Download Ch 25 Guided Reading Key

Chapter 25 – Grading Rubric – 17 pts total
1. Contrast and compare the atmospheric conditions on the early earth with the modern earth.
½ pt - The early earth’s atmosphere was a reducing one with H2, H2O, CH4, and NH3.
½ pt - The modern earth’s atmosphere is an oxidizing one with O2 and N2.
2. Describe the “steps” of Chemical Evolution as suggested by Oparin and Haldane.
½ pt each, 2 pts
Monomer formation, polymer formation, protobionts, genetic information.
3. The Miller and Urey experiment is often viewed as a Level 1 item for AP Biology students.
Describe their experiment and justify its importance for an AP Biology Reader.
1 pt - The Miller & Urey experiment duplicated the early earth conditions in a lab.
Description of the apparatus and starting materials needed.
½ pt – Justification - Monomers were formed showing that the first step of Oparin &
Haldane was correct.
4. Discuss the RNA world hypothesis and its supporting evidence.
½ pt – that RNA was the first genetic molecule
½ pt – RNA can easily be made under abiogenesis conditions, it can self-replicate, it can
catalyze reactions, etc.
5. Describe three limitations of using fossils for comparisons of organisms.
Any three answers, ½ pt each, 1 ½ pts total.
They do not show DNA relationships or if two similar organisms could interbreed, they can
be hard to find, often in fragments, rare, (or other acceptable answer).
6. Discuss and justify TWO evidences supporting an endosymbiotic origin of mitochondria and
chloroplasts. Any 2 answers ½ pt each, 1 pt total
circular DNA like bacteria, small ribosomes, no histones on DNA, similar membranes or
other acceptable answer
7. Early organisms like the cyanobacteria reproduce only by binary fission. Explain how this
method of reproduction would like effect their rate of evolution and justify your answer.
½ pt - Slow down evolution
½ pt – Justification - there is little recombination of DNA into new types
(no sexual reproduction, mutation only) for evolution to work with.
8. Discuss what the observations of the life forms found around the volcanic vents on the ocean
floor are suggesting about the possible origin of life on Earth.
1pt - These areas could have supported the origin of life. They have the necessary
chemicals and energy sources. They would have been protected by catastrophic events
such as meteors or damaging UV light, excessive heat etc.
9. Plate tectonics shows that the major continental land areas of earth have drifted over
geological time. Discuss what affect the moving land masses might have had on the
climate and environmental changes and the resulting consequences on evolution of life on our
planet.
1 pt - Moving land masses would change air and water currents over time. This
would have changed the weather or climate of an area. Changes in the
environment would have driven evolution.
10. Contrast and compare the following situations and justify your responses:
a) the speed of evolution on a planet does not have plate tectonics and the climate of the
planet is extremely stable.
½ pt - If the climate is stable, the speed of evolution would be gradual and slow.
½ pt – Justification – once you have the best adaptations to the environment, there is
little need or natural selection to evolve further.
b) the speed of evolution on a planet with a very thin crust resulting in regular and sever
plate tectonic movement.
½ pt – the speed of evolution would be more rapid.
½ pt – Justification - regular meteor impact would make for a very unstable
environment and organisms would constantly adapt to the changing conditions.
11. Explain and justify why is it likely that Hox genes have played a major role in the evolution
of novel morphological forms.
1pt – Hox genes control the spatial development of an organism. Changes in these genes
and their expression can result in major changes in the development of organisms
and give rise to different body forms.
12. Identify and describe an evo-devo example of your choice for an AP Biology Reader.
½ pt – Identity, ½ pt Description (any acceptable example such as Pitx 1 etc.)
13. Discuss how the Darwinian concept of descent with modification explains the evolution of
complex structures as the vertebrate eye.
1 pt – vision was a trait that gave selective advantage. Mutations that improved vision would
be accumulated over time as they were advantageous.
14. The species of plants and animals in India are greatly different from species in nearby
southeast Asia. Discuss how this observation can be explained.
1 pt – India is on its own geological plate and evolution occurred in an isolated environment
for many years. Eventually India joined with Asia. By that time, the plants and
animals were already very different in evolution than in nearby southeast Asia.