OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

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Get ready for the OCR GCSE Biology exam with our comprehensive quiz, featuring flashcards and multiple choice questions. Understand the exam format, key topics, and effective study strategies to excel.

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What role does the hormone auxin play in phototropism?

It inhibits growth on the light side
It stimulates growth on the shaded side
It remains constant throughout the plant
It encourages leaf drop to reduce water loss

The correct answer is: It stimulates growth on the shaded side

Auxin plays a crucial role in the plant growth response known as phototropism, which is the way plants grow towards light. When a plant is exposed to light from one direction, auxin is distributed unevenly; it accumulates more on the shaded side of the plant. This increased concentration of auxin on the shaded side stimulates growth in that area. As a result, the cells on the shaded side elongate more than those on the light-exposed side, causing the plant to bend towards the light. By promoting growth on the shaded side, auxin enables the plant to optimize its photosynthesis by allowing it to capture more light for energy production. This mechanism highlights the importance of auxin in helping plants adapt to their environment for survival and growth. The other options do not accurately reflect the role auxin plays in responding to light stimuli.