ANWSER
Question 1:
a. Write concisely on “Microbial growth”.
Answer: Microbial growth refers to the increase in the number of microorganisms rather than an increase in their size. It occurs through binary fission in bacteria and budding in yeasts. Growth is influenced by factors such as temperature, pH, nutrient availability, and moisture.
b. Food gets easily contaminated by microorganisms when in contact with the soil, discuss briefly.
Answer: Soil is a natural reservoir for microorganisms, including bacteria, fungi, and viruses. When food comes into contact with contaminated soil, it can pick up pathogens such as Clostridium botulinum, Bacillus cereus, and Escherichia coli. These microorganisms can cause food spoilage and foodborne illnesses if proper hygiene and handling practices are not followed.
c. Write short notes on the following:
i) Mesophiles
Answer: Mesophiles are microorganisms that thrive at moderate temperatures, typically between 20°C and 45°C. Many human pathogens, such as Escherichia coli and Salmonella, are mesophiles.
ii) Hypertonic solution
Answer: A hypertonic solution has a higher solute concentration outside the cell than inside. This causes water to move out of the microbial cell by osmosis, leading to dehydration and inhibition of microbial growth.
iii) Obligate anaerobes
Answer: Obligate anaerobes are microorganisms that cannot survive in the presence of oxygen. They rely on anaerobic respiration or fermentation for energy production. Examples include Clostridium botulinum.
iv) Neutrophils
Answer: Neutrophils are a type of white blood cell that plays a crucial role in the immune system by engulfing and destroying pathogens. In microbiology, neutrophilic microorganisms thrive in environments with a neutral pH (around 7).
Question 2:
a. Define the following:
i) Probiotics
Answer: Probiotics are live beneficial bacteria that provide health benefits when consumed in adequate amounts, primarily by improving gut flora balance. Examples include Lactobacillus and Bifidobacterium.
ii) Fermentation
Answer: Fermentation is a metabolic process in which microorganisms break down carbohydrates into simpler compounds, such as alcohol, acids, or gases, in the absence of oxygen. It is used in food production, such as in yogurt, bread, and alcohol.
iii) Food safety
Answer: Food safety refers to the measures taken to ensure that food is free from harmful contaminants, preventing foodborne illnesses. It includes proper handling, cooking, storage, and hygiene practices.
iv) Enzymatic activity
Answer: Enzymatic activity is the rate at which an enzyme catalyzes a biochemical reaction. Microorganisms produce enzymes that aid in food spoilage, digestion, and industrial processes such as fermentation.
v) Moisture loss
Answer: Moisture loss is the reduction of water content in food, leading to changes in texture, flavor, and microbial stability. Drying food helps in preservation by preventing microbial growth.
b. Define food spoilage.
Answer: Food spoilage is the deterioration of food due to microbial activity, chemical reactions, or physical changes, making it unfit for consumption. Signs of spoilage include odor, discoloration, and texture changes.
c. List any three food spoilage organisms.
Answer:
- Escherichia coli
- Pseudomonas species
- Clostridium botulinum