Matric Notes Biology Class 10th Ch 16 Man and His Environment Short Questions
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Q1: Define the terms: species, biosphere and ecosystem.
Ans: They are the following:
➢ Species: The first level of ecological organization is the specie. A specie may be define as: A group of organisms which can interbreed freely in nature to produce fertile offspring is called species.
➢ Biosphere: All ecosystem of the world together form the biosphere. It includes all the ecosystem of the planet Earth. In other words, the biosphere consist of all the organisms present on the earth and all region of the earth where they live.
Range: Biosphere ranges from the floor of the ocean to the tops of the highest mountains.
Thickness: It is about 20 kilometer thick. The biosphere make a thin layer surrounding the planet earth. If you consider the earth as of the size of an apple, then the biosphere will be a thick as the apple’s skin.
➢ Ecosystem: The self-sufficient unit of an environment that is found as result of interactions between its biotic community and the abiotic component of environment interact with each other to form an ecosystem.
Types of ecosystem: There are two types of ecosystem.
1. Natural ecosystem:
Examples
• A lake
• A forest
2. Artificial ecosystem:
Example:
Q2: Differentiate between population and community?
Ans: Population
A group of the organisms of the same species inhabiting a specific geographical areas (habitat) at a particular time is called a population.
• Population of student in a school.
• Population of frog in a pond.
• Population of pine tree in a forest.
Community
All the population that live in a habitat and interact in various with one another are collectively called a community.
• All the fish
• Turtles
• Plants
• Algae
• And bacteria in the pond make up ecosystem.
Q3: Differentiate between food chain and food web.
Ans: Food chain
A series of an organisms with in an ecosystem, in which each organisms feeds on the one before it and is fed by the one after it is called food chain.
Example: Following is the food chain in an ecosystem:
Explanation: The base of food chain is always formed by a plant (producer). It is eaten by a primary consumer, which is preyed upon by a secondary consumer. The secondary consumer may be eaten by a tertiary consumer. A food chain, can therefore be presented as, 𝑷𝒓𝒐𝒅𝒖𝒄𝒆𝒓→𝑷𝒓𝒊𝒎𝒂𝒓𝒚 𝒄𝒐𝒏𝒔𝒖𝒎𝒆𝒓 →𝑺𝒆𝒄𝒐𝒏𝒅𝒂𝒓𝒚 𝒄𝒐𝒏𝒔𝒖𝒎𝒆𝒓→𝑻𝒆𝒓𝒕𝒊𝒂𝒓𝒚 𝒄𝒐𝒏𝒔𝒖𝒎𝒆𝒓
Advantages: A food chain involves a nutritive interaction among the biotic components of an ecosystem.
Number of Trophic level: Usually there are 4 or 5 trophic levels. Shorter food chain provide greater available energy and vice versa.
Food web: A network of food web which are interconnected at various trophic levels is called food web.
Explanation: In nature, food chain are very complex, as one organisms may be food source of many other organisms. Thus, instead of a simple linear food chain, there is web like structure formed by these inter-linked food chains. Such interconnected food chain collective make food webs.
Advantages: A food web benefits life science lessons on physical and behavioral adaptations of plants and animals by representing a pattern of consumption based upon natural survival attributes and instincts.
Q4: How does deforestation affect the environment?
Definition: The cleaning of forest by natural causes or human is called deforestation.
Effects: The effects of deforestation includes:
2. Drought
3. Landslides
4. Soil erosion
5. Global warming
6. Loss of habitat of many species
Other effects: Deforestation has many negative effects on the environment.
➢ Loss of habitat: The most dramatic impact is a loss of habitat for millions of species. 70% of the Earth’s land animals and plants live in forest, and many cannot afford deforestation since it results in the destruction of their home.
➢ Climate change: Deforestation also result in climate change. Forest soil are moist, but without protection from sun-blocking tree cover, they quickly dry out.
➢ Water cycle: The trees also help perpetuate the water cycle by returning water vapors back into the atmosphere. Without trees to fulfil these roles, many former forest lands can quickly become barren deserts.
➢ Absorbing greenhouse gases: Trees also play a critical role in absorbing the greenhouse gases that are responsible for global warming.
