities of living organisms are affected ?
Answer :-The activity of living organisms are affected by the abiotic components of the ecosystem.
Question : 7 Name the types of ecosystem.
Answer :-natural ecosystem and human made ecosystem
Question : 8 Give some examples of natural ecosystems.
Answer :- Forests,ponds and lakes
Question : 9 Give some examples of artificial ecosystems.
Answer :- gardens and crop fields
Question : 10 Gardens and crop fields are which type of ecosystem?
Answer :- Gardens and crop fields are human made ecosystems.
Question :11 How can organisms be grouped ?
Answer :- Organisms can be grouped as producers, consumers and decomposers.
Question : 12 On which basis organisms can be grouped ?
Answer :- According to the manner in which they obtain their sustenance from the environment they can be grouped.
Question : 13 Which organisms can make organic compounds from inorganic compounds?
Answer :- sugar and starch
Question : 14 Who are the producers in the ecosystem ?
Answer :- Green plants and some blue algae which can produce food by photosynthesis come under this category and they are known as .producers.
Question : 15 Which substance is converted into energy by chlorophyll ?
Answer :- Sunlight
Question : 16 Who are the consumers in the ecosystem ?
Answer :- Consumers are those which consume the food produced,either directly from producers or indirectly by feeding on other consumers.
Question : 17 How can consumers be classified ?
Answer :- Consumers can be classified as herbivores,carnivores,omnivores and parasites.
Question : 18 Give an example of herbivores.
Answer :- Cow, and zebra.
Question : 19 Give an example of carnivores.
Answer :- Lion and crocodile
Question : 20 Give an example of omnivores.
Answer :-Dog and cat
Question : 21 Give an example of parasites.
Answer : Lice and ticks
Question 22 Who are the decomposers ?
Answer Decomposers are the microorganisms that break down the complex organic substance into simpler inorganic substances that go into the soil.
Question 23 What happens when an organism dies ?
Answer the microorganism comprising bacteria and fungi break down the dead remains and waste product of organisms into simpler substance.
15.1.1 Food Chains and Webs
Question : 24 Define the food chain?
Answer :The series or organisms taking part at various biotic levels form the food chain.
Question 25 Each step or the level of the food chain forms what?
Answer : Each step of level of the food chain forms a trophic level.
Question 26 Who is at the first trophic level?
Answer : The autotrophs or the producers at the first trophic level.
Question 27 What is the function of the autotrophs ?
Answer : Fix up the solar energy and make it available for heterotrophs or the consumers.
Question 28 Who is at the second trophic level?
Answer : The herbivores or the primary consumers are at the second trophic level.
Question 29 Who is at the Third trophic Level?
Answer : Small carnivorous or the secondary consumers are at the Third trophic Level.
Question : 30 How does the food act ?
Answer :The food acts as a fuel to provide us energy to do work.
Question 31 Who is at the fourth trophic level ?
Answer : The larger carnivore or the tertiary consumers are at the four trophic level.
Question 32 The interactions among various components of the environment involves what ?
Answer : It involves the energy between various components of the environment.
Question : 33 The autotrophs capture what from the environment ?
Answer: The autotrophs capture the energy present in sunlight.
Question : 34 What autotrophs do with sunlight ?
Answer: The autotrophs convert it into chemical energy.
Question : 35 Write the flow of energy in the environment.
Answer: From autotrophs the energy goes to the heterotrophs and decomposers.
Question : 36 From autotrophs the energy goes to whom?
Answer : From autotrophs the energy goes to the heterotrophs and decomposers.
Question: 37 The green plant captures ……% Half the energy of Sunlight?
Answer : a- 30%
b – 50 %
c- 1 %
d- 0.01%
Question : 38 When green plants are eaten by primary consumers a great deal of energy is lost as heat to the environment where does the energy go?
Answer : When green plants are eaten by primary consumers a great deal of energy is lost as heat to the environment. Some amount goes to digestion and doing work and the rest goes towards growth and reproduction.
Question 39 : How much percent of eaten by primary consumers is turned into its own body and made available for the next level ?
Answer : An average of 10%
Question 40 : How much percent can be taken as the average value for the amount of organic matter?
Answer : 10% can be taken as an average value for the amount of organic matter.
