Suresh prepares slides with pollen grains in different sugar concentrations. Class 9

Suresh prepares slides with pollen grains in different sugar concentrations. Class 9

Question 1.

Suresh prepares slides with pollen grains in different sugar concentrations (0%, 2.5%, 5%, 7.5%, 10%) to study the germination of pollen. Class 9

(i) What are the different hypotheses which can be tested using this set-up?

(ii) What parameters should be kept the same in this set-up?

Answer:

(i) The following hypotheses can be tested:

Pollen germination rate increases as sugar concentration increases up to an optimal level. There is an optimal sugar concentration at which pollen germination is highest; both lower and higher concentrations result in reduced germination. Pollen grains do not germinate in the absence of sugar (0% concentration). Too high a sugar concentration (osmotic stress) inhibits pollen germination compared to moderate concentrations.

(ii) The following parameters (variables) should be kept constant: Type of pollen grains used (same species and same batch). Amount of pollen grains placed on each slide. Temperature and humidity of the environment. Duration for which pollen is allowed to germinate before observation. Volume of sugar solution used on each slide. pH of the solution. Microscope magnification and light conditions for observation.