Question

Who provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch? (a) Sachs (b) Engelmann (c) Van Niel (d) Blackmann

Short answer

Julius von Sachs provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch, hence the correct answer is (a) Sachs.

Step-by-step solution

Identify the Contribution

To solve this exercise, we must recall the scientific history and identify which scientist provided the evidence that glucose is formed during photosynthesis and is then stored in the form of starch.

Recall Historical Experiments

We remember that Julius von Sachs, a German botanist, is known for his work on photosynthesis, including his experiments in the 19th century that showed that starch is a product of the photosynthetic process in plants. He used iodine to stain leaves and showed that starch accumulation occurs in areas that receive light.

Choose the Correct Answer

Based on historical experiments and contributions, Julius von Sachs is the scientist who provided evidence that glucose is formed during photosynthesis and is then stored as starch. Therefore, the correct answer is (a) Sachs.

Key concepts

Julius von Sachs

Julius von Sachs was a pioneering German botanist who made significant advances in plant physiology and is renowned for his profound impact on our understanding of photosynthesis. His influential work in the latter half of the 19th century led to the discovery that plants convert light energy into chemical energy.

Von Sachs was particularly interested in how plants produce and store food. In his experiments, he ingeniously used iodine to stain parts of plants and observed that starch, a complex carbohydrate, was forming in areas exposed to light. This was critical evidence supporting the idea that photosynthesis involves the transformation of carbon dioxide and water into glucose, utilizing light energy—glucose that is sometimes subsequently stored as starch in plant tissues.

His research not only unveiled the mystery of plant nourishment but also led to the development of new methods in plant physiology research, influencing many future scientists. The educational materials on photosynthesis often reference his experiments as a foundation for understanding how sunlight is essential for plant life.

Starch in Plants

Starch plays a critical role as an energy storage molecule in plants. It is the way by which plants store the glucose produced during photosynthesis—a process for which Julius von Sachs found pivotal evidence. Starch accumulates primarily in the chloroplasts of plant cells and serves as a reserve of energy that plants can access when photosynthesis is not possible, like during the night.

Interestingly, starch is not immediately formed during photosynthesis. Initially, plants produce simple sugars like glucose, which can be rapidly used for energy or growth. Then, when excess glucose is present, it links together to form the more complex molecule starch. This transition from glucose to starch in plants is both an efficient storage strategy and a vital part of plant metabolism.

It is vital for students to understand the conversion of sunlight into chemical energy (glucose), and then its storage as starch, which ultimately underpins the energy flow in ecosystems and the food web. The simple concept that photosynthetic organisms are the base for most life on Earth hinges on molecules like starch.

Biological Experiments

Biological experiments have been essential in uncovering the complexities of life processes, such as photosynthesis. Julius von Sachs’ work is a prime example of how methodical experimentation can yield profound insights. In the classroom, understanding how these experiments are designed and interpreted is as important as the results they produce.

Experiments in biology often start with a hypothesis—an educated guess based on observation. Scientists then design experiments to test this hypothesis, collect data, and analyze the results. Von Sachs' use of iodine to detect starch presence is a classic biological experiment that combines observation with chemical analysis to draw a conclusion about plant physiology.

In an educational setting, it is important to remember that encouraging students to think like scientists—to question, hypothesize, test, and conclude—fosters a deeper understanding of biology. Students can recreate some of von Sachs' experiments to see the formation of starch in plants firsthand, solidifying their grasp on the process of photosynthesis and the scientific method.