lecture quiz 1 Flashcards
The City of Kingston is next to a large body of water. You might notice that the temperature of both the land and the water is higher in the day than it is at night. You might also notice that the land surrounding the water feels hotter than the water during the day, while the land surrounding the water may feel colder than the water during the night. How does hydrogen bonding relate to this?
The water is cooler than the land during the day as the extensive hydrogen bonding of water means it absorbs lots of thermal energy while experiencing only a small increase in temperature.
Plankton are microscopic organisms that live in water, and their survival is impacted by the concentration of salt in the water. Many Canadian municipalities apply salt to roads and sidewalks in the winter to melt the ice, making it safer to drive. However, much of this salt ends of in local water bodies such as lakes and rivers. What is likely to occur to the plankton?
What will this increased concentration of salt do to the plankton?
The population of plankton will evolve higher salt tolerance due to the selection of mutations that increase salt tolerance.
Consider a plant cell that produces a protein hormone that is to be secreted from the cell to travel throughout the organism. Describes which structures, and in which order, the protein hormone would encounter as it is exported from the cell?
Vesicles moving along microtubules, plasma membrane, secondary cell wall, primary cell wall.
Your friend is interested in studying the movement of mitochondria within a eukaryotic cell. Your friend tells you that they plan to do this with brightfield (unstained) light microscopy. Do you think this is a good choice of method, and why?
No, because brightfield (unstained) light microscopy has poor contrast, making it difficult to identify organelles.
Imagine you are working in a microbiology lab. You perform an experiment where you take a culture of bacterial cells, transfer them to a new solution (Solution A), and then determine the number of living cells. You are surprised by the result: there are no living cells! What is a possible explanation for this?
Solution is (isotonic, hypertonic, hypotonic) resulting in…
Solution A is hypertonic for your bacterium, resulting in the diffusion of water out of the cells.
Imagine that you are given an unknown cell sample. You visualize the sample under the microscope and you notice that it has a large rough endoplasmic reticulum. Based on this observation, what can you say about the function of this cell?
The cell is likely producing many glycoproteins.
A few scientists think that peroxisomes also have an endosymbiotic evolutionary origin, although most scientists disagree with this hypothesis. What hypothetical discovery would provide support for the hypothesis that peroxisomes evolved from bacteria?
endosymbiont theory:the evolutionary origins of mitochondria/chloroplast
Determining that the majority of proteins in peroxisomes have prokaryotic origin.
Imagine that you are given an unknown cell sample. You visualize the sample under the microscope and you notice that it has a large number of peroxisomes. Based on this observation, what can you say about the function of this cell?
The cell might degrade large amounts of fatty acids.
What would changing the carbohydrates associated with the plasma membrane cause?
It would likely change which viruses can infect the cell.
Your microbiologist friend isolated two new bacteria and stored them in separate tubes. One bacterium was isolated from the ice of Antarctica and the other from a thermal vent. However, your friend accidentally wiped the labels off of the tubes storing the bacteria and no longer know which bacterium was isolated from the Antarctica and which was isolated from the thermal vent. Why might you be able to determine which bacterium was isolated from which location by examining the membrane lipid composition?
membrane fluidity and fatty acids
To maintain proper membrane fluidity, bacteria growing at high temperatures are likely to have more saturated fatty acids in their membrane.
Imagine that you are given an unknown cell sample. You visualize the sample under the microscope and you notice that the dark spot in the nucleus is smaller than in most cells. Based on this observation, what can you say about the function of this cell?
The cell is producing only a small amount of rRNA.
Imagine you are an astronaut and you are the first person to walk on Mars. You make the surprising discovery that there are “bacteria-like organisms” on Mars. Which of the following do not need to be true for you to consider these “bacteria-like organisms” as living?
- They must be able to grow.
- They must be able to transform energy
- They must be able to evolve.
- They must be able to communicate
They must be able to communicate
Consider a hypothetical amino acid whose side chain forms a hydrogen bond with the oxygen atom of a water molecule. What does that say about the charge of the side chain of the amino acid?
The side chain of the amino acid is positively charged.
Your friend is studying a cell, but they are unsure if it is an animal cell, plant cell, or a prokaryotic cell. They ask you for you help in identify the cell. The cell contains a cell wall, ribosomes, and flagella, and it lacks mitochondria. Based on this information, is the cell:
A prokaryotic cell
Consider a hypothetical cell where the import of glucose is powered through the coupled export of sodium ions. What does that say about it’s electrochemical gradient?
Sodium is moving down its electrochemical gradient.
