Question

Out of 8 ascospores formed in neurospora, the arrangement is 2a: 4A: 2a showing.
A. No crossing over
B. Some meiosis
C. Second generation division
D. First generation division

Answer 1

Hint:
> Neurospora: It is the genus which belongs to the class of ascomycetes of kingdom fungi
> It is regarded as nerve spore.
> Special types of striations are seen on the spore that resembles axons.
> Best known species is Neurospora Crassa.

Complete answer:
Ascomycetes are commonly known as sac-like fungi that are mostly unicellular in nature.
They are saprophytic, decomposers, parasitic in nature.
The asexual type of spores is conidia that are produced exogenously on special mycelium called conidiophores.
Condia germinate to produce mycelium.
Sexual spores are known as ascospores which are produced endogenously in a sac like ascus.
These are arranged in different types of fruiting bodies known as ascocarps.
Claviceps and neurospora are the examples of this class that are used extensively in biochemical and genetic work.
In Neurospora after crossing over between the gene and centromere, the paired arrangement of ascospores is AA aaaa AA or 2a: 4a: 2a.
This is known as second division segregation.
It is widely used as a model organism and can survive on minimal media.
Ascospores are produced by meiosis.
Ascospore restores the haploid individuals of either mating type.
The genus Neurospora of class ascomycetes includes homothallic species which means in which a single haploid individual carries both the mating type loci and can undergo self-fertilization which further leads to meiosis and sexual type of reproduction.

So, the correct option is option C. Second generation division.

Note: The second generation division or meiosis II is called equational division.
The two sperm cells split again producing four types of sperm cells each with 23 or n number of chromosomes.