Q.Define "environment" in the ecological sense, naming its two broad components.

Xerophytes show both a thick cuticle and sunken stomata as adaptations to minimise water loss in arid habitats.

Xerophytes are plants adapted to survive in water-scarce (arid/desert) environments. Their key adaptations to reduce transpirational water loss include:

• A thick, waxy cuticle on the leaf/stem surface, which reduces water loss through the epidermis.
• Sunken (recessed) stomata, often located in pits and surrounded by hairs, which trap a layer of humid air near the stomatal pore and reduce the rate of transpiration.

Other common xerophytic adaptations include reduced leaf surface area (spines instead of leaves), deep/extensive root systems, succulent water-storing tissues, and CAM photosynthesis in some species.

Among the major terrestrial biomes, the tropical rain forest is defined by its warm, humid climate (high year-round temperature and heavy rainfall), which supports its extremely high biodiversity.

Different terrestrial biomes are classified largely by their temperature and precipitation (climate) regimes:

• Tropical rain forest: found near the equator; characterised by consistently warm temperatures (roughly 20–34°C) and very high, evenly distributed rainfall (often >200 cm/year) and high humidity — this warm, wet climate supports the greatest biodiversity of any biome (e.g., Amazon, Western Ghats forests).
• Temperate forest: moderate temperatures with distinct seasons, moderate rainfall.
• Coniferous forest (taiga): cold climate with long, harsh winters and short summers.
• Arctic tundra: extremely cold, low precipitation, permanently or seasonally frozen ground.

Since the question asks specifically for the "warm and humid" biome, the tropical rain forest is the correct match.

Autecology looks at one species at a time, in detail, in relation to its habitat and environmental factors.

Autecology (from 'auto-' meaning self/single) is the branch of ecology concerned with the study of a SINGLE species — its individual organisms or a population of that one species — in relation to the environmental factors (abiotic and biotic) affecting it, including its distribution, abundance, adaptations, and life-history traits. It contrasts with synecology, which studies groups of different species (communities) and their interactions with each other and the environment.

Xerophytes are adapted to conserve water, so they show all the listed features — the correct answer is (d).

Xerophytes are plants adapted to survive in dry (arid) habitats with scarce water. Their adaptations all aim to minimise transpiration and store water:

• (a) Thick cuticle — a waxy layer on the leaf/stem cuts down water loss by evaporation.
• (b) Sunken stomata — stomata lie in pits, trapping moist air and reducing transpiration.
• (c) Water-storing tissue — succulent parenchyma stores water for use during drought.

Since xerophytes commonly possess all three, option (d) is correct.

Synecology = community ecology — the study of an entire community of organisms and its interactions with the environment (in contrast to autecology, the study of one species).

Synecology (community ecology) is the study of the structure, composition, development and relationships of a whole biological community — that is, of many populations of different species living together — in relation to their physical environment and to one another.

It is distinguished from autecology, which deals with the ecology of a single species or individual in relation to its environment.