Question

Decide if the