Question 41 : How many steps are there in a food chain?
Answer : Food chain generally consists of only three or four steps.
Question 42: How much usable energy remains after the fourth trophic level ?
Answer : Very little usable energy remains after the fourth trophic level.
Question 43: The greater numbers of _____ in the trophic level of an ecosystem?
Answer : a- secondary consumer
b- Producer
c- Primary consumer
Question 44: What is a food web?
Answer : A system of many food chains that are related to and dependent on each other is called a food web.
Question 45: What does the food web consist of?
Answer :Food web consists of many food chains.
Question 46 : The flow of energy is________.
Answer : a- directional
B- unidirectional
Question 47 : Why does the energy which passes to the herbivores not come back to autotrophs ?
Answer : As it moves progressively through the various trophic levels it is no longer available to the previous level.
Question 48 : Why does the energy available at each trophic level get diminished?
Answer : The energy available at each trophic level gets diminished progressively due to loss of energy at each level.
Question 49 : How does water get polluted?
Answer : the reason is use of several pesticides and other chemical to protect our crops from disease and paste this chemical are either way wash down into the soil or into the water bodies.
Question 50 : Why do these chemicals accumulate progressively at each trophic level?
Answer : As these chemicals are not degradable,these get accumulated progressively at each trophic level.
Question 51 : What is biological magnification?
Answer : As human beings occupy the top level in any food chain,the maximum concentration of these chemicals gets accumulated in our bodies.
Question 52 : What is the reason why our food grains such as wheat and rice ,vegetable and fruits,contain varying amounts of pesticide residues?
Answer : The reason is biological magnification.
QUESTIONS
Question What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer : The various steps in a food chain at which the transfer of food take place are called trophic levels.Example –
GRASS——-INSECTS————–FROG—————-BIRD
in this food chain
1- grass represents the first trophic level .
2-Grasshopper represent the second trophic level
3- frog represent the Third trophic Level
4 Birds represent the fourth trophic level.
Question What is the role of decomposers in the ecosystem?
Answer Decomposer breakdown dead and waste material into simpler inorganic substances that go into the soil and are used once again by several plants.
15.2 HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT?
15.2.1 Ozone Layer and How it is Getting Depleted
Question : Ozone layer is made up of what?
Answer :It is made up of three atoms of oxygen.
Question :What is the ozone layer?
Answer :Ozone layer is deadly poison and at higher levels of the atmosphere it performs an essential function. It absorbs harmful ultraviolet rays that come from the sun.
Question : What is the function of the ozone layer?
Answer : It shields the surface of the earth from ultraviolet radiation from the sun.
Question : How ultraviolet radiation damages the organism?
Answer : It is known to cause skin cancer in human beings.
Question : Ozone at the higher level of atmosphere is a product of………..
Answer : Ozone at the higher level of atmosphere is a product of UV radiation.
Question ; How is ozone formed?
Answer : The higher energy UV radiation split apart from molecular oxygen (O2) into free oxygen (O) atoms .These atoms combine with molecular oxygen to form ozone.
Question :How is the ozone layer depleting?
Answer :It is depleting due to synthetic chemicals like CFCs which are used in refrigerants and in fire extinguishers.
Question :In which year the amount of ozone in the atmosphere began to drop?
Answer : In the 1980s
Question : The use of chemicals like CFC has……….. the ozone layer.
Answer : a- dangered
b- endangered
c- Protect
Question : In which year the United Nations environment programme succeeded in forging and agreements?
Answer : In the year 1987
Question : What is mandatory for all the manufacturing companies ?
Answer: To make CFC free refrigerators throughout the world.
15.2.2 Managing the Garbage we Produce
Question : Why is plastic not degraded by bacteria?
Answer : Plastic is not degraded by the bacteria because they do not have enzymes which are used to degrade plastic.
Question : Difference between biodegradable and non – biodegradable with example?
Answer :Biodegradable :The substances which can decompose by microorganisms eg.Paper,food waste etc.
Non biodegradable :The substances which cannot decompose by microorganisms. Eg. Plastic, thermocol etc.
Question :Why does the same enzyme not break down everything we eat?
Answer :Because enzymes are specific in their action, specific enzymes are needed for the breakdown of a particular substance.
