Class 10 Science

Life Processes NCERT Exemplar Problems

MCQ Part 3

Question 25: Which of the following is an incorrect statement?

  1. Organisms grow with time
  2. Organisms must repair and maintain their structure
  3. Movement of molecules does not take place among cells
  4. Energy is essential for life processes

    Answer:(c) Movement of molecules does not take place among cells

Question 26: The internal (cellular) energy reserve in autotrophs is

  1. Glycogen
  2. Protein
  3. Starch
  4. Fatty acid

    Answer: (c) Starch

Explanation: Plants store food in the form of starch

Question 27: Which of the following equations is the summary of photosynthesis?

  1. 6CO2 + 12H2O → C6H12O6 + 6CO2 + 6H2O
  2. 6CO2 + H2O + Sunlight → C6H12O6 + O2 + 6H2O
  3. 6CO2 + 12H2O + Chlorophyll + Sunlight → C6H12O6 + 6O2 + 6H2O
  4. 6CO2 + 12H2O + Chlorophyll + Sunlight → C6H12O6 + 6CO2 + 6H2O

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

Question 28: Choose the event that does not occur in photosynthesis.

  1. Absorption of light energy by chlorophyll
  2. Reduction of carbon dioxide to carbohydrates
  3. Oxidation of carbon to carbon dioxide
  4. Conversion of light energy to chemical energy

    Answer: (c) Oxidation of carbon to carbon dioxide

Explanation: Carbon dioxide comes from atmosphere, rather than being made by plants

Question 29: The opening and closing of the stomatal pore depends upon

  1. Oxygen
  2. Temperature
  3. Water in guard cells
  4. Concentration of CO2 in stomata

    Answer: (c) Water in guard cells

Explanation: Entry of water in guard cells results in opening of stoma and reverse of it results in closing of stoma.

Question 30: Choose the forms in which most plants absorb nitrogen

  1. Proteins
  2. Nitrates and Nitrites
  3. Urea
  4. Atmospheric nitrogen
  1. (1) and (2)
  2. (2) and (3)
  3. (3) and (4)
  4. (1) and (4)

    Answer: (b) (2) and (3)

Explanation: Protein is made by plants by utilising nitrogen. Plants cannot take up atmospheric nitrogen. So, options (1) and and (4) can be easily ruled out.

Question 31: Which is the first enzyme to mix with food in the digestive tract?

  1. Pepsin
  2. Cellulase
  3. Amylase
  4. Trypsin

    Answer: (c) Amylase

Explanation: Salivary amylase from saliva is the first enzyme to mix with food.

Question 32: Which of the following statement(s) is (are) correct?

  1. Pyruvate can be converted into ethanol and carbon dioxide by yeast
  2. Fermentation takes place in aerobic bacteria
  3. Fermentation takes place in mitochondria
  4. Fermentation is a form of anaerobic respiration
  1. (1) and (3)
  2. (2) and (4)
  3. (1) and (4)
  4. (2) and (3)

    Answer: (c) 1 and (4)

Explanation: Fermentation is a form of anaerobic respiration which takes place in cytoplasm and liberates ethanol/lactic acid and carbon dioxide.

Question 33: Lack of oxygen in muscles often leads to cramps among cricketers. This results due to

  1. Conversion of pyruvate to ethanol
  2. Conversion of pyruvate to glucose
  3. Non conversion of glucose to pyruvate
  4. Conversion of pyruvate to lactic acid

    Answer: (d) Conversion of pyruvate to lactic acid

Explanation: Accumulation of lactic acid in muscles results in muscle cramps.

Question 34: Choose the correct path of urine in our body

  1. kidney → ureter → urethra → urinary bladder
  2. kidney → urinary bladder → urethra → ureter
  3. kidney → ureters → urinary bladder → urethra
  4. urinary bladder → kidney → ureter → urethra

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

Question 35: During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the

  1. Cytoplasm
  2. Chloroplast
  3. Mitochondria
  4. Golgi body

    Answer: (a) Cytoplasm

Explanation: Lactic acid is formed after anaerobic respiration in muscle cells and this happens in cytoplasm.