Solutions of Our Environment Lakhmir Singh Manjit Kaur LAQ, HOTS and MCQ Pg No. 227 Class 10 Biology
41A. What is meant by biodegradable waste materials? Give two examples of biodegradable wastes.
Answer
→ Biodegradable waste materials are those that can be recycled or can be decomposed by bacteria and do not cause pollution. For example- Paper, wood, wool, fruits are biodegradable.
41B. Which of the following materials are non-biodegradable?
Aluminum wire, Tea leaves, Synthetic fibre, wool.
Answer
→ Non-biodegradable materials are those that cannot be degraded by bacteria. Amongst the given options, Aluminum wire and synthetic fibre are non-biodegradable.
42A. What is meant by non-biodegradable waste materials ? Give two examples of non-biodegradable wastes.
Answer
→ Non-biodegradable waste materials are those that cannot be recycled or cannot be degraded by bacteria and thus cause pollution. For example- Plastic, synthetic fibre, aluminum wire, DDT insecticide are non-biodegradable.
42B. Which of the following materials are biodegradable?
Animal bones, Iron nails, Plastic mugs, Leather belts, Silver foil.
Answer :
→ Biodegradable substances are those that can be degraded by bacteria and do not cause pollution. Amongst the following, Animal bones and leather belts are biodegradable.
43A. Define an ecosystem. Give examples of any two ecosystems.
Answer
→ Functional unit of the environment comprising of the living and non-living components where the living organisms interact amongst themselves and with the non-living components as well is known as ecosystem.
For example- A grassland ecosystem where plants, animals and micro-organisms live in an environment together and grasses are the primary form of vegetation.
A forest ecosystem is a woodland unit where plants, animals and micro-organisms function all together with the non-living components of the environment.
43B. List the biotic and abiotic components of an ecosystem.
Answer :
→ Biotic components of an ecosystem are the living components that are inter-dependent and shape the ecosystem together. For example- producers make food for consumers; consumers after death are degraded by decomposers.
Abiotic components of an ecosystem are the non-living components. For example-light, temperature, water, soil, carbon dioxide, nitrogen, etc.
44A. What is a food chain? Give one example of a simple food chain.
Answer :
→ Food chain is defined as a series/ chain of organisms wherein each organism is dependent on the other for energy (food).
Example of a simple food chain-
Zebra eats grasses and are in turn eaten by lions.
44B. What is a 'food web'? Show its formation.
Answer
→ Food Web is a network of interlocking and interdependent food chain which tells us what-eats-what in an ecological community and thus describing the relationship between species.
Formation of a food web – In the food web given below, the flow of energy is shown by the direction of arrows. There are three food chains in the given food web. The food web begins from grass which is producer, it provides food to grasshopper, mice, rabbit which are eaten by lizards, and snake. Lizards, snakes, and rabbits are eaten by hawk which is carnivore. Thus, the food web begins at producers (grass) and ends in top carnivore (hawk).
45A. What is meant by 'environment'?
Answer :
→ Environment refers to the conditions where living organisms like plants, animals, human beings lives or functions. It is the physical and biological world together.
45B. What type of substances are the major pollutants of the environment? Name two such substances.
Answer
→ Non-biodegradable substance are the major pollutants of the environment. Since they cannot be recycled, degraded by bacteria they cause pollution. Substances like plastics, synthetic fibre, and Aluminum wire are non-biodegradable.
45C. Name the organisms whose uncontrolled activities are damaging the environment.
Answer
→ Human beings are the organisms whose uncontrolled activities are damaging the environment. Human beings are destroying the environment for their needs for example deforestation which leads to destruction of natural habitat for wildlife. Human beings are polluting the environment by not adapting measures to control pollution. Use of polythene bags is one such example. Every household uses polythene bags which are discarded after use and are non-biodegradable; they pollute the environment.
45D. Explain why, it is better to use paper bags than plastic bags.