Question :Why will we not get any energy if we eat coal?
Answer :Because we do not have enzymes to digest or breakdown it.
Question: In which condition will the plastic degrade?
Answer: The plastic will be degraded by physical processes and conditions like heat and pressure.
Question :Which of the following is non biodegradable?
Answer : a- paper
b- wood
c- plastic
d- cloth
Question : Which substances are said to be biodegradable?
Answer : Substances that are broken down by biological processes are said to be biodegradable.
Question : Which substances are said to be non biodegradable?
Answer : Substances that are not broken down by biological processes are said to be non biodegradable.
Question :The waste we generate may be….……….and ……………..
Answer Biodegradable and non-biodegradable
Question: Write the ways to deal with wastes?
Answer : –Recycling
– preparation of compost
Question:How can we reduce the problem of non biodegradable waste that we generate?
Answer :1) Improvements in our lifestyle resulted in greater amounts of waste material.
2) By the process of Reduce, Reuse, Recycle.
3)and stop the use of plastics and their products.
Question : Using kulhads as disposable cups to serve tea in trains, proved to be a bad idea. Why?
Answer ; Yes because making kulhads on a large scale leads to the loss of the fertile topsoil.
QUESTIONS
Question Why are some substances biodegradable and some non-biodegradable?
Answer because some substances are organic in nature that easily decomposed
and some are synthetic that do not decompose in nature.
Question : Give any two ways in which biodegradable substances would affect the environment.
Answer :1)They may produce a foul smell during the decomposition
2)also some harmful gases are produced such as carbon dioxide, methane.
Question : Give any two ways in which non-biodegradable substances would affect the environment.
Answer 1:It may cause soil pollution
2)It cannot decompose by microorganism.
Disposable cups in trains
QUESTIONS
Question What is ozone and how does it affect any ecosystem?
Answer : Ozone(o3) is an isotope of oxygen; it is a molecule formed by three atoms of oxygen. At the higher levels of the atmosphere ozone performs an essential function. It shields the surface of Earth from ultraviolet radiation from the Sun. These radiation are highly damaging to organisms and can cause skin cancer to human beings.
Question How can you help in reducing the problem of waste disposal? Give any two methods.
Answer : By Reducing, reusing and recycling Non Biodegradable substances
By separating biodegradable substances from Non Biodegradable substances
OR
Answer :1 Separating biodegradable and nonbiodegradable substances before dumping.
2)Recycle the non-biodegradable waste material.
EXERCISES
Question 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
Answer grass, flower and leather
Question 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
Answer Grass, goat and human.
Question Which of the following are environment-friendly practices?
(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop you on her scooter
(d) All of the above
Answer All of the above.
Question What will happen if we kill all the organisms in one trophic level?
Answer : The food chain Would end and an ecological balance would be the affect :
1- If the herbivores are killed that the carnivores would not able to get food and would die
2- if carnivores are killed then the population of herbivores would increase to unsustainable levels
3-If producers are killed then the nutrient cycle in that area would not be complete.
Question Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?
Answer :Yes, because the impact of removing all the organisms in a trophic level removing producers will affect herbivores heavily due to absence of food and they will die.
Question What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer As human beings occupy the top level in any food chain the maximum concentration of these chemicals get accumulated in our body this phenomena is known as Biological magnification.
Yes, the level of this magnification will be different at different levels of the ecosystem Because the chemical entered in the producer green plants that transfer to another trophic level and in the higher trophic level that get higher concentration of chemical as compared to lower level.
Question What are the problems caused by the non-biodegradable wastes that we generate?
Answer the problem caused by non biodegradable waste are
1 This substance cannot degrade and break down with microorganisms.
2 It affects the trophic levels and food chain in the ecosystem.
3 if the quantity of non biodegradable waste increase it is a problem to dump this waste
Question If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer :Yes,it will also create problems as the numbers of decomposers will be quite low so waste cannot be broken down into harmless simpler substances at times and it spreads diseases.
Question Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Answer :Using CFCs in the refrigerator and in a fire extinguisher depletes the ozone layer.
Steps taken are :
1) Limited use of CFCs chemicals.
2)Avoid buying material filled with CFCs.
3)Buy a refrigerator which is CFCs free.