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相变在生物系统中也具有重要的作用。比如''' 脂质双层lipid bilayer'''的形成，''' 蛋白质折叠protein folding'''和''' DNA解链DNA melting'''过程中的''' 坍塌转变coil–globule transition'''，''' DNA缩合DNA condensation'''过程中的液晶转变，以及具有相变特征的配体与DNA和蛋白质的结合。<ref>{{cite journal | doi=10.1080/07391102.2000.10506578 | pmid=10798534 | title=Long-range interactions between ligands bound to a DNA molecule give rise to adsorption with the character of phase transition of the first kind | year=2000| author = D.Y. Lando and V.B. Teif| journal=J. Biomol. Struct. Dynam. | volume=17 | issue=5 | pages=903–911  }}</ref>

相变在生物系统中也具有重要的作用。比如''' 脂质双层lipid bilayer'''的形成，''' 蛋白质折叠protein folding'''和''' DNA解链DNA melting'''过程中的''' 坍塌转变coil–globule transition'''，''' DNA缩合DNA condensation'''过程中的液晶转变，以及具有相变特征的配体与DNA和蛋白质的结合。<ref>{{cite journal | doi=10.1080/07391102.2000.10506578 | pmid=10798534 | title=Long-range interactions between ligands bound to a DNA molecule give rise to adsorption with the character of phase transition of the first kind | year=2000| author = D.Y. Lando and V.B. Teif| journal=J. Biomol. Struct. Dynam. | volume=17 | issue=5 | pages=903–911  }}</ref>

曾经有观点认为生物系统可能位于临界点附近。例如蝾螈视网膜中的神经网络<ref>{{cite arXiv|eprint=1407.5946|last1=Tkacik|first1=Gasper|title=Thermodynamics for a network of neurons: Signatures of criticality|last2=Mora|first2=Thierry|last3=Marre|first3=Olivier|last4=Amodei|first4=Dario|last5= Berry II|first5=Michael J.|last6=Bialek|first6=William|class=q-bio.NC|year=2014}}</ref> bird flocks<ref>{{cite journal|last1=Bialek|first1=W|last2=Cavagna|first2=A|last3=Giardina|first3=I|title = Social interactions dominate speed control in poising natural flocks near criticality|journal=PNAS|volume=111|issue=20|pages=7212–7217|year = 2014|bibcode=2014PNAS..111.7212B|doi=10.1073/pnas.1324045111|pmid=24785504|pmc=4034227|arxiv=1307.5563}}</ref>，果蝇中的鸟群基因表达网络和'''<ref>{{cite journal | last1=Krotov |first1=D|last2=Dubuis|first2=J O|last3=Gregor|first3=T|last4=Bialek|first4=W|title = Morphogenesis at criticality|journal = PNAS|year = 2014|doi=10.1073/pnas.1324186111|pmid=24516161|pmc=3956198|volume=111|issue=10|pages=3683–3688|arxiv=1309.2614|bibcode=2014PNAS..111.3683K}}</ref> 蛋白质折叠protein folding'''<ref>{{cite journal|last1=Mora|first1=Thierry|last2=Bialek|first2=William|title = Are biological systems poised at criticality?|journal = Journal of Statistical Physics|volume=144|issue=2|pages=268–302|year = 2011 |arxiv=1012.2242 |doi= 10.1007/s10955-011-0229-4|bibcode=2011JSP...144..268M}}</ref> 。但是，尚不清楚替代原因是否可以解释某些现象来支持关键性论证。另一个观点认为，生物有机体具有两个重要的相变特性：宏观行为的变化和系统在临界点的一致性。<ref>{{cite journal |last1=Schwab|first1=David J|last2=Nemenman|first2=Ilya|last3=Mehta|first3=Pankaj|title = Zipf's law and criticality in multivariate data without fine-tuning|journal = Physical Review Letters|volume=113|issue=6|pages=068102|year = 2014 |arxiv=1310.0448 |bibcode= 2014PhRvL.113f8102S|doi= 10.1103/PhysRevLett.113.068102|pmid=25148352|pmc=5142845}}</ref> It has also been suggested that biological organisms share two key properties of phase transitions: the change of macroscopic behavior and the coherence of a system at a critical point.<ref>{{Cite journal|last1=Longo|first1=G.|last2=Montévil|first2=M.|date=2011-08-01|title=From physics to biology by extending criticality and symmetry breakings|url=https://www.academia.edu/23155991|journal=Progress in Biophysics and Molecular Biology|series=Systems Biology and Cancer|volume=106|issue=2|pages=340–347|doi=10.1016/j.pbiomolbio.2011.03.005|pmid=21419157|arxiv=1103.1833}}</ref>

