General Science Solutions Solutions for Class 7 Science Chapter 4 Nutrition In Living Organisms are provided here with simple step-by-step explanations. These solutions for Nutrition In Living Organisms are extremely popular among Class 7 students for Science Nutrition In Living Organisms Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the General Science Solutions Book of Class 7 Science Chapter 4 are provided here for you for free. You will also love the ad-free experience on Meritnation’s General Science Solutions Solutions. All General Science Solutions Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

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Question 1:

Classify according to food-type.
tiger, cow, vulture, bacteria, deer, goat, human, fungus, lion, sparrow, buffalo, frog, cockroach, tick.

Answer:

tiger- carnivore 
cow- herbivore 
vulture- scavenger
bacteria- decomposers
deer- herbivore
goat- herbivore
human- omnivore
fungus- decopmosers
lion- carnivores
sparrow- herbivore
buffalo- herbivore
frog- carnivore
cockroach- carnivore
tick- parasite

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Question 2:

Match the pairs.
 

Group 'A' Group 'B'
(1) Parasitic plant (a) Mushroom
(2) Insectivorous plant (b) Lichen
(3) Saprophytic plant (c) Drosera
(4) Symbiotic plant (d) Cuscuta

Answer:

Group 'A' Group 'B'
(1) Parasitic plant (d) Cuscuta
(2) Insectivorous plant (c) Drosera
(3) Saprophytic plant (a) Mushroom
(4) Symbiotic plant (b) Lichen

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Question 3:

Answer the following questions in your own words.
(a) Why do living organisms need nutrition ?
(b) Explain the process of production of food in plants.
(c) What is meant by parasitic plants ? Name their different types with examples of each.
(d) Explain the various steps of nutrition in animals.
(e) Name some unicellular organisms in which all life-processes take place within their unicellular body.

Answer:

a. Nutrition is the process of uptake of nutrients from food and utilizing them for various functions of the cells. Nutrition is required for purposes like:

  • supplying the energy required for doing work
  • for growth and development of the body
  • to fight diseases
  • to replace the damaged cells and repair tissues

b. Leaves are the food factories of plants. They are the sites where the synthesis of food occurs in plants. The leaves of plants contain a green pigment called chlorophyll. This pigment captures the sun’s energy, which is used to prepare food from carbon dioxide and water. The process of synthesis of food using sunlight, carbon dioxide, and water is known as photosynthesis. During the process of photosynthesis, the leaves containing chlorophyll convert carbon dioxide and water into carbohydrates in the presence of sunlight. Carbohydrates, which are produced during photosynthesis, are ultimately converted into starch to be stored in plants.This process can be represented in the form of the following equation:



c. Cuscuta survives by growing on the body of another plant and deriving nutrients from this plant in the process. This mode of nutrition is known as parasitic mode of nutrition. Cuscuta is known as a parasite as it depends on another plant for its survival. The plant on which it grows is known as the host. Cuscuta can be seen around in the form of yellow tubular structures growing on the stems of other plants. It is devoid of leaves. Another such example of parasitic plants is Loranthus.


 d.  The various steps of nutrition in animals are:
  • Ingestion − The process of taking in of food into the body is called ingestion. Ingestion of food in humans is done with the help of the buccal cavity. 
  • Digestion − The process where conversion of food into soluble form occurs.
  • Absorption − The nutrients from the digested food are absorbed in the small intestine with the help of finger-like projections called villi.
  • Assimilation − The absorbed nutrients are transported via the blood vessels to the different organs, to be utilised for different life processes. 
  • Egestion − The process of removal of faecal matter through the anus is called egestion. 


e. The unicellular organisms in which all life processes take place within their body are- Amoeba, Paramoecium and Euglena.

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Question 4:

Give reasons.
(a) Insectivorous plants are attractively coloured.
(b) Butterflies have a long tube-like proboscis.

Answer:

a. Insectivorous plants are attractively coloured so that they can attract insects and feed upon them. Insectivorous plants grow in soil or water which are deficient in nitrogen compounds and in order to meet this deficiency, they feed on insects.

b.  Butterflies have a long tube like proboscis which is a straw-like structure which enables them to drink juices and nectar. It is coiled-up like a garden hose when it is not in use.

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Question 5:

Prepare and complete the flowchart according to type of nutrition.

Answer:

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Question 6:

Think and answer.
(a) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms ?
(b) Which organisms are greater in number - autotrophs or heterotrophs ? Why?
(c) The number of heterotrophs found in desert regions is smaller. However, they are found in greater numbers in the sea. Why is this so ?
(d) What damage or harm do ectoparasitic and endoparasitic animals cause ?
(e) Why is plant food not produced in any other parts of the plant except the green ones ?

Answer:

a. By preparing variety of foodstuffs and dishes at home, we do not become autotrophic. Autotrophic is a term which is used for organisms which can produce their own food. We humans depend on plants for our food and the products which we get from them are used by us to make a variety of foodstuffs. Also, autotrophic organisms contain chloroplast which is an absolute necessity to be classified as an autotroph and we do not possess any such structures. So, we cannot be considered autotrophs.

b. Autotrophs are the organisms which are greater in number. It is because heterotrophs are dependant on autotrophs to meet their food requirements. If heterotrophs exceed the number of autotrophs, then all the autotrophs will vanish and so will be the heterotrophs. However, this is not the case because autotrophs are always more than heterotrophs so that they can help in sustaining the heterotrophs.

c. The conditions in deserts are extremely difficult for survival of organisms. Not all kinds of organisms can survive in such harsh climatic conditions, which means there are only few types of organisms which would be found in this region. Since, there are not many kinds of plants and animals which are found in this region, heterotrophs would not be able to survive and would die of starvation. That is why less heterotrophs are found in desert areas. However, in case of a habitat like sea, there are plenty of organisms which are found in region ranging from aquatic plants, to small fishes to big fishes. It is an environment which supports the survival of heterotrophs and thus more heterotrophs are found in this region.

d. Parasitism is a type interaction in which one of the partners is benefited because it resides outside or inside the body of the host and gets free accommodation and food while the host is affected due to loss of nutrients. Ectoparasites and endoparasites devoid the host of its nutrition. Some of the parasites are known to cause diseases like Ascaris/roundworm which is an endoparasite of intestine causes ascariasis. Another example is of Wuchereria which causes elephantiasis or filariasis. It is an endoparasite which lives in lymphatic vessels of lower limbs.
Lice or ticks which are found in humans and dogs respectively are examples of ectoparasites. They absorb the nutrients from their host.

e. Plant food is produced by a special process known as photosynthesis. The process of photosynthesis requires specialised structures called chloroplasts and these structures are found only in green regions of plants. The green colour of specific parts of plants is due to the presence of chlorophyll pigment present in these chloroplasts. Structures in plants which do not contain chloroplast, do not appear green in colour and are not capable of producing food.
 



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