AP Biology Essay Topics, Part 1: Natural Selection and More

The key to mastering the AP Biology essay section is practice….there is no shortcut. Make sure that you cover all the key points of every topic because you don’t know what will turn up on the test. Below are some possible essay topics. When writing your essay, include and elaborate on as many of the points as possible. And include definitions and explanations of key terms.

Below are possible essay topics with some key points.

1. Natural Selection/Speciation

Darwin's concepts:

• Overproduction
•  Limited resources
• Heritable variations among individuals of the same species
• Natural selection of most favorable phenotypes
• Changing gene pools over time (microevolution)
• Allopatric speciation based on geographic barriers
• Sympatric speciation/plants/polyploidy
• Isolating mechanisms
• Prezygotic (eg: temporal, behavioral)
• Postzygotic (eg: hybrid breakdown)

2.      Reliance Of Organisms On Bacteria

• Origins of eukaryotes – mitochondria and chloroplasts – endosymbiosis and lines of evidence
• Nitrogen cycle – making N2, NH4+ and NO3- for plant use
• Creating O2 in atmosphere – cyanobacteria
• Decomposers – rapid recycling of organic molecules
• Digestion in intestines/breakdown of cellulose

• Use in biotechnology:
-Plasmids
- Universal genetic code
- Use of their restriction enzymes
-  Cloning of transgenic bacteria
- Production of animal proteins (eg: insulin)

3.      Importance of surface area/volume ratios in biology – many examples, so you may have to choose from a list

• Internal membranes of mitochondria (cristae) and chloroplasts (thylakoids) for biochemical pathways

• Mitosis and creation of daughter cells to keep high surface area to volume ratios
- Replication of DNA
- Continuity of DNA through generations

• Plants
- Leaf structure to maximize photosynthesis
- Root hairs for maximum uptake of water and minerals

•  Human body
• Lungs/alveoli – maximum diffusion of gases
• Small intestine – villi and microvilli
• Structure of red blood cells – biconcave discs

Good luck on the AP biology Exam!

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