Q.1 Which of the following is the primary energy currency in microbial metabolism?
ATP
NADH
FADH2
GTP
Explanation - Adenosine triphosphate (ATP) is the universal energy currency of cells, used in most energy-requiring processes.
Correct answer is: ATP
Q.2 Which enzyme catalyzes the first step of glycolysis?
Hexokinase
Phosphofructokinase
Pyruvate kinase
Enolase
Explanation - Hexokinase phosphorylates glucose to glucose-6-phosphate, the first step in glycolysis.
Correct answer is: Hexokinase
Q.3 The electron transport chain in bacteria is located in the:
Cytoplasm
Nucleoid
Cell membrane
Ribosome
Explanation - In bacteria, the electron transport chain is embedded in the cytoplasmic membrane, unlike eukaryotes where it is in the mitochondria.
Correct answer is: Cell membrane
Q.4 Which pathway is primarily responsible for generating NADPH in bacteria?
Glycolysis
Pentose phosphate pathway
TCA cycle
Glyoxylate cycle
Explanation - The pentose phosphate pathway generates NADPH, which is essential for biosynthetic reactions and antioxidant defense.
Correct answer is: Pentose phosphate pathway
Q.5 Which of the following best describes fermentation?
Aerobic oxidation of glucose
Anaerobic breakdown of glucose without electron transport chain
Photosynthesis
Protein degradation
Explanation - Fermentation is an anaerobic process where organic molecules serve as both electron donors and acceptors, bypassing the electron transport chain.
Correct answer is: Anaerobic breakdown of glucose without electron transport chain
Q.6 In the bacterial TCA cycle, the conversion of succinate to fumarate is catalyzed by:
Succinate dehydrogenase
Fumarase
Citrate synthase
Isocitrate dehydrogenase
Explanation - Succinate dehydrogenase catalyzes the oxidation of succinate to fumarate and also participates in the electron transport chain.
Correct answer is: Succinate dehydrogenase
Q.7 Which of the following microbes can perform oxygenic photosynthesis?
Cyanobacteria
Purple sulfur bacteria
Green sulfur bacteria
Methanogens
Explanation - Cyanobacteria perform oxygenic photosynthesis similar to plants, releasing oxygen as a byproduct.
Correct answer is: Cyanobacteria
Q.8 In anaerobic respiration, the final electron acceptor can be:
Oxygen
Nitrate
Carbon dioxide
Both nitrate and carbon dioxide
Explanation - Anaerobic respiration uses alternative electron acceptors like nitrate, sulfate, or carbon dioxide instead of oxygen.
Correct answer is: Both nitrate and carbon dioxide
Q.9 Which of the following is NOT a high-energy compound?
ATP
PEP (phosphoenolpyruvate)
Glucose
Acetyl-CoA
Explanation - Glucose is an energy source but not considered a high-energy compound like ATP or PEP.
Correct answer is: Glucose
Q.10 Which pathway allows bacteria to grow on two-carbon compounds like acetate?
Glycolysis
TCA cycle
Glyoxylate cycle
Pentose phosphate pathway
Explanation - The glyoxylate cycle bypasses CO2-releasing steps of TCA cycle, allowing growth on two-carbon compounds.
Correct answer is: Glyoxylate cycle
Q.11 Which molecule acts as the primary electron donor in oxygenic photosynthesis?
H2O
H2S
NADPH
CO2
Explanation - In oxygenic photosynthesis, water is split to donate electrons, releasing oxygen as a byproduct.
Correct answer is: H2O
Q.12 In chemolithotrophs, energy is derived from:
Organic compounds
Inorganic compounds
Light
Fermentation products
Explanation - Chemolithotrophs oxidize inorganic compounds like H2, NH3, or Fe2+ to generate energy.
Correct answer is: Inorganic compounds
Q.13 Which bacterial metabolic process produces methane?
