Biological Reproduction

Isogamous type of sexual reproduction is found in Ulothrix and in majority, the plants are heterothallic. The gametes are found in large number, i.e. 32 to 64 in each gametangium.

On the basis number of estrous cycle (breeding cycle), females of some species can be monoestrous and diestrous. Monoestrous animals are those in which only one estrous cycle can be seen in a year. For example, dogs, fox etc. Whereas, diestrous animals are those in which two estrous cycles are seen in a year. For example, horse, goats etc. So, the correct option is A.

Organisms produced by sexual reproduction have characters from both the parents and are not exactly identical to the parents.

Conjugation is an exchange of genetic material i.e, mode of sexual reproduction in lower organisms.
Scalariform conjugation: It takes place during the night and between the recently divided cells of the conjugating participating filaments. Opposite cells of two filaments develope a conjugation tube by lying side by side and parallel to each other. The conjugation tube between two filament looks like a ladder, through which gamete from one gametangia passes through to fuse with the passive gamete of another filament.

Anisogamy is a type of sexual reproduction which involves the fusion of two dissimilar gametes.

In almost all frogs, egg fertilization happens outside the female's body instead of inside. The female releases her eggs and the male releases his sperm at the same time. In order to make sure that the sperm reach the eggs, the male and female get into a mating posture called amplexus. The male climbs onto the female's back and clasps his forelegs around her middle. 

Reproduction is a process of producing offsprings from parents. It can be sexual, asexual or vegetative. Only sexual reproduction involves the fusion of gametes. It ensures continuity of a species by producing its own kind and also a transfer of genes in further generations.

In sexual reproduction, an egg cell from female and a sperm from a male fuse to form a zygote, precursor to an embryo offspring. The offspring is generally distinct from parents. Both the gametes contain half the number of required chromosomes, that is they are haploid in nature. The zygote contains the exact number of chromosomes required. This is how chromosome number is conserved from generation to generation. The zygote undergoes further cell division to form an embryo. 

Apogamy, diplospory, and sporophytic budding are forms of apomixis, which is the formation of seeds without fertilization. Germination of a vegetative propagule is a method of vegetative reproduction, not seed formation.

Ovoviviparous is the method of reproduction in which animals produce eggs, but instead of laying the eggs, the eggs develop within the mother's body. The eggs hatch within the mother. After hatching, they remain inside the mother for a time and are nourished there. 

Option C viviparous

Fertilised ovary is technically called fruit. But if ovary develops into fruits, without fertilisation, it is called parthenocarpic fruit. Such fruits are generally seedless. Some common examples found in nature are: Citrus, banana, etc., Parthenocarpy can be artificially induced too by application of certain plant hormones, especially, auxins and gibberellins.

• Reproduction is an essential process required for continuity of life and survival of species generation after generation. 
• An individual has a limited lifespan and lives for a defined time period but species survive and evolve for a much longer duration. Reproduction serves no other purpose and is not required for energy production or growth of an organism.