SAMPLE QUESTIONS ON EVOLUTION
1. Explain Oparin´s theory about the origin of life and how the experiment Stanley Miller did in
1953 supported this theory.
Oparin´s theory is also called the prebiotic chemical evolution and was stated at the beginning
of the 1920s by the biochemist Alexander Oparin, and it said that the organic molecules
appeared on Earth thanks to the inorganic compounds that evolved into the most primitive
forms of life.
Inorganic compounds such as CH4, N2, H2… reacted to give organic compounds such as
aminoacids or nucleotids, which are the molecules of life.
The hard conditions of the primitive atmosphere favoured these chemical reactions.
In Miller´s experiment the conditions of Oparin’s primitive atmosphere were simulated in the
laboratory and, by using electrodes that generated electric shocks, Miller found out that amino
acids, sugars and some precursors of nucleic acids appeared.
2. Explain Lamarck´s theory about evolution.
Lamarck stated that when environments changed, organisms had to change their behavior to
survive. If they began to use an organ more than they did in the past, it would increase in its
lifetime. For example, if a giraffe stretched its neck for the highest leaves of a tree its neck
would become longer. Its offspring would inherit the longer neck, and continued stretching
would make it longer still over several generations. Meanwhile organs that organisms stopped
using would shrink and even disappear.
3. Explain Darwin´s theory about evolution.
There are morphological variability among the individuals of the same species. Some
individuals are better adapted to some environmental conditions because they have some
specific morphological features.
The organisms that are better adapted have more possibilities to survive and to reproduce. The
offspring inherit the features of their parents. This is called natural selection and this is how
evolution occurs: the better features for each environment spread because the organisms which
have those features survive and reproduce more.
4. What are the main differences between Lamarck´s and Darwin´s theories? Which of them do
scientists believe is correct?
Scientists believe that the theory that is closer to reality is Darwin´s.
Lamarck believed that during the lifetime of an animal, its use of some organs would develop
these organs in order to adapt to the environment. These changes acquired in life are transmitted
to the offspring.
On the other hand Darwin states that no changes acquired during a lifetime are transmitted to
the offspring. What happens is that in a community not all the individuals are the same. The
individuals that, by chance, are better adapted to the enviorenment will survive and transmit
their features to their offspring. This is called natural selection.
5. What is neodarwinism?
It is Darwin´s theory but introducing our knowledge of DNA to explain why there is variability
among the members of a certain community.
The variability is caused by mutations in the DNA and by the recombination of the genes of the
two parents in the sexual reproduction.
The concept of natural selection is the same in neodarwinism.
6. There are three pieces of evidence for evolution: paleontological, biological and molecular.
Explain each one of them.
-Paleontological evidence: Taken together, fossils can be used to construct a fossil record,
which is a timeline of fossils reaching back through history.
-Biological
 Homologies: homologous organs have the same structure but different function.They
prove the existence of a common ancestor.
 Vestigial structures: these are structures found in an organism with little or no known
function. Such structures are thought to be remnants of a structure that at one time had a
function in an ancestral species.
-Molecular
 Genomic evidence: the genetic material (DNA) is very similar between different
species. The more related two species are, the more similar their DNA is.
 Proteomic evidence: the proteins that different species produce in their bodies are very
similar.
7. What does LUCA mean and how is it related to evolution? Explain.
LUCA means Last Universal Common Ancestor. Nowadays it is believed that all species are
related and that we all come from a common ancestor that existed millions of years ago.