Question - five sets of identical plants, all with the same starting mass, were grown. Each set was given a different treatment. After two weeks of growth the plants were reweighed and all had increased in mass. These were the average masses of the plants in each of the five sets after two weeks:
-ideal conditions = 34g
-only half of the minerals = 26g
-only half of the light = 18g
-only half of the air = 28g
-only half of the water = 20g
(I) name the control variables during this investigation = same plant and same starting mass
(Ii) Discuss the fact that the average masses have been given = you don’t know the range and how even the mass increase was.
(iii) which one was the control = ideal
(Iv) which treatment affected the growth the most = half the light
(V) suggest the reason for the ‘half the light’ result = light is essential for photosynthesis which produces the starch + sugar plants need for survival.
(Vi) suggest the reason for the ‘half of the minerals’ result = nitrates supply oxygen which is needed to make proteins for healthy growth. Reduces plants ability to photosynthesise and grow properly.
(Vii) suggest the reason for the ‘half of the air’ result = plants roots need air, plants take in co2 from the air to use in the process of photosynthesis.
are they correct??
Yes, they're all correct . However, in question one, you could be more specific by saying that the same plant species is used. Also, for question, most air is taken in through the leaves. To be even more specific, you could say that carbon dioxide diffuses into the plant leaves through the stomata (opened by guard cells) where it is then used in the process of photosynthesis, to produce glucose (which is then stored as starch).