The example using the potato cylinders is a bit confusing. To me, the aim of that experiment is to find out the water potential of the potato tissue. It is not looking at the relation between an independent and a dependent variable. Thus, even the rate of osmosis is only a method to find out the water potential of the tissue. I wonder if it can be considered as the dependent variable, or, using the same logic, the percentage change in weight of the potato tissue also has the same function.
Thanks so much for the comment, Mr. Tong. Indeed, the aim of the experiment is to find out the water potential of the potato tissue. By the resutls of the 6 set-up, the water potential of the potato cells could be found (estimated). In the design of the exp, the conc of sucrose solution is changing (IV) and it affected the rate of osmosis (DV) and the % change in mass is just a measurement. When I read your comment, I think of the exp: the effect of temp on the activity of amylase. For this aim, the IV and DV are obviously shown in the aim. However, when the aim changes to: Find the optimum temp of amylase activity. The aim is not for studying a causal relationship but the design of the experiment still has to use relationship between temp and the activity of amylase. By comparing and interpreting the results of each experiment, the aim is achieved.
@@BiologyMan But finding optimum temperature still means that you are finding the temperature at which the enzyme is working at its highest rate. Thus, rate of enzyme activity is still obviously the dependent variable. On the other hand, in the potato experiment, the aim of the experiment is not to find out the rate of osmosis under different sucrose concentration. OK, maybe you can still say that you want to find out the sucrose concentration at which there is no net osmosis. Then the rate of osmosis may be called the dependent variable. However, the logic still holds if I say that I want to find out the sucrose concentration at which there is no net change in weight. In that case, does it make change in weight also becoming the dependent variable?
Dependent variable is not always quantitative. For example, in the experiments that study the need of light in photosynthesis, whether the plant can carry out photosynthesis is the dependent variable; but it may not be measured as a quantitative variable.
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不同組織的自變量為何不是4個? 薯仔點解唔當既?
Anyway, your hard work is highly appreciated. I may be just too picky XD
No, your comments make me think! LIKE!
The example using the potato cylinders is a bit confusing. To me, the aim of that experiment is to find out the water potential of the potato tissue. It is not looking at the relation between an independent and a dependent variable. Thus, even the rate of osmosis is only a method to find out the water potential of the tissue. I wonder if it can be considered as the dependent variable, or, using the same logic, the percentage change in weight of the potato tissue also has the same function.
Thanks so much for the comment, Mr. Tong. Indeed, the aim of the experiment is to find out the water potential of the potato tissue. By the resutls of the 6 set-up, the water potential of the potato cells could be found (estimated). In the design of the exp, the conc of sucrose solution is changing (IV) and it affected the rate of osmosis (DV) and the % change in mass is just a measurement.
When I read your comment, I think of the exp: the effect of temp on the activity of amylase. For this aim, the IV and DV are obviously shown in the aim. However, when the aim changes to: Find the optimum temp of amylase activity. The aim is not for studying a causal relationship but the design of the experiment still has to use relationship between temp and the activity of amylase. By comparing and interpreting the results of each experiment, the aim is achieved.
@@BiologyMan But finding optimum temperature still means that you are finding the temperature at which the enzyme is working at its highest rate. Thus, rate of enzyme activity is still obviously the dependent variable. On the other hand, in the potato experiment, the aim of the experiment is not to find out the rate of osmosis under different sucrose concentration. OK, maybe you can still say that you want to find out the sucrose concentration at which there is no net osmosis. Then the rate of osmosis may be called the dependent variable. However, the logic still holds if I say that I want to find out the sucrose concentration at which there is no net change in weight. In that case, does it make change in weight also becoming the dependent variable?
Dependent variable is not always quantitative. For example, in the experiments that study the need of light in photosynthesis, whether the plant can carry out photosynthesis is the dependent variable; but it may not be measured as a quantitative variable.