Question 1

What are tropic responses in plants?

Accepted Answer

Tropic responses are growth movements in plants that occur in response to environmental stimuli. These responses are directional, meaning the plant grows towards or away from the stimulus. Common types of tropic responses include phototropism (response to light), geotropism (response to gravity), and hydrotropism (response to water). Understanding these responses is crucial for the Cambridge IGCSE Coordinated Science curriculum as they illustrate how plants coordinate and respond to their environment.

Question 2

How does phototropism work in plants?

Accepted Answer

Phototropism is the growth response of a plant in direction to light. In phototropism, plant shoots typically grow towards the light source, which is known as positive phototropism. This occurs because the hormone auxin accumulates on the shaded side of the plant, causing cells there to elongate more than those on the light-exposed side, thus bending the plant towards the light. This concept is important in the Cambridge IGCSE Coordinated Science syllabus as it demonstrates plant adaptation and survival strategies.

Question 3

What is the difference between positive and negative tropic responses?

Accepted Answer

Positive tropic responses occur when a plant grows towards a stimulus, such as roots growing towards gravity (positive geotropism) or shoots growing towards light (positive phototropism). Negative tropic responses occur when a plant grows away from a stimulus, such as roots growing away from light (negative phototropism). These distinctions are essential for understanding plant behavior and are covered in the Cambridge IGCSE Coordinated Science curriculum under Coordination and Response.

Question 4

Why is geotropism important for plant growth?

Accepted Answer

Geotropism, also known as gravitropism, is crucial for plant growth as it ensures that roots grow downwards into the soil (positive geotropism) to anchor the plant and absorb water and nutrients, while shoots grow upwards (negative geotropism) to access light for photosynthesis. This directional growth is vital for plant stability and survival, making it a key topic in the Cambridge IGCSE Coordinated Science syllabus.

Question 5

How do hormones influence tropic responses in plants?

Accepted Answer

Plant hormones, particularly auxins, play a significant role in tropic responses. Auxins are distributed unevenly in response to stimuli such as light and gravity, causing differential growth rates in plant cells. For example, in phototropism, auxins accumulate on the shaded side of the plant, promoting cell elongation and causing the plant to bend towards the light. Understanding the role of hormones in tropic responses is a fundamental aspect of the Cambridge IGCSE Coordinated Science curriculum, highlighting the complex coordination mechanisms in plants.

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