Chapter 7 Review Questions

List and define the terms used to express a microbe's optimal growth temperature.

minimum growth temperature: growth temperature lowest temperature at which an organism will grow and reproduce optimum growth temperature: growth temperature temperature at which a specific organism exhibits maximum growth and reproduction maximum growth temperature: highest temperature at which a specific organism will grow and reproduce psychrophiles: -5 to 20C, with optimum growth at ~10C mesophiles: 20-45C, with optimum growth at ~37 C psychotroph: describes organisms that that are able to grow at temps below 10C , but grow best in mesophile range thermophiles: 45 - 80C, with optimum growth at ~55 C hyperthermophiles: can grow at emps greater than 80C, some up to 105C

Summarize three ways in which microbes function in the presence of oxygen.

those that use oxygen and can detoxify it, those that can neither use oxygen nor detoxify it, those that don't use oxygen but can detoxify it.

Summarize the steps of binary fission used by bacteria.

The circular chromosome is copied The 2 chromosomes are attached to the cell membrane the cell grows and elongates until it is about twice its original size cytokenesis occurs and there are 2 new daughter cells.

Differentiate between macronutrients and micronutrients.

The main difference between macronutrients and micronutrients is that human body requires macronutrients in larger quantities whereas micronutrients are needed in smaller quantities. The major macronutrients are carbohydrate, protein and fat which contribute to the bulk of our food. They are the structural and energy-giving caloric constituents of our foods. Meanwhile, micronutrients such as vitamins, minerals and phytochemicals are essential for maintaining a good health.

Identify the effects of isotonic, hypotonic, and hypertonic conditions on a bacterial, a fungal, and a helminthic cell.

with cell wall isotonic - water level are equal on inside and outside of cell. hypotonic-water gos into cell and cell wall prevents cell wall from bursting hypertonic - water diffuses and shrinks protoplast from cell wall without cell wall -isotonic- rates of diffusion are equal in both directions -hypotonic- diffusion of water into the cell causes it to swell and may or may not burst if no mechanism exists to remove water -hypertonic- water diffusing out of the cell causes it to shrink and become distorted

Compare and contrast the four phases of growth in a bacterial growth curve.

1. Lag Phase: Relatively "flat" period. Newly inoculated cells require a period of adjustment, enlargement, and synthesis. The cells are not yet multiplying at their maximum rate. The population of cells is so sparse that the sampling misses them. Length of lag period varies from one population to another 2. Exponential Growth Phase: When the growth curve increases geometrically. Cells reach the maximum rate of cell division. Will continue as long as cells have adequate nutrients and the environment is favorable 3. Stationary Growth Phase: The population enters a survival mode in which cells stop growing or grow slowly. The rate of cell inhibition or death balances out the rate of multiplication. Depleted nutrients and oxygen. Excretion of organic acids and other biochemical pollutants into the growth medium. 4. Death Phase: The curve dips downward. Cells begin to die at an exponential rate.

Describe the different types of active, bulk transport.

Bulk transport: the movement of macromolecules (ex polysaccahrides and proteins) in and out of the cell, requires energy to occur endocytosis and exocytosis are two types of bulk transport Active transport: Movement from low concentration using transport proteins and energy.

Compare and contrast the processes of diffusion and osmosis.

Compare: move molecules from high to low Contrast: osmosis is water, diffusion everything else

Define doubling time and describe how it leads to exponential growth.

Doubling time- the time required for a complete fission cycle. It leads to exponential growth because offspring leads to double generation.

List and describe the major types of microbial symbioses.

Mutualism: both partners benefit. ... Commensalism: only one species benefits while the other is neither helped nor harmed. ... Parasitism: One organism (the parasite) gains, while the other (the host) suffers.

Differentiate between a chemoheterotroph, a chemoautotroph, a photoautotroph and a photoheterotroph.

Photoautotrophs are microbes get their energy from light and their carbon for inorganic compounds. Chemoautotrophs are microbes that get their energy from chemicals and get their carbon from inorganic compounds. Photoheterotrphs are microbes that get their energy from light and carbon from organic compounds. Chemoheterotrophs get their energy from chemicals and carbon from organic compounds.

Differentiate between a saprobe and a parasite.

Saprobes feed primarily on organic detritus from dead organisms. Parasites derive nutrients from the cells or tissues of a host.

Differentiate between synergism and antagonism.

Synergism is multiple hormones combined as antagonism is one single hormone. the presence of normal microbiota that protect the body by competing with pathogens in a variety of ways, and that prevent pathogens from invading the body

Identify physical factors (other than temperature and oxygen) that microbes must contend with in the environment.

pH, osmotic pressure, and radiation and hydrostatic atmospheric pressure