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Science case /data -based (4 Marks)

Our Environment · Jharkhand Board (JAC) STD 10 (Jharkhand - English Medium). 11 questions.

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case /data -based (4 Marks)

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11 questions · timed · auto-graded

Question 14 Marks
Students in a school listened to the news read in the morning assembly that the mountain of garbage in Delhi, suddenly exploded and various vehicles got buried under it. Several people were also injured and there was traffic jam all around. In the brain storming session the teacher also discussed this issue and asked the students to find out a solution to the problem of garbage. Finally they arrived at two main points – one is self management of the garbage we produce and the second is to generate less garbage at individual level.
  1. Suggest two measures to manage the garbage we produce.
  2. As an individual, what can we do to generate the least garbage? Give two points.
  3. List two values the teacher instilled in his students in this episode.
Answer
  1. Measures to manage garbage:
  • Throwing the garbage we generate in dustbins.
  • Separation of wet and dry wastes.
  • Sorting of waste materials as biodegradable and non-biodegradable.
  • Composting of biodegradable materials.
  • Recycling of non-biodegradable materials.
  1. We can adopt the following practices to generate less garbage:
  • Avoid using plastic bags, instead use bags made of cloth and paper.
  • Avoid the use of tissue paper, instead use your own cloth napkin.
  • Make use of washable cups, mugs and plates instead of disposables.
  • Use kitchen wastes to make compost for increasing soil fertility.
  1. Values instilled by the teacher in students:
  • Sense of responsibility towards the environment.
  • Social awareness.
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Question 24 Marks
Read the following and answer any three questions from: (i) to (iv).Ozone layer is present in the earth's atmosphere. It is in the form of a protective shield. It contains three oxygen atoms ($O_3$) which are formed as a consequence of photochemical reactions in the environment. Ozone absorbs harmful ultraviolet radiations of the sun. In this way, it protects all living beings on the earth. The thinning of ozone layer due to various human activities allows more UV radiations to pass through it which leads to harmful effects on man, animals and plants.
  1. Ozone layer is present in which layer of the atmosphere?
     
  2. Enhanced UV-radiations would affect humans and other animals, write cause of it.
     
  3. Give some name and example of depletion of ozone layer?

    OR
  4. what is photochemical reactions?
Answer
  1. (c) Stratosphere.
Explanation:

Ozone is present in the stratosphere of the earth's atmosphere between 20 to 26km above sea level.
  1. (d) All of these.
  2. (a)
    S. No
    I
    II
    III
    IV
    (a)
    F
    T
    T
    F
Explanation:

Ozone hole was first discovered over Antarctica in 1985. Ozone absorbs UV-radiations in the range 2000-2900A.
  1. (d) All of these.
Explanation:

The substances that deplete the ozone layer are called ozone depleting substances (ODS). The main ODS are chlorofluorocarbons, halons, methane, nitrous oxide, carbon tetrachloride and chlorine.
  1. (b) V → II → IV → I → VI → III
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Question 34 Marks
Read the following and answer three questions from: (i) to (iii).In any given ecosystem, all living organisms are linked in a systematic chain with respect to their mode of manufacturing food/ feeding habits. This sequential interlinking of organisms involving transfer of food energy from producers through a series of organisms with repeated eating and being eaten is called the food chain. A food chain may have 3-4 trophic levels.
  1. What is food chain?
     
  2. how many trophic levels food chain have?
  1. a) Food chains are sustained by producers and ______.
    b) all living organisms are linked with which chain?
Answer
  1. (b) It adds adaptability and competitiveness to the organisms.
Explanation:

Since a food chain is a sequential flow of food energy, it does not add to the adaptability and competitiveness of the organism.
  1. (a) Grasshopper.
​​​​​​​Explanation:

In the given food chain, A is a primary consumer that feeds on grass and being eaten by frog. Therefore, among the given organisms, A should be grasshopper.
  1. (c) Grass → Rabbit → Wild cat → Tiger.
  2. (d) Decomposers.
  3. (a) Food chain may terminate at level of herbivore.
​​​​​​​​​​​​​​Explanation:

In a food chain, there is repeated eating in which each group eats the smaller one and is eaten by the larger one.
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Question 44 Marks

Read the following and answer any three questions from: (i) to (iv).
A group of ecologists studied and monitored the change in population of three animal species X, Y and Z over a period often years. During their research, they found that a new animal species W appeared in the area and its population was also monitored.
  1. Which animal species will unlikely to be alive in IO years without some intervention?
     
