Question 1

What are the primary factors affecting growth in plants?

Accepted Answer

Growth in plants is influenced by several factors, including light, water, temperature, and nutrients. Light is crucial for photosynthesis, which provides the energy needed for growth. Water is essential for maintaining cell turgor and transporting nutrients. Temperature affects enzymatic activities and metabolic rates, while nutrients like nitrogen, phosphorus, and potassium are vital for various physiological functions. Understanding these factors is essential for IB DP Biology students studying plant biology.

Question 2

How do hormones regulate plant growth?

Accepted Answer

Plant hormones, or phytohormones, play a critical role in regulating growth and development. Auxins promote cell elongation, especially in the stem. Cytokinins stimulate cell division and influence nutrient mobilization. Gibberellins are involved in seed germination and stem elongation. Abscisic acid helps in stress responses and dormancy, while ethylene influences fruit ripening and leaf abscission. These hormones interact in complex ways to ensure proper growth and adaptation to environmental changes, a key concept in IB DP Biology.

Question 3

What is the role of meristems in plant growth?

Accepted Answer

Meristems are regions of undifferentiated cells in plants that are capable of division and growth. They are crucial for primary and secondary growth. Apical meristems, located at the tips of roots and shoots, contribute to the elongation of plant parts. Lateral meristems, such as the vascular cambium and cork cambium, are responsible for the thickening of stems and roots. Understanding meristems is fundamental for students studying plant biology in the IB DP curriculum.

Question 4

How does phototropism affect plant growth?

Accepted Answer

Phototropism is the growth response of a plant in direction to light. It is primarily controlled by the hormone auxin, which redistributes to the shaded side of the plant, causing cells to elongate more on that side and the plant to bend towards the light. This adaptation maximizes light absorption for photosynthesis, a critical process for plant growth. Phototropism is an important topic in IB DP Biology as it illustrates how plants adapt to their environment.

Question 5

What is the significance of secondary growth in plants?

Accepted Answer

Secondary growth refers to the increase in thickness or girth of plant stems and roots, primarily due to the activity of the vascular cambium and cork cambium. This growth is significant for providing structural support and increasing the plant's ability to transport water and nutrients. It is especially important in woody plants, allowing them to grow taller and withstand environmental stresses. Understanding secondary growth is essential for IB DP Biology students as it highlights the complexity of plant development.

Growth in plants

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