AP Biology
Saturday Study Session 3
Evolution as a Process
Student Packet
Session 3 – Change over Time
Multiple Choice Questions
1) Following clear-cutting of a deciduous forest several hundred years ago, the land was colonized by
herbaceous species which, over time, were replaced largely by shrubs, then by forest trees. Assuming the
growth of the shrubs and trees was enhanced by the soil-holding properties of the herbaceous plants,
which of the following processes BEST describe the progression from herbaceous plants to forest trees?
A)
B)
C)
D)
Primary succession and facilitation.
Primary succession and inhibition.
Secondary succession and facilitation.
Secondary succession and inhibition.
2) Asteroids contain an element not normally found on Earth called Iridium. The asteroid that hit the earth 65
million years ago, and is believed to have caused the extinction of the dinosaurs, contained Iridium. So a
layer of Iridium is found around the Impact zone. This zone of rock is called the K-T boundary. If a fossil is
limited to undisturbed geological strata shallower than the K-T boundary, then it:
A)
B)
C)
D)
existed more recently than the reptiles known as dinosaurs.
became extinct during the Cretaceous era.
was abundant on Earth at the time of the asteroid impact.
Is more than 65 million years old.
3) Stanley Miller and Harold Urey performed an experiment to show that organic (carbon containing biotic
molecules) could be produced, under the conditions of the early earth atmosphere, from inorganic
compounds such as methane gas - CH4, Hydrogen gas – H2, Ammonia – NH3, and water vapor. Which early
earth condition did Miller and Urey’s experimental apparatus NOT attempt to simulate directly?
A)
B)
C)
D)
Intense lightning storms
Warm, swirling oceans
Intense UV bombardment
Reducing atmosphere
4) Today all known prokaryotic and eukaryotic organisms are DNA based. It is hypothesized though, that RNA
replicating molecules evolved first with in the protobionts over 3.5 billion years ago. What probably
accounts for the switch to DNA-based genetic systems during the evolution of life on Earth?
A)
B)
C)
D)
RNA is too involved with translation of proteins and cannot provide multiple functions.
DNA forms the rod-shaped chromosomes necessary for cell division.
Replication of RNA occurs too quickly to support life.
DNA is chemically more stable and replicates with fewer errors (mutations) than RNA.
5) The Oxygen revolution, also known as the Oxygen crisis, occurred about 2.5 billion years and changed
Earth’s environment dramatically. Which of the following adaptations took advantage of this change?
A) The evolution of chloroplasts when early protists engulfed photosynthetic cyanobacteria.
B) The evolution of cellular respiration, which used free oxygen to help harvest more energy from fuel
molecules.
C) The evolution of photosynthetic pigments that protected early algae from the corrosive effects of
oxygen.
D) The evolution of multi-cellular eukaryotic colonies from symbiotic communities of prokaryotes.
6) Which of these is arranged in the appropriate sequence from the earliest to the most recent event?
A) Origin of Earth, origin of prokaryotes, beginning of the accumulation of atmospheric oxygen, oldest
eukaryotic cell fossils, origin of multicellular eukaryotes, colonization of land by plants and fungi, first
land animals evolve.
B) Origin of Earth, origin of prokaryotes, oldest eukaryotic cell fossils, beginning of the accumulation of
atmospheric oxygen, origin of multi-cellular eukaryotes, colonization of land by plants and fungi, first
land animals evolve.
C) Origin of Earth, origin of prokaryotes, oldest eukaryotic cell fossils, origin of multi-cellular organisms,
colonization of land by plants and fungi, beginning of the accumulation of atmospheric oxygen, first
land animals evolve.
D) Origin of Earth, beginning of the accumulation of atmospheric oxygen, origin of prokaryotes, oldest
eukaryotic cell fossils, origin of multicellular eukaryotes, colonization of land by plants and fungi, first
land animals evolve.
Math Grid-In
Scientists use various different methods to try and establish the age of fossils. One such method, for fossils less
than 75,000 years old, is to compare the amount of radioactive Carbon-14 to normal Carbon-12. Both forms of
Carbon are assimilated in to the organism as it feeds over time. When the organism dies, it quits accumulating
Carbon in its body. Over time the Carbon 14 breaks down to become Nitrogen-14. If the half-life of Carbon-14 is
about 5,730 years, then a fossil that has one-eighth the normal proportion of Carbon-14 to Carbon-12 is probably
how many years old?
Short Free Response
1) Lynn Margulis in the early 1960’s proposed the Endosymbiotic Hypothesis. This hypothesis uses the
cellular organelles known as chloroplasts and mitochondria to help support the hypothesis. Explain what
the Endosymbiotic Hypothesis is trying to propose and state THREE facts of supporting evidence that
encompasses both the chloroplast and mitochondria.
2) The hypothesized evolution of the first protobionts in the early primordial oceans involved four major
processes. These processes are:
1) Abiotic synthesis of amino acids and nucleic acids.
2) Using energy from the surrounding environment, take monomers and generate complex polymers.
3) RNA/DNA molecules form, stabilize, and gain the ability to self-replicate (reproduce).
4) Formation of a protobiont lipid based membrane to compartmentalize complex chemical reactions.
Briefly explain why each step is necessary to form a “living” cell.
Long Free Response
4. The diagram above shows the succession of communities from annual plants to hardwood trees in a
specific area over a period of time.
(a) Discuss the expected changes in biodiversity as the stages of succession progress as shown in the
diagram above.
(b) Describe and explain THREE changes in abiotic conditions over time that lead to the succession, as
shown in the diagram above.
(c) For each of the following disturbances, discuss the immediate and long-term effects on ecosystem
succession.
(i) Avolcanoerupts,coveringa10-square-kilometerportionofamatureforestwithlava.
(ii) A10-square-kilometerportionofamatureforestisclear-cut.