Question

Корни растений обычно растут вертикально вниз, в глубь почвы. А какой механизм позволяет ИМ ориентировать свой рост именно в этом направлении? Для выяснения ЭТОГО вопроса учёные придумали клиностат приспособление, котором Можно зафиксировать горшок с растением или чашки Петри со средой, на которой растут растения, и вращать их вокруг своей оси примерно с частотой 1 оборот в минуту. При таком вращении корни перестают расти в глубь почвы Начинают загибаться вверх, иногда даже закручиваясь в спираль. Какой механизм ориентации корней, ПО Вашему мнению, является наиболее реальным?

Answer 1

Ответ:

геотропизм

Объяснение: В корнях есть особые органеллы – амилопласты, в них накапливается крахмал, что придаёт амилопластам значительный вес. Амилопласты давят на клетки и передают сигнал о расположении корня в пространстве. При вращении амилопласты по очереди давят на разные стороны клетки, поэтому корень не может сориентировать рост в одном направлении.

Answer 2

Mechanism of Root Orientation in Plants

The mechanism that allows plant roots to orient their growth vertically into the soil is known as gravitropism or geotropism. Gravitropism is a plant's response to gravity, which influences the direction of root growth. When a plant is placed horizontally or at an angle, the root tip detects the gravitational pull and responds by growing in the opposite direction, towards the center of the Earth.

The process of gravitropism involves the redistribution of auxin, a plant hormone, in response to gravity. Auxin is synthesized in the shoot tips and transported downwards through the plant. When the root tip detects gravity, it redistributes auxin to the lower side of the root, inhibiting growth on that side and promoting growth on the upper side. This differential growth causes the root to bend and grow vertically downwards, towards the center of gravity.

To investigate the mechanism of root orientation, scientists have developed a device called a clinostat. A clinostat is a rotating apparatus that can hold a plant pot or a Petri dish with a growing medium, allowing it to be rotated around its axis at a controlled speed, usually around one revolution per minute. By subjecting plants to continuous rotation, the gravitational stimulus is eliminated, and the roots no longer grow vertically downwards. Instead, they start to bend upwards, sometimes even spiraling.

While the clinostat experiment disrupts the normal gravitropic response, it does not provide a definitive answer to the exact mechanism of root orientation in plants. However, it suggests that gravity plays a crucial role in guiding root growth in the vertical direction. The redistribution of auxin is likely involved in this process, but further research is needed to fully understand the underlying molecular and cellular mechanisms.

In conclusion, the mechanism of root orientation in plants is primarily governed by gravitropism, which involves the redistribution of auxin in response to gravity. The clinostat experiment, which disrupts the normal gravitropic response, demonstrates that gravity is a key factor in guiding root growth vertically into the soil. However, more research is needed to uncover the precise molecular and cellular mechanisms involved in this process.