Nutrition in Living Organisms | Class 7 | Science | Chapter 4 | Maharashtra State Board
Welcome to this educational video where we will explore the topic of nutrition in living organisms. We will begin by discussing the importance of nutrition in living beings and what it actually means. Moving on to Autotrophic plants, we will take a closer look at their transportation system and how they fix nitrogen. We will also examine Heterotrophic plants, including insectivorous and saprophytic plants, and how they obtain their nutrition. Next, we will move on to nutrition in animals and explore the different types of nutrition found in them, such as holozoic, saprozoic, and parasitic nutrition. We will classify animals according to the type of food they eat, such as herbivores, carnivores, omnivores, scavengers, and decomposers. Throughout the video, we will use engaging visuals and examples to help you understand the concepts better. By the end of the video, you will have gained a comprehensive understanding of nutrition in living organisms, and how different organisms obtain their nutrients. So, sit back and join us on this exciting journey of exploring the fascinating world of nutrition!
Questions & Answers
1. Classify according to food-type.
Carnivores | Tiger, lion |
Herbivores | Cow, deer, goat, buffalo |
Scavengers | Vulture |
Decomposers | Fungus, bacteria |
Granivores | Sparrow |
Insectivores | Frog |
Omnivores | Human, cockroach |
Ectoparasites | Tick |
2. Match the pairs.
Group 'A' | Answer | Group 'B' |
Parasitic plant | Cuscuta | Mushroom |
Insectivorous plant | Drosera | Lichen |
Saprophytic plant | Mushroom | Drosera |
Symbiotic plant | Lichen | Cuscuta |
3. Answer the following questions in your words.
(a) Why do living organisms need nutrition?
Ans. Living organisms need nutrition due to the following:
To supply the energy required for doing work,
For growth and development of the body,
To replace the damaged cells and repair tissues,
To fight diseases.
(b) Explain the process of production of food in plants.
Ans.
Green plants can produce their own food. With the help of sunlight and chlorophyll, plants make their own food in their leaves, using water and nutrients from the soil and carbon dioxide from the air.
This process is called as photosynthesis. In this process plants give out oxygen and take in carbon dioxide.
(c) What is meant by parasitic plants? Name their different types with examples of each.
Ans. The plants that grow on the body of other plants to obtain food are called as parasitic plants. There are two types of parasitic plants:
Holoparasites: e.g. Rafflesia.
Hemiparasites: e.g. Loranthus.
(d) Explain the various steps of nutrition in animals.
Ans. Steps of nutrition in animals are as follows:
Ingestion: Food is taken into the body.
Digestion: Conversion of food into simple soluble forms.
Absorption: Transfer of soluble food to the blood.
Assimilation: Utilization of absorbed food by cells and tissues for energy production, growth and repair.
Egestion: Removal of waste products and undigested food from body.
(e) Name some unicellular organisms in which all life processes take place within their unicellular body.
Ans. Unicellular organisms like amoeba, euglena, paramecium in which all life processes take place within their unicellular body.
4. Give reasons.
(a) Insectivorous plants are attractively coloured.
Ans.
Insectivorous plants generally grow in soil or water deficient in nitrogen compounds.
The plant body of the Drosera burmanii has a flower like appearance. It grows close to the ground. Even its leaves are attractively pink or red in colour with hairs at the margin.
Droplets of a sticky substances found on tips of the hairs attract insects.
These plants consume insects to fulfil their need for nitrogen. To attract the insects these plants are attractively coloured.
(b) Butterflies have a long tube-like proboscis.
Ans. Holozoic mode of nutrition means the feeding of solid and liquid food by animals. Butterflies live on nectar from flowers. Therefore, to suck the nectar from flowers, they have a long tube-like structure called proboscis.
5. Prepare and complete the flowchart according to type of nutrition.
6. Think and answer.
(a) We prepare a variety of foodstuffs and dishes at home. Are we then autotrophic organisms?
Ans. We prepare a variety of foodstuffs and dishes at home but we are not autotrophic organisms. In autotrophic organisms they have chlorophyll in their body and food is prepared here with help of sunlight, water and CO2 for the organisms. But the food which we prepare at home is not generated in our body.
(b) Which organisms are greater in number – autotrophs or heterotrophs? Why?
Ans. Autotrophs have chlorophyll in the cell and here the organic food is prepared using sunlight, water and CO2. They do not depend on any other organism for survival. But the heterotrophs depend on autotrophs and other organisms for survival. Hence autotrophs are more in number than heterotrophs.
(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?
Ans. In desert region due to scarcity of water and excess heat, very few cactus are found as autotrophs compared to sea. As autotrophs are less, number of heterotrophs dependent on autotrophs are smaller. Whereas in sea due to greater numbers of autotrophs, greater number of heterotrophs are found.
(d) What damage or harm do ectoparasitic and endoparasitic animals cause?
Ans. Ectoparasitic animals suck the blood of the animal on which it remains and endoparasitic animals get readymade food from the body of animal in which it remain. This way both the parasites make the animal weak by sucking their blood or by eating prepared food from them.
(e) Why is plant food not produced in any other parts of the plant except the green ones?
Ans. Plant food is not produced in any other parts of the plant except the green ones because only green part contains chlorophyll and chlorophyll is very necessary for the production of food.
E X T R A
1. Fill in the blanks.
Leaves have microscopic openings called stomata.
In the process of photosynthesis plants take in carbon dioxide and oxygen gas is given out.
The xylem transports minerals and water from roots to all aerial parts of the plant.
The phloem transports the food from the leaves to other parts of the plant.
Plants produce carbohydrates by the process of photosynthesis.
