In the Fungus Neurospora,a Standard Lab Strain Carrying the Auxotrophic

question 6

Essay

In the fungus Neurospora,a standard lab strain carrying the auxotrophic mutation m was crossed to a prototrophic strain isolate from a burned sugar cane field.There were three types of asci as shown below,where the symbol "ab" means an aborted ascospore whose m locus constitution could not be tested.
$$\begin{array} { l l l } \text { Type I } & \text { Type 2 } & \text { Type 3 } \\m & a b & m \\m & a b & m \\m & a b & a b \\m & a b & a b \\+ & a b & a b \\+ & a b & a b \\+ & a b & + \\+ & a b & +\end{array}$$
Explain the origin of each ascus type.

---

Definitions:

Extant Cetaceans

Currently living whale, dolphin, and porpoise species that are members of the order Cetacea.

Hind Feet

The rear feet or legs of an animal, often specialized for various functions such as jumping, running, or climbing.

Modern Cetaceans

Refers to the current species of whales, dolphins, and porpoises, highly adapted marine mammals with a fully aquatic lifestyle.