Question

Which of the following correctly represents the type of life cycle patterns from the options given?

a) 1. Diplontic 2. Haplodiplontic 3. Haplontic
b) 1. Haplodiplontic 2. Haplontic 3. Diplontic
c) 1. Haplontic 2. Diplontic 3. Haplodiplontic
d) 1. Diplontic 2. Haplontic 3. Haplodiplontic
e) 1. Haplontic 2. Haplodiplontic 3. Diplontic

Answer 1

Hint: The lifecycle of the organism involves the time period from birth till death. During that life cycle, the ploidy of the cells present in our body changes from time to time. The haploid gametes fuse together to form a diploid individual.

Complete answer:
-The diplontic life cycle occurs when the zygote form is diploid in nature and it grows to form a diploid and multicellular organism. This zygote when fully grown produces haploid cells which are called the gametes. The gametes are produced by the reductional division or meiosis. The gametes that fuse to form the zygote and the cycle continues. Humans have a diplontic life cycle.
-The haplontic life cycle occurs when the zygote or the multicellular stage is haploid in nature. When a diploid zygote is formed it forms haploid spores as soon as possible. These spores are produced inside the sporangia. The spores then grow by mitosis and form a haploid multicellular organism. The grown-up organism then produces haploid spores by the process of mitosis. The gametes produced then fuse together to form the zygote which then produces spores. And this haplontic cycle continues. It occurs mostly in the fungi and some algae.
-The haplodiplontic stage two multicellular division takes place and leads to the formations of two multicellular individuals. The diploid zygote grows by the process of mitosis and forms a diploid organism. It produces sporophyte and it then produces the haploid spores by the process of meiosis. These spores grow and form haploid organisms and produce haploid gametes by the process of mitosis. This is the haplodiplontic life cycle or is known as the alternation of generations.

So, the answer is ‘1. diplontic, 2. haplontic, 3. haplodiplontic’.

Notes:
The haplodiplontic life cycle is the most complex life cycle as one organism changes its cellular level from diploid to haploid. It usually occurs in some algae and in all the plants. The simplest life cycle is the diplontic life cycle and it occurs in humans.