The branches of a plant always grow towards light, a chameleon changes colours to match its surroundings and cuckoos lay eggs in the nest of a crow. These are simply examples of organisms interacting with their surroundings or environment and its components. How do you think we got to know about why and how these interactions happen? It could be done by studying the relationships between organisms and their environment.
Ecology is the study of the relationship of living beings with other living organisms and their surrounding physical environment. Ernst Haeckel coined the term “Ecology”.
Ecology is considered with different levels at which the living world is organised. So before we dive into deeper aspects of ecology, don’t you think we should understand the different levels of organisation of the living world??
The organisation of the living world starts at the level of macromolecules which organise into cells, then tissues, organs, organ systems and ultimately form an organism. But is an organism the highest level of organisation in the living world or are there higher levels of organisation that ecology is concerned with? There are various levels of ecological organisation. It includes: organism, population, community, ecosystem, biome and biosphere. Let us learn more about this.
Organisms are any single individual. A human, a fish, a tiger, a palm plant, a Spirogyra are examples of an organism. As we see here this single fish is an organism.
Population is the group of individuals that belong to the same species. When more than one individual comes together it is called population.
When the different groups of population gather in an area, it is called community. For example, here different populations of fishes and seahorses are forming a community of aquatic organisms in the sea.
A stable system, formed when multiple groups of biological communities interact with each other and their physical environment, is known as the ecosystem. In the ecosystem, organisms depend on each other and on the environment. In a marine ecosystem, fishes, planktons, aquatic plants depend on each other and comprise the biotic communities of the ecosystem. The sea/ocean water, the sunlight, dissolved air, temperature of the water, etc also play a very crucial role in the survival of the living organisms and influence their life. These non-living components of the physical environment comprise the abiotic components of the ecosystem.
A biome is a large community of vegetation and the wildlife adapted to a specific climate. Any regional unit that has a particular type of plants, animals and climate is categorised as biome.
The difference in climates results in the occurrence of different kinds of flora and fauna which are adapted to specific climates.
The major reasons for the climatic variations are two: different durations of temperature in different regions and the annual variation in precipitation (rainfall or snowfall).
The distribution of biomes based on climates is called biomes distribution.
Various biomes are tundra, conical forest, temperate forest, tropical forest, hot desert and grassland.
The Tundra region receives the least sunlight. The climate of this region is very cold. The precipitation is in the form of snow and only some herbs, shrubs, grasses, lichens and mosses are present. This biome is found in the Arctic region.
Coniferous forests are present in very cold regions and are located to the south of Tundra region. Cold regions of Asia, North America and Europe contain these forests. They have evergreen coniferous trees which have long needle-like leaves. Coniferous forests have moderate precipitation and greater plant and wildlife biodiversity compared to the Tundra.
Temperate forests have higher sunlight, temperature and precipitation/ rainfall than grasslands. The leaves of trees of such forests are broad and tall (25-30 metres).
Tropical forests are present near the tropical regions and receive heavy rainfall with hot temperature. They have rich biodiversity. Buttresses, climbers and epiphytes are present here. Areas of South America, parts of Africa, Southeast Asia exhibit the presence of tropical forests.
Hot deserts have very high temperatures, very little rainfall and perpetual water scarcity. Thar and Sahara are some examples of hot deserts. Deep rooted shrubs, ephemerals, succulents and xerophytes are present in it.
Ephemerals are plants with short life cycles and grow in extreme water scarce regions.
Succulents are plants with thick fleshy tissues adapted to water storage.
Xerophytes are species of plant that have adaptations to survive in an environment with little liquid water.
Grasslands are present in regions with high temperature and moderate precipitation. Thus, vegetation mainly consists of tall grasses and trees are lacking. Many grass eating herbivores are present in the grassland. This habitat is known as prairie in North America, pampas in South America, veld in Southern Africa, downs in Australia, and steppe in Asia.
