ICSE Living Science Biology for Class 6 Solutions Chapter 8 Our Environment
Check Your Progress
Write true or false for each statement. Rewrite the false statements correctly.
Question 1.
The layer of air surrounding earth is called the biosphere.
Answer:
False. The layer of air surrounding earth is called the atmosphere.
Question 2.
Ozone prevents the entry of ultraviolet rays to the earth.
Answer:
True
Question 3.
Thick vegetation is found in deserts.
Answer:
False : Scarce vegetation is found in deserts.
Question 4.
The transfer of energy from one level to another in food chains increases at each level.
Answer:
False. The transfer of energy from one level to another in food chains decreases at each level.
Question 5.
Food chains start with decomposers.
Answer:
False. Food chains start with producers.
Practice Question 1.
The gas which prevents the entry of ultraviolet rays to the earth is ozone.
Answer:
True.
Practice Question 2.
Omnivores eat both plants and animals.
Answer:
True.
Practice Question 3.
The very hot and winterless zone of the earth is called the tropical zone.
Answer:
True.
Check Your Progress Fill in the blanks.
Question 1.
We should avoid the use of ……………….. articles.
Answer:
We should avoid the use of non-biodegradable articles.
Question 2.
Introduction of unwanted, harmful material into an environment leads to ………………..
Answer:
Introduction of unwanted, harmful material into an environment leads to pollution.
Question 3.
…………. and ……….. are the major greenhouse gases.
Answer:
Water vapour and carbon dioxide are the major greenhouse gases.
Question 4.
Enhanced greenhouse effect has caused ………………..
Answer:
Enhanced greenhouse effect has caused global warming.
Question 5.
………… and ……….. have put tremendous pressure on natural resources.
Answer:
Growth of human popluation and industries have put tremendous pressure on natural resources.
Practice Question 1.
……………….. leads to frequent floods as rainwater is not absorbed by roots of trees.
Answer:
Deforestation leads to frequent floods as rainwater is not absorbed by roots of trees.
Practice Question 2.
……………….. pollution is caused by fumes and gases from vehicles and factories.
Answer:
Air pollution is caused by fumes and gases from vehicles and factories.
Practice Question 3.
Tea leaves and coffee beans are obtained from ………………..
Answer:
Tea leaves and coffee beans are obtained from plants.
Practice Question 4.
Wool is obtained by ……………….. which means shaving off the hair of sheep.
Answer:
Wool is obtained by shearing which means shaving off the hair of sheep.
Practice Question 5.
The management of honeybees for commercial purposes is called ………………..
Answer:
The management of honeybees for commercial purposes is called apiculture.
A. Tick the most appropriate answer.
Question 1.
The part of the earth which is made up of water is called
a. biosphere.
b. hydrosphere,
c. atmosphere.
d. lithosphere.
Answer:
b. hydrosphere.
Question 2.
Which of the following group comprises the abiotic components of the earth ?
a. Only plants
b. Both plants and animals
c. Air, water and soil
d. Plants, animals and microorganisms
Answer:
c. Air, water and soil
Question 3.
Animals depend on plants for
a. food alone.
b. shelter alone,
c. carbon dioxide.
d. food and oxygen.
Answer:
d. food and oxygen.
Question 4.
The dead and decaying plants and animals are fed upon by –
a. consumers.
b. decomposers,
c. producers.
d. herbivores.
Answer:
b. decomposers.
Question 5.
Carbon dioxide is a ……………….. house gas.
a. green
b. blue
c. red
d. white
Answer:
a. green
Practice Question 1.
Sulphur dioxide and other gases given out by industries cause
a. rain.
b. flood.
c. acid rain.
d. none of these
Answer:
c. acid rain.
Practice Question 2.
The production and management of fishes is called
a. breeding.
b. agriculture,
c. shearing.
d. pisciculture.
Answer:
d. pisciculture.
Practice Question 3.
Which of the following is a primary consumer in the following food chain ?
Green plants —» Grasshopper —» Frog -> Snake -» Eagle
a. Green plants
b. Eagle
c. Grashopper
d. Snake
Answer:
c. Grashopper
B. Fill in the blanks.
Question 1.
………….. is the outer solid layer of earth covered with soil and rocks.
Answer:
Lithosphere is the outer solid layer of earth covered with soil and rocks.
Question 2.
Plants, animals and microorganisms constitute the components of an environment.
Answer:
Plants, animals and microorganisms constitute the biotic components of an environment.
Question 3.
Green plants which make their own food are called …………
Answer:
Green plants which make their own food are called producers/ autotrophs.
Question 4.
