Biological Reproduction

Anisogamy is found in human beings, earthworms and pilas.Anisogamy refers to a form of sexual reproduction involving the union or fusion of two dissimilar gametes .The smaller gamete is considered to be male (sperm cell), whereas the larger gamete is regarded as female (egg cell).

The correct answer is option (3).

The phenomenon in which one generation of certain plants and animals reproduces asexually, followed by a sexually reproducing generation. Also known as alternation of generations.

Polyspory is the occurrence of more than four spores from a spore mother cell.

Apogamy was first reported by Farlow (1874). It can be defined as the development of a sporophyte directly from the gametophyte without the intervention of sex organs and gametes

 Hydra exhibits exogenous budding.

On being cut, the two parts of hydra can regenerate the other part because it is a simple organism. Bud also helps it in reproduction, but on being cut, regeneration ability plays the role. The two parts cannot be two individuals unless they regenerate. Lastly, hydra does not produce spores as it reproduces by budding.

To develop a whole body from a fragment is possible by proliferation (i.e. repeated division and consequent growth) of cells. This is called regeneration. On the contrary, in budding, a complete organism forms a new individual from a bud, and in fission, the cells divide into two. Fusion is said to occur when two cells combine to mix their traits (like in bacteria) and it is uncommon.

Leishmania has a specific organisation of body. It has a whip-like flagella on one end. Due to this, when its fission occurs, it divides the body such that both get the flagella (duplicated). This is possible in binary fission, but not in multiple fission, which will require the division to occur in different planes.

Plasmodium grows rapidly inside a human body and for this, it divides by multiple fission because binary fission will produce less number of organisms. Since it is a unicellular organism, so regeneration and spore formation do not occur in Plasmodium.

Sexual reproduction involves two parents and their gametes fuse to form a new individual. Thus, formation of gametes is a part of sexual reproduction. Fission, regeneration and spore formation are all asexual methods of reproduction.

Asexual reproduction involves only one parent and its cells divide by mitosis (without any change in chromosomes number). Thus, there is no change in genetic makeup of new cells, and the offsprings are identical to parents. Since this method of reproduction involves simple cell division (without any change in number or traits of chromosomes), so it is faster than sexual method. Thus, here only option (3) is incorrect.

Multiple fission, regeneration and spore-formation, all require the formation of a large number of new cells by repeated division of initial or few cells. But in binary fission, only one division occurs and produces two daughter cells. Thus, binary fission is the fastest mode of reproduction. In fact, cells are known to produce daughter cells in twenty minutes of time from their own birth by binary fission.

'Bread molds' are a type of fungi and reproduce by spore formation. In asexual reproduction, the mold makes spores inside a sporangium. When the spores are ready to leave and spread more molds, the sporangium breaks open and lets the spores float out. In sexual reproduction, its hyphae touch the hyphae of another Rhizopus mycelium. When they fuse, they make round balls called zygospores. After some time, the zygospore makes another sporangium, which then makes spores. During this sexual process, genetic recombination takes place, as with all eukaryotes. 

Higher plants have complex structures and they have specialised parts to perform asexual (vegetative) reproduction. For example, leaves, stem, roots, etc. This formation of new organism from vegetative parts of a plant is called vegetative propagation. On the contrary, spore formation, budding and regeneration are reproductive methods found in lower organisms or plants.