Term
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Definition
| Bacteria are prokaryotic and unicellular beings. Bacteria have simple organization, they present an external cell wall, plasma membrane, circular DNA within the cytoplasm and ribosomes for protein synthesis. Some bacteria are encapsulated, i.e., they have a polysaccharide capsule outside the cell wall. |
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Term
| Are bacteria the only prokaryotic beings? |
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Definition
Prokaryotic beings are classified into two big groups: archaebacteria and bacteria (this last also known as eubacteria).
Compared to bacteria, archaebacteria have basic differences, like the chemical compositions of their plasma membrane and cell wall and different enzymes related to DNA and RNA metabolism. |
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Term
| What are halophile, thermoacidophile and methanogen archaebacteria? |
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Definition
| There are three peculiar types of archaebacteria. The halophile archaebacteria only survive in salt-rich environments (even salinity of the sea is not enough for them). Thermoacidophile archaebacteria are characterized by living under high temperatures and low pH. The methanogen archaebacteria are those that liberate methane gas (CH4), they are found in swamps. |
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Term
| What are the main ecological roles of bacteria? |
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Definition
| Bacteria are responsible for the decomposition process at the end of food chains and food webs; in this process, they also liberate utile gases and nutrients for other living beings. Bacteria that live within the digestive tube of ruminants and of some insects digest cellulose for these animals. Some bacteria also participate in the nitrogen cycle, making fixation of nitrogen, nitrification and denitrification, almost always in mutualist ecological interaction with plants. |
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Term
| In which environments do bacteria live? |
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Definition
| Bacteria can be found in various environments throughout the planet. There are bacteria in the air, in fresh water, on the surface, in the intermediate depth and on the bottom of the sea, in soils, in our skin and practically in all terrestrial environments through which air circulates freely. Some bacteria can be found in volcanic craters under extremely high temperatures. |
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Term
| How are bacteria classified according to the production of organic material for the energetic metabolism? |
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Definition
| Most bacteria are heterotroph, they do not produce their own food. There are also autotroph bacteria: chemosynthetic bacteria or photosynthetic bacteria. |
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Term
How are bacteria classified according to their need for oxygen?
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Definition
| According to their necessity of oxygen bacteria are classified into anaerobic (those that survive without oxygen) and aerobic (those that do not survive without oxygen) |
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Term
| What is meant when it is said that a bacteria is an obligate anaerobe? |
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Definition
Obligate anaerobes are those living beings that do not survive in the presence of oxygen. For example, the bacteria Clostridium tetani, agent of tetanus, is an obligate anaerobe.
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Term
According to their morphology how are bacteria classified?
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Definition
| Bacteria present different morphological patterns. A bacterium can be classified into coccus, bacillus, or spirochete. |
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Term
| What is the main constituent of the cell wall of bacteria? |
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Definition
| The bacterial cell wall is made of peptidoglycans. |
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Term
| What are plasmids? What is the importance of plasmids for the recombinant DNA technology? |
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Definition
| Plasmids are circular fragments of DNA that are accessories to the main bacterial DNA. Plasmids are important for genetic engineering because genes from other organisms are inserted into them to produce recombinant beings |
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Term
| How do bacteria reproduce? |
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Definition
| Bacteria reproduce by binary fission (scissiparity). Some bacteria however present a kind of sexual reproduction (transformation, transduction or conjugation) with a combination of genetic material from different individuals. |
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Term
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Definition
| Ecology is the field of Biology that studies the relationship between living beings and between living beings and the environment. |
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Term
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Definition
| A species is a set of living beings able to cross among themselves generating fertile offspring. |
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Term
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Definition
| A population is a set of individuals of the same species found in a given place in a given time. |
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Term
| What is a community? What is the difference between the concepts of community and population? |
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Definition
A community is a set of populations of living beings that live in the same region and interact with each other.
In Ecology a population is a set whose members (living in a given place in a given time) are part of the same species. A community is a set of populations of different species (living in a given place in a given time). |
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Term
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Definition
| Biotic factors are living beings (plants, animals and microorganisms) that are part of a given environment. |
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Term
| What are abiotic factors? |
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Definition
| Abiotic factors are the nonliving elements that constitute a given environment, like light, temperature, minerals, water, gases, atmospheric pressure, etc. |
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Term
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Definition
| An ecosystem is a system composed of biotic and abiotic factors in interaction. |
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Term
| What are autotrophic beings? What are heterotrophic beings? |
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Definition
| Autotrophic beings are those that can produce their own food, i.e., that make organic material from inorganic compounds. Heterotrophic beings are those that need to incorporate organic material to nourish themselves. Therefore heterotrophs depend on the production of the autotrophs. |
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Term
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Definition
| A biome is a prevailing ecosystem constituted by similar biotic and abiotic factors present in one or more regions of the planet. |
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Term
| What are the major terrestrial biomes? |
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Definition
| The major terrestrial biomes are: tundra, taigas (or boreal forest), temperate forests, tropical forests, grasslands and deserts. |
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Term
| What is the primary energy source for life on earth? |
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Definition
| The primary energy source for life on earth is the sun. |
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Term
| What is the main means by which autotrophic beings obtain energy? |
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Definition
| The main means by which autotrophs obtain energy is photosynthesis. (There are also chemosynthetic autotrophs.) |
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Term
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Definition
| Mutualism is the ecological interaction in which both participants benefit and that is obligatory for their survival. |
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Term
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Definition
| Commensalism is the ecological interaction in which one individual benefits while the other is neither benefited nor harmed. |
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Term
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Definition
| Parasitism is the ecological interaction in which a being lives at the expense of another. |
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Term
| What is ecological succession? |
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Definition
| Ecological succession is the changing sequence of communities that live in an ecosystem during a given time period. |
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Term
| What are pioneer species? |
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Definition
| Pioneer species are those first species that colonize places where previously there were no living beings, like, for example, algae that colonize bare rocks. |
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Term
| What is the climax stage of an ecological succession? |
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Definition
| The climax stage is the stage of the ecological succession in which the community of an ecosystem becomes stable and does not undergo significant changes |
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