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IB DP Biology Questions

9.3 Growth in Plants

Question 1

What allows plants to exhibit indeterminate growth and continuously form new organs and tissues?

A. Differentiation of cells in the root apical meristem.

B. Presence of undifferentiated cells in the plant meristems.

C. Elongation of cells in the vascular tissue.

D. Absence of plant hormones in the shoot apex.

Question 2

How does mitotic cell division in the shoot apical meristem contribute to plant growth?

A. It provides cells for root extension and nutrient absorption.

B. It inhibits the production of plant hormones.

C. It provides cells necessary for stem extension and leaf development.

D. It leads to the differentiation of vascular tissue.

Question 3

Which plant hormones are primarily involved in regulating cell division, elongation, and differentiation in the shoot apex?

A. Abscisic acid, ethylene, and jasmonic acid.

B. Auxins, gibberellins, and cytokinins.

C. Salicylic acid, brassinosteroids, and strigolactones.

D. Florigen, traumatin, and systemin.

Question 4

What is the role of auxin efflux pumps in plant growth and development?

A. They prevent the formation of auxin concentration gradients in plant tissues.

B. They set up concentration gradients of auxin in plant tissues, directing growth.

C. They inhibit the active transport of auxin into the cell wall.

D. They decrease the sensitivity of plant tissues to auxin.

Question 5

How does auxin affect cell growth rates in plants?

A. By decreasing the pattern of gene expression.

B. By inhibiting the production of proteins involved in cell wall modification.

C. By changing the pattern of gene expression, leading to the production of growth-related proteins.

D. By disrupting the concentration gradients of auxin in plant tissues.

Question 6

a) Explain how the presence of undifferentiated cells in plant meristems contributes to indeterminate growth and the continuous formation of new organs and tissues. [4]

b) Discuss how mitotic cell division in the shoot apical meristem is essential for stem extension and leaf development. [3]

Question 7

a) Detail the role of plant hormones such as auxins, gibberellins, and cytokinins in regulating cell division, elongation, and differentiation in the shoot apex. [4]

b) How do auxin efflux pumps contribute to setting up concentration gradients of auxin in plant tissues, and how does this affect the direction of plant growth and development? [3]

Question 8

a) Discuss plant tropisms, including phototropism, gravitropism, and thigmotropism, and explain how they enable plants to adapt to their environment. [4]

b) How does auxin affect cell growth rates by altering the pattern of gene expression, and what is the significance of this in plant growth? [3]

Question 9

a) Explain the concept of indeterminate growth in plants and how it differs from determinate growth in animals. [3]

b) How do undifferentiated cells in the meristems contribute to the continuous formation of new tissues and organs in plants? [4]

c) Discuss the significance of the shoot apical meristem in stem extension and leaf development. [3]

Question 10

a) Detail the roles of auxins, gibberellins, and cytokinins in plant growth, focusing on their impact on cell division and elongation. [4]

b) How do plant tropisms, including phototropism and gravitropism, enable plants to optimise their growth in response to environmental conditions? [3]

c) Explain the mechanism by which auxin efflux pumps establish auxin concentration gradients and their influence on plant development. [3]

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