Chapter 1- Nutrition in Plants (Questions with Answers) - 4

• Nutrition in Plants – Questions Page

  Nutrition in Plants

   

  Question 77: 
  How do plants obtain the raw materials from the surroundings?

  Answer: 

  Water and minerals present in the soil are absorbed by the roots. Carbon dioxide from air is taken in through the tiny pores present on the surface of the leaves. The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight.

   

  Question 78: 
  Explain the mode of nutrition in fungi.

  Answer: 

  They secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it. This mode of nutrition in which organisms take in nutrients in solution form from dead and decaying matter is called saprotrophic nutrition.

   

  Question 79: 
  Why do farmers keep adding fertilizer and manure time to time?

  Answer: 

  Plants absorb minerals and nutrients from the soil. So, their amounts in the soil keep on declining. Fertilisers and manures contain nutrients such as nitrogen, potassium, phosphorous, etc. These nutrients need to be added from time to time to enrich the soil.

   

  
  
  
  
  

  Question 80: 
  Can plants use nitrogen directly?
  Or
  Why do plants take nitrogen from the soil?

  Answer: 

  Though nitrogen gas is available in plenty in the air, plants cannot use it in the manner they can use carbon dioxide. They need nitrogen in a soluble form. The bacterium called Rhizobium can take atmospheric nitrogen and convert it into a usable form.

   

  Question 81: 
  If the pitcher plant is green and carries out photosynthesis, then why does it feed on insects?
  Or
  Why do some plants feed on insects?

  Answer: 

  These plants grow in soil that is deficient in nitrogen. All living things must have nitrogen. These plants (e.g. pitcher plant) are green and carry out photosynthesis to obtain a part of the food required by them. So, they feed on insects to obtain the nitrogen needed for their growth.

   

  Question 82: 
  How farmer is benefited from symbiotic relationship between rhizobium bacteria and legumes? 

  Answer: 

  This association is of great significance for the farmers. The bacterium called Rhizobium present in leguminous plant can take atmospheric nitrogen and convert it into a soluble form. So, they do not need to add nitrogen fertiliser to the soil in which leguminous plants are grown.

   

  
  
  
  
  

  Question 83: 
  How do plants transport raw materials to the food factories of the plants?

  Answer: 

  Water and minerals are transported to the leaves by the vessels which run like pipes throughout the root, the stem, the branches and the leaves. They form a continuous path or passage for the nutrients to reach the leaf. The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight.

   

  Question 84: 
  Nitrogen is an essential nutrient for plant growth. But farmers who cultivate pulse crops like green gram, bengal gram, black gram, etc. do not apply nitrogenous fertilisers during cultivation. Why?

  Answer: 

  Rhizobium can take atmospheric nitrogen and convert it into a usable form. But Rhizobium cannot make its own food. So it often lives in the roots of gram, peas, moong, beans and other legumes and provides them with nitrogen. In return, the plants provide food and shelter to the bacteria. Thus, there is no need to apply nitrogenous fertilisers to the leguminous crops.

   

  Question 85: 
  From where do the plants obtain nitrogen?

  Answer: 

  Nitrogen is present in abundance in gaseous form in the air.

  However, plants cannot absorb nitrogen in this form. Soil has certain bacteria that convert gaseous nitrogen into a usable form and release it into the soil. These soluble forms are absorbed by the plants along with water. Farmers add fertilisers rich in nitrogen to the soil.

   

  
  
  
  
  

  Question 86: 
  Can we say that the insectivorous plants are partial heterotrophs? 
  Or
  Why are insectivorous plants called partial heterotrophs?

  Answer: 

  These plants grow in soil that is deficient in nitrogen. All living things must have nitrogen. These plants are green and carry out photosynthesis to obtain a part of the food required by them. They feed on insects to obtain the nitrogen needed for their growth. So, we can say that the insectivorous plants are partial heterotrophs.

   

  Question 87: 
  Explain symbiotic relationship in rhizobium and leguminous plants. 

  Answer: 

  The bacterium called Rhizobium can take atmospheric nitrogen and convert it into a soluble form. But Rhizobium cannot make its own food. So it lives in the roots of gram, peas, moong, beans and other legumes and provides them with nitrogen. In return, the plants provide food and shelter to the bacteria. They, thus, have a symbiotic relationship.

   

  Question 88: 
  Give a brief description of the process of synthesis of food in green plants?

  Answer: 

  The synthesis of food in plants occurs in leaves. Therefore, all the raw materials must reach there. Water and minerals present in the soil are absorbed by the roots and transported to the leaves. Carbon dioxide from air is taken in through stomata present on the surface of the leaves. Chlorophyll helps leaves to capture the energy of the sunlight. This energy is used to synthesis (prepare) food from carbon dioxide and water.