Carbohydrates are made from carbon, hydrogen, oxygen.
Proteins are made from carbon, hydrogen,oxygen and nitrogen.
Leguminous plants contain rhizobium micro-organisms.
Micro-organisms like azotobacter are present in soil.
Lichen is of a symbiosis between algae and fungi.
The scientist Johannes Burman identified Drosera plant in Sri Lanka in 1737.
Fungi like mushroom and yeast are saprophytes.
Removal of waste products and undigested food from the body is called Egestion.
Amoeba moves with the help of pseudopodia.
Butterflies suck food with a tube like proboscis.
The bobcat or udmanjar is an ant eating animal found in India.
Seed eating animals are called granivores.
Fruit eating animals are called frugivores.
Animals that obtain their food from both plants and animals are called omnivores.
Roundworms are known as endoparasites.
2. Give Scientific Reasons.
(a) Micro-organisms like Rhizobium are useful.
Ans. Rhizobium micro-organisms are useful because plants cannot take gaseous nitrogen from air. These micro-organisms absorb atmospheric nitrogen and convert it into its nitrate, a compound which is useful for plant.
(b) Lichen is an example of a symbiotic nutrition.
Ans. Lichen is a symbiosis between algae and fungi in which fungi provides water, minerals, as well as shelter to algae and in return the algae provide food to the fungi. So Lichen, is an example of symbiotic nutrition.
(c) Drosera burmanii is an insectivorous plant.
Ans. Droseraburmanii grows in a soil which has nitrogen deficiency. It feeds upon insects to obtain nitrogen, so it is an insectivorous plant.
(d) Human is an omnivores.
Ans. Humans obtain their food from both, plants and animals. So, human is an omnivores.
(e) Tapeworm is an endoparasite.
Ans. Tapeworm lives inside the body of other animals and obtain its food. So, tapeworm is an endoparasite.
(f) Decomposers are important for the ecosystem.
Ans. Decomposers feed on dead and decaying matter and therefore indirectly clean the ecosystem. If decomposers were not there then nutrients would not be able to return back and get recycled. Therefore decomposers are very important for the ecosystem.
(g) Cuscuta is a total parasite while Loranthus is a partial parasite.
Ans. Cuscuta is a nongreen yellow thread-like plant completely dependent on the host plant, Loranthus is a partial parasitic because it can prepare its own food and it only takes water and minerals from the host plant.
3. Answer the following in your own words.
(a) Classify the types of nutrients.
Ans. There are two types of nutrients. Nutrients like carbohydrates, proteins and fats are required in large quantity. These are macro-nutrients. Minerals and vitamins are required in very small quantity. They are called micro-nutrients.
(b) Explain the types of nutrition.
Ans. There are two types of nutrition. Some organisms can produce their own food and thus nourish themselves. This is called autotrophic nutrition. Some organisms depend on other organisms, plants and animals for their food. This is called heterotrophic nutrition.
(c) Write differences between xylem and phloem.
Ans. The xylem transports minerals and water from the root to all aerial parts of the plant. The phloem transports the food (glucose) from the leaves to other parts of the plant where it is either consumed or stored.
(d) Name the micro-organisms which help in biological fixation of nitrogen. How?
Ans. Two different types of micro-organisms can bring about biological nitrogen fixation. Root-nodules of leguminous plants contain the micro-organism rhizobium. These micro-organisms absorb atmospheric nitrogen and convert it into its nitrate, a compound. Micro-organisms like azotobacter are present in soil. They also convert atmospheric nitrogen into nitrates.
(e) What is symbiotic nutrition? Give one example of it.
Ans. Two or more than two different types of plant live together to fulfill their needs of nutrition, protection, support etc. with each other’s help. This type of nutrition is called symbiotic nutrition.
e.g. Lichen is an example of symbiosis between algae and fungi.
(f) What are called saprophytic plants? Give Examples.
Ans. Plants which obtain the food from dead and decaying bodies of other organisms are called saprophytic plants e.g. Yeast and mushrooms.
(g) Write about Drosera burmanii.
Ans. It is an insectivorous plant. The scientist Johannes Burman identified this plant in Sri Lanka in 1737. Hence, the plant is named after him. It grows close to the ground.Its leaves are attractively pink or red in colour with hairs at the margin. Droplets of a sticky substance found at the tips of the hairs attract insects. It grows in a place where deficiency of nitrogen in the soil. To get nitrogen for its growth, it eats insects.
4. Explain the terms.
(a) Herbivores:
Ans. Animals that depend on plants only for their food are called Herbivores.
(b) Carnivores:
Ans. Animals that depend on other animals for their food are called Carnivores.
(c) Granivores:
Ans. Animals that eat grains (seed) are called Granivores.
(d) Frugivores:
Ans. Animals that eat fruits are called frugivores.
(e) Omnivores:
Ans. Animals that obtain their food from both plants and animals are called omnivores.
(f) Scavengers:
Ans. Animals that obtain their food from dead bodies of animals are called Scavengers.
(g) Decomposers:
Ans. Microbes which obtain their food by decomposing the dead bodies of organisms or other materials are called decomposers.
(h) Ectoparasitic nutrition:
Ans. Some animals live on the body surface of other animals and obtain their food by sucking their blood. This is called ectoparasitic nutrition.
(i) Endoparasitic nutrition:
Ans. Some animals live inside the body of other animals and obtain their food. This is called endoparasites nutrition.
(j) Symbiotic nutrition:
Ans. In some cases, two or more than two different types of plants live together to fulfil their needs of nutrition, protection, support etc. with each other’s help. This type of nutrition is called symbiotic nutrition.
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