Ecosystem (Short Questions and Answers)


Short Questions and Answers

One mark questions with answers

1. Ecosystem contains

(a) producers

(b) consumers

(c) decomposers

(d) all the above

Answer: (d) all the above

2. The term ecosystem was coined by

(a) Odum

(b) Ernst Haeckel

(c) Tansley

(d) Reiter

Answer: (c) Tansley

3. Which of the following ecosystems has highest gross primary productivity?

(a) grasslands

(b) coral reefs

(c) mangroves

(d) rainforest

Answer: (a) grasslands

 4. The 10% energy transfer law of food was given by

(a) Stanley

(b) Wiesman

(c) Lindemann

(d) Tansley

Answer: (c) Lindemann

 5. Niche of a species means

(a) the specific place where an organism lives

(b) the specific function of species

(c) the habitat and specific function of a species

(d) none of these

Answer: (c) the habitat and specific function of a species

 6. Part of the earth that inhabits living organism is called

(a) biome

(b) biotrophy

(c) biosphere

(d) biodata

Answer: (c) biosphere

7. The pyramid of numbers in grassland ecosystem will be

(a) linear

(b) upright

(c) irregular

(d) inverted

Answer: (b) upright

8. The pyramid of energy is

(a) always upright

(b) always inverted

(c) both upright and inverted

(d) none of the above

Answer: (a) always upright

 9. The planktonic forms of plants are

(a) autotrophs

(b) heterotrophs

(c) chemotrophs

(d) insectivorous types

Answer: (a) autotrophs

 10. A community is

(a) a collection of plants and animals

(b) organisms living in a habitat

(c) autotrophs and heterotrophs

(d) web of life

Answer: (b) organisms living in a habitat

11. Ecosystem has two components

(a) plants and animals

(b) weeds and trees

(c) biotic and abiotic

(d) frogs and mentions

Answer: (c) biotic and abiotic

12. The organisms at the base of food chain are

(a) herbivores

(b) photosynthetic plants

(c) saprophytic plants

(d) carnivores

Answer: (b) photosynthetic plants

 13. In abiotic components of an ecosystem which of the following occurs

(a) flow of energy

(b) cycling of materials

(c) consumers

(d) flow of energy and cycling of material

Answer: (b) cycling of materials

 14. The recycling of elements in an ecosystem is called

(a) chemical cycle

(b) geological cycle

(c) biogeochemical cycle

(d) geochemical cycle

Answer: (c) biogeochemical cycle

15. Which of the following is a correct sequence of food chain?

(a) fallen- leaves- bacteria- insect- larvae- birds

(b) phytoplankton – zooplankton- fish

(c) grasses-fox-rabbit

(d) grasses-chamelion-insects-birds

Answer: (b) phytoplankton – zooplankton- fish

Two marks questions with answers

1. What do you understand by the term ecosystem?

Answer: The ecosystem comprises the biotic community and the non-living environment.  It is the basic functional unit as it includes both the organism and its environment, each influencing the properties of the other and both necessary for the survival and maintenance of life.  A.G.Tansley in 1935 coined the word ecosystem.  Some examples of natural ecosystems are ponds, lakes, oceans, grasslands, forests, deserts, tundras and so on.  An ecosystem be it a pond, forest, desert or tundra has the following two components; abiotic and biotic components

2. What is artificial ecosystem?

Answer: Man maintains and manipulates artificial ecosystems.  These include croplands like wheat, maize and rice fields.  Man changes the biotic components of artificial ecosystems by adding chemical fertilizers, biofertilizers and insecticides.

3. Differentiate between food chain and food web.

Answer: A food chain is a single series of trophic levels where as a food web is a multiple series of trophic levels. Each food chain is distinct from other food chains whereas a food web consists of a number of interconnected food chains. In case of food chain only one type of organisms are available as food for higher trophic level organisms whereas in food web several types of organisms are available at each trophic level.

4. What are ecological pyramids?

Answer: Ecological pyramids are graphical representations of various ecological parameters at the successive trophic levels of food chains with producers at the base, top carnivores at the apex and intermediate levels in between. Ecological pyramids were first prepared by Elton (1927) hence they are also called eltonian pyramids.

5. Differentiate between upright pyramid and inverted pyramid.

Answer: In case of upright pyramid the base bar comprising produces is the largest whereas in case of inverted pyramid the base bar comprising produces is the smallest. In upright pyramid the bar of vertex of the pyramid comprising top consumers is the smallest whereas in inverted pyramid the bar of vertex of the pyramid comprising consumers is the largest. Pyramid of energy is always upright. Inverted pyramid occurs in case of number and biomass pyramid when either the size or turnover of the producers is large.

