50 things every biologist should know

C. William Birky, Jr. birky at u.arizona.edu
Tue Apr 12 14:06:22 EST 2005

I agree with Mary on these points.

For example, I teach general genetics and say that Mendel's model of
heredity had five parts:
=85 Alleles (alternative versions of a gene) segregate at
gametogenesis, one to each gamete, half receiving one allele and half
the other. ("Mendel's first law or law of segregation").
=85 Different pairs of alleles segregate independently of each other
("Mendel's second law or law of independent segregation").
=85 Genes in the zygote are transmitted to all the cells in the plant
as cells divide.
=85 Genes are inherited equally from both parents (biparental
inheritance) via the gametes when they fuse at fertilization.
=85 Fertilization is random with respect to genotype of the gametes.

I do think that at least some higher-order taxa are "real" in the
sense that they correspond to deep divisions in the tree of life, but
the next ones below Bacteria, Archaea, and Eukarya may not all be of
comparable depth or significance, and in any event, are too many to
ask any student to memorize. I suspect that the author of the
question is thinking of the thoroughly discredited five or four

Bill Birky

>In article <d3e6tf$1a7$1 at mercury.rfcgr.mrc.ac.uk>,
>Jeff Houlahan  <jeffhoul at unbsj.ca> wrote:
> >5.  What are the four unique properties of water?
> >15.  What are the four principles of Mendelian genetics?
>I really dislike this type of question because it comes so close
>to "please read the exam-setter's mind."  Why four unique properties
>of water--why not two, or seven?  Doubtless the examiner has
>something specific in mind, but the candidate could know a *lot*
>about water and not be able to guess which specific properties
>the examiner is thinking of.
>I was taught Mendelian genetics in terms of Mendel's First Law
>and Mendel's Second law.  I have a PhD in genetics and feel that
>I know a bit about it, but I would have trouble figuring out which
>four things were wanted here.  I could probably guess, but it's not
>testing my knowledge of genetics, it's testing my dim memory of
>textbook formulations.
> >26.  What are the kingdoms of living organisms?
> >27.  Finish the following Kingdom, Phylum...
>These mainly depend on which textbook the examinee learned from, and
>are pretty meaningless nowadays.  A good chunk of the field believes
>that the higher-order grades do not correspond to any biological
> >30.  What comes first: the adaptation or the selective pressure?
>This is an "ideology question" meant to scare out a specific wrong
>view, but a balanced answer to it involves "It depends" and "Could
>be either one" and "Define your terms" and other things that make
>it an iffy exam question.
> >31.  What is meant by the inheritance of acquired traits, who made this
> >claim, and why was he wrong?
>This is the kind of question that will trip up candidates with a
>deeper knowledge of the subject, because what's often said about
>Lamarc's work and what he actually did are somewhat different, and
>also because there are a number of specialized cases where acquired
>traits *are* inherited, depending on how you define "inherited".
>(Consider polyglutamate repeat diseases, or cilium direction in
> >32.  What is the object of natural selection?
>Even more ideology.... I can't see any way to answer this short
>of reading the examiner's mind.  (And that's putting aside that it
>could mean either "What is the goal of natural selection?" or
>"On what object does natural selection act?")
> >33.  Are cladogenesis and anagenesis synonymous terms?
>I will vouch for the fact that you can work in phylogenetics for
>decades and not know the answer to this question.  (I don't
>think I've ever *seen* the term "anagenesis.")
> >37.  What is mitosis and what happens during mitosis?
> >38.  What is meiosis and what happens during meiosis?
>These I like very much.  More questions of this sort would be
>In general, I dislike these questions because they don't seem to
>test the candidate's biology so much as their knowledge of
>You might see if previous years of the GRE-Biology are available,
>or test-prep guides for the GRE.  It covers this sort of ground
>very, very thoroughly and the questions have been somewhat debugged.
>On the other hand, you might figure that your candidate passed
>the GRE to get *into* grad school, and try to focus more on
>usable general knowledge.  The mitosis/meiosis questions work for
>me on this level, and many of the ecology ones (describe the
>flow of water etc.)
>Mary Kuhner mkkuhner at eskimo.com

C. William Birky, Jr.
Professor of Ecology and Evolutionary Biology
Member, Graduate Interdisciplinary Programs in Genetics
Biological Sciences West
1041 E. Lowell
University of Arizona
Tucson, AZ 85721
Office phone: 520-626-6513
Lab phone: 520-626-5108
Fax: 520-621-9190
Email: birky at u.arizona.edu

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