Answer :
→ It’s better to use paper bags than plastic bags because paper is recyclable whereas plastic is not. Plastic cannot be degraded and they pollute the environment; whereas paper is biodegradable and does not cause any pollution. Moreover, even if burned, paper will not cause much pollution but plastics on burning will release toxic chemicals into the environment thus polluting the environment.
Multiple Choice Questions (MCQs)-Pg-228
46. Which of the following constitutes 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 is eaten by goat and Goat may be eaten by Human.
47. In a food chain, the initial organism is usually:
A. Photosynthetic
B. Herbivore
C. Saprophytic
D. Parasitic
Answer
→ It is the Photosynthetic organisms that produce food, for example plants, which are further eaten by consumers.
48. Which of the following represents a possible food chain found in a pond:
A. a
B. b
C. c
D. d
Answer
→ This represents a possible food chain in a pound. Green algae produce food which is consumed by mosquito larvae (primary consumers/zooplankton). Mosquito larvae are eaten by fishes that are secondary consumers.
49. Which of the following are decomposers of dead organisms?
| Bacteria | Fungi | Viruses |
| (a) no | yes | yes |
| (b) yes | no | yes |
| (c) yes | yes | no |
| (d) yes | yes | yes |
A. a
B. b
C. c
D. d
Answer
→ Bacteria, Fungi are decomposers of dead organisms as they breakdown the organic matter in dead and decaying organisms and feeds on them. Whereas. Viruses are not decomposers of dead organisms.
50. Which of the following is an artificial ecosystem?
A. pond
B. crop field
C. lake
D. forest
Answer
→ Crop field is an artificial ecosystem because it is a man-made ecosystem. Man makes field to grow crops and does necessary activities that are required by crops to grow. Thus, it is an artificial ecosystem.
51. Disposable plastic plates should not be used because:
A. they are made of light-weight materials
B. they are made of toxic materials
C. they are made of biodegradable materials
D. they are made of non-biodegradable materials
Answer
→ Plastics cannot be degraded and as a result they pollute the environment and threaten health.
52. In a food chain, the third trophic level is always occupied by:
A. Carnivores
B. Herbivores
C. Decomposers
D. Producers
Answer
→ The first trophic level is occupied by producers and the second by herbivores.
53. Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as:
A. Eutrophication
B. Pollution
C. Bio-magnification
D. Accumulation
Answer
→ The process of accumulation of pesticides at each trophic level increases with increase in trophic levels in a food chain. This is known as bio-magnification.
54. If a grasshopper is eaten by a frog, then the energy transfer will be from:
A. Producer to decomposer
B. Producer to primary consumer
C. Primary consumer to secondary consumer
D. Secondary consumer to tertiary consumer
Answer
→ Primary consumer to secondary consumer; Grasshopper is a primary consumer which feeds on plants. Frogs are secondary consumers which eat grasshoppers.
55. An ecosystem includes:
A. all living organisms
B. non-living objects
C. both living organisms and non-living objects
D. all living organisms and input of sun's energy
Answer
→ Both living organisms and non-living objects. An ecosystem is a function unit of environment where living organisms interact with each other and the non-living objects.
56. The decomposers in an ecosystem:
A. convert inorganic material to simpler forms
B. convert organic material to inorganic forms
C. convert inorganic material into organic compounds
D. do not break down organic compounds
Answer
→ Decomposers like bacteria and fungi breakdown the organic components present in the dead and decaying matter of plants and animals into simpler inorganic forms.
57. What will happen if deer is missing in the food chain given below?
Grass → Deer → Tiger
A. The population of tigers increases
B. The population of grass decreases
C. Tigers will start eating grass
D. The population of tigers decreases and the population of grass increases.
Answer
→ The population of tigers decreases and the population of grass increases.
This is because tigers will not have food if deer go missing and hence will starve to death on not getting food and their number would decrease. On the other hand, the population of grass will increase because there will be no deer’s to eat them.
