The Dna

In the double helix structure of DNA, the two strands are complementary, meaning adenine pairs with thymine and cytosine pairs with guanine. The strands run in opposite directions (anti-parallel), with one strand oriented in the 5’ to 3’ direction and the other in the 3’ to 5’ direction.

Plasmids are circular DNA molecules capable of autonomous replication. They are commonly found in prokaryotic cells like bacteria, not in eukaryotic cells.

{Glomus} species form mycorrhizal associations with plant roots. These fungi enhance the absorption of nutrients, particularly phosphorus, and improve water uptake. They also provide resistance to root pathogens and increase the plant’s tolerance to drought and salinity.

In the fertilised embryo sac of an angiosperm: A: Degenerating synergids – Synergids disintegrate after fertilization. B: Zygote – Formed by the fusion of the male gamete and the egg cell. C: Primary Endosperm Nucleus (PEN) – Formed by the fusion of the second male gamete with two polar nuclei. D: Degenerating antipodals – Antipodals disintegrate after fertilization.

Pseudocopulation refers to the process where a male insect is attracted to the flower's patterns, mistaking them for a female insect. The male attempts to copulate, inadvertently transferring pollen and pollinating the flower.

Flocs are masses of bacteria and fungi that aggregate during the secondary treatment of sewage. These flocs help in the breakdown of organic matter in wastewater, significantly reducing BOD (Biochemical Oxygen Demand).

Pleiotropism refers to the phenomenon where a single gene influences multiple phenotypic traits. For example, the gene responsible for sickle-cell anaemia affects both the shape of red blood cells and oxygen transport efficiency.

The ‘rop’ gene regulates the plasmid copy number by controlling the replication of the plasmid within the host cell.

The symptoms of malaria do not appear immediately because the parasite undergoes an incubation period within the human liver and red blood cells before multiplying. Symptoms appear after 10–14 days, once the merozoites are released into the bloodstream, causing fever, chills, and other symptoms.

Transgenic animals are organisms that have had foreign genes inserted into their genome using recombinant DNA technology.

An ecological pyramid represents the trophic structure and functional levels in an ecosystem, such as energy, biomass, or number of organisms at each trophic level.