Question

Organisms at the cellular level cannot maintain homeostatsis. True or false?

Answer 1

No organism can "maintain" homeostasis. Everything dies in the long run! Other than that, it depends on the organism. Unicellular organisms like bacteria have no problem maintaining homeostasis at a cellular level, [but complex multicellular organisms like us are dependent on the other cells and organ systems of our body (not to mention other organisms) to survive].

Answer 2

thats what i found anyway

Answer 3

@jtyla False. @PRAETORIAN.10 Homeostasis does not have anything to do with death, in that manner. It just means maintain a consistent internal environment. All cells have to be able to maintain an environment enough for enzymes, etc to function. If they do not, yes they do die. It is a "all squares are rectangles but not all rectangles are squares" type thing. Failure of homeostasis can cause death, but not all death, even at the cellular level, is caused by failure of homeostasis.

Answer 4

@praetorian "No organism can "maintain" homeostasis." i doubt this statement !

Answer 5

Actually, some animals are immortal in the fact that they never die from aging.

Turritopsis dohrnii
Lobsters
Planarian flatworms

So, technically, not everything dies. And lobsters also never stop growing, which means that the longer they live the larger they get. The reason we don't see a 500 pound lobster is because the larger they are, the more appetizing they look.

That would be about life, but homeostasis isn't just about life, it's about maintaining a balanced internal environment, like mrdoldum said. So, FALSE! :D

Answer 6

@jcp910 That is an absurd claim. You are attempted to make absence of evidence evidence of absence. I ask you, how do you know a lobster does not die of old age? You could only know if you know how every lobster ever on Earth died. I

For the vast majority of cells, replication of chromosomes results in base pair loss at the end of the telomeres and even for the few cells that fix this issue, mutations and other DNA decaying reactions will occur meaning senescence is possible. Other examples, such as the immortal jellyfish, just reproduce asexually and create genetically identical copies. This is why biological immortality is not the same thing as plain immortality.

http://mcb.berkeley.edu/courses/mcb135k/telomeres.html

You are also wrong about the growth. Many fully aquatic species do have indeterminate growth, but the rate of growth slows with time. Another constraint on growth is the physics of life. At some point, growth must essentially plateau because things like gravity, diffusion, osmosis, etc, and this is seen in the lobster and other species with indeterminate growth. This is why you will not see 500 pound lobsters.

http://slgo.ca/en/lobster/context/cycle.html

Answer 7

It's not an absurd claim, the jellyfish reverts back to it's 'baby' state when it gets too old or if it's injured. You're right about the growth thing, I just didn't want to explain it too much because it takes too much time. Also, they can grow incredibly large, with the largest lobster found being 44 pounds.

Answer 8

@jcpd910 It is quite absurd. You want to prove an absolute, meaning that the jellyfish is truly immortal. There is only one way to do that, know everything about every jellyfish ever. However, only one example is needed for it to be wrong.

Also, it does not revert back to a "baby" state. It returns to a polyp state that spawns clones. This is simple asexual reproduction, except it appears to that every cell returns to a initial Medusa state. So again, immortal in a biological sense? So far as we know. Immortal in the non-biologist sense, no.

Answer 9

http://en.wikipedia.org/wiki/Turritopsis_dohrnii
"Turritopsis dohrnii, the immortal jellyfish, is a species of small jellyfish which is found in the Mediterranean Sea and in the waters of Japan. It is unique in that it exhibits a certain form of "immortality": it is the only known case of an animal capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary stage."

Answer 10

@jcpd910 Yes, I know. Did you not read my post? What do you think happens when it returns to a colonial stage? It asexually reproduces. Meaning they are clones. It is not the same as a individual organism living forever, completely unaffected by age. This is why I said "biological immortality" is not the same as non biological immortality.

The fact is that any mutation that occurs in one of the new cells after returning to a colonial state means that that cell and its subsequent daughters will all be genetically distinct from all the other cells originally in the colony, even if it is only one base pair. It is important to carefully define what we mean by "immortal". We do not mean that a single individual organism will remain in one state complete immune to old age.

Answer 11

@jcpd910 And, even so, we still cannot know if this process in the jellyfish is truly indefinite, because we simply cannot live forever to find out.

Answer 12

Mrddoldum, I thank you for your effort on this topic, but I believe we are spamming everyone who replied to it. Thank you for educating me. :D

Answer 13

@jcpd910 I just want people to be absolutely clear we are talking about biological immortality and not what will come to mind when most people hear "immortality." I know I am a bit of an arse about these types of things, but that is because I want to make things clear for students. As I said in another thread, and many others, I do teach so it is a strongly held belief of mine that should be as clear as possible to give everyone the same chance and understanding and answering it.