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Ch. 27 - Diversification of Eukaryotes
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All textbooksFreeman 8th EditionCh. 27 - Diversification of EukaryotesProblem 12

Chapter 26, Problem 12

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Physarum is a plasmodial slime mold, whereas Dictyostelum is a cellular slime mold. Compare and contrast movement by the migrating slug stage of Dictyostelium to the plasmodial stage of Physarum.

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Hi everyone here's our next question. Which of the following is not true about slime mold. Well, let's look to our answer choices, remembering. We're looking for a false statement. Choice A says there are units cellular sacrifice. It's well a sacrifice is something that lives oops on dead or decaying organic material. And this statement is true. Um although slime molds can get quite large, they are uni cellular and they are sacrifice living on dead and dying organic material. So since this statement is true, it is not our answer choice. B says they're often present as an aggregate called plasmodium, which is a multi nucleotide stage. This is also true when we mentioned that some slime molds can get very large. That is the case with Plasmodium when it sort of becomes a very large aggregate with many nuclei. But again, multicellular no cell walls between those nuclei. Um a large amount of cytoplasm and that's called plasmodium. So that's true. And therefore not our correct answer choice. E says they have characteristics of both fungi and animals. Well, that's true. Um like fungi, they are sacrifice. So that's similar to fungi and then like animals um they have sentry als in their cells. Those are those 22 black structures that help organize the micro tubules um organize the spindle in cell division and animals have central's so do slime molds while higher plants and most fungi do not. So that's an animal like characteristic. So that's a true statement and therefore not our answer. So we're down to choice D. Which says they exclusively belong to the kingdom of fungi. Well, that is false because they're not fun guy. Rather they're a member of the kingdom pro Teesta their protests. So Choice D. Is our correct answer. Which of the following is not true about slime mold Choice D. They exclusively belong to the kingdom of fungi. See you in the next video.
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Textbook Question

Consider the following: Plasmodium has an unusual organelle called an apicoplast. Recent research has shown that apicoplasts are derived from chloroplasts via secondary endosymbiosis and have a large number of genes related to chloroplast DNA. Glyphosate is one of the most widely used herbicides. It works by poisoning an enzyme located in chloroplasts. Biologists are testing the hypothesis that glyphosate could be used as an antimalarial drug in humans. How are these observations connected?

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Textbook Question

Suppose a friend says that we don't need to worry about the rising temperatures associated with global climate change. She claims that increased temperatures will make planktonic algae grow faster and that carbon dioxide (CO2) will be removed from the atmosphere faster. According to her, this carbon will be buried at the bottom of the ocean in calcium carbonate shells. As a result, the amount of carbon dioxide in the atmosphere will decrease and global warming will decline. Comment.

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Textbook Question

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Which of the following best describes movement in Physarum? a. Cilia propel the slime mold. b. Flagella propel the slime mold. c. The slime mold moves by amoeboid motion. d. The slime mold moves by gliding motility.

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Textbook Question

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Does an organism without a brain have the ability to use an externalized 'memory'—a spatial 'slime map' that the organism uses to avoid moving to regions where it has been before? Researchers addressed this question by placing a U-shaped trap between Physarum and its food (see diagram that follows). Twenty-three out of 24 slime molds reached the food when plain agar was used as the growth substrate. However, when the agar was coated with extracellular slime, only 8 of 24 found the food. The mean time in hours that it took the successful slime molds to reach the food when placed on plain agar or agar pre-coated with extracellular slime was compared (P=0.012). Use the P value provided to determine if the difference is significant or not. What conclusion can be drawn from the graph shown here?

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Textbook Question

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Propose an experiment that would test whether the coating of extracellular slime changed the speed at which the slime mold moved across the substrate.

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Textbook Question

When placed at the perimeter of a maze with food in the center, the plasmodial slime mold Physarum polycephalum explores the maze, retracts branches from dead-end corridors, and then grows exclusively along the shortest path possible to the food. How does Physarum do this? One theory is that it leaves behind slime deposits—an externalized 'memory' that 'reminds' it not to retry dead ends. Develop simple experiments to test whether Physarum prefers (1) brightly lit or dark environments; (2) dry or moist conditions; (3) oats or sugar as a food source.

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