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Q1. Name the two amides found in plants.  

Solution

Asparagine and glutamine  

Q2. Define critical concentration.

Solution

The concentration of essential elements below which the growth of plants is retarded is called the critical concentration.

Q3. Deficiency of which of the following can cause yellowing of intravenous regions of leaves?

• 1) Phosphorus
• 2) Copper
• 3) Potassium
• 4) Calcium

Solution

Interveinal chlorosis (i.e. yellowing of intravenous regions of leaves) occurs due to the deficiency of potassium.

Q4. In cabbages, ‘Whiptail’ is a characteristic deficiency disease. It is caused by the deficiency of

• 1) Molybdenum
• 2) Magnesium
• 3) Chlorine
• 4) Boron

Solution

In cabbages, ‘Whiptail’ is caused by the deficiency of molybdenum which is characterised by the distortion of young leaves, a long mid-rib and poorly developed ragged blades.

Q5. Name the deficiency symptom in which leaves turn yellow.

Solution

Chlorosis

Q6. What is the least concentration of minerals which can be detected in plants by using modern techniques?  

Solution

The least concentration of minerals which can be detected in plants by using modern techniques is 10^-8 g/ml.  

Q7. Which one of the following microbes forms a symbiotic association with plants and helps them in their nutrition.

• 1) Aspergillus
• 2) Azotobacter
• 3) Trichoderma
• 4) Glomus

Solution

Glomus is a fungus which forms a symbiotic association with the roots of plants (mycorrhiza) and helps them to absorb their nutrition.

Q8. The middle lamella mainly contains  

• 1) K  
• 2) Mg  
• 3) Na  
• 4) Ca  

Solution

Calcium is required for the synthesis of pectin in the middle lamella of the cell wall.  

Q9. Which is essential for root hair growth?  

• 1) S  
• 2) Mo  
• 3) Ca  
• 4) Zn  

Solution

Calcium is essential for the development of root hair as well as the root and stem apices.  

Q10. Name the element required for the photolysis of water during photosynthesis.

Solution

Manganous ions or chlorine ions

Q11. Name the element found in plants growing near nuclear testing sites.  

Solution

Radioactive Strontium  

Q12. With the help of examples explain the role of essential elements in activating or inhibiting enzymes.

Solution

Magnesium is an activator for ribulose bisphosphate carboxylase-oxygenase as well as for phosphoenol pyruvate carboxylase. Both enzymes play an integral role in CO₂ fixation in photosynthesis. Zinc ions activate alcohol dehydrogenase and the molybdenum of nitrogenase during nitrogen fixation.

Q13. The deficiency of which element affects the process of photosynthesis

• 1) Magnesium
• 2) Calcium
• 3) Chlorine
• 4) Sulphur

Solution

The deficiency of chlorine affects the process of photosynthesis as it plays an important role in PS II during photosynthesis.

Q14. Name parts of the plant where potassium is required in abundant quantities. State any two functions of potassium ions in plants.

Solution

Potassium ions are required in the meristematic tissues, buds, leaves and root tips. Potassium helps to maintain an anion-cation balance in cells. Potassium is required in all phosphorylation reactions.

Q15. Excess of manganese induces deficiency of other elements in plants. Justify.

Solution

Many times, excess of an element inhibits the uptake of another element by the plant. Manganese when becomes toxic (i.e. present more than its required concentration) causes brown spots to appear around the chlorotic veins. Manganese competes with iron for uptake. It competes with magnesium for binding with enzymes. It inhibits the calcium translocation in the shoot apex. Hence, excess of manganese induces deficiency of other elements in plants.

Q16. Name the two amino acids which contain sulphur.

Solution

The two amino acids which contain sulphur are cysteine and methionine.

Q17. Name the following: Aerobic nitrogen-fixing bacteria Anaerobic nitrogen-fixing bacteria

Solution

Aerobic nitrogen-fixing bacteria - Azotobacter Anaerobic nitrogen-fixing bacteria - Rhodospirillum

Q18. The function of leghaemoglobin in the root nodules of legumes is

• 1) Expression of the nif gene
• 2) Inhibition of nitrogenase activity
• 3) Nodule differentiation
• 4) Oxygen removal

Solution

Leghaemoglobin is a red-coloured pigment found in the root nodules of leguminous plants. It combines with oxygen and thus helps in oxygen removal from root nodules.

Q19. What is nitrogen fixation? State the two natural sources to provide energy for nitrogen fixation.

Solution

The process of conversion of nitrogen to ammonia is called nitrogen fixation. Ultraviolet radiation and lightning provide energy for nitrogen fixation.

Q20. Name the element which activates the enzyme nitrogenase during nitrogen metabolism.

Solution

Molybdenum

Q21. Name the element which plays an important role in biological nitrogen fixation.  

• 1) Copper  
• 2) Manganese  
• 3) Molybdenum  
• 4) Zinc  

Solution

Molybdenum activates the enzymes involved in nitrogen metabolism and hence plays an important role in nitrogen fixation.  

Q22. Manganese in toxic concentrations leads to the deficiency of

• 1) Sulphur
• 2) Phosphorus
• 3) Potassium
• 4) Iron

Solution

Manganese in toxic concentrations leads to the deficiency of calcium, iron and magnesium as it competes with iron and magnesium for nutrient uptake.

Q23. The function of leghaemoglobin (a red pigment) in root nodules of leguminous plant is  

• 1) To regulate the Mo supply in cells  
• 2) To regulate production of phenolic compounds  
• 3) To regulate O₂ supply in cells  
• 4) To regulate CO₂ supply in cells  

Solution

Leghaemoglobin is a red pigment which gives a pinkish appearance to the nodules of leguminous plants. It combines with oxygen and regulates O₂ supply in cells.  

