A seed treatment uses gibberellic acid to favour germination by opposing ABA's dormancy-promoting effects. Which hormone class is being applied?

• Abscisic acid
• Cytokinins
• Gibberellins

A young shoot is lit from one side. How does it bend toward the light?

• Auxin on the shaded side promotes faster elongation there
• Auxin on the lit side promotes faster elongation there, bending the shoot toward light
• Roots push the shoot upward while leaves pull it sideways toward the light

Which pair of responses can ethylene promote?

• Ripening in some fruits and leaf senescence
• Seed dormancy and drought-related stomatal closure
• Cell division in cultures and release of side-bud growth

How can removing a growing shoot tip encourage side buds to grow?

• Removing the tip adds auxin to every bud, forcing all of them to grow at once
• Removing the tip reduces its auxin signal, which can release side buds
• Removing the tip eliminates every hormone, so all side buds grow without signals

In many responsive tissue cultures, increasing auxin relative to cytokinin can favour root formation over shoot formation. True or false?

Which sequence links hormone detection by a receptor to a change in target-gene transcription?

• Receptor binding changes ion channels, producing a response without changing target-gene transcription
• Receptor binding changes signalling proteins, which alter transcription-factor activity and transcription
• The hormone first changes target-gene transcription; newly made proteins then activate its receptor and relay

ABA reaches two tissues at the same concentration. One responds, but the other does not. Which interpretation is justified?

• Receptor or downstream differences could explain the result; it does not locate the cause
• The result locates the difference at ABA receptors, so downstream signalling need not be tested
• Equal ABA concentrations establish equal receptor activity, so the difference must be downstream

Two cultures of the same tissue have the same auxin-to-cytokinin ratio but different total hormone doses. Sam predicts identical root formation. Which claim is justified?

• The shared ratio guarantees identical root formation in both cultures, even if the absolute doses differ
• The higher total dose guarantees shoot formation, while the lower total dose guarantees root formation
• The ratio alone is insufficient; the different absolute doses may affect root formation