Q5: Distinguish between herbivore, carnivore, and omnivore.
Ans: Herbivore: The animals that feed on plants are called herbivores. The herbivores are the primary consumers. They feed directly on plants or products of plants.
Examples: Cattle, Deer, Rabbit, Grasshopper
Carnivores:- The animals that feed on meat of other animals are called carnivores. The carnivores are the secondary consumers.
Example:- Fox, Frog, Predatory birds, many fishes, snakes.
Omnivores: The animals that feed on plants and animals are called omnivores.
Example:- Human being
Q6: Outline the role of bacteria in the nitrogen cycle.
Ans: Role of bacteria in the nitrogen cycle: 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 symbioses and many are free-living.
➢ Ammonification and nitrification The breakdown of the proteins of dead organisms and nitrogenous wastes (urea, uric acid etc.) to ammonia is called ammonification. It is done by ammonifying bacteria.
➢ Nitrification: The process of conversion of ammonia into nitrites and nitrates is called nitrification. It is done by nitrifying bacteria.
Formation of nitrites: First, ammonia is converted into nitrites by bacteria like:
• Nitrosomonas
Formation of nitrates:
The nitrites are then converted into nitrates by other bacteria like:
• Nitrobacteria
➢ Denitrification: The biological process in which nitrates and nitrites are reduced to nitrogen gas by denitrifying bacteria is called dentrification. By this process nitrogen is returned to atmosphere.
Excessive denitrification reduces soil fertility and is stimulated by:
• Lack of aeration
Q7: How can overpopulation affect the environment?
Ans: Over population: The condition of being populated with excessively large numbers of people.
It has the following affect on population.
Loss of fresh water: Water is the one of the basic element of life. As the human population increased so also the consumption of fresh water also increased. So, it is difficult to provide fresh water to over populated areas.
Water pollution: The problem with water is not only overconsumption but also pollution. The toxin substances from factories are discharged into waterway or filed so then it polluted water and destroy water bodies.
Soil degradation: Population growth result increases the demand for food production. Farmers began to cultivate on dry, hilly and nutrient-poor areas due to limited arable land so it causes land to lose nutrients and lead to soil degradation.
Deforestation: The search for more agricultural farmland causes more cultivation. The slash-and-burn cultivation leads to deforestation.
Loss of biodiversity:Deforestation, water pollution, soil degradation leads to loss of many wild life habitat.
Q8: Name any five sources of water pollution?
ANS: Five sources of water pollution:
Following are the five sources of water pollution:
1. Sewage: Sewage is one of the major pollutants of water. It contains organic matter and the excrete of human and other animals. Organic matter encourages the growth of micro-organisms which spread diseases.
2. Industrial wastes: The wastes of industries (acids, alkalis, dyes and other chemicals) are disposed in nearby water bodies. These wastes change the pH of water and are harmful or even fatal to aquatic organisms.
3. Hot water: Certain industries release a lot of hot water from their cooling plants. It results in heating up of water bodies and kills aquatic life.
4. Fertilizers and pesticides: Fertilizers and pesticides enter into water bodies with the rain water flow and the ground water by seepage. These chemicals remain in water for a long time and can enter food chains.
5. Oil leakage: Oil tankers and offshore petroleum refineries cause leakage into water. Oil floats on the water surface and prevents atmospheric oxygen from mixing in water. So, aquatic animals begin to die due to oxygen shortage.
Q9: Define nitrogen fixation and nitrification.
Ans: Nitrogen fixation: Nitrogen fixation is a process where N2 is converted into ammonium with the help of certain bacteria.
For example: Rhizobium
Nitrogen fixing bacteria often formed symbiotic relationship with the legume (beans and peas). In addition to nitrogen fixing bacteria, high energy natural events such as lightning, forest, fires and even hot lava flows can cause the fixation of smaller amount of nitrogen.
Nitrification: Some of the ammonium produced by decomposition is converted to nitrate via a process called nitrification. Nitrification is accomplished by two groups of bacteria.
✓ Second group of bacteria (Nitrobacteria) converts nitrites into nitrates.
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