Q24. State the reason due to which the minerals become available to the roots of plants.

Solution

Weathering and break down of rocks

Q25. Name the bacterium which can produce nodules on non-leguminous Alnus.  

Solution

Frankia  

Q26. What are the symptoms of chlorosis? Name any six elements whose deficiency causes necrosis.  

Solution

Chlorosis occurs due to a lack of chlorophyll and the leaves turn yellow.     Deficiency of nitrogen, potassium, iron, manganese, zinc and sulphur causes necrosis.  

Q27. Molybdenum is the essential constituent of  

• 1) Growth regulators  
• 2) Chlorophyll  
• 3) Respiratory chain  
• 4) Nitrogenase  

Solution

Molybdenum is the essential constituent of nitrogenase enzyme. Nitrogenase is a Mo-Fe protein and catalyses the conversion of atmospheric nitrogen into ammonia.  

Q28. State the role of Nitrobacter in nitrogen fixation.  

Solution

Nitrobacter oxidises nitrite into nitrate.  

Q29. Draw a well-labelled diagram of a typical setup of nutrient solution culture.  

Solution

Typical setup of nutrient solution culture:        

Q30. Describe the importance of calcium in cell division.

Solution

Calcium pectate is necessary for the formation of the middle lamella, a part of the cell wall. Hence, calcium is important in the synthesis of the cell wall during cell division. It is required for the formation of the mitotic spindle.

Q31. When is an element considered toxic for plants?

Solution

Any mineral concentration which reduces the dry weight of plant tissues by 10% is toxic for plants.

Q32. Which one of the following elements in plants is not remobilised?

• 1) Phosphorus
• 2) Sulphur
• 3) Potassium
• 4) Calcium

Solution

Calcium is an immobile element. It cannot be remobilised in plants, so its deficiency symptoms first appear in younger tissues rather than older ones. Phosphorus, potassium and sulphur are mobile elements. They can be remobilised in plants, so their deficiency symptoms first appear in older tissues.

Q33. What is the name given to the movement of ions?  

Solution

Flux  

Q34. Write the forms in which boron is absorbed by plants.  

Solution

are the forms in which boron is absorbed by plants.  

Q35. Name any one bacterium which oxidises ammonia to nitrite.

Solution

Nitrosomonas/Nitrococcus

Q36. Name the enzyme for which Zn²⁺ acts as an activator.

Solution

Alcohol dehydrogenase

Q37. Which plant tissues die in necrosis?

Solution

Leaf tissues

Q38. Name the vegetables which are produced commercially by using hydroponics.

Solution

Seedless cucumber, tomato and lettuce

Q39. State the criteria which decide the essentiality of elements.

Solution

Criteria which decide the essentiality of elements: The element must be necessary for plant growth and reproduction. In the absence of such elements, plants do not complete their lifecycles. The deficiency of the element cannot be met by supplying some other element. The element must be directly involved in plant metabolism.

Q40. Which element is responsible for the opening and closing of stomata to some extent?

Solution

Potassium

Q41. Name the first phase of uptake of ions in the outer space of cells.  

Solution

Apoplast  

Q42. Name the elements whose deficiencies are visible in senescent leaves.  

Solution

Nitrogen, potassium and magnesium  

Q43. Name the elements responsible for the following functions:     Maintenance of the ribosome structure   Activation of catalase   Germination of pollen grains   Photolysis of water  

Solution

Maintenance of the ribosome structure - Magnesium   Activation of catalase - Iron   Germination of pollen grains - Boron   Photolysis of water - Chlorine  

Q44. Explain the method of hydroponics.

Solution

In hydroponics, a series of experiments are conducted in which roots of plants are immersed in a nutrient solution. Then an element is either added or removed or provided in varied concentration in the solution according to its suitability to the plant and its growth. Plants are grown in tubes or troughs placed at a slight incline. A pump is provided which circulates the solution from a reservoir to the elevated end of the tube. The solution flows down the tubes and returns back to the reservoir. The roots of the plants get bathed continuously in an aerated solution.

Q45. Represent diagrammatically the development of root nodules in soyabean.  

Solution

Development of root nodules in soyabean:        

Q46. Write the chemical equations of the two steps involved in the conversion of ammonia to nitrates.  

Solution

Step one: Ammonia to nitrite ions   Step two: Nitrites to nitrate ions  

Q47. Name the technique of growing plants in a nutrient solution.

Solution

Hydroponics is the technique of growing plants in a nutrient solution.

Q48. Name the parts of the plants which require potassium ions more abundantly.

Solution

Meristematic tissues, buds, leaves and root tips require potassium abundantly.

Q49. What did Julius von Sachs demonstrate?  

Solution

Julius von Sachs demonstrated that plants could be grown in a defined medium in the complete absence of soil and such plants also attain maturity.  

Q50. What is denitrification? Name the bacteria which perform denitrification.

Solution

Reduction of nitrate present in the soil into nitrogen is called denitrification. Bacteria Pseudomonas and Thiobacillus perform denitrification.

Q51. Name the compound which when reacts with ammonia forms glutamic aid.  

Solution

α-ketoglutaric acid  

Q52. Name the element essential for the synthesis of auxin.

Solution

Zinc ions are required for the synthesis of auxin.

Q53. Represent diagrammatically the relationship between atmospheric, soil and biomass nitrogen pool during the nitrogen cycle.

Solution