Question

q12. (s c.6.n.1.1 ) a student investigates how water temperature affects the amount of oxygen fish need. which step is most important for designing a valid experiment? test only one fish keep all conditions the same except temperature change many variables at once record results without a control group

Explanation:

In a valid experiment to test the effect of water - temperature on fish oxygen needs, only the variable of interest (temperature) should be changed. Keeping all other conditions the same helps isolate the effect of temperature and avoid confounding variables. Testing only one fish may lead to unreliable results due to individual variation. Changing many variables at once makes it impossible to determine which variable is causing the observed effect. Recording results without a control group makes it difficult to assess the impact of the independent variable.

Answer:

Keep all conditions the same except temperature