Question

Consider the following statements with respect to reproduction in the lower living organisms.
(i) Organisms like yeast and planaria reproduce asexually by means of budding.
(ii) True regeneration is observed in hydra.
(iii) Protonema of mosses multiplies by fragmentation.
(iv) In unicellular organisms like bacteria, algae, and Amoeba reproduction is synonymous with growth, i.e., an increase in the number of cells.
(a) (i) and (ii) correct
(b) (ii) and (iii) correct
(c) (i) and (iv) correct
(d) (ii) and (iv) correct
(e) (iii) and (iv) correct

Answer 1

This is the process in which a new individual or offspring is formed from the parent organism or organisms. It is of two types, one in which both the parent organism is involved and in the other one single parent organism is required. In the lower living organisms, the most commonly occurred mode of reproduction is that in which a single parent organism is sufficient to produce a new individual.

Complete answer:
From the given four statements with respect to reproduction in the lower living organisms, two are correct. The true statements are:
-Fragmentation is the process by which the protonema of mosses multiply and in unicellular organisms like bacteria, algae, and Amoeba reproduction is synonymous with growth, i.e., an increase in the number of cells.
-In mosses, the protonema is an extensive branched system of multicellular filaments that are rich in chlorophyll.
-Fragmentation is an asexual mode of reproduction in which the body of the organism is broken or divided into two or more pieces or fragments. Each of these fragments grows or develops into mature or fully grown individuals that seem to be protonema of mosses multiply clones of the original organism.
-The small pieces or fragments are often scattered by the wind, water, or animals. When the moss fragment reaches a suitable environmental condition, it can develop into a new plant.
-In the lower level organisms such as filamentous cyanobacteria, molds, lichens, sponges, acoel flatworms, some annelid worms, and sea stars this mode of reproduction is most commonly found.
-The unicellular organisms like bacteria, algae, and Amoeba reproduce asexually by the process of binary fission to produce a new individual. In this process, the parent body undergoes mitotic division to form two or more individuals, i.e., the number of cells increases. Hence, we can say that in unicellular organisms reproduction is synonymous with growth.

So, the correct answer is, ‘(iii) and (iv) correct’.

Note:
-The accumulation of hormones that influence the further growth of newly formed cells is initiated in this protonema stage.
-Fragmentation is an asexual mode of reproduction in which the body of the organism is broken or divided into two or more pieces or fragments.
-In a unicellular organism, the parent body undergoes mitotic division to form two or more individuals.