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To determine the effect of a plant parasite on the plant’s growth, an experiment was carried out with alfalfa plants - VCE - SSCE Biology - Question 4 - 2005 - Paper 1
Question 4
To determine the effect of a plant parasite on the plant’s growth, an experiment was carried out with alfalfa plants. Two alfalfa seeds were planted into each of 30 ... show full transcript
Worked Solution & Example Answer:To determine the effect of a plant parasite on the plant’s growth, an experiment was carried out with alfalfa plants - VCE - SSCE Biology - Question 4 - 2005 - Paper 1
Step 1
Why was the dry weight of the plants measured?
Answer
The dry weight of the plants was measured to provide an indication of plant growth and biomass. This metric reflects the amount of organic matter in the plants, which is a critical parameter in assessing their overall health and development. Water content can vary among individual plants, making it an unreliable indicator of growth when comparing results. Thus, measuring dry weight ensures that the assessment focuses on the actual growth of plant material.
Step 2
Suggest what the root parasites were obtaining from the plant.
Answer
The root parasites were likely obtaining essential nutrients from the alfalfa plants. This could include substances such as glucose, which serves as a primary energy source, as well as other necessary nutrients that support their growth and functioning.
Step 3
Given the data above, state one conclusion about the effect of the parasites on the alfalfa.
Answer
The data indicates that the presence of root parasites negatively affects the growth of alfalfa plants. The total dry weights of groups with parasites (927 gm for Odontites rubra and 968 gm for Rhinanthus serotinus) were significantly lower than that of the control group (1483 gm). This suggests that the parasites may be reducing or slowing down the plant's growth by siphoning off vital resources.