Question

What is the nature of the oogonium and the secondary oocyte? Which process results in the formation of the secondary oocyte?
        A) A diploid oogonium forms a haploid oocyte by the process of mitosis.
        B) A haploid oogonium forms a diploid oocyte by the process of meiosis.
        C) A diploid oogonium forms a haploid oocyte by the process of meiosis.
        D) A haploid oogonium forms a haploid oocyte by the process of meiosis.

option A is wrong / what is the correct answer

QUESTION 7
Spawning is often triggered by a signal such as water temperature or day length. What is an advantage of using this type of signal versus using individual courtship behaviors?
        A) It allows many individuals to spawn simultaneously
        B) It is the only way a single male and female can time gamete release simultaneously
        C) Males and females do not have to choose individual mates.
        D) A and C
        E) A and B
        F) A, B and C

A is wrong here too / give correct answer

Answer 1

First Question : (About oogenesis)

Answer: c. A diploid oogonium forms a haploid oocyte by the process of meiosis.

Reason:

Oogonia (singular. Oogonium) is a diploid cell. This diploid cell doesn't give raise to oocyte in a single step process. The formation of secondary oocyte from oogonium is as follows:

Oogonium (diploid) undergoes one mitotic differentiation to form the primary oocyte. Since primary oocytes are formed by mitotic division, the ploidy level of cell doesn't change. That is, primary oocytes are also diploid. This primary oocyte undergoes meiotic division to form the secondary oocyte and then the ovum. To be more precise, meiosis consists of two rounds of division, the first one called as Meiosis I is a reduction division, through which the secondary oocytes are formed (reduction division means, there is a reduction in ploidy level). Hence, the secondary oocyte is haploid. After the formation of secondary oocyte, the second meiotic division viz. Meiosis II occurs. Meiosis II is also called as equational division as there is no change in ploidy level (i.e. Haploid ova is formed from haploid secondary oocyte). Thus, ovum is formed.

It all starts with thd diploid oogonium, and though it undergoes both mitosis and meiosis, as far as gamete (ovum) production is concerned meiosis is the most important step. Hence, option c is the right answer.

(Note:- Meiosis I is completed just before ovulation. In vertebrates (especially mammals), the female gamete production is arrested at particular stages of cell division at different phases of life cycle. )