Biology

A:

The number of fish in the world is always changing due to reproduction, predation, human consumption and environmental factors, among other reasons. Thus, it cannot be known exactly how many fish there are in all.

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  • What is a taxonomic key?

    Q: What is a taxonomic key?

    A: A taxonomic key is a method used to classify and identify objects and organisms. It shows a series of choices about the characteristics of different organisms. A user picks from these choices and ultimately finds the identity of a specimen.
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  • How do vestigial structures support evolution?

    Q: How do vestigial structures support evolution?

    A: Vestigial structures support the theory of evolution by adding observable evidence to the model of common ancestry. Vestigial structures are not necessarily without function. In fact, according to Austin Cline at About.com, it isn't possible to demonstrate that any anatomical feature serves no purpose. Instead, a vestigial structure is one that shows clear homology with a similar feature in related organisms but whose purpose is no longer clear.
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  • What is the source of silk?

    Q: What is the source of silk?

    A: Silk comes from the cocoons of certain insects, such as the mulberry silkworm. When the insects create their cocoons, harvesters extract the fibers and spin them into thread. Each cocoon may contain more than 1,000 yards of fibers, but it takes several to create thread strong enough to make cloth.
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  • What do dead lice eggs look like?

    Q: What do dead lice eggs look like?

    A: Lice eggs, also called nits, look like small sesame seeds, and they are attached firmly to the hair. Dead lice eggs stay afixed to the hair and remain in the hair if they're not removed properly.
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  • What is a functional adaptation?

    Q: What is a functional adaptation?

    A: A functional adaptation is a structure or behavior that has arisen sometime in the evolutionary history of a species to aid in that species', or its predecessors', survival. A waterproof eggshell, for example, is a functional adaptation that arose among reptiles in response to the need to lay eggs in dry, dessicating environments where permeable eggshells would have dried out.
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  • What are some characteristics of a Volvox?

    Q: What are some characteristics of a Volvox?

    A: Characteristics of a Volvox include the fact that each cell contains two flagella, which aids in movement through water, and the colonies reproduce asexually. The cells of a Volvox are held together by protoplasm strands.
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  • What is an example of parasitism?

    Q: What is an example of parasitism?

    A: One example of parasitism is when a tick draws blood from a deer to survive. Parasitism represents a relationship between two species in which one of the animals (or plants) obtains a benefit at the expense of another.
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  • Where do algae live?

    Q: Where do algae live?

    A: Algae live in bodies of water and damp places and are commonly found in both aquatic and terrestrial environments. Terrestrial algae mostly live in moist, tropical areas. They prefer wet places, because they do not have vascular tissues and the other necessary adaptations to survive on land.
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  • How do fungi reproduce?

    Q: How do fungi reproduce?

    A: Fungi reproduce in one of two ways: asexually through mitosis, or sexually through meiosis. Sexual reproduction occurs far less frequently than asexual production and usually only when necessary to adapt to environmental change.
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  • What is the main artery in your body?

    Q: What is the main artery in your body?

    A: According to WebMD, the main artery in the body is the aorta. It is connected to the left ventricle of the heart. The aorta branches off into a web of numerous smaller arteries that exist all over the body.
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  • What are the eight levels of biological classification?

    Q: What are the eight levels of biological classification?

    A: The eight levels of biological classification are domain, kingdom, phylum, class, order, family, genus and species. These levels are an important part of taxonomy, which is the science of identifying species and organizing them according to systems of classification.
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  • What is zooplankton?

    Q: What is zooplankton?

    A: Zooplankton are small animals that live in water. They are generally weak swimmers and range in size from 2 micrometers to 8 inches long; they also live close to the surface.
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  • At what temperature do viruses die?

    Q: At what temperature do viruses die?

    A: While extreme high or low temperatures technically do not kill viruses, the influenza virus and many others are deactivated at temperatures ranging from 165 to 212 degrees Fahrenheit, the boiling point for water. Since viruses lack many of the basic structures and functions necessary to be considered a living organism, they technically cannot die.
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  • What are the main characteristics of algae?

    Q: What are the main characteristics of algae?

    A: Algae are any eukaryotes, other than plants, that conduct photosynthesis. They range from single-celled organisms to multicellular seaweeds over 180 feet in length with specialized organs. They are found in most environments, especially very wet ones, perhaps most notably the oceans, where they are the dominant producers.
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  • What is reverse osmosis?

    Q: What is reverse osmosis?

    A: Reverse osmosis occurs when concentrated water is pushed through a membrane to produce fresh water on the other side, according to About.com chemistry section. Reverse osmosis allows water molecules to pass from concentrated solutions to make fresh water, and it keeps foreign particles at bay.
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  • Why are decomposers important?

    Q: Why are decomposers important?

    A: Decomposers are important because they are crucial for the proper functioning of ecosystems. They recycle the minerals found in dead plants and animals back into the food chain. Ecosystems do not waste energy or materials, and as such, the decomposers capitalize on any remaining energy in a dead organism and make the minerals available to the entire biome.
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  • What are the general characteristics of bacteria?

    Q: What are the general characteristics of bacteria?

    A: Bacteria are typically single-celled organisms called prokaryotes that may serve as digestive aids, cause disease or aid in decomposition. Unlike eukaryotes, they do not have nuclei. Bacteria contain their DNA and other genetic material as a single strand in their cytoplasm, and they reproduce through a process called binary fission.
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  • What is Charles Darwin famous for?

    Q: What is Charles Darwin famous for?

    A: Charles Darwin, an English scientist, wrote the book, "On the Origin of Species by Means of Natural Selection," which has served as the basis for modern theories concerning evolution since its publication in 1859. While evolutionists existed before his time, Darwin's theory of natural selection changed the way humans think about the natural world.
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  • What are the waste products of respiration?

    Q: What are the waste products of respiration?

    A: In animals, such as humans, the waste products of aerobic respiration are water and carbon dioxide, and the waste product of anaerobic respiration is lactic acid. Aerobic respiration is a series of reactions that sees oxygen being consumed in order to release energy from glucose. Anaerobic respiration occurs when there is an oxygen debt in cells.
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  • How do the body's systems work together?

    Q: How do the body's systems work together?

    A: The human body is comprised of several different systems that must work together to carry out the various processes necessary for good health. According to the University of Washington, the nervous system controls many of these various systems directly. For example, when the body needs to alter the beating rate of the heart or blood pressure, the brain sends the message to do so via nerve impulses.
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  • What are the advantages and disadvantages of an endoskeleton?

    Q: What are the advantages and disadvantages of an endoskeleton?

    A: Advantages of an endoskeleton include strong weight-bearing properties and even growth, while disadvantages include less protection and leverage for muscles. Endoskeletons are generally found in larger animals due to better weight support, as exoskeletons can limit growth due to weight.
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