………….. are carnivores that feed on dead animals.
Answer:
Scavengers are carnivores that feed on dead animals.
Question 5.
Microorganisms which decompose dead plants and animals are called …………
Answer:
Microorganisms which decompose dead plants and animals are called decomposers.
Practice Question 1.
…………. is the study of interaction between living organisms and their environment.
Answer:
Ecology is the study of interaction between living organisms and their environment.
Practice Question 2.
The flow of energy in the form of food is only in ……………….. direction.
Answer:
The flow of energy in the form of food is only in one direction.
Practice Question 3.
Food chains are interconnected to make a ………………..
Answer:
Food chains are interconnected to make a food web.
Practice Question 4.
Introduction of unwanted, harmful material into an environment leads to ………………..
Answer:
Introduction of unwanted, harmful material into an environment leads to pollution.
C. Differentiate between the following.
1. Hydrosphere and atmosphere
2. Producers and consumers
3. Consumers and decomposers
4. Food chain and food web
Answer:
1. Hydrosphere and atmosphere
Hydrosphere :
a. It forms the part of the earth which is made up of water.
b. It includes water in all forms in the form of pond, ocean, glacier, lakes etc.
Atmosphere :
a. The mixture of gases surrounding the earth surface form atmosphere.
b. It includes all gases like oxygen, nitrogen, carbon- dioxide and also water vapours.
2. Producers and consumers
Producers :
a. They can make their own food using solar energy.
b. All green plants perfor – ming photosynthesis are producers.
c. They are also called autotrophs.
d. A food chain always starts with a producer.
Consumers :
a. They cannot make their own food and depend on plants and other animals for it.
b. All animals, birds, microbes are consumers.
c. They are also called heterotrophs.
d. They come after producer in a food chain.
3. Consumers and decomposers
Consumers :
a. They are organisms that cannot make their own food and depend on either plants or other animals for their food.
b. They are also called heterotrophs.
c. e.g. deer, tiger, vulture.
d. They come between producers and decomposers in a food chain.
Decomposers :
a. They are micro-organisms and worms that feed upon the remains of dead plants and animals for energy and return the nutrients to the soil.
b. They are also called nature’s scavengers.
c. e.g. bacteria, fungi, earthworm.
d. They end a food chain.
4. Food chain and food web
Food chain :
a. A series of organisms which are linked with each other through a process of eating and being eaten up form a food chain.
b. e.g. of food chain
Food web :
a. Inter-connected food chains form a food web.
b. e.g. of food web
D. Find the odd one out. Give reasons.
Question 1.
lion, cow, leopard, tiger
Answer:
cow : cow is a herbivore whereas the other animals are carnivores.
Question 2.
deer, goat, vulture, horse
Answer:
vulture: vulture is a scavenger whereas the other three are herbivores.
Question 3.
bear, rat, crow, human being
Answer:
crow : crow lays eggs whereas the other three are mammals
i. e. give birth to young ones.
E. Answer the following in short.
Question 1.
What is environment ?
Answer:
Environment is the surrounding or conditions in which an organism lives. It includes both biotic and abiotic components around us. e.g. Environment of a fish in a pond includes living things such as plants, insects and fishes and non-living things like water, gases, rocks etc.
Question 2.
What is the greenhouse effect ?
Answer:
About one-third of the solar energy that reaches earth is reflected back by the atmosphere directly. The rest two-third reaches the earth’s surface and heats it However, to maintain the energy balance, the earth radiates back the heat. This radiated heat is absorbed by some gases and water vapour in the atmosphere and reflected back to the earth to keep it warm. This is called the greenhouse effect and the gases that trap earth’s radiation are called greenhouse gases.
Question 3.
What are the various components of the biosphere ?
Answer:
The various components of the biosphere are :
a. atmosphere (air) – layer of gases that surround the earth.
b. lithosphere (land) – the soiled portion of the earth.
c. Hydrosphere (water) – the water in form of liquid, ice or vapours on the earth. It covers 70% of earth’s surface.
Question 4.
What kind of organisms are first level consumers ?
Answer:
First level consumers or primary consumers are those organisms which eat plants (producers). They can be a herbivore or an omnivore in a food chain, e.g. deer, elephant, cow come first after the producers in a food chain and are primary consumers.
F. Answer the following in detail.
Question 1.
What factors make earth a habitable planet ?
Answer:
Factors making earth a habitable planet are :
- Optimum distance from the sun-which makes the earth neither too hot nor too cold.
- Presence of atmosphere – Which has essential gases like oxygen, carbon dioxide, nitrogen, etc.
- Presence of water.
