Short Essay Practice ap exam Review Fall 2014 short essay #1

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In Earth’s early history, the evolution of photosynthesis in simple cells occurred before the evolution of more complex cells.
Briefly describe the significance of photosynthesis being present first.

Discuss one piece of evidence that supports the theory that chloroplasts and mitochondria are evolved from prokaryotic cells.

Significance of Photosynthesis (3 Points Max)

  • (+ ½ ) Mentioning that photosynthesis releases oxygen as a by-product.

  • (+ ½ ) Mentioning that photosynthesis led to an increase in atmospheric oxygen.

  • (+ ½ ) Mentioning that the presence of oxygen in the atmosphere allowed the evolution of cellular respiration.

  • (+ ½ ) Mentioning that oxygen allowed ells to generate more energy and grow larger and more complex.

  • (+ ½ ) Mentioning that the first photosynthetic cells were prokaryotic.

  • (+ ½ ) Mentioning that eukaryotic cells could not evolve until there was a higher level of atmospheric oxygen.

Evidence of Endosymbiosis (1 Point Max)

  • (+1) Mentioning that chloroplasts and mitochondria have their own DNA.

  • (+1) Mentioning that chloroplasts and mitochondria make their own ribosomes (similar in size to bacterial ribosomes).

  • (+1) Mentioning that chloroplasts and mitochondrial DNA consist of a single, circular molecule (like that of bacterial DNA).

  • (+1) Mentioning that chloroplasts and mitochondria replicate by a process similar to prokaryotes (binary fission).

  • (+1) Mentioning that the inner membranes of both organelles have enzymes homologous to those found in prokaryotes.

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