Absence of oxygen means anaerobic respiration ; which has 2 different pathways.
First Pathway ; Alcoholic fermentation which takes place in yeast.
Pyruvate is decarboxylated into ethanal releasing co2 as waste product.
Ethanal is toxic , so its reduced by help of NADH to ethanol in presence of alcohol dehydrogenase enzyme , and Free NAD is released to continue glycolysis.
2) The second pathway is Lactic fermentation which takes place in mammalian muscles.
Pyruvate accepts hydrogen and is converted to lactate by the help of enzyme lactate dehydrogenase , again free NAD is released to continue glycolysis.
Hope I made it clear enough :)
Symbiosis in lichens is the mutually helpful symbiotic relationship of greenalgae and/or blue-green algae(cyanobacteria) living among filaments of a fungus, forming lichen. The algaeor cyanobacteria benefit their fungalpartner by producing organic carbon compounds through photosynthesis
ANSWER:
Problem faced include; habitat loss and degradation, disease outbreak, invasive species, pollution, over‐exploitation/overfishing, climate change etc.
EXPLANATION:
Problem:
Habitat loss and degradation, disease outbreak, invasive species, pollution, over‐exploitation/overfishing, and climate change are notable problems experienced by freshwater and marine fishes.
Solution:
Anthropogenic activities and stressors that rapidly threaten freshwater and marine fishes are curbed through legislation and other means to prevent extinction of fishes.
Through conservation programs that plans for individual species to more species of entire faunas of a particular location also boost population size and prevent hunting of threatened or endangered species in both realms.
Overtime, genetically modified fishes which can develop resistance to diseases are introduced to the realm.
Moreso, waste channels through which pollutants gets into the water bodies are well-treated for safety of fishes.
There are three basic shapes
Viruses are at the heart of this century-old debate. Viruses<span> are parasites that infect plants, animals, fungi and bacteria. They consist of genetic material surrounded by a protein coat and are unable to grow or reproduce without a host. The classification of viruses has confused scientists for nearly 100 years. Originally they were viewed as poisons. In fact, the word ''virus'' is Latin for ''poison.'' They have since been viewed as living creatures, then mere bio-chemical compounds, and, most recently, somewhere in between chemical compounds and lifeforms.</span>Non-cellular life<span> refers to organisms, such as viruses, that exist without any cells, and it is a very controversial topic. The cell theory, which is one of the fundamental tenets of biology, states that all living things are composed of cells and that cells are the basic units of life. So the idea that something can be considered alive without having cells is an issue that is up for debate.
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