58. Organisms which synthesize carbohydrates from inorganic compounds by using radiant energy are called:
A. decomposers
B. producers
C. herbivores
D. carnivores
Answer
→ Producers i.e. plants use inorganic components water and carbon dioxide in the presence of chlorophyll and sunlight to synthesize carbohydrates and release oxygen as a by-product.
59. Organism of a higher trophic level which feed on several types of organisms belonging to a number of lower trophic levels constitute the:
A. Ecosystem
B. Food web
C. Ecological pyramid
D. Food chain
Answer
→ A food web is a system of interlocking food chains. So, the organism of a higher trophic level that feeds on several types of organisms belonging to a number of lower trophic level will constitute the food web.
60. In the following groups of materials, which group/groups contain only non-biodegradable materials ?
(i) wood, paper, leather
(ii) polythene, detergent, PVC
(iii) plastic, detergent, grass
(iv) plastic, Bakelite, DDT
A. (iii)
B. (iv)
C. (i) and (iii)
D. (ii) and (iv)
Answer
→ Polythene, detergent, PVC, Plastic, Bakelite and DDT are non-biodegradable materials i.e. they cannot be degraded.
60. In the following groups of materials, which group/groups contain only non-biodegradable materials ?
(i) wood, paper, leather
(ii) polythene, detergent, PVC
(iii) plastic, detergent, grass
(iv) plastic, Bakelite, DDT
A. (iii)
B. (iv)
C. (i) and (iii)
D. (ii) and (iv)
Answer
→ Polythene, detergent, PVC, Plastic, Bakelite and DDT are non-biodegradable materials i.e. they cannot be degraded.
61. Which of the following statement is incorrect?
A. all green plants and blue green algae are producers
B. green plants get their food from readymade organic compounds
C. producers prepare their own food from inorganic compounds
D. plants convert solar energy into chemical energy
Answer
→ Green plants get their food from readymade organic compounds.
Green plants or producers do not get their food from readymade organic compounds. Instead they use inorganic compound water and carbon dioxide to synthesize food in the presence of chlorophyll and sunlight.
62. Which of the following group of organisms are not constituents of a food chain?
(i) Grass, lion, rabbit, wolf
(ii) Plankton, man, fish, grasshopper
(iii) Wolf, grass, snake, tiger
(iv) Frog, snake, eagle, grass, grasshopper
A. (i) and (iii)
B. (iii) and (iv)
C. (ii) and (iii)
D. (i) and (iv)
Answer
→ Plankton, man, fish, grasshopper; Wolf, grass, snake, tiger are not group of food chain. Plankton and fish belong to aquatic food chain. Similarly, Wolf does not exist in a food chain with grass snake and tiger.
63. In the figure given alongside, the various trophic levels are shown in the form of a pyramid. At which trophic level the maximum energy is available?
A. T4
B. T2
C. T1
D. T3
Answer
→ Maximum energy is available at the lowest trophic level which is T1 here. The lowest trophic level in a food chain is producers. Producers have the maximum energy that they absorb from the sun. 10% of energy that they absorb from the sun is transferred to the next trophic level and so on (10% energy rule).
64. One of the following is not a biodegradable material. This one is:
A. cotton
B. animal bones
C. aluminum foil
D. wood
Answer
→ Aluminum foil is a non-biodegradable material.
Cotton, animal bones and wood are degradable.
65. Which of the following is not a non-biodegradable material?
A. Nylon socks
B. Plastic school bag
C. Jute carry bag
D. Polyester clothes
Answer
→ Plastic school bags are non-biodegradable.
Nylon, Jute, Polyester are degradable.
66. The use of one of the following will pollute the environment. This one is:
A. paper carry bags
B. cotton cloth carry bags
C. nylon cloth carry bags
D. jute carry bags
Answer
→ Nylon is a polymer of plastic and since plastic is non-degradable and create pollution in the environment, thus nylon cloth carry bags will pollute the environment.