曾经有观点认为生物系统可能位于临界点附近。例如蝾螈视网膜中的神经网络<ref>{{cite arXiv|eprint=1407.5946|last1=Tkacik|first1=Gasper|title=Thermodynamics for a network of neurons: Signatures of criticality|last2=Mora|first2=Thierry|last3=Marre|first3=Olivier|last4=Amodei|first4=Dario|last5= Berry II|first5=Michael J.|last6=Bialek|first6=William|class=q-bio.NC|year=2014}}</ref> bird flocks<ref>{{cite journal|last1=Bialek|first1=W|last2=Cavagna|first2=A|last3=Giardina|first3=I|title = Social interactions dominate speed control in poising natural flocks near criticality|journal=PNAS|volume=111|issue=20|pages=7212–7217|year = 2014|bibcode=2014PNAS..111.7212B|doi=10.1073/pnas.1324045111|pmid=24785504|pmc=4034227|arxiv=1307.5563}}</ref>，果蝇中的鸟群基因表达网络和'''<ref>{{cite journal | last1=Krotov |first1=D|last2=Dubuis|first2=J O|last3=Gregor|first3=T|last4=Bialek|first4=W|title = Morphogenesis at criticality|journal = PNAS|year = 2014|doi=10.1073/pnas.1324186111|pmid=24516161|pmc=3956198|volume=111|issue=10|pages=3683–3688|arxiv=1309.2614|bibcode=2014PNAS..111.3683K}}</ref> 蛋白质折叠protein folding'''<ref>{{cite journal|last1=Mora|first1=Thierry|last2=Bialek|first2=William|title = Are biological systems poised at criticality?|journal = Journal of Statistical Physics|volume=144|issue=2|pages=268–302|year = 2011 |arxiv=1012.2242 |doi= 10.1007/s10955-011-0229-4|bibcode=2011JSP...144..268M}}</ref> 。但是，尚不清楚替代原因是否可以解释某些现象来支持关键性论证。<ref>{{cite journal |last1=Schwab|first1=David J|last2=Nemenman|first2=Ilya|last3=Mehta|first3=Pankaj|title = Zipf's law and criticality in multivariate data without fine-tuning|journal = Physical Review Letters|volume=113|issue=6|pages=068102|year = 2014 |arxiv=1310.0448 |bibcode= 2014PhRvL.113f8102S|doi= 10.1103/PhysRevLett.113.068102|pmid=25148352|pmc=5142845}}</ref> 另一个观点认为，生物有机体具有两个重要的相变特性：宏观行为的变化和系统在临界点的一致性。<ref>{{Cite journal|last1=Longo|first1=G.|last2=Montévil|first2=M.|date=2011-08-01|title=From physics to biology by extending criticality and symmetry breakings|url=https://www.academia.edu/23155991|journal=Progress in Biophysics and Molecular Biology|series=Systems Biology and Cancer|volume=106|issue=2|pages=340–347|doi=10.1016/j.pbiomolbio.2011.03.005|pmid=21419157|arxiv=1103.1833}}</ref>

二阶相变的特征是在某些'''无标度特性scale-free properties'''中出现了'''分形fractals'''。众所周知，蛋白质球是通过与水的相互作用形成的。'''蛋白质肽链protein peptide chains'''上形成侧基的'''氨基酸amino acids'''有20种（从'''亲水性hydrophilic'''到'''疏水性hydrophilic'''都有）使亲水性的氨基酸位于球状表面附近，疏水性的氨基酸更靠近球状中心。实验人员在一个在与溶剂相关的且表面积大于5000个蛋白质片段的区域中发现了二十个分形。<ref>{{cite journal|last1=Moret|first1=Marcelo|last2=Zebende|first2=Gilney|title = Amino acid hydrophobicity and accessible surface area|journal = Physical Review E|date=January 2007|volume=75|issue=1|pages=011920|doi=10.1103/PhysRevE.75.011920|pmid=17358197|bibcode=2007PhRvE..75a1920M}}</ref>这些[[分形]]的存在证明了蛋白质在二阶相变的临界点附近起作用。

二阶相变的特征是在某些'''无标度特性scale-free properties'''中出现了'''分形fractals'''。众所周知，蛋白质球是通过与水的相互作用形成的。'''蛋白质肽链protein peptide chains'''上形成侧基的'''氨基酸amino acids'''有20种（从'''亲水性hydrophilic'''到'''疏水性hydrophilic'''都有）使亲水性的氨基酸位于球状表面附近，疏水性的氨基酸更靠近球状中心。实验人员在一个在与溶剂相关的且表面积大于5000个蛋白质片段的区域中发现了二十个分形。<ref>{{cite journal|last1=Moret|first1=Marcelo|last2=Zebende|first2=Gilney|title = Amino acid hydrophobicity and accessible surface area|journal = Physical Review E|date=January 2007|volume=75|issue=1|pages=011920|doi=10.1103/PhysRevE.75.011920|pmid=17358197|bibcode=2007PhRvE..75a1920M}}</ref>这些[[分形]]的存在证明了蛋白质在二阶相变的临界点附近起作用。

 

在处于压力下的生物群中（接近临界转变时），相关性会增强，波动也会增加。许多以人、小鼠、树木和草类植物为研究对象的实验都得出了支持性的结果。<ref>{{cite journal|last1=Gorban|first1=A.N.|last2=Smirnova|first2=E.V.|last3=Tyukina|first3=T.A.|title=Correlations, risk and crisis: From physiology to finance|journal=Physica A: Statistical Mechanics and Its Applications|date=August 2010|volume=389|issue=16|pages=3193–3217|url=https://www.researchgate.net/publication/222687003|doi=10.1016/j.physa.2010.03.035|arxiv=0905.0129|bibcode=2010PhyA..389.3193G}}</ref>

在处于压力下的生物群中（接近临界转变时），相关性会增强，波动也会增加。许多以人、小鼠、树木和草类植物为研究对象的实验都得出了支持性的结果。<ref>{{cite journal|last1=Gorban|first1=A.N.|last2=Smirnova|first2=E.V.|last3=Tyukina|first3=T.A.|title=Correlations, risk and crisis: From physiology to finance|journal=Physica A: Statistical Mechanics and Its Applications|date=August 2010|volume=389|issue=16|pages=3193–3217|url=https://www.researchgate.net/publication/222687003|doi=10.1016/j.physa.2010.03.035|arxiv=0905.0129|bibcode=2010PhyA..389.3193G}}</ref>