- Gravitational force – Which holds atmosphere and water in place.
- Presence of minerals – Which are required for the growth and sustenance of plant and animal life.
Question 2.
Explain the flow of energy in a food chain with the help of a diagram.
Answer:
As only green plants can trap energy from the Sun, all food chains start with plants or producers and energy is transfered through these chains. Solar energy is converted into the chemical energy of food by green plants. Some energy gets stored in plants and rest is used up by them. When plants are eaten by herbivores, the energy stored in them gets transferred to herbivores.
Again, herbivores use up some energy and store a part of it. This stored energy is further transferred to camivororous animals when they eat herbivores. Thus, energy passes on from producers to herbivores and then to carnivores as one organism eats the other. The flow of energy is always in one direction and only 10% of energy is transferred to the next level.
Example :
Sun
↓
Grass (Producer)
↓
Rabbit (Primary consumer)
↓
Snake (Secondary consumer)
↓
Eagle (Tertiary consumer)
Question 3.
wine a snort note on tne dependence of animals on plants.
Answer:
Animals are dependent on plants as :
a. Herbivores depend on plants for their food.
b. Some animals depend on trees for their shelter e.g. Ants, birds, monkeys.
c. Animals also depend on plants for oxygen necessary for respiration.
Question 4.
Write five human activities which have led to an imbalance in nature.
Answer:
Human beings are changing the environment to suit their needs and hence causing an imbalance in nature as following :
a. Factories and industries release poisonous harmful wastes into air, water and land.
b. Exhaust from vehicles lead to air pollution.
c. Excessive use of non-biodegradable plastic bags is a threat to the environment.
d. Cutting of trees has led to decreased rainfall and soil erosion.
e. Hunting of animals for bones, skin etc. lead to extinction of animals affecting the food chain.
Question 5.
What is global warming. How can you prevent it ?
Answer:
Any increase in the concentration of green house gases lead to enhanced trapping of heat in the atmosphere and rising of temperature across the earth which is called global wanning. We can prevent global warming by checking the concentration of green house gases like carbon dioxide, methane, nitrous, oxide, ozone etc in the air. Steps to prevent this are :
- Plant more trees to increase forest cover. Plants absorb carbon dioxide.
- Increase use of renewable energy sources such as wind, water and Sun instead of coal, petrol, etc.
- Reduce, reuse and recycle household items.
- Avoid using plastics, polythene and other non-biodegradable articles.
Question 6.
Write a short note on pond ecosystem.
Answer:
Plants, animals and microorganisms living in the pond are its biotic components. Green plants such as algae and water lily are producers. Small animals like tadpoles, snails and insects eat plants and form primary consumers. Larger animals such as fish and frogs who eat the primary consumers, are called secondary consumers.
The bacteria and fungi are decomposers as they feed on dead plants and animals and release simple nutrients into the environments.
Non-living or abiotic component of pond ecosystem include light, water, temperature and dissolved oxygen carbon dioxide and other gases. Plants use dissolved carbon dioxide for preparing their food. They release oxygen, which is used for respiration by animals and by bacteria for decomposition of dead matter. Hence, pond is an example of ecosystem where biotic and abiotic components interact in a habitat.
Praticle Question 1.
How does the correct distance of the earth from the sun make it a living planet ?
Answer:
The distance between the sun and the earth is such that the earth receives just the right amount of solar energy. So, it is neither too hot nor too cold. This makes earth’s land and water warm enough to sustain life and hence make earth a living planet.
Praticle Question 2.
How do plants depend upon animals ?
Answer:
Plants depend upon animals for:
a. Pollination and dispersal of seeds.
b. Nutrients/mirierals in soil formed by decomposition of animal excreta and dead organisms.
c. Caroon-aioxiue reieaseu oy aiimiais uuring icspuauuu for photosynthesis.
Praticle Question 3.
How are carnivorous animals dependent upon plants ?
Answer:
Carnivorous animals are indirectly depenedent upon plants for food as they eat herbivores which feed on plants. They also get oxygen for respiration from plants.
Praticle Question 4.
Why are scavengers and decomposers important for the environment ?
Answer:
Scavengers and decomposers feed on dead organisms by breaking down the remains into simple substances. This releases the minerals from the decaying organisms into the environment which are reused by plants to grow. Hence, scavengers and decomposers help not only in the cleaning of the environment but also in the recycling of the minerals.
Praticle Question 5.
Why do all food chains start with plants ?
Answer:
All food chains start with plants because all energy comes from the sun and only green plants can trap this solar energy and prepare food. Thus, solar energy is converted into chemical energy of food in plants. From plants only, the energy flows to other animals in a food chain. So, without plants, a food chain cannot start.
