One drug might prevent a large number of virions from replicating, but just a few will be unaffected. Because the virus is constantly changing, it makes it very hard to design drugs and vaccines against it. HIV mutates quickly because it makes frequent mistakes while replicating its genome. This ability to adapt is what makes human immunodeficiency virus (HIV) as hard to treat as it is. The virus can eventually reenter the lytic phase when conditions are right. Sometimes a host does not have enough energy or supplies to support the virus to actively replicate, so it will switch to the lysogenic phase. A virus can live in two different phases – the lytic phase (where the virus actively replicates in a host cell) and the lysogenic phase (where the viral DNA incorporate itself into the cell’s DNA and multiples whenever the cell multiplies). Unlike the previous requirement, which required an immediate response, adaptation is a process that takes place over time. Viruses definitely adapt to their surroundings. Still, very few things in biology are black and white, so let’s check out how viruses do with the rest of the list before we make our final decision.Īdaptation and evolution happen through unintentional changes (mutations) that are advantageous to an entire species. Though some have argued that the capsid and envelope help virions resist change in their environment, the general consensus is that viruses do not pass this first requirement for life. Calculus is a College Board endorsed AP Calculus AB and AP Calculus BC consultant and teaches at Diamond Bar High School in Diamond Bar.
2009 BC CALCULUS RESPONSE FREE
This criterion asks whether an individual virion is capable maintaining a steady-state internal environment on its own. 2010 answers to free response AP questions 2009 answers to free response AP questions 2008 answers to free response AP questions. Viruses do not have nuclei, organelles, or cytoplasm like cells do, and so they have no way to monitor or create change in their internal environment. AP Computer Science A Exam Multiple Choice Explanations>2009 AP Computer Science A Exam. Certain virus strains will have an extra membrane (lipid bilayer) surrounding it called an envelope. The AP Program releases the free-response questions for. A single virus particle is known as a virion, and is made up of a set of genes bundled within a protective protein shell called a capsid. AB FRQ 2011 ( New to the exam in 2011, the calculator-required free response section contains only 2 questions, while the non-calculator section contains 4 questions.) AB FRQ 2012. AB FRQ 2008 AB MC 4 (solutions are on p.9-17) AB FRQ 2009. AB FRQ 2007 AB MC 3 questions & Solution here. Homeostasis is all about balance – can something control its internal temperature, or its internal contents? In earlier drafts of criteria for life, the requirement was that living things must be made of cells. AB FRQ 2006 AB MC 2 questions & Solution here.
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