These biomes with their local as well as regional variations, give rise to a wide variety of habitats with unique characteristics. While some of these habitats exhibit conditions favourable for survival, some can be very harsh. The key elements responsible for such variations in the conditions of any habitat are both the biotic as well as abiotic components. However, organisms have evolved to develop adaptations that have been naturally selected to help them survive in their respective habitats.
Each organism occupies a unique niche in its habitat. Niche is characterised by the definite range of conditions that an organism can tolerate, the resources it utilises and the distinct functional role that it plays in the ecological system. It is the position or status of an organism within its community and ecosystem resulting from the organism's structural and functional adaptation. Example: – Parrot eats the fruits and helps in dispersal of seeds, earthworm lives in the soil and increases its fertility.
Ecosystems are present in all the biomes on earth. Biosphere is a global ecosystem composed of abiotic and biotic factors. Biosphere is also called ecosphere. It’s a sum of all ecosystems.
Question 1. Assertion: The flora and fauna in deserts have adapted to withstand the extreme climate in their habitat.
Reason: Deserts are terrestrial biomes and they have an extremely arid climate.
a. Both the assertion and reason are true and the reason correctly explains the assertion.
b. Both the assertion and reason are true but the reason does not correctly explain the assertion .
c. The assertion is true but the reason is false .
d. Both assertion and the reason are false.
Solution: Deserts are terrestrial biomes that are characterised by an extremely arid climate. To survive in these harsh conditions both desert vegetation and animals have various adaptations. For example, desert plants such as cactus (Opuntia) have enlarged fleshy stems (phylloclade) to store water and perform photosynthesis. Animals in the desert such as the camel, sweat less and urinate less frequently to conserve water.
Hence the correct option is a.
Question 2. Annual variations are seen in intensity and duration of temperature on Earth. Major biomes on earth will be formed when such variations are combined with annual variations in precipitation, They are illustrated in the diagram. Which of the following biomes has the maximum and minimum mean annual temperature respectively?
a. Tropical rainforest and desert
b. Tropical rainforest and Arctic tundra
c. Temperate rainforest and arctic tundra
d. Desert and coniferous forest
Solution: Tropical rainforests have 200 cm of rainfall per year. Tropical rain forests are very warm. They have an average daily temperature of 28°C. Arctic and alpine tundra are characterised by less than 25 centimetres of precipitation annually and extremely cold temperatures (-34 to -6 degree celsius).
Hence the correct option is b.
Question 3. Which of the following is the basic unit of study in Ecology?
Solution: Ecology is the study of organisms and their interactions with each other and their environment. An organism is the basic unit in Ecology, followed by population, community, ecosystem, biome and biosphere. Ecological interaction is impossible without an organism.
Hence the correct option is d.
Question 4. How many of the following are major biomes of India?
Deserts, Taiga, Deciduous forests, Tropical rainforests, Sea coasts, Tundras, Grasslands, Alpine region.
Solution: Biomes are very large ecological areas on the Earth's surface and each has its own fauna (animals) and flora (plants) that have adapted to their environment. Major biomes of India are deciduous forests, deserts, sea coasts and tropical rainforests.
Hence, the correct answer is option c.
Question 1. What is ecology?
Solution: Ecology is the study of the relationship of living beings with other living organisms and their surrounding physical environment. Ernst Haeckel coined the term “Ecology”. There are various levels of ecological organisation. It includes: organism, population, community, ecosystem, biome and biosphere.
Question 2. What do you mean by an ecosystem?
Solution: A stable system, formed when multiple groups of biological communities interact with each other and their physical environment, is known as the ecosystem. In the ecosystem, organisms depend on each other and on the environment.
Question 3. Differences between habitat and niche?
Solution: Habitat is the place where organisms live. It is the place where all the environmental conditions are present that is like a home for an organism. But niche is the position or status of an organism within its community and ecosystem resulting from the organism's structural and functional adaptation.
Question 4. There are six levels of organisation in ecology. Which are they?
Solution: There are various levels of ecological organisation. It includes: organism, population, community, ecosystem, biome and biosphere.