IELTS
JOURNAL
109
Exercise 49: True, False, Not Given
Read the following text about photosynthesis in plants.
Although some of the steps in photosynthesis are still not completely
understood, the overall photosynthetic equation has been known since the
1800s.
Jan van Helmont began the research of the process in the mid-1600s when he
carefully measured the mass of the soil used by
a plant and the mass of the
plant as it grew. After noticing that the soil mass changed very little, he
hypothesised that the mass of the growing plant must come from the water, the
only substance he added to the potted plant. His
hypothesis was partially
accurate—much of the gained mass also comes from carbon dioxide as well as
water.
In 1796, Jean Senebier,
a Swiss pastor, botanist, and naturalist,
demonstrated
that green plants consume carbon dioxide and release oxygen under the
influence of light. Soon afterwards, Nicolas-Théodore
de Saussure showed that
the increase in mass of the plant as it grows could not be due only to uptake of
CO2, but also to the incorporation of water.
According to the text, are the following statements true, false or not given?
1. We now fully understand the process of photosynthesis.
2. Van Helmont's hypothesis did not take into account that plants consume carbon
dioxide.
3. De Saussure demonstrated that both carbon dioxide and water contribute to an
increase in mass in plants as they grow.
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