Unit 16 Man and his Environment Short Questions

Q.62 What are the effects of denitrification?
Q.1 What are the different levels of ecological organization?
Answer:
The different levels of ecological organization are:
(i) species (ii) population (iii) community (iv) ecosystem (v) biosphere
Q.2 Define ecosystem and its components.
Answer:
The self-sufficient unit of an environment that is formed as a result of interactions between its communities and the abiotic components is called ecosystem. Its components are:
Biotic components :
The living parts of the environment. The non-living parts of the are called biotic components:
Examples:

Producers (Plants, Algae and Cyanobacteria)
Consumers (Animals; Protozoa)
Decomposers (Bacteria and Fungi)

Abiotic components
The non-living parts of the are called abiotic components
Examples:
• Temperature
• Air
• Water
• Soil and Light
Q.3 How flow of energy is different from that of materials?
Answer:
The flow of energy in different trophic levels of ecosystem is unidirectional while the flow of
materials is two directional. It flows from one trophic level to another by means of food chains and food web.
Q.4 Define food chain. Give one example
Answer:
A food chain is a series of organisms within an ecosystem, in which each organism feeds on the one before it and is fed by one after it.
Example
Grass → Grasshopper → Sparrow → Hawk
Q.5 Define food web.
Answer:
In nature, food chains are very complex, as an organism may be the food source of many other organisms. So there is a web like structure formed by these interlinked’ food chains. Such interconnected food chains collectively make food web.
OR
It may also be defined as, “a network of food chains which are interconnected at various trophic levels”.
Q.6 What do you mean by the concept of 3 Rs with reference to the conservation of natural resources?
Answer:
It means Reduce, Reuse and Recycle the materials. Many materials such as paper, plastic, glass etc can be recycled. This decreases the volume of refuse and helps in the conservation of natural resources.
Q.7 Define Acid rains.
Answer:
Certain chemicals such as oxides of sulphur and nitrogen when react with water vapours in the presence of sunlight to form sulphuric acid and nitric acid. These acids remain as vapours at high temperatures. As temperature falls, the acids begin to condense into liquid form and mix with rain or snow, on the way down to the earth. This makes rain acidic with pH range of 3-6.
Q.8 What is ammonification?
Answer:
Ammonification is the breakdown of the proteins of dead organisms and nitrogenous wastes (urea, uric acid etc.) to ammonia. It is done by ammonifying bacteria.
Q.9 What is atmospheric nitrogen fixation?
Answer:
Thunderstorms and lightning convert atmospheric gaseous nitrogen into nitrous acid and nitric acid. The acids in turn combine with other salts to produce ‘nitrates’ this is called atmospheric nitrogen fixation.
Q.10 What are biogeochemical cycles. (Board 2013-14)
Answer:
Biogeochemical cycles are the cyclic pathways through which materials move from environment to organisms and back to the environment. e.g. carbon cycle, nitrogen cycle etc.
Q.11 What is biological nitrogen fixation?
Answer:
Some bacteria also have the ability to transform gaseous nitrogen into nitrates. It is called biological nitrogen fixation. Some of these nitrogen fixing bacteria live as symbionts and many are free living.
Q.12 Define Biosphere.
Answer:
All ecosystems of the world together form the biosphere. It includes all the ecosystems of the earth. In other words, the biosphere consists of all organisms present on the earth and all regions of the earth where they live. Biosphere ranges from the floor of oceans to the top of the highest mountains. It is about 20 km thick.
Q.13 What is carbon cycle?
Answer:
The biogeochemical cycle in which carbon flows between organisms and the environment is called carbon cycle.
Q.14 What are carnivores? Write the types of carnivores.
Answer:
Those animals that feed upon other animals are called carnivores. Types of carnivores
a) Primary carnivores
Those carnivores that feed upon herbivores are called primary carnivores. Examples
Fox, frog, predatory birds, many fishes and snakes.
b) Secondary carnivores
Those carnivores that feed upon primary carnivores are called secondary carnivores. Examples
Wolf and owl etc.
c) Tertiary carnivores
Those carnivores that feed upon secondary carnivores are called tertiary carnivores. They are
not eaten by any other animals. So they are also called top carnivores.
Examples
Lion, Tiger etc.
Q.15 Define commensalism with examples.
Answer:
It is a type of symbiosis in which one partner is benefited while the other is neither benefited
nor harmed.
Example
Epiphytes are small plants found growing on other larger plants for space only. They absorb water and minerals from the atmosphere and prepare their own food. The larger plants are neither benefited nor harmed in any way.
Q.16. Differentiate between intraspecific competition and interspecific competition.
Answer:
Intraspecific competition:
The competition between the members of the same species are called members of different species are called Intraspecific competition.
Interspecific competition:
The competition between the members of the same species are called Interspecific competition
Q. 17 What are consumers?
Answer:
These are the heterotrophs in an ecosystem. These organisms are unable to synthesize their food and so depend upon producers for food. The animals are the major consumers of all the ecosystems.
