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What process moves water across a semi-permeable membrane and what are the different types of osmotic environments?
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Osmosis is the movement of water. The types of osmotic environments are hypertonic, isotonic, and hypotonic.
Explain the role of hydrogen in microbial cells.
Hydrogen helps maintain pH, forms hydrogen bonds, and serves as an energy source in respiration.
Describe the difference between photoautotrophs and chemoautotrophs.
Photoautotrophs use sunlight for energy, whereas chemoautotrophs derive energy from chemical compounds.
What are the six essential nutrients required by all microbial cells?
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur.
Describe the gas requirements of obligate aerobes and facultative anaerobes.
Obligate aerobes require oxygen for growth, while facultative anaerobes prefer oxygen but can grow in its absence.
What is turbidity and how is it used to measure microbial growth?
Turbidity refers to the cloudiness of a culture broth, which increases with microbial growth. It can be measured using a spectrophotometer to estimate cell density.
Define mutualism, commensalism, and parasitism in the context of symbiotic relationships.
Mutualism benefits both organisms, commensalism benefits one while the other is unaffected, and parasitism benefits one organism at the expense of the other.
Define macronutrients and give three examples relevant to microbial nutrition.
Macronutrients are nutrients needed in large amounts. Examples include Carbon (C), Hydrogen (H), and Oxygen (O).
What pH range do neutrophils, acidophiles, and alkalinophiles prefer?
Neutrophils prefer pH 6-8, acidophiles thrive in acidic environments (low pH), and alkalinophiles prefer basic or alkaline conditions (high pH).
Explain the difference between direct counting and genetic probing for population measurement.
Direct counting involves manually or mechanically counting cells, whereas genetic probing uses techniques like PCR to estimate cell numbers without cultivating them.
What temperature ranges do psychrophiles and thermophiles prefer for growth?
Psychrophiles prefer temperatures between 0-15°C, while thermophiles thrive at 45-80°C.
Define phagocytosis and pinocytosis.
Phagocytosis is the process of engulfing large particles, whereas pinocytosis involves the ingestion of liquid into the cell.
Contrast passive transport with active transport and provide an example of each.
Passive transport does not require energy and moves molecules from high to low concentration (e.g., simple diffusion). Active transport requires energy and moves molecules from low to high concentration (e.g., sodium-potassium pump).
Explain binary fission and its relation to generation time.
Binary fission is a common method of asexual reproduction in bacteria where the cell divides into two. Generation time is the time required for one cell to divide into two.
Differentiate between organic and inorganic nutrients with examples.
Organic nutrients contain carbon, such as carbohydrates, lipids, and proteins. Inorganic nutrients do not contain carbon, such as water, gases, and metals.
List and describe the four phases of microbial growth curves.
Lag Phase: Acclimation, no new growth. Log Phase: Exponential growth. Stationary Phase: Growth stabilizes due to resource limitations. Death Phase: Decline in population due to resource depletion.
What are the primary sources of carbon for autotrophs and heterotrophs?
Autotrophs use carbon dioxide (CO2) while heterotrophs obtain carbon from organic molecules like carbohydrates, lipids, and proteins.
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