Heterosis is the phenomenon in which progeny of various varieties of a species or crosses between species exhibit greater biomass, as well as the speed of development, and fertility of either of the parents. Various models have been posted to explain heterosis, including the concept of dominance, overdominance, and pseudo-overdominance.

Totipotency is the ability of a cell to differentiate and give rise to a whole new organism. Totipotency is exhibited by the cells such as embryonic stem cells that can differentiate into any type of body cell.

Artificial hybridization helps to develop quantitative outcomes in the cattle. Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. It results in homozygosity, which can increase the chances of offspring being affected by deleterious or recessive traits. An individual who inherits such deleterious traits is colloquially referred to as inbred.

Write the application of plant tissue culture.

The culturing of isolated protoplasts or cells or tissue or organ on a nutrient medium under controlled aseptic conditions to produce complete plant or plant parts is called tissue culture. The application of plant tissue culture follows:- Micropropagation or clonal propagation:- Through the process of cell, tissue and organ culture a large number of plants can be raised in small areas and in less time. As all the plants in tissue culture are genetically identical, this procedure is also known as clonal propagation. Production of virus-free plants:- Asexually reproducing crop plants are prone to viral infection The meristem or shoot tip culture produces virus-free plants. Synthetic seeds/artificial seeds: - The somatic embryos/plantlets encapsulated in protective capsules of calcium alginates to prevent desiccation are known as artificial seeds. These are used for rapid propagation of crop plants. Secondary metabolites production: - Plant tissue culture involving large scale cell suspension cultures are in use of commercial production of secondary metabolites like alkaloids, tannin, resin, latex etc. Embryo rescue: - It has been observed that in some instances of interspecific crosses through pollination and fertilization are successfully completed, the embryo does not develop after an initial stage. In such cases, immature embryos are dissected out from the fruit (seeds) and grown in a nutrient medium to develop into plantlets. This technique of growing immature embryos is known as embryo rescue. Endosperm culture: - It is employed to produce triploids. This is used to produce seedless apple, pear etc., having good commercial values. Haploid plants : Haploid plant can be created by culture of haploid cells such as pollen grains, gamete, etc. Haploids can be used to generate genetic homozygotes by doubling of chromosomes using colchicine.

What is single cell protein? Give two examples.

The single-cell protein (SCP) refers to the protein (biomass) obtained from any unicellular or multicellular organisms like algae and yeast, which are used as food sources or additives. Humans or other animals may consume this protein as food or food additives. Some common microbes used as SCP producers are bacteria including Methylophilus, Methylotrophus, Brevibacterium and cyanobacteria including Spirulina.

The undifferentiated mass of the cells formed from the division of explant in an artificial media, under controlled conditions is called a callus. Callus contains actively dividing meristematic cells that are totipotent and are capable of giving rise to a whole plant.

Totipotency is the ability of a cell to differentiate and give rise to a whole new organism. Totipotency is exhibited by the cells such as embryonic stem cells that can differentiate into any type of body cell.

Artificial hybridization helps to develop quantitative outcomes in the cattle. Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. It results in homozygosity, which can increase the chances of offspring being affected by deleterious or recessive traits. An individual who inherits such deleterious traits is colloquially referred to as inbred.