You will answer these questions using your own words. You won’t copy and paste from elsewhere because that only harms your own understanding. These questions are your best practice on how to apply the concepts from this module to new scenarios. Take it seriously so you can do well on the exams.
Questions for group discussion:
- Explain the theory of Endosymbiosis and give three (3) pieces of evidence that supports it.
- A) Let’s say you are going to design a cell, would you make it large or small? Explain your choice. B) How come eukaryotic cells are about 10X larger than prokaryotic cells and are still able to function?
- Explain why the cell membrane is modeled as a Fluid Mosaic: A) Why is it called fluid, and B) Why is it called a Mosaic?
- Some bacteria are capable of adjusting the fluidity of their membranes to the temperature of the environment. For example, they use desaturases, which are enzymes that turn saturated fatty acids into desaturated ones. In which season would cells need this enzyme (summer or winter, when would it be most beneficial for bacteria)? Explain. Indicate which fats are more fluid, saturated ones or unsaturated ones?
- Compare osmosis, simple diffusion, facilitated diffusion and active transport: A) describe their differences and B) explain when cells have to use each one.
- Some animals are osmoconformers, meaning that they maintain the tonicity/osmolarity of their body fluids equal to that of the external environment. Hydroids, a type of cnidarian, are osmoconformers. But they don’t move and thus are adapted to the environment they live in. A) What would happen if you take a marine hydroid and transfer it into a freshwater aquarium? B) What would happen if you take a freshwater hydroid and transfer it into a saltwater aquarium? C) Sharks are extraordinary osmoconformers. Sharks store urea in their tissues and use it to match the tonicity of their tissues to that of the surrounding environment. Some sharks can move from saltwater to freshwater, hypothesize what changes will sharks do in order to adjust when moving from saltwater to freshwater and vice versa. Explain your answer in terms of tonicity and specify the direction of water movement and urea concentration.