Study Questions on Sexual Reproduction in Fungi.

1. What is meant by the terms "heterothallic" and "heterokaryotic?" Are these conditions dependent on one another? What are the derivations of these words and how do the derivations help you to remember what they mean?

2. Genetic recombination in fungi can take place by the parasexual cycle and during sexual reproduction.

a.How do the recombination events differ in these two processes?

b. How does the process of formation of the haploid stage differ between the parasexual cycle and sexual reproduction? Describe this in terms of nuclear division.
 

3. What are the three events, in sequence, for sexual reproduction in fungi in general? Describe or define each event.
 

4. There are 5 general ways in which fungi have sex - that is, 5 ways of bringing compatible nuclei together. Name them and describe them briefly.
 

5. What are "mating types" in fungi? How do bipolar (unifactorial) and tetrapolar (bifactorial) fungi differ?

6. Describe two different sexual reproduction methods that require motile gametes. What phylum of fungi uses these methods?

7. What are fungi called that are capable of making both male and female gametangia on the same thallus? Are these fungi self-fertile? Explain.
 

8. What is the predominant nuclear state of Ascomycetes? Oomycetes? Basidiomycetes? What determines this?
 

9. Before nuclear fusion in fungi, gametes contain how many sets of chromosomes?

10. How many mating type loci are there in bipolar mating systems? Do all bipolar mating type systems have the same possible number of alleles?

12. In a bipolar mating type system, in any cross, how many different mating types will there be among the progeny of a cross?

13a. What phylum of fungi has species that have tetrapolar mating? How many mating type loci are there in these systems?

13b. In a tetrapolar mating system, how many different mating types will there be among the progeny of a cross. Draw an example to explain your answer.

14. The following crosses were performed (mating types of parents are listed):

(a) A1 x A5
(b) A1B2 x A1B4

What do the listed mating types tell you about the type of mating system?

In cross (a), what percentage of your sibling progeny will you be able to mate with?

In cross (b), what percentage of your sibling progeny will you be able to mate with?

For both answers, list the mating types of the progeny, and which progeny each mating type is able to mate with.

15. What is the advantage for a fungus of having sexual reproduction? What is the advantage of asexual reproduction? Which occurs more frequently? Explain.

16. How do the Oomycota differ from the true fungi in the order of events of sexual reproduction? What is the consequence?

17. What factors may induce sexual reproduction in fungi?

18. What roles do hormones play in fungal sexual reproduction? Give an example.