DAV school class 7science ch 1,2,3fair please class 7 DAV class 7 students. Answers this please. l will make you brainlist give me right answer.chapter name is also mantion.
Answers
What are 'stomata'? Where are they normally found?
:
green plants are called heterotrophs.
They are producers. They are consumers.
For example, all green plants, cynobacteria, etc. For example, all animals like cow, lion and humans.
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Question 2:
How will you test a leaf for starch? Mention any precautions you will take.
ANSWER:
Test for starch:
Pluck one of the green leaves that have been exposed to sunlight.
Boil that leaf in water for 5 minutes to soften it.
compounds?
ANSWER:
Rhizobium are the bacteria which are present in the soil and convert atmospheric nitrogen into soluble compounds.
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Question 5:
What type of plant is Cuscuta?
ANSWER:
Cuscuta is a parasitic plant which obtains food from the other plants.
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Question 6:
What do you call a mutually beneficial relationship between two living organisms?
ANSWER:
Symbiosis is the mutually beneficial relationship between two living organisms.
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Question 7:
Name one organism that gets its food from dead and decaying matter.
ANSWER:
Mushroom gets its food from dead and decaying matter.
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Question 8:
When iodine is added to starch, it becomes __________ in colour.
ANSWER:
When iodine is added to starch, it becomes blue-black in colour.
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Question 9:
What is the ultimate source of all the energy needs of our body?
ANSWER:
Food is the ultimate source of all the energy needs of our body.
Note: Although sun is the ultimate source of energy for all living beings. But the energy requirements of our body is fulfilled by the food obtained from the plants.
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Question 10:
Saprophytes are green in colour. True or false?
ANSWER:
False, as saprophytes are non-green plants.
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Question 11:
Some green plants are also heterotrophic in nature. True or false?
ANSWER:
True.
Some green plants are heterotrophic in nature. For example, plants like pitcher plant feeds on insects.
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Question 12:
Which cells control the opening and closing of stomata?
ANSWER:
The guard cells control the opening and closing of stomata.
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Question 4:
All animals−whether herbivores, carnivores or omnivores−depend on plants for their food. Discuss.
ANSWER:
Plants are capable of making their own food. All animals whether herbivores, carnivores or omnivores can not make their own food; hence, they depend on the plants for their food. Herbivores feed on plants to obtain nutrition. Again, the carnivores eat herbivores to obtain nutrition. Thus, carnivores indirectly depend on plants for their food. Omnivores, on the other hand, can directly obtain food from plants or indirectly consume animals which feed on plants. Thus, all animals ultimately depend on plants for their food.
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Question 5:
Explain the following with the help of an example for each:
(a) parasitic nutrition
(b) symbiosis
(c) saprotrophic nutrition
ANSWER:
(a) Parasitic nutrition: Parasites feed on other living organisms to obtain nutrition. This mode of nutrition is referred to as parasitic nutrition. For example, non green plants like dodder which can not synthesise their own food, grows over other plants and sucks nutrition from them using their root like structure.
(b) Symbiosis: The mutually beneficial relationship between two organisms is termed as symbiosis. For example, lichens are association between alga and fungi. Alga supplies food to its fungal partner, while fungi provides shelter to its algal partner.
(c) Saprotrophic nutrition: Organisms which feed on dead and decaying matter are called saprotrophs, and this mode of obtaining nutrition is called saprotrophic nutrition. For example, mushrooms, fungi and bacteria
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Question 6:
Why are manures and fertilizers added to the soil in a farm?
ANSWER:
Manures and fertilisers are added to the soil in order to enrich its organic composition and replenish the nutrients in it.
ANSWER:
Parasites Partial Parasites
Parasites are non green plants which feed on other plants. Partial parasites are green plants which can synthesis their own food but absorb water and minerals from other plants.
We make our own food in the kitchen. This means that humans are also autotrophs. Do you agree? Give reasons.
ANSWER:
Humans can not synthesize their own food; therefore, they are heterotrophs. We make our own food in the kitchen but the raw materials that we use to cook the food are either obtained from plants or from animals. Thus, humans, directly or indirectly, depend upon plants for their food. For example, we cook vegetables obtained from plants and meat obtained from animals.