Examples
Animals, Fungi, Protozoans and many of the Bacteria.
Q.18 What are decomposers?
Answer:
Those organisms that break down the complex organic compounds of dead matter (of plants and animals) into simple compounds. They secrete digestive enzymes into dead and decaying organic matter to digest the organic material. Products of digestion are absorbed for their own use and remaining substances are added to the environment for reuse.
Examples
Bacteria and fungi
Q.19 Define Deforestation and describe its causes.
Answer:
Deforestation means clearing of forests by natural causes or humans.
Causes of deforestation
• Large areas of forests have been cleaned for agriculture, factories, roads, rail tracks and
mining.
• Humans cut trees for getting wood (Timber), which is then used for making structures and for
heat production.
• Human preys upon forest animals, which are the predators of many insect pests. In this way
insect pests destroy forests by eating the shoots and spreading diseases.
Effects of deforestation
Floods
Droughts
Landslides
Soil erosions
Global warming
Loss of habitat of many species
Q.20 What is meant by denitrification?
Answer:
It is a biological process in which nitrites and nitrates are reduced to gaseous nitrogen by denitrifying bacteria. In this way, nitrogen is returned to the atmosphere.
Q.21 What is ecological pyramid?
Answer:
Ecological pyramid can be defined as, “A representation of the number of individuals or amount of biomass or energy present in various trophic levels of a food chain”:
Q.22 Define environment.
Answer:
An organism’s environment is the sum of physical (abiotic) and biological (biotic) conditions which influence that organism.
Q.23 What is eutrophication?
Answer:
Enrichment of water with inorganic nutrients (nitrates and phosphates) is called eutrophication.
Q.24 What is Global Warming and describe its effects.
Answer:
The addition of greenhouse gases (e.g. carbon dioxide, methane, ozone) in atmosphere increases the temperature of the earth. Gases in the atmosphere do not allow solar radiations to reflect back into space. As a result, heat remains within the earth’s atmosphere and increases its temperature. This is called global warming. Effect of global warming
Due to global warming, polar ice-caps and glaciers are melting faster than the time taken for new ice layers to form. Sea water is also expanding causes sea level to rise due to melting glaciers, rivers overflow and cause floods.
Q.25 Differentiate between intraspecific interactions and interspecific interactions.
Answer:
Intraspecific interactions
Interspecific interactions The interactions between the members of The interactions between the members the same species are called Intraspecific of different species are called Inerspecific interactions.
interactions.
Q.26 Define mutualism.
Answer:
The type of symbiosis in which both partner get benefit from each other and neither is harmed.
Example
Termites eat wood but are unable to digest it. A protozoan lives in its intestine. It secretes ‘cellulase’ enzyme to digest the cellulose of wood. In turn, the termite provides food and shelter to the protozoan.
Q. 27 What are natural resources?
Answer:
Every thing we use e.g. food, petrol etc. is obtained from natural resources. They are of two
types.
(i) Renewable
(ii) Non-renewable
Q.28 What is nitrification?
Answer:
After the formation of ammonia, it is converted into nitrites and nitrates. This is called nitrification and is done by nitrifying bacteria.
Q.29 What is nitrogen cycle?
Answer:
The flow of nitrogen between environment and the organisms is called nitrogen cycle.
Q.30 What is nitrogen fixation?
Answer:
Conversion of nitrogen gas into nitrates is called nitrogen fixation.
Q.31 What are non-renewable resources and renewable resources?
Answer:
The renewable natural resources e.g. air are reproduced easily but the non-renewable resources (e.g. minerals and fossils fuels) are not replenished once they get depleted.
Q.32 What is overpopulation?
Answer:
Increase in population beyond the carrying capacity of an area or environment is called over population.
Q.33 Define phytoplankton?
Answer:
Photosynthetic organisms that float on the surface of water, are called phytoplankton.
Q.34 Define Pollution and pollutants.
Answer:
Pollution is defined as any undesirable change in the physical, chemical or biological characteristics of air, water and land that may harmful for humans, other living organisms and natural resources. The substances that actually cause pollution are called pollutants.
Q.35 Define parasitism.
Answer:
It is a type of symbiosis in which smaller partner (parasite) derives food and shelter from the body of larger partner (host) and, in turn, harms it.
Q.36 What is predation?
Answer:
An interaction between animals of two species or a plant and an animal, in which the predator attacks, kills and feeds on the smaller animal called prey.
Q.37 What are producers?
Answer:
These are the autotrophs in an ecosystem. These organisms are able to synthesize complex organic compounds (food) from inorganic raw materials. Producers form the basis of any ecosystem.
Examples
Plants, Algae and Cyanobacteria
Q.38 Define pyramid of biomass.
Answer:
It is a graphic representation of biomass present per unit area at various trophic levels of a food chain.
Example
In a terrestrial ecosystem, the maximum biomass is of producers and decomposers have lesser biomass.
Q.39 Define pyramid of numbers.
