Wilmott's bubbler is used for:

Question

Accepted Answer

The correct option is 2: Photosynthesis experiments

Wilmott's bubbler, often simply referred to as a bubbler, is a classic and highly effective piece of laboratory apparatus specifically designed to provide a visual and quantifiable measure of the rate of oxygen gas evolution during the process of photosynthesis in aquatic plants. The principle is based on the fact that when an aquatic plant, such as *Hydrilla* or *Elodea*, is placed underwater and illuminated, the oxygen produced as a byproduct of photosynthesis is released as bubbles from the cut end of the stem. The bubbler is a simple device that standardizes this process: a conical flask containing the submerged plant and water (often with sodium hydrogen carbonate to ensure a supply of carbon dioxide) is fitted with a capillary tube positioned to collect and release the oxygen bubbles. By simply counting the number of bubbles released from the capillary tube over a fixed period of time (e.g., one minute), researchers and students can accurately determine the rate of gas production. This easily measurable output makes the bubbler an ideal tool for investigating the effects of various environmental factors, such as changing light intensity, temperature, or the concentration of carbon dioxide, on the rate of photosynthesis.

The incorrect option is 1: Transpiration experiments

Transpiration is the essential biological process involving the loss of water vapor from the plant, primarily through the stomata of the leaves. This physiological process is traditionally measured using a piece of equipment called a **potometer** (or transpirometer), which quantifies the rate of water uptake by a plant shoot. The fundamental physical process being measured by the bubbler is the volume of gas produced, whereas a potometer measures the volume of liquid water absorbed. The Wilmott's bubbler, which is calibrated to count oxygen bubbles, is entirely unsuitable for accurately measuring the rate of water loss or water movement, which is the key parameter in transpiration experiments.

The incorrect option is 3: Plant growth studies

Plant growth studies focus on the increase in size, mass, or volume over a long duration, typically involving measurements of parameters such as height, stem circumference, leaf area, or biomass accumulation (fresh or dry weight). While photosynthesis provides the energy for growth, Wilmott's bubbler is designed to measure the *instantaneous* or *short-term* physiological rate of oxygen production—a metabolic activity—rather than the sustained, structural changes of the organism. Specialized tools like linear scales, weighing balances, and leaf area meters are the instruments of choice for the long-term, non-destructive, or destructive quantification involved in measuring plant growth.

The incorrect option is 4: Plant tissue culture

Plant tissue culture refers to a complex set of *in vitro* techniques used to grow or multiply plant cells, tissues, or organs under sterile, carefully controlled, and nutrient-rich conditions. This procedure requires specialized, sterile equipment, including laminar flow hoods and aseptic conditions within test tubes, petri dishes, or culture vessels. The Wilmott's bubbler is a relatively simple device intended for whole-organism or organ-level physiological experiments conducted under non-sterile, ambient laboratory conditions. Therefore, the apparatus has no practical application in the controlled, sterile environment necessary for the initiation or maintenance of plant tissue culture.