Q.Write the effects of light on plants.

Tropical regions show high species diversity largely because their stable climate (temperature, humidity, day-length) throughout the year favours greater rates of speciation and specialisation -- a true Assertion correctly explained by a true Reason.

Ecologists have long observed that species diversity is generally much higher in the tropics than in temperate or polar regions -- a pattern with several supporting explanations, one of which is climatic stability. Because seasonal fluctuations in temperature, humidity and day length (photoperiod) are comparatively mild and consistent in tropical regions across the year (unlike sharply seasonal temperate/polar climates), organisms there face fewer extreme environmental stresses and can specialise into narrower ecological niches, promoting higher rates of speciation and th …

Homeostasis is the maintenance of a stable internal environment regardless of external fluctuations.

Most organisms are able to maintain a constant internal environment (temperature, osmotic concentration, pH etc.) through physiological (sometimes behavioural) means, a phenomenon called homeostasis (e.g., mammals and birds are 'regulators' that keep body temperature and osmotic concentration constant regardless of the environment).

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Diapause is a dormant, resting stage in which growth and development are temporarily halted until conditions improve.

Many organisms, especially small ones like zooplankton in lakes and ponds, cannot always escape unfavourable conditions (such as extreme temperature, low oxygen, or scarcity of food) by moving away. Instead, they enter a stage of suspended development/dormancy ca …

Abiotic factors are the non-living, physico-chemical components of an ecosystem (temperature, water, soil, light, etc.); bacteria, being living organisms, are part of the biotic community instead.

Ecosystems are made up of abiotic components (temperature, water/humidity, soil composition, light, pH, nutrients) and biotic components (all living organisms — producers, consumers, decomposers). Among the options, temperature, soil and water are all classic abiotic factors that shape where and how organisms live …