Like all organisms, bacteria need energy, and they can acquire this energy through a number of different ways.
Some bacteria depend on other organisms for survival. For example, some bacteria live in the roots of legumes, such as pea plants ( Figure 1.1). The bacteria turn nitrogen-containing molecules into nitrogen that the plant can use. Meanwhile, the root provides nutrients to the bacteria. In this relationship, both the bacteria and the plant benefit, so it is known as a mutualism. Other mutualistic bacteria include gut microbes. These are bacteria that live in the intestines of animals. They are usually beneficial bacteria, needed by the host organism. These microbes obviously dont kill their host, as that would kill the bacteria as well.
Bacteria known as decomposers break down wastes and dead organisms into smaller molecules. These bacteria use the organic substrates they break down to get their energy, carbon, and nutrients they need for survival.
Bacteria can also be chemotrophs. Chemosynthetic bacteria, or chemotrophs, obtain energy by breaking down chemical compounds in their environment. An example of one of these chemicals broken down by bacteria is nitrogen-containing ammonia. These bacteria are important because they help cycle nitrogen through the environ- ment for other living things to use. Nitrogen cannot be made by living organisms, so it must be continually recycled. Organisms need nitrogen to make organic compounds, such as DNA.
Photosynthetic bacteria use the energy of the sun to make their own food. In the presence of sunlight, carbon dioxide and water are turned into glucose and oxygen. The glucose is then turned into usable energy. Glucose is like the "food" for the bacteria. An example of photosynthetic bacteria is cyanobacteria, as seen in the opening image. These bacteria are sometimes called blue-green algae, although they are not algae, due to their numerous chlorophyll molecules.
Other bacteria are parasitic and can cause illness. In parasitism, the bacteria benefit, and the other organism is harmed. Harmful bacteria will be discussed in another concept.
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photosynthetic bacteria evolved before photosynthetic plants.
--> a. true b. false
mutualistic bacteria kill their prey.
a. true --> b. false
nitrogen gas in the atmosphere has a strong bond that cannot be broken by many organisms. instead bacteria break the bond so other organisms have access to the nitrogen. organisms need nitrogen to make
a) food. b) organelles. --> c) dna. d) cells.
what type of bacteria lives in the roots of legumes, such as pea plants?
a) photosynthetic --> b) mutualistic c) decomposer d) herbivore
what do decomposers obtain from the material they break down?
a) carbon b) nutrients c) energy --> d) all of the above
which of the following is a photosynthetic bacterium?
a) staphylococcus aureus b) escherichia coli --> c) cyanobacteria d) lactobacilli
the nitrogen cycle is the biogeochemical cycle that recycles nitrogen through ecosystems. which two types of bacteria are involved in the nitrogen cycle?
a) photosynthetic and chemotrophic b) decomposers and photosynthetic c) mutualistic and photosynthetic --> d) mutualistic and chemotrophic
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