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There are two reasons why a Hydra does not need a circulatory system. 1) It is small. The body wall has only two cell layers separated by a non-cellular layer, xo substances have only a short distance to move. Over these short distances diffusion is adequate. 2) It has a large surface area compared with its volume (large SA:V ratio). This is because its body is hollow, so it can absorb substances over the inner surface as well as the outer surface. See http://en.wikipedia.org/wiki/Circulation_%28physiology%29
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∙ 15y ago
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∙ 14y agobecause of diffusion, small organism do not need circulatory system because thy are too small
Wiki User
∙ 13y agoNutrients and gases can diffuse directly across the cell membrane, thereby eliminating a need for such a complex system!
Wiki User
∙ 11y agobecause they dont.
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∙ 9y agor54e769
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What is one difference between one-celled organisms and cells in a organ?
One-celled organisms are their own thing. They, by themselves, take in energy, maintain homeostasis, and carry out other essential life processes. There are other cells that make up organs, and those organs make up organ systems, and those organ systems make up an organism. Those cells that make up organs can't survive alone; they need the support of other cells, organs, and organ systems to survive.
Why don't plants require complex organ systems?
because they get their energy from photosynthesis they don't need an organ or an organ system to get rid of their waste products
When do organisms need protection?
Mutualism occurs when organisms need protection (e.g., "guest defenders" or "guest cleaners"), when immobile organisms need to reproduce (e.g., pollinators or seed dispersers), and when organisms need to expand tolerances.
Can my friend be tested to see if he's an organ donor match for me before I need the organ yet?
If you are discussing live organ donation, such as part of the liver or a kidney, and you are medically expected to need such a donation at some point, then yes your friend can be tested for matching to you prior to the need for a donated organ.
How does protists circulation work?
No, they do not. Because they have such a thin Cell Membrane, all the nutrients they need can be absorbed through diffusion or active transport.
Do all organisms need an organ?
Not every organism need organs.Unicellular organisms do not have any way.
What is one difference between one-celled organisms and cells in a organ?
One-celled organisms are their own thing. They, by themselves, take in energy, maintain homeostasis, and carry out other essential life processes. There are other cells that make up organs, and those organs make up organ systems, and those organ systems make up an organism. Those cells that make up organs can't survive alone; they need the support of other cells, organs, and organ systems to survive.
Why does the arm need many organ systems?
Just does. Deal with it.
Why do you need to study the human organ systems?
because this is our human body
Are organ systems related?
They all work together to make an organism.
Do all organisms have a organ system?
No, because if you have a single celled organism, you don't have enough cells to make a tissue, so you won't have enough tissue to make organs, and you won't have any organs to create an organ system.
Why don't plants require complex organ systems?
because they get their energy from photosynthesis they don't need an organ or an organ system to get rid of their waste products
Why have large organisms devolped systems like the respirtory system?
because they need to breath!
Why is the tissue specialization an advantage to multicellular organisms?
Tissue specialization has an advantage for multicellular organisms because it can make organs or organ systems. Have cells that can specialize means the cells can cooperate to form these organs.
Why does the body need so many organs systems?
Each organ system is specialized with doing only one job.
What are some ways that humans organ systems interconnect?
its depend where you live and what kind of food do you eat there do you get oxygen more or less
How do living organisms maintain the organization of their internal systems?
Living things are organized internally by there tissues,organs,and organ systems.
