NCERT Exemplar Problems
MCQ Part 3
Question 25: Which of the following is an incorrect statement?
- Organisms grow with time
- Organisms must repair and maintain their structure
- Movement of molecules does not take place among cells
- 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
- 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?
- 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
Question 28: 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
Explanation: Carbon dioxide comes from atmosphere, rather than being made by plants
Question 29: The opening and closing of the stomatal pore depends upon
- Water in guard cells
- 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
- Nitrates and Nitrites
- Atmospheric nitrogen
- (1) and (2)
- (2) and (3)
- (3) and (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?
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?
- 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)
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
- 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
Explanation: Accumulation of lactic acid in muscles results in muscle cramps.
Question 34: 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
Question 35: During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the
- Golgi body
Answer: (a) Cytoplasm
Explanation: Lactic acid is formed after anaerobic respiration in muscle cells and this happens in cytoplasm.