 Three marks questions with answers

 1. What are the abiotic components of an ecosystem?

Answer: The non-living environment (abiotic), such as the air, water, soil and the basic elements and compounds of the environment is one of the components of an ecosystem.  These non-living substances enter into the body of the living organisms, take part in metabolic activities and then return to the environment.  The abiotic portion of the ecosystem is conveniently divided into three parts:

a).  The climatic regime and physical factors like temperature, relative humidity etc.

b).  The inorganic substances such as water, carbon, nitrogen, sulphur, phosphorus and so on, which are involved in the cycling of materials in the ecosystem.

c).  Organic substances like proteins, carbohydrates, lipids etc, which largely form the living body and link the abiotic and biotic components.

2. What are the biotic components of an ecosystem?

Answer: The biotic or living component of the ecosystem is divided into producers, consumers and decomposers.

(1) Producers: Producers or energy transducers are those which convert solar energy into chemical energy with the help of inorganic substances such as water and CO2 and organic substances such as enzymes.  These producers are autotrophic organisms, largely green plants.

(2) Consumers: Consumers are heterotrophic organisms, chiefly animals.  Depending upon their food habits, consumers may either be herbivores (plant eaters) or carnivores (flesh eaters).  Herbivores consume plants.  They may be insects, zoo-planktons or animals like deer, cattle, elephants etc.  Carnivores consume flesh and usually prey on herbivores and other carnivores.  The carnivore may be an insect like a praying mantis or a large animal like a tiger or lion.

(3) Decomposers: The decomposers are also heterotrophic organisms but depend on dead organic matter for their food.  They are chiefly microorganisms like bacteria, actinomycetes and fungi.  These break down complex organic matter like cellulose, hemicellulose, chitin etc., found in the plant and animal body and ultimately release simple substances used by the producers.

3. What are the functional attributes of an ecosystem?

Answer:  Each ecosystem has some functional attributes which keeps its component part running together.  The following seven aspects are considered as functional attributes of the ecosystem:

  1. Biological diversity and maintenance of stability.
  2. Primary and secondary productivity.,
  3. Food chain relationship.
  4. Energy flow.
  5. Material cycling.
  6. Homeostasis and feedback.
  7. Development and evolution of ecosystems.

4. Explain briefly grassland ecosystems.

Answer: A grassland ecosystem is characterized by the presence of herbaceous plant cover without trees.  A wide variety of grass species dominates it.  Along with the grasses, are present several herbaceous dicotyledenous species, especially of leguminous plants which play an important role in nitrogen economy. All the organic and inorganic substances present in the soil are essential for the plant growth.  The elements such as C, H, O, N, P, S, K etc. are made available in the form of gases (CO2) or inorganic salts (e.g., nitrates, phosphates, sulphates etc.).  The biotic components include producers which are mainly grasses, such as species of Cynodon, Dicanthium, Digitaria, Setaria, Sporobolus etc.  Besides these, a few small shrubs are also present which increase the productivity.

The consumers of the grasslands are herbivorous feeding mainly on grasses such as grazing animals (e.g., cows, buffaloes, deer, sheep, rabbits).  Some insect species that eat the leaves of grasses (e.g., Cicincella, Leptocorcia, Oxyrachis) are also present.  Besides this, several carnivores, feeding on herbivorous (e.g., fox, jackal, snake, frog) also form the biotic component of the grasslands.  Several microbes, (e.g., Rhizopus, Mucor, Penicillium, Fusarium etc.).  These microbes help in decay process and break the complex organic molecules into their inorganic constituents.

5. Discuss Pond or Lake Ecosystem.

Answer: As light passes down the waters of pond or lake, it is gradually absorbed and scattered.  Much of it is used in photosynthesis by phytoplankton near the surface.  Here the colour of light becomes green, partly because the chlorophyll of algae selectively absorbs blue and red wavelengths.  Further down, there occurs a certain depth at which oxygen production by photosynthesis equals the respiratory consumption of oxygen by all organisms.  This is termed as compensation depth.  The region above this depth is known as euphotic zone, in which more organic matter is formed than is consumed.  In the region below the compensation depth, decomposition is the predominant process.

Zonation of lake according to light intensity has a profound influence in the distribution of organisms.  Shallow part of the euphotic zone termed as the littoral zone, contain various rooted aquatic plants such as Nymphaea, Trapa, Jussiaea, etc.  Aquatic life is richest in the littoral zone around the lake edges.  Here sunlight penetrates to the bottom and supports rooted aquatic plants.  In the open surface waters of the lake, termed as the limnetic zone, the dominant floating organisms are floating algae (e.g., Ulothrix, Spirogyra, Volvox,  Microcystis, Spirulina and diatoms), herbivores, rotifers, small arthropods and carnivorous animals. Beneath the limnetic zone, the chief input of energy is dead organic matter that falls from above. Various kinds of decomposers, fish and invertebrates consume this dead matter or one another.  At the bottom of lake, the decomposers use up dissolved oxygen as they convert dead organic matter back into inorganic nutrients.