Auxin can be bioassayed by(a)Lettuce hypocotyl elongation(b)Avena coleoptile curvature(c)Hydroponics(d)Potometer

Auxin, a plant hormone responsible for promoting growth and development, can be bioassayed using several methods. Among the options you've provided:

(a) Lettuce hypocotyl elongation: This is a common method for bioassaying auxin. Auxin promotes cell elongation, so by measuring the elongation of lettuce hypocotyls (the stem-like structures of young seedlings), you can infer the presence and effectiveness of auxin.

(b) Avena coleoptile curvature: This is another classic bioassay method. Auxin causes bending or curvature in the growth of oat (Avena) coleoptiles (protective sheaths covering emerging leaves or stems) due to differential growth rates on the two sides. The degree of curvature can indicate the concentration of auxin.

(c) Hydroponics: While hydroponics itself is a method of growing plants without soil by providing nutrients through water, it can also be used in auxin bioassays. By controlling the concentration of auxin in the nutrient solution and observing the plant's responses, you can assess the effect of auxin.

(d) Potometer: A potometer is a device used to measure the rate of water uptake by a plant. While this method isn't typically used for direct auxin bioassays, it can indirectly provide information about plant growth and water uptake, which can be influenced by auxin.

In summary, both (a) Lettuce hypocotyl elongation and (b) Avena coleoptile curvature are commonly used methods for directly bioassaying auxin activity. Hydroponics and potometers are related to plant growth and water uptake, which can be influenced by auxin but are not direct methods for auxin bioassays.