  2. Which species is most likely be the food source of W?
     
  3. What will be the likely consequence if population of X completely declines?

    OR
     
  4. A) What would be the most probable reason for the constant population of Z?
    B) What could be the reason for declining of X?
Answer
  1. (b) X
Explanation:
As population of Xis declining constantly, it is most unlikely to be alive in next 10 years.
  1. (b) Y
Explanation:
When population W appears in the area, there is decline in population of X and Y but as X is continuously decreasing and W becomes somewhat constant, this implies that W is not feeding on X. On the other hand as population of Y is becoming constant, population W also shows constant numbers. This shows that species Wis likely to feed on species Y.
  1. (c) Population of Z remains unchanged.
  2. (c) Ratio of death rate and birth rate is nearly equal in the population of Z.
​​​​​​​​​​​​​​​​​​​​​Explanation:
As the population of Z is nearly constant, this may due to the nearly equal ratio of death and birth rate.
  1. (d) Both (a) and (b).
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Question 54 Marks

Read the following and answer any three questions from: (i) to (iv).
Food web is a network of food chains which become interconnected at various trophic levels so as to form a number of feeding connections amongst different organisms of a biotic community. Different food webs operate in different ecosystems. One such food web operating in an ecosystem is given ahead. Study it carefully and answer the following.
  1. What is the primary energy input in this food web?
     
  2. How many food chains are operating in the given food web?
     
  3. When a new species 'X' was introduced into the community, the population of toads rose and population of skunks fell over the subsequent two weeks. Species 'X' is most likely to be what?
    OR
     
  4. a) Which organisms in the food web passes most of its energy to the subsequent trophic levels?
    b) Which organisms would be most affected if the oak tree fails to flower?
Answer
  1. (c) Sunlight.
​​​​​​​​​​​​​​Explanation:
The sun is the primary source of energy for almost all ecosystems. Sunlight is converted to chemical energy during photosynthesis by the oak tree.
  1. (d) 14.
​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Explanation:
A total of 14 food chains are operating in the given food web.
  1. (c) A predator of skunks only.
Explanation:
A new predator of skunks would result in the fall of its population and thus corresponding rise in the population of toad since less would be preyed upon. A predator of skunk is unlikely to be the prey of toad.
  1. (d) Oak tree.
​​​​​​​Explanation:
The oak tree is the producer, thus the most energy passes through the oak compared to other organisms. By the time energy reaches the higher trophic levels, significant energy would have been lost between trophic levels.
  1. (c) Deer and mice.
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Question 64 Marks
Read the following and answer any three questions from: (i) to (iv).An ecosystem may be defined as a structural and functional unit of the biosphere comprising living organisms and their non-living environment which interact by means of food chains and biogeochemical cycles resulting in energy-flow, biotic diversity and material cycling to form a stable, self-supporting system.
  1. The two basic processes involved in an ecosystem are?
     
