Chapter 22, Problem 1MC

In an alternation of generations life cycle, spores develop into that produce gametes that fuse to give rise to.

a. haploid gametophytes; diploid sporophytes

b. diploid gametophytes; haploid sporophytes

c. haploid sporophytes; diploid gametophytes

d. diploid sporophytes; haploid gametophytes

Summary Introduction

Introduction:

Alternation of generations is referred to a phenomenon, which occurs in many organisms, mostly in plants, in which they have two different life forms in a single life cycle. Plant showing alternation of generations can exist in two phases gametophyte and sporophyte.

Answer to Problem 1MC

Correct answer:

In the alteration of generation, the spores develop in haploid gametophyte, which gives rise to gametes that fuse to produce the diploid sporophyte.

Explanation of Solution

Explanation for the correct answer:

Option (a) is given that in the alteration of generations, the spores form haploid gametophytes that give rise to gametes, which fuse to produce diploid sporophytes. In the alteration of generation, the spores develop in haploid gametophyte, the gametophyte is haploid. This gametophyte gives rise to the male and female gamete by the process of mitosis. The fertilization of the male and the female gamete gives rise to diploid sporophyte. This sporophyte can undergo meiotic division, which produces spores. Hence, option (a) is correct.

Explanation for incorrect answers:

Option (b) is given that in the alteration of generations, the spores form diploid gametophytes that give rise to gametes, which fuse to produce haploid sporophytes. The gametophytes are the haploid structures, which fuses to form of the diploid zygote, the zygote later develops into sporophyte, which is diploid. So, it is an incorrect option.

Option (c) is given that in the alteration of generations, the spores form haploid sporophytes; that give rise to gametes, which fuse to produce diploid gametophytes. The spores form the haploid gametophytes and gametophyte result in the formation of gametes. These gametes fuse to form the diploid zygote, which forms diploid sporophyte. So, it is an incorrect option.

Option (d) is given that in the alteration of generations, the spores form diploid sporophytes that give rise to gametes, which fuse to produce haploid gametophytes. The diploid spores form the haploid gametophyte, and the fusion of two gametophyte result in the formation of diploid zygote and lately the zygote forms the diploid spores. So, it is an incorrect option.

Hence, options, (b), (c), and (d) are incorrect.

Conclusion

Thus, it can be concluded that the haploid spores develop in the haploid gametophyte. The gametophyte produces the male and the female gametes by the process of mitosis. The fusion of the male and the female gametes gives rise to the diploid sporophyte, which can undergo the meiotic divisions to form haploid spores.