KSEEB SSLC Class 10 Science Solutions Chapter 15 Our Environment
KSEEB SSLC Class 10 Science Solutions Chapter 15 Our Environment
Karnataka SSLC Class 10 Science Solutions Chapter 15 Our Environment
KSEEB SSLC Class 10 Science Chapter 15 Intext Questions
Text Book Part I Page No. 140
Question 1.
What are the trophic levels? Give an example of a food chain and state the different trophic levels in it.
Answer:
Each step or level of a food chain is called Trophic levels.
Example for Food chain
Here grass is a producer because it prepares its own food. This grass is eaten by herbivores means secondary, small carnivores (Frog) are tertiary and higher carnivores are in the fourth level.
Question 2.
What is the role of decomposers in the ecosystem?
Answer:
Microorganisms, comprising bacteria and Fungi, break-down the dead remains and waste products of organisms. These microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.
Text Book Part I Page No. 142
Question 1.
Why are some substances biodegradable and some non-biodegradable?
Answer:
Substances that are broken down by biological processes are said to be biodegradable. Eg: paper and peel of a fruit. But plastic leather etc. are not broken down. These are called Non-biodegradable.
Question 2.
Give any two ways in which biodegradable substances would affect the environment.
Answer:
- Leaves of the plants decay and reduces soil fertility,
- Bio-degradable substances have carbon. When this is burnt, CO2 and CO are produced and causes air pollution.
Question 3.
Give any two ways in which non-biodegradable substances would affect the environment.
Answer:
- As these are not decomposing, they cause air pollution and water pollution.
- Plastic enters stomach of many animals and causes death of animals.
Text Book Part I Page No. 144
Question 1.
What is ozone and how does it affect any ecosystem?
Answer:
Ozone at the higher levels of the atmosphere is a product of UV radiations acting on O2 molecule. The higher energy UV radiations split apart some molecular Oa in free oxygen (O) atoms. These atoms then combine with the molecular O2 to form Ozone.
Ozone shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms for example, it is known to cause skin cancer in human beings.
Question 2.
How can you help in reducing the problem of waste disposal? Give any two methods.
Answer:
- We must minimise the usage of plastics,
- We can collect wastes and by this we can produce gas which is an alternate source of energy.
KSEEB SSLC Class 10 Science Chapter 15 Textbook Exercises
Question 1.
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:
(b) Grass, wood and plastic.
Question 2.
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:
(b) Grass, goat and human.
Question 3.
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:
(d) All of the above.
Question 4.
What will happen if we kill all the organisms in one trophic level?
Answer:
If we kill all the organisms in one trophic level, the population size of organisms in lower level increases uncontrollably and the number of organisms in higher trophic level decreases due to non¬availability of food. This results in an imbalance in ecosystem.
Question 5.
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:
- Removing producers: All the heterotrophs die.
- Removing herbivores: Carnivores would not get food.
- Removing carnivores: Herbivores would increase to unsustainable levels.
- Removing decomposers: Organic wastes, plant, and animal dead remains would pile up.
- The role of each and every species belonging to every trophic level is unique.
- No, the organisms of any trophic level cannot be removed without damaging the ecosystem.
Question 6.
What is the biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Answer:
Some harmful chemicals enter our bodies through the food chain, one of the reasons is the use of several pesticides and other chemicals to protect our crops from disease and pests. These chemicals are either washed down into the soil or into the water bodies. From the soil, these are absorbed by the plants along with water and minerals and from the water bodies these are taken up by aquatic plants and animals.
This is one of the ways in which they enter the food chain. This phenomenon is known as biological magnification. This level of magnification be different at different levels of the ecosystem.
Eg: Spraying of DDT will remain for a long time in the environment.
Question 7.
What are the problems caused by the non-biodegradable wastes that we generate?
Answer:
- Non-aesthetic look.
- Death of cattle by ingestion of plastic bags.
- The quality of soil is adversely affected.
- Biomagnification of harmful chemicals like DDT in birds disturb their calcium metabolism.
- Non – biodegradable wastes cause pollution of soil and water.
Question 8.
If all the waste we generate is biodegradable, will this have no impact on the environment?
Answer:
If all the waste we generate is biodegradable, there is a imbalance in nature. Because with the increase of wastes there is decrease in the number of decomposers. These wastes spread every where and microbes are more which causes many diseases to us.
Question 9.
Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?
Answer:
Damage to the ozone layer causes so many problems. At the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet radiation from the sun. If ozone layer is damaged no organism can survive. The following are the steps being taken to limit this damage.
- We should minimize the use of vehicles.
- We should not encourage the burning of fossilic fuels.
- It is now mandatory for all the manufacturing companies to make CFC- free refrigerators throughout the world.
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