Describe inheritance of kappa particles in Paramecium and shell coiling in Lymnaea.

In Paramecium, the inheritance of kappa particles is a form of symbiosis where the kappa particles are passed down from one generation to the next. Kappa particles are small, virus-like particles that live inside the cytoplasm of Paramecium cells and provide protection against certain strains of bacteria. When a Paramecium cell divides, the kappa particles are also divided and distributed to the daughter cells, ensuring that the symbiotic relationship is maintained in the next generation.

In Lymnaea, the inheritance of shell coiling is a genetic trait that determines the direction in which the shell of the snail coils. This trait is passed down from parent snails to their offspring through their genetic material. The direction of shell coiling is determined by a single gene with two alleles, one for left-handed coiling and one for right-handed coiling. Offspring inherit one allele from each parent, which determines the direction of their shell coiling. This trait can be influenced by environmental factors as well, but the genetic inheritance plays a significant role in determining the shell coiling pattern in Lymnaea snails.

Inheritance of Kappa Particles in Paramecium

- Kappa particles are symbiotic bacteria that live in the cytoplasm of certain strains of Paramecium.
- They protect their host from the toxic effects of a pesticide called paramecin.
- Kappa particles are inherited in a non-Mendelian manner, known as cytoplasmic inheritance.
- When a paramecium with kappa particles divides, the particles are randomly distributed to daughter cells.
- As a result, some daughter cells inherit kappa particles and become resistant to paramecin, while others do not.

Shell Coiling in Lymnaea

- In the snail Lymnaea, the direction of shell coiling (right-handed or left-handed) is genetically determined.
- The gene responsible for shell coiling shows incomplete dominance.
- Heterozygous individuals (Ss) have an intermediate phenotype, with their shells coiled slightly to the right or left.
- Homozygous dominant individuals (SS) have right-handed shells, while homozygous recessive individuals (ss) have left-handed shells.

Key Differences

- Parental contribution: Kappa particles are maternally inherited (provided by the mother), while the shell coiling gene is inherited from both parents.
- Mechanism of inheritance: Kappa particles are inherited non-Mendelianly, while shell coiling is inherited Mendelianly.
- Dominance: Kappa particles exhibit no dominance (paramecin resistance or susceptibility is inherited equally from either parent), while the dominant allele for shell coiling is right-handedness.
- Phenotype: Kappa particles determine resistance to a pesticide, while the shell coiling gene determines the direction of shell coiling.