A) 

(a) Explain why budding, fragmentation and regeneration are considered the sexual mode of reproduction? 

(b) Describe the regeneration process in planaria using clear diagrams. 

                                                                                                          OR

B) 

Mention the total number of chromosomes along with the sex chromosomes that are present in a human female and a human male. Explain how in sexually producing organisms the number of chromosomes in the progeny remains the same as that of the parents.

 

A) 

(a) Budding, fragmentation and regeneration are all considered Asexual modes of reproduction because these methods involve only one parent. Asexual reproduction is a kind of reproduction by which offspring arise from a single organism (single parent) and inherit the genes of that parent only. Thus The offspring will be exact genetic copies of the parent. 

Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud. 

Fragmentation is also a type of asexual reproduction in which an organism is split into two. 

(b) Regeneration is again a type of asexual reproduction in which organisms can be regenerated from a single parent. 

Regeneration is a form of asexual reproduction. It is the tendency of a simple organism to re-grow its lost parts. Planaria can be cut into the desired number of pieces, and each piece grows through specialized cells into a complete organism. 

                                                                                                          OR

B) 

The total number of chromosomes present in both human males and females is 46. Out of these,2 chromosomes are sex chromosomes. The two sex chromosomes present in males are X and Y, while in the female, both sex chromosomes are X. 

A new individual is formed during sexual reproduction, and it is formed by the fusion of gametes from both parents. These gametes are haploid in nature, i.e. only one set of chromosomes is present in them. Meiosis is responsible for their formation. It is a type of cell division which reduces chromosome number to half. During fertilisation, these haploid gametes are fused, and the two nuclei of these two gametes fuse and the chromosome number are then restored to normal. Hence, the progeny formed has the same number of chromosomes as that of the parents.