   

  
  
  
  
  

  Question 89: 
  Explain symbiotic relationship with the help of example.

  Answer: 

  Some organisms live together and share shelter and nutrients. This is called symbiotic relationship. For example, in organisms called lichens, a chlorophyll-containing partner, which is an alga, and a fungus live together. The fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis.

   

  Question 90:
  Fill in the blanks of the paragraph given below with the words provided in the box. [Chlorophyll, Energy, Food, Carbon dioxide. Water, Photosynthesis]

  (Note: A word can be used more than once)

  Leaves have a green pigment called ____(a)_____ which captures _____(b) _____ from sunlight. This ______(c)________ is used in the process of _____(d)_____ and along with other raw materials like ______ (e) _____ and ____ (f) ______ synthesises ______.

  Answer: 

  (a) chlorophyll

  (b) energy

  (c) energy

  (d) photosynthesis

  (e) carbon dioxide

  (f) water

  (g) food

   

  
  
  
  
  

  Question 91: 
  Define cells, cell membrane, nucleus and cytoplasm.

  Answer: 

  Cells - the bodies of living organisms are made of tiny units called cells.

  Cell membrane - The cell is enclosed by a thin outer boundary, called the cell membrane.

  Nucleus - Most cells have a distinct, centrally located spherical structure called the nucleus.

  Cytoplasm - The nucleus is surrounded by a jelly-like substance called cytoplasm.

   

  Question 92: 
  Differentiate between autotrophs and heterotrophs.

  Answer:

  Autotrophs	Heterotrophs
  Green plants synthesise food for themselves by the process of photosynthesis. They are autotrophs.	A few plants and all animals are dependent on others for their nutrition and are called heterotrophs.

   

  Question 93: 
  Distinguish between a parasite and a saprotroph.

  Answer: 

  Difference between a parasite and a saprotroph

  Parasite	Saprotroph
  1. They live in or on another organism (its host) and get their nutrients from that host.	1. They secrete digestive juices on the dead and decaying matter and convert it into a solution. Then they absorb the nutrients from it.
  2. They feed on living organisms.	2. They feed on dead and decaying matter.
  3. The organism on which it depends is called host.	3. They depend upon dead and decaying organisms.
  4. Example of parasite - Cuscuta	4. Example of saprotroph - Fungi

   

  
  
  
  
  

  Question 94: 
  Show with the help of a sketch that the plants are the ultimate source of food.

  Answer

  
  

   

  Question 95: 
  Can we imagine life on earth in the absence of photosynthesis?

  Answer: 

  No, we cannot imagine life on earth in the absence of photosynthesis. In the absence of photosynthesis there would not be any food. The survival of almost all living organisms directly or indirectly depends upon the food made by the plants. Besides, oxygen which is essential for the survival of all living organisms is produced during photosynthesis. In the absence of photosynthesis, life would be impossible on the earth.

   

  
  
  
  
  

  Question 96: 
  Wild animals like tiger, wolf, lion and leopard do not eat plants. Does this mean that they can survive without plants? Can you provide a suitable explanation?

  Answer: 

  Wild animals like tiger, wolf, lion and leopard do not eat plants. But they feed on herbivore animals. Herbivorous animals obtain their food directly from plants. If there are no plants, herbivorous animals will not survive and thus carnivorous animals feeding on them will also not survive. Hence, directly or indirectly all the living organisms depend on plants for food.

   

  Question 97: 
  Draw a diagram showing photosynthesis.

  Answer: 

  
  

   

  
  
  
  
  

  Question 98: 
  Write a note on pitcher plant?
  Or
  How does a pitcher plant catch insects?
  Or
  Explain the nutrition in pitcher plant.
  Or
  How do pitcher plants get their nutrition?
  Or
  How does pitcher plant derive its food from insects?

  Answer: 

  The pitcher-like structure is the modified part of the leaf. The apex of the leaf forms a lid which can open and close the mouth of the pitcher. Inside the pitcher there are hair which are directed downwards. When an insect lands in the pitcher, the lid closes and the trapped insect gets entangled into the hair. The insect is digested by the digestive juices secreted in the pitcher.

   

  Question 99: 
  How nutrients are replenished in the soil? 

  Answer: 

  Plants absorb mineral nutrients from the soil. So, their amounts in the soil keep on declining. Fertilisers and manures contain plant nutrients such as nitrogen, potassium, phosphorous, etc. These nutrients need to be added from time to time to enrich the soil. The bacterium called Rhizobium present in the roots of legumes plants can take atmospheric nitrogen and convert it into a soluble form. This way Rhizobium bacterium also helps to replenish nitrogen in the soil.