67. One of the following is not a consumer. This one is:
A. Giraffe
B. Antelope
C. Algae
D. Alligator
Answer
→ Algae are producer.
68. Which of the following is not a producer?
A. Grass
B. Zooplankton
C. Phytoplankton
D. Paddy
Answer
→ Zooplankton; Zooplankton is a primary consumer.
Grass, phytoplankton and paddy are producers.
69. One of the following is a micro-consumer. This one is:
A. ant
B. lice
C. fungi
D. mosquito
Answer
→ Fungi; Fungi is a micro-consumer. They feed by breaking down complex organic compounds of dead and decaying matter.
70. Which of the following act as decomposers in an ecosystem?
A. Lactobacillus bacteria
B. Cyanobacteria
C. Putrefying bacteria
D. Rhizobium bacteria
Answer
→ They recycle nitrogen from dead organisms.
71. One of the following helps in the recycling of materials in an ecosystem. This one is:
A. Autotrophs
B. Saprotrophs
C. Omnivores
D. Carnivores
Answer
→ Saprotrophs (decomposers) derives nutrition from dead and decaying organic matter and thus recycles material in an ecosystem.
72. In the food chain comprising of a snake, grass, insect, and frog, the secondary consumer is:
A. Insect
B. Snake
C. Frog
D. Grass
Answer
→ Grass is producer. Insect is primary consumer as it eats grass. Frog eats insects, so it is a secondary consumer.
73. Sahara Desert was formed over a period of time due to one of the following uncontrolled activities of man:
A. Excessive cutting down of forest plants and trees
B. Excessive killing of large herbivores
C. Excessive killing of large carnivores
D. Excessive use of poisonous chemicals called herbicides
Answer
→ Carnivores i.e. lions were captured by the Romans and no carnivores were left to eat herbivores. So herbivores increased in number and they ate up all the vegetation, turning the forest into Desert.
Questions Based on High Order Thinking Skills (HOTS)-Pg-230
74. The sea water contains water beetles, tadpole, fish and weeds.
(a) Write a food chain comprising all the given organisms.
(b) Which organisms in the food chain is
(i) Herbivore
(ii) Carnivore
(c) Which organisms are
(i) Predators
(ii) Prey
(d) Which organisms can trap solar energy to make food?
(e) Which organism is a secondary consumer?
Answer
→ a) Food Chain= Weeds-Tadpoles-Water beetles-Fish
b) i) Tadpole are herbivore since they eat weed plants.
ii) Water beetle and fish are carnivore
c) i) Predators in this food chain are water beetles and fish. Water beetle eats tadpole i.e. it preys on tadpole. Fish eats water beetles i.e. it preys on water beetles
ii) Prey in this food chain are Tadpoles and water beetle. Tadpole is eaten by water beetle and water beetles are eaten by fish.
d) Weeds can trap solar energy to make food since they are green plants and contain chlorophyll.
e) Secondary consumer here is water beetle. The primary consumer is tadpole that eats weeds. The secondary consumer is water beetle, it eats tadpoles.
75. The following is a food chain that ends with human:
Plants → bee → human
(a) Explain how plants provide food for bees.
(b) How do bees provide food for humans?
(c) How does this food chain differ from a usual food chain involving human such as: plants goat human?
(d) Do you think that the food chain given in this question can really be regarded as a food chain? Explain your answer.
Answer
→ a) Bees suck nectar from flowers of the plants. Bees collect nectar and convert it to honey.
b) Humans obtain honey from bees. The honey in bees comes from sucking nectar from flowers.
c) In a food chain comprising plant goat humans, humans directly eat goat meat. Whereas, in this food chain of plants bees and humans, humans do not directly eat bees, they eat honey obtained from bees. In this way the two food chains differ.
d) The food chain given in the question is not really a food chain because humans do not directly eat the bee as a food; they first obtain food from bees in the form of honey and then consume honey.
76. A food chain occurring in the sea which provides food for many people can be written as:
Phytoplankton → Zooplankton → X → Y
(a) Name one phytoplankton.
