(a) Define ecosystem. Discuss the structure and functions of ecosystem. (20 marks) (b) What is apiculture? Describe the various…

An ecosystem is a functional unit in which biotic communities interact with their abiotic environment through energy flow and nutrient cycling. The term was coined by A. G. Tansley in 1935 and elaborated by E. P. Odum. Indian examples include Western Ghats forests, Sundarbans mangroves and Thar desert ecosystems.

Structure of ecosystem. Structurally, an ecosystem has biotic and abiotic components. Biotic components are producers (plants, algae, cyanobacteria), consumers (herbivores, carnivores, omnivores) and decomposers (bacteria, fungi). Abiotic components include physical factors such as light, temperature, water, soil and topography, and chemical factors such as pH, salinity, oxygen, carbon dioxide and nutrients. These form trophic levels: producers, primary consumers, secondary consumers and decomposers.

Functions of ecosystem. Functionally, an ecosystem performs energy flow and nutrient cycling. Solar energy enters through producers and passes through trophic levels; Lindeman’s 10% law states that only about 10% of energy is transferred from one trophic level to the next, the rest being lost as heat. Nutrients such as carbon, nitrogen, phosphorus and water are recycled through biogeochemical cycles. Ecological pyramids represent trophic structure. The pyramid of energy is invariably upright, while pyramids of numbers and biomass may be inverted, as in a tree ecosystem (numbers) or a marine phytoplankton ecosystem (biomass). Odum’s systems approach highlighted ecosystem services, homeostasis and stability, central to valuation of services such as pollination, water regulation and carbon sequestration.

Apiculture and beekeeping. Apiculture is the science and practice of managing honeybee colonies for honey, wax, pollen, propolis and pollination. In India, the main managed species are Apis cerana indica and Apis mellifera; wild species such as Apis dorsata and Apis florea are ecologically important and their products may be collected, but they are not normally maintained in hives for systematic apiculture. Beekeeping methods range from traditional fixed-comb hives made of logs, clay pots or bamboo, to transitional top-bar hives, and modern movable-frame hives such as the Langstroth hive and the Newton or Indian hive. Movable frames allow inspection, disease control, swarm management and honey extraction without destroying combs. Institutions such as the National Dairy Development Board and the Khadi and Village Industries Commission have promoted apiculture as a rural livelihood, especially among small farmers and tribal communities.

Uses of honey. Honey is a nutrient-rich source of sugars, vitamins and minerals. Medicinally, it has antimicrobial, anti-inflammatory and wound-healing properties and is used in traditional and modern preparations. It is also used in cosmetics, food processing, pharmaceuticals and industrial applications such as flavouring or preservative. Its pollination value is equally important for crop productivity and ecosystem health.

SEM and TEM. Scanning electron microscopy and transmission electron microscopy differ systematically. In SEM, a focused electron beam scans the surface of a specimen; secondary electrons emitted from the surface form a three-dimensional image of surface ultrastructure. In TEM, the electron beam passes through an ultrathin specimen; transmitted electrons form a two-dimensional image of internal organelles and membranes. Specimen preparation differs: SEM samples are usually dehydrated, critical-point dried and coated with metal, while TEM samples require ultrathin sectioning and heavy-metal staining. Resolution is higher in TEM, about 0.1–0.5 nm, compared with 3–10 nm in SEM; TEM also achieves greater magnification. SEM has greater depth of field and can examine larger, solid, dry or coated samples, whereas TEM requires very thin, conductive or stained sections. In zoology, SEM is used for studying insect cuticles, pollen grains, feather surfaces and parasite morphology, while TEM is used for visualizing mitochondria, nuclei, membranes, viruses and disease-related cellular changes.

Thus, ecosystem understanding, sustainable apiculture and electron microscopy are interconnected in modern zoology: ecological principles guide conservation and livelihoods, beekeeping applies pollinator biology to rural development, and electron microscopy provides the ultrastructural evidence needed for taxonomy, pathology and applied research.