Praticle Question 3.
Rearrange this food chain in the correct order:
Mouse → Snake → Grain → Owl
Answer:
Grain → Mouse → Snake → Owl
Practice Question 4.
Write a short note on the dependence of human beings on plants.
Answer:
Human beings depend on plants for various reasons as follows:
a. We get food from plants, e.g. fruits, vegetables.
b. Fungi like yeasts help in fermentation and production of antibiotics. Some bacteria are used to make cheese and alcohol.
c. we get ruooer, paper, wood, jute, medicines, cotton etc. from plants.
d. Oxygen needed for respiration by humans is released by plants during photosynthesis.
e. Plants help in maintaing a balance of gases in nature.
Practice Question 5.
What is poultry farming ? Name three poultry birds.
Answer:
The practice of keeping and breeding the poultry birds for their eggs and meat is called poultry farming, e.g. Hens, ducks, turkey, geese. .
Practice Question 6.
How can we get silk from silk moth ?
Answer:
The female silk moth lays eggs which transform into worm like caterpillars called larva (silk worm). These caterpillars have silk glands with the help of which they weave thread like structures around its body to form cocoons. In silk farm, the thread is very carefully unwound from the cocoons and then treated chemically to make silk yam.
Practice Question 7.
Write five products each that we receive from plants and animals.
Answer:
Five products that we receive from plants are – paper, wood, mbber, medicines and fibres like jute, cotton.
Five products that we receive from animals are – eggs, milk, meat, silk and honey.
Practice Question 8.
After visiting a picnic spot why must you always carry the rubbish home ?
Answer:
We must always cany our rubbish home after visiting a picnic spot because if we throw the wastes like plastic bottles, cans, wrappers there, it will not only make the place look awful but also lead to land pollution as plastics and polythenes are non-biodegradable waste i.e. cannot be decomposed by bacteria. It can also become a breeding ground for disease causing insects and rodents. Some rubbish like glass bottles/ cans can cause injuries to others also.
Practice Question 9.
How does air pollution cause acid rain ?
Answer:
Air pollution is caused by fumes and gases released by the exhausts of vehicles and factories. They contain gases like carbon-dioxide, sulphur-dioxide and oxides of nitrogen. These gases in the air react with water vapour to form acid. This mixture of acids and rain water fall on earth as acid rain.
Practice Question 10.
Define water pollution and noise pollution.
Answer:
Water pollution : It refers to the contamination of water bodies such as lakes, rivers, oceans and groundwater with undesirable harmful material caused by human activities. It can be harmful to plants and animals which live there.
Noise pollution : The unwanted sounds in the environment which can be annoying, distracting or harmful is called noise pollution. Its also called sound pollution. It is caused by vehicles, aircrafts, industries etc.
G. Give reasons for the following :
Question 1.
A plant or an animal may belong to several food chains.
Answer:
Most consumers have more than one source of food. Plant can be eaten by a cow, rabbit, goat, etc. so a plant belongs to several food chains. Similarly, animals, like frogs eat grasshoppers and caterpillars, snakes eat rabbits as well as lizards, mice and rats. Rats are also eaten by hawks. Thus, an animal may also be a part of several food chains. Such interconnected food chains form a food web.
Question 2.
Consumers depend on producers in a food chain.
Answer:
Consumers depend on producers in a food chain because they cannot make their own food and derive energy from plants.
Question 3.
Deforestation should be checked.
Answer:
Deforestation i.e. cutting down of trees should be checked because it leads to an ecological imbalance by causing soil erosion, loss of habitat of animals, loss of wildlife, frequent floods, decreased rainfall and global warming.
Question 4.
Air pollution is harmful to us.
Answer:
Air pollution leads to many respiratory diseases in humans. Heart and lung disorders are also induced by air pollution. It also leads to the acid rain which harms living organisms as well as historical monuments.
The ozone layer depletion by air pollution lets the harmful UV rays enter the atmosphere. These UV rays are carcinogens (cancer cuasing).
Practice Question 1.
Animals in a food chain are consumers.
Answer:
Animals in a food chain are consumers because they cannot make their own food and need to consume (eat) plants or other animals for food energy.
Practice Question 2.
We should not use too many fertilizers and insecticides.
Answer:
We should not use too many fertilizers and insecticides because it leads to land as well as water pollution causing damage to the living and non-living components present there. Too much use of these chemicals on crops also leads to health disorders in humans and other animals.
H. Number the organisms in the correct sequence to complete the food chain.
Answer:
Living Science Biology Class 6 ICSE Solutions