(b) Name two zooplanktons.
(c) What could be X?
(d) Name the organism which Y could be.
(e) Which organism in the above food chain is a
(i) Primary consumer, and
(ii) Tertiary consumer
Answer
→ a) Algae is one phytoplankton found in the sea. It is a producer and it makes its own food by photosynthesis i.e. using water, carbon dioxide in the presence of sunlight and chlorophyll.
b) Crustacea, krill, copepods, protozoa, tadpole are few examples of zooplankton in the sea.
c) X could be small fishes; fishes feed on zooplankton in aquatic food chain.
d) Y could be a carnivorous fish or it can also be a man. Both, Carnivorous fish and humans feed on small fishes.
e) i) Primary consumer in the above food chain are zooplankton as they feed on phytoplankton like algae.
ii) Tertiary consumer in the above food chain can be carnivorous fish or man as they eat small fishes i.e. secondary consumers.
77. Some hunters are roaming in the plush green forest of Africa. They spot a deer and kill it. They decide to roast the deer there and then eat it. When the hunters had just finished enjoying the feast of roasted deer, a lion attacks them. The lion kills one of the hunters and eats his flesh.
(a) Write a food chain which provides food to lion in this case.
(b) Which animal (other than deer) the lion could look for food if he did not get the hunter as prey?
(c) Which other animal in the forest could have been in place of lion?
(d) How does the above food chain differ from the food chain such as:
plants → goat → man?
a) Humans are at the end of most of the food chains in which they occur (as this picture of man taking home a fish for food shows)
b) But sometimes luck runs out and humans are forced to become food for others (as this picture of lion eating a man shows). Here the human is no longer at the end of food chain. Look at the miracle of GOD: hunter has become hunted!
Answer
→ a) Food chain
Plants → Deer → hunter (man) → Lion
b) If the lion did not get hunter as a prey, he could look for rabbits in the forest
c) There could have been tiger in place of lion, in the forest. Tiger too are flesh eating animal, they could have attacked the hunter.
d) In this food chain (plant—goat--man) man is at the end and he is eating the flesh of goat. Man is a predator here.
Whereas, in the other food chain (plants—deer—man—lion) man is not at the end of the food chain and is being eaten up by the lion. Man is a prey here.
78. What would happen to the number of rabbits and grass plants if the number of foxes:
(a) Increased
(b) Decreased
Answer
→ a) If the fox population increased, the number of rabbits will decrease because more foxes will feed on rabbits thus decreasing the population of rabbits and as a result of decrease in number of rabbits, the grass plants will increase as there will be few rabbits to feed on grass.
b) If the number of foxes decreased, the number of rabbits will increase as there will be few foxes to feed on rabbits and hence it will increase the population of rabbits. When the population of rabbits will increase there will be a decrease in population of grass plants, as more and more rabbits will eat grasses so there will be a decline in grass plants.
79. What would happen to the number of grass plants and foxes if the number of rabbits:
(a) Increased
(b) Decreased
Answer
→ a) Rabbits eat grass and if they increase in number, soon the grass population would decline because rabbits will feed on grass faster than they can regrow.
b) Fox feeds on rabbits. If the number of rabbits decreased, soon the fox population will decrease because it will not get to feed on rabbits and foxes would begin to die because of starvation. And if the rabbits will decrease, the grass plants will increase in number because there will be less population of rabbits to eat grass plant.
80A. Match the terms given in column I with the terms given in column II and column III having the same meaning:
Answer
→ (A)
i) consumer-Carnivore-3rd trophic level
ii) Primary consumer-Herbivore- 2nd trophic level
iii) Producer-Autotroph-1st trophic level
iv) Tertiary consumer-Large Carnivore-4th trophic level.
80B. Give one example of a food chain having four organisms. Below each organism write the three appropriate terms from the part (a) above which you think it represents.
Answer
→ (B) Food chain – Grass-Grasshopper-Frog-Snake.