  2. Give two examples of not an artificial ecosystem?
     
  3. What is the role of fungi and bacteria in an ecosystem?
     
  4. What would one of the likely result if all decomposers in a particular ecosystem were wiped out?
Answer
  1. (d) Cycling of materials and flow of energy.
  2. (b) Lake.
​​​​​​​​​​​​​​Explanation:

Artificial ecosystems are maintained by man and hence are also termed as man-made or man engineered ecosystems. In these ecosystems, man maintains/ disturbs the natural balance by the addition of energy and planned manipulations. Common examples of artificial ecosystems are croplands, orchards, gardens, aquarium, etc.
  1. (c) Release nutrients from dead organic matter.
​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Explanation:

Fungi and bacteria are decomposers which serve to convert carbon locked up in dead organic matter into carbon dioxide, which can then be utilized by plants during photosynthesis. A, B and O are incorrect since decomposers do not increase the amount of nutrients, energy and carbon dioxide in the ecosystem. They merely allow cycling of nutrients, including carbon, to occur.
  1. (a) The atmospheric reservoir of carbon dioxide would decline.
  2. (d) Permanent ecosystems are self-supporting natural ecosystems that maintain themselves for relatively long duration.
​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Explanation:

Primary or first-order consumers include the animals which eat plants or plant products. They are called herbivores. As the herbivores feed on plants/ plant products and convert them into animal matter, they are often called key industry animals. Inorganic substances, e.g., carbon, nitrogen, oxygen, calcium, phosphorus, etc. and their compounds (water, carbon dioxide, etc.) constitute the main abiotic components. These occur either in the form of compounds dissolved in water, in the soil or in free state in the air.
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Question 74 Marks
Composting is the process where organic wastes are degraded into compost.
The diagram shows the details of the process.

Image
9. What can be concluded from the diagram?
A. Composting helps in recycling plastic scraps.
B. Composting absorbs heat from the environment.
C. Composting takes place only in the presence of oxygen.
D. Composting takes place in the presence of either oxygen or carbon dioxide.
10. Which of these will reduce if compost is used in place of inorganic fertilizer in farms?
Circle ‘Yes’ or ‘No’ for the correct response.

Will this reduce?

Yes or No

Moisture in the farm soil

Yes/No

Microorganisms in the farm soil

Yes/No

Chemical residue in the farm soil

Yes/No

Answer
9. C. Composting takes place only in the presence of oxygen.
10. No
Yes
No
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Question 84 Marks
Alisha digs a pit in her garden and puts the following items in it.
● paper cups
● glass bowls
● fruit peels
● rubber slippers
She then covers the pit with soil.
8. Which item will decompose first?
Answer
8. Mentions fruit peels as the response.
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Question 94 Marks
The pair of reactions show the formation of ozone (O₃).
$ O _2 \stackrel{ UV }{\longrightarrow} O + O$
$O + O _2 \longrightarrow O _3$
6. What is the role of ultraviolet (UV) rays in the reaction?
7. The ozone layer of the atmosphere shields the Earth’s surface from the ultraviolet radiations of
the Sun.
Which of these is likely to increase in humans with depletion of the ozone layer?
A. AIDS
B. COVID
C. Jaundice
D. Skin Cancer
Answer
6. Mentions that UV rays help in splitting oxygen molecules into free oxygen.
7. D. Skin cancer
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Question 104 Marks
The picture shows the different trophic levels of an ecosystem.

Image

5. Which level consists of herbivores?
A. Level 1
B. Level 2
C. Level 3
D. Level 4

Answer
5. B. Level 2
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Question 114 Marks
The table shows some organisms and their food sources in an ecosystem.

Organism

Food source

Frog

Cricket, Grasshopper

Cricket

Grass

Snake

Frog, Shrew

Shrew

Cricket, Grasshopper

Grasshopper

Grass

Eagle

Snake, Shrew

1. Identify the primary consumer(s) in the ecosystem.
A. Snake
B. Shrew
C. Frog and Shrew
D. Cricket and Grasshopper
2. A snake eats a frog.
What percentage of energy of the frog is transferred to the snake?
A. 1%
B. 2%
C. 10%
D. 90%
3. Which of these represents the correct food web of the ecosystem?

Image

4. Which organism has the largest biomass in the ecosystem?
A. Grass
B. Snake
C. Eagle
D. Grasshopper

Answer
1. D. Cricket and Grasshopper
2. C. 10%
3. B. Image
4. A. Grass
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