Life Processes

Choose the event that does not occur in photosynthesis

• Absorption of light energy by chlorophyll
• Reduction of carbon dioxide to carbohydrates
• Oxidation of carbon to carbon dioxide
• Conversion of light energy to chemical energy
  
  Answer: (c) Oxidation of carbon to carbon dioxide [Reduction of carbon dioxide releases oxygen which is utilised for making carbohydrates.]

The opening and closing of the stomatal pore depends upon

• Oxygen
• Temperature
• Water in guard cells
• Concentration of CO₂ in stomata
  
  Answer: (c) Water in guard cells [Entry of water in guard cells results in opening of stoma and reverse of it results in closing of stoma.

Choose the forms in which most plants absorb nitrogen

• Proteins
• Nitrates and Nitrites
• Urea
• Atmospheric nitrogen
  • (1) and (2)
  • (2) and (3)
  • (3) and (4)
  • (1) and (4)
    
    Answer: (b) (2) and (3) [Protein is made by plants by utilising nitrogen. Plants cannot take up atmospheric nitrogen.]

Which is the first enzyme to mix with food in the digestive tract?

• Pepsin
• Cellulase
• Amylase
• Trypsin
  
  Answer: (c) Amylase [salivary amylase from saliva is the first enzyme to mix with food.]

Which of the following statement(s) is (are) correct?

• Pyruvate can be converted into ethanol and carbon dioxide by yeast
• Fermentation takes place in aerobic bacteria
• Fermentation takes place in mitochondria
• Fermentation is a form of anaerobic respiration
  • (1) and (3)
  • (2) and (4)
  • (1) and (4)
  • (2) and (3)
    
    Answer: (c) 1 and (4) [Fermenation is a form of anaerobic respiration whic takes place in cytoplasm and liberates ethanol/lactic acid and carbon dioxide.]

Lack of oxygen in muscles often leads to cramps among cricketers. This results due to

• Conversion of pyruvate to ethanol
• Conversion of pyruvate to glucose
• Non conversion of glucose to pyruvate
• Conversion of pyruvate to lactic acid
  
  Answer: (d) Conversion of pyruvate to lactic acid [Accumulation of lactic acid in muscles results in muscle cramps.]

Choose the correct path of urine in our body

• kidney → ureter → urethra → urinary bladder
• kidney → urinary bladder → urethra → ureter
• kidney → ureters → urinary bladder → urethra
• urinary bladder → kidney → ureter → urethra
  
  Answer: (c) kidney → ureters → urinary bladder → urethra

During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the

• Cytoplasm
• Chloroplast
• Mitochondria
• Golgi body
  
  Answer: (a) Cytoplasm [Lactic acid is formed after anaerobic respiration in muscle cells and this happens in cytoplasm.]

Which of the following shows the correct equation for photosynthesis?

• 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6CO₂ + 6H₂O
• 6CO₂ + H₂O + Sunlight → C₆H₁₂O₆ + O₂ + 6H₂O
• 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6O₂ + 6H₂O
• 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6CO₂ + 6H₂O
  
  Answer: (c) 6CO₂ + 12H₂O + Chlorophyll + Sunlight → C₆H₁₂O₆ + 6O₂ + 6H₂O