Her conclusion is invalid because using sand instead of soil slows down plant growth. Fertilizer, on its own, does not 'greatly' increase the size of the plant.
The correct way to do this experiment would be to keep all other parameters same, except the fertilizer. This will give her accurate results.
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Answer: Possession of Valves
Explanation: Veins possess valves which ensures that blood flows in only one direction. Valves helps blood to flow back to the heart against gravitational force.
Arteries don't have valves because the pressure originating from the heart is capable of causing the blood to flow in one direction.
Answer:
(UV) radiation is with recent research showing that UV radiation has the capacity to degrade folate in human blood and skin.