Chapter 24, Problem 1VCQ

Figure 24.14 Which of the following statements is true?

1. A dikaryotic ascus that forms in the ascocarp undergoes karyogamy, meiosis, and mitosis to form eight ascospores.

A diploid ascus that forms in the ascocarp undergoes karyogamy, meiosiis, and mitosis to form eight ascospores.

A haploid zygote that forms in the ascocarp undergoes karyogamy, meiosiis, and mitosis to form eight ascospores.

A dikaryotic ascus that forms in the ascocarp undergoes plasmogamy, meiosis, and mitosis to form eight ascospores.

Summary Introduction

Introduction:

Among fungi, Asus is found as the sac-like structure, which contains the haploid structures known as ascospores. These filamentous ascomycetes from the hyphae, which are divided by the septa. These hyphae allow streaming of cytoplasmic matrix from one cell to another.

Answer to Problem 1VCQ

Correct answer:

The correct answer is an option (a).

Explanation of Solution

Explanation for the correct answer:

Option (a)- Dikaryotic hyphae are produced, in which two haploid nuclei. These dikaryotichyphae can be homo or heterokaryotic. In each cell, two haploid nuclei fuse in the process of karyogamy and result in the diploid nucleus, then undergo meiosis and led to the ascospore formation. After the formation, the ascospores germinate and form hyphae.

Explanation for incorrect answer:

Option (b)- A diploid ascus does not undergo karyogamy, meiosis,and mitosis to form the eight ascospores because only dikaryotic undergo karyogamy. Hence, this option is incorrect.

Option (c)- In the same way, a haploid zygote does not undergo the karyogamy, meiosis,andmitosis. Hence, this option is incorrect.

Option (d)- A dikaryotic ascus only formed by the process of karyogamy not by the plasmogamy meiosis and mitosis to form eight ascospores. Hence, this option is incorrect.

Conclusion

Dikaryotic hyphae are produced in which two haploid nuclei with the help of karyogamy, not by the plasmogamy. Hence, the correct answer is option (a).