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[3 Mark Questions]

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5 questions · timed · auto-graded

Question 13 Marks
Which of the following are biodegradable and which non-biodegradable?
Glass bottle, Paper, Ball point pen refill, Hay, DDT, Wheat, Cake, Wood, Polythene bag, Jute bag, Cotton cloth, Grass, Vegetable peels.
Answer
Glass bottle – Non-biodegradable Paper – Biodegradable Ball point pen refill – Nonbiodegradable Hay – biodegradable DDT – Non- biodegradable Wheat – Biodegradable Cake – Biodegradable Wood – Biodegradable Polythene Bag – Non-biodegradable Jute Bag – Biodegradable Cotton Cloth – Biodegradable Grass – Biodegradable Vegetable peels – Biodegradable.
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Question 23 Marks
What is meant by a primary consumer, secondary consumer and a tertiary consumer? Give one example of each.
Answer
The animals which eat only plants are called Herbivores. All herbivores are primary consumers.
Example: Goat.
The small carnivores which feed on herbivores (primary consumers) are called secondary consumers.
Example: Frog.
The Large carnivores (or top carnivores) which feed upon the small carnivores (secondary consumers) are called tertiary consumers.
Example: Lion.
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Question 33 Marks
What is ozone? How is it formed?
Answer
Ozone is a poisonous gas. It is made up of three atoms of oxygen combined together. It is formed high up in the atmosphere by the action of ultraviolet radiation on oxygen gas. The high energy ultraviolet radiation (UV radiation) coming from the sun splits oxygen gas into free oxygen atoms.
$\ \ \ \ \ \ \ \ \text{O}_{2}\ \ \ \ \ \ \xrightarrow[\text{From sun}]{\text{UV radiation}}\ \ \ \ \ \ \ \ \ \ \ \text{O}\ \ \ \ \ \ \ \ \ + \ \ \ \ \ \ \ \ \ \ \text{O}\\\ {^\text{Oxygen molecules}}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ {^\text{Oxygen atom}}\ \ \ \ \ \ \ \ \ \ \ {^\text{Oxygen atom}} $
The free oxygen atoms thus produced are very reactive. One oxygen atom reacts with an oxygen molecule to form an ozone molecule:
$\ \ \ \ \ \ \ \ \ \ \text{O}_{2}\ \ \ \ \ \ \ \ \ +\ \ \ \ \ \ \ \ \text{O}\ \ \ \ \ \ \ \ \rightarrow\ \ \ \ \ \ \ \ \text{O}_{3}\\\ {^\text{Oxygen molecules}} \ \ \ \ \ \ \ \ {^\text{Oxygen atom}}\ \ \ \ \ \ \ {^\text{Ozone molecule}}$
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Question 43 Marks
With the help of a flow diagram, describe how energy from the sun flows through various trophic levels.
Answer
The energy from sun flows through various trophic levels. The food and energy are transferred from producer organisms to herbivores and from herbivores to carnivores, through the food chain. First Step – The green plants trap solar energy with the help of green pigment called chlorophyll which converts the sunlight energy into chemical energy. This gets stored as carbohydrates in the plants. About 1% of the sun’s energy falling on the leaves is used by the plants in the process of photosynthesis and stored as chemical energy of food. The plants utilize the stored energy for their metabolic activities like respiration and growth. Some of the energy is not utilised and it is released as unusable heat into the environment. Second Step – The plants are eaten up by herbivores and the chemical energy of plants is transferred to them. The herbivores utilize this energy for various metabolic activities and release unused energy as heat energy to the environment.
Third Step – The herbivores are eaten up by carnivores. The chemical energy stored in the flesh of herbivores is transferred to the carnivores and they utilise this energy for their metabolic activities like respiration and growth and some of the energy which remains unutilised, is released into the environment. This process of transfer of energy is repeated with large carnivores and so on.
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Question 53 Marks
What is a ‘food web’? Show its formation.
Answer
The interconnected food chains operating in an ecosystem which establish a network of relationships between various species is called a food web. In this food web, we can see a network of numerous pathways along which the food flows within grass land community. This food web starts from the plants which is producer and end in top carnivore hawk.
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[3 Mark Questions] - Science STD 10 Questions - Vidyadip