Science (086) — AI-generated practice question

Plants respond to gravity through geotropism. Roots show positive geotropism (grow downward, towards gravity), while shoots show negative geotropism (grow upward, away from gravity). This opposite response occurs because the two organs have different sensitivities to the growth hormone auxin — the same concentration that promotes cell elongation in shoots inhibits growth in roots.

This is useful for survival: roots growing downward anchor the plant firmly in soil and absorb water and minerals, while shoots growing upward receive sunlight for photosynthesis. Together, these opposite responses ensure the plant can carry out all essential life functions.

Source: Chapter 6, Section 6.2.2 — Movement Due to Growth

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• The key term is geotropism (gravity + tropism). Roots = positive geotropic; shoots = negative geotropic.
• Examiners expect you to name the hormone (auxin) and note that the same stimulus causes opposite effects in roots vs. shoots.
• The survival benefit must cover both organs — marks are split between root function (anchorage/absorption) and shoot function (photosynthesis/light capture).
• Do not confuse geotropism with phototropism (light stimulus).