Answer:
It is a graphic representation of the number of individuals per unit area at various trophic levels
of a food chain.
Example
Usually, producers are present in large number, primary consumers are in lesser number, and secondary consumers are fewer.
Q.40 Define symbiosis.
Answer:
It is a relationship between members of different species, in which they live together for longer or shorter period of time.
Example
Lichens (Association between algae and fungi)
Q.41 Define Ecology.
Answer:
The study of the interrelationship between living organisms and their environment is called ecology.
Q. 42 Define Species.
Answer:
A species is a group of organisms which can interbreed freely in nature to produce fertile offspring.
Example
Human, Cat, Dog etc.
Q.43 Differentiate between Population and Community.
Answer:
Population
A group of the organisms of the same species inhabiting a specific geographical area at a particular time is called a population
Example
Number of rats in a field
Community
All the populations that live in a habitat and interact in various ways with one another are collectively called a community.
Example
Forest is an example of community.
Q.44 Define Ecosystem
Answer:
The self-sufficient unit of an environment that is formed as a result of interactions between its biotic communities and the abiotic components is called ecosystem.
Q.45 What are herbivores?
Answer:
These animals feed directly on plants or products of plants. They are also called primary consumers.
Examples
Cattle, deer, rabbit, grasshopper etc.
Q.46 What are omnivores?
Answer:
Those consumers that eat animal flesh as well as plants and plant products are called omnivores. Examples
Human, Crow
Q.47 Define trophic level.
Answer:
Trophic level is the level at which an organism feeds in food chain. The first trophic level is made of producers; the second of primary consumers and so on.
Q.48 Define pyramid of energy.
Answer:
It is a graphic representation of energy present in a biomass of living organisms at various trophic levels of a food chain.
Example
The amount of energy is decreased from producers to decomposers as some amount of energy is used by the organisms to perform work while some of it is lost as heat.
Q.49 What is meant by assimilation?
Answer:
It is a process in which the nitrates are absorbed by plants and are utilized for making proteins, nucleic acid etc. Animals take nitrogenous compounds from plants. The utilization of nitrates by organisms is called assimilation.
Q.50 What is parasite?
Answer:
A parasite is an organism that gets shelter and food from its host and in return harms it.
Examples
Plasmodium, Amoeba etc.
Q.51 Differentiate between ectoparasites and endoparasites.
Answer:
Ectoparasites
Ectoparasites live outside i.e. on the surface of host’s body and get food from them.
Examples
Mosquitoes, leeches, lice etc
Endoparasites
Endoparasites live inside the body of host and get food and shelter.
Examples
Bacteria, viruses, tapeworm, Ascaris,
Entamoeba, Plasmodium etc.
Q.52 Define Urbanization.
Answer:
Urbanization means growing of cities. People move from rural areas to cities in search of better jobs, education opportunities and higher standards of living.
Q.53 What are primary consumers? Give one example.
Answer:
The organisms which feed directly on plants or products of plants are called primary consumers. e.g. sheep, goat etc.
Q.54 Write four effects of air pollution.
Answer:
i. Smog formation
ii. Acid rains iii. Ozone depletion
iv. Global warming
Q.55 Define pollutants.
Answer:
The substance that actually cause pollution called pollutants. They may be industrial effluents, domestic wastes, medical wastes etc. Pollutants are of two types:
Q.56 What is noise? Write its Effects.
Answer:
Unwanted and annoying sounds are termed as noise. Effects of noise pollution are aggression, hearing loss, depression, hypertension etc.
Q.57 What is green house effect?
Answer:
Certain gases trap heat in environment. These gases act like the glass in a green house which does not allow the inner heat to escape. When sunlight reaches to earth surface, much of its energy is converted into heat energy. Earth reflects the heat energy back into space in the form of infra-red radiation. Green house gases (CO2, CH4,Nitrous oxide) trap these infra-red radiations and send it back to earth.
Q.58 What is global warming?
Answer:
The addition of green house gases (e.g; carbon dioxide, methane, ozone) in atmosphere increases the temperature of the earth. These gases remain in the lowest part of earth’s atmosphere and do not allow solar radiations to reflect back into the space. As a result, heat remains within the Earth’s atmosphere and increases its temperature. This is called global warming.
Q.59 Differentiate between DHF and DSS.
Answer:
Both are types of dengue fever, and have different symptoms:
DHF
Dengue haemorrhagic fever (DHF) results in blood bleeding, low levels of blood platelets and blood plasma leakage.
DSS
In Dengue shock syndrome (DSS), blood platelets and blood plasma leakage.
Q.60 Define biomass?
Answer:
The total amount of living or organic matter in an ecosystem at any time is called biomass.
Q.61 Define nutrient cycle?
Answer:
The movement of elements and inorganic compounds from environment to organisms and back to environment.
Q.62 What are the effects of denitrification?
Answer:
Excessive denitrification reduces soil fertility and is stimulated by water-logging, lack of aeration and accumulation of organic matter in the soil.