Propose an experiment to test whether Pilobolus shoots its sporangia preferentially toward light. Hypothesize why such a preference might be advantageous.

Select True or False for each statement.

T/FLinked genes are always inherited together.

T/FGenetic map distances measure the number of nucleotides between a pair of genes.

T/FThe farther apart genes are on a chromosome, the more likely there is to be a crossover between these genes during meiosis.

T/FCrossing over occurs between genes on different homologs of a homologous chromosome pair.

Some fungi have elaborate mechanisms for dispersing spores. For example, the “squirt gun” fungus Pilobolus, which grows in cow dung, forcibly shoots off tiny black sporangia filled with spores. Any sporangia that are flung onto fresh grass are likely to be eaten by a grazing cow, passed through its digestive system unharmed, and deposited in a new batch of dung. The spores carried within the sporangia are perfectly positioned to grow into a new mycelium.

Would you describe the association between Pilobolus and cows as a symbiotic relationship? Explain your answer.

Explain the process of extracellular digestion that occurs during the growth of Pilobolus mycelia through dung.

Using high-speed video, researchers have measured several variables associated with sporangium discharge in various spore-shooting fungi. Based on the data in the table shown here, how do the launch speed and acceleration of Pilobolus compare with those of the other fungi?

How does launch speed for each species compare with the top speed of 44 km/h reached by Jamaican athlete Usain Bolt during his 2009 world-record-setting 100-m race?