Methanogenesis
Fermentation
Denitrification
Sulfate reduction
Explanation - Methanogenesis is carried out by archaea, producing methane from substrates like CO2 and H2.
Correct answer is: Methanogenesis
Q.14 Which is the first stable product of the Calvin cycle?
3-Phosphoglycerate
Glucose
Ribulose-1,5-bisphosphate
Glyceraldehyde-3-phosphate
Explanation - CO2 fixation in the Calvin cycle produces 3-phosphoglycerate as the first stable compound.
Correct answer is: 3-Phosphoglycerate
Q.15 What is the net ATP gain from glycolysis per glucose molecule?
2 ATP
4 ATP
6 ATP
8 ATP
Explanation - Although glycolysis generates 4 ATP, 2 are consumed in the process, giving a net gain of 2 ATP per glucose.
Correct answer is: 2 ATP
Q.16 Which of the following is a proton motive force used for in bacteria?
ATP synthesis
Flagellar movement
Nutrient transport
All of the above
Explanation - The proton motive force drives ATP synthesis, motility, and active transport across membranes.
Correct answer is: All of the above
Q.17 In anaerobic bacteria, sulfate can be reduced to:
Oxygen
Methane
Hydrogen sulfide
Nitrogen
Explanation - Sulfate-reducing bacteria use sulfate as an electron acceptor, producing hydrogen sulfide.
Correct answer is: Hydrogen sulfide
Q.18 Which enzyme catalyzes the oxidative decarboxylation of pyruvate?
Pyruvate dehydrogenase
Lactate dehydrogenase
Aconitase
Citrate synthase
Explanation - Pyruvate dehydrogenase converts pyruvate into acetyl-CoA, linking glycolysis to the TCA cycle.
Correct answer is: Pyruvate dehydrogenase
Q.19 The major storage form of carbon in many bacteria is:
Polyhydroxybutyrate (PHB)
Glycogen
Cellulose
Chitin
Explanation - Many bacteria store carbon and energy in the form of polyhydroxybutyrate granules.
Correct answer is: Polyhydroxybutyrate (PHB)
Q.20 Which bacterial group uses reverse electron transport for NADPH generation?
Purple bacteria
Cyanobacteria
Methanogens
Firmicutes
Explanation - Purple non-sulfur bacteria use reverse electron transport to generate reducing power (NADPH).
Correct answer is: Purple bacteria
Q.21 Which of the following is an example of a facultative anaerobe?
Escherichia coli
Clostridium botulinum
Methanobacterium
Lactobacillus
Explanation - E. coli can grow in both the presence and absence of oxygen, making it a facultative anaerobe.
Correct answer is: Escherichia coli
Q.22 The enzyme nitrogenase is responsible for:
Nitrate assimilation
Nitrogen fixation
Denitrification
Ammonia oxidation
Explanation - Nitrogenase catalyzes the conversion of atmospheric nitrogen (N2) into ammonia (NH3).
Correct answer is: Nitrogen fixation
Q.23 In photosynthetic bacteria, bacteriochlorophyll absorbs light mainly in the:
UV region
Blue and red regions
Infrared region
Yellow region
Explanation - Bacteriochlorophyll absorbs light in the infrared region, unlike plant chlorophyll that absorbs blue and red.
Correct answer is: Infrared region
Q.24 Which coenzyme is directly involved in redox reactions in microbial metabolism?
NAD+/NADH
Coenzyme A
Biotin
Folic acid
Explanation - NAD+/NADH acts as an electron carrier in oxidation-reduction reactions of microbial metabolism.
Correct answer is: NAD+/NADH
Q.25 Which type of bacteria can survive only in the absence of oxygen?
Facultative anaerobes
Microaerophiles
Obligate anaerobes
Aerotolerant anaerobes
Explanation - Obligate anaerobes cannot survive in the presence of oxygen as they lack enzymes to detoxify reactive oxygen species.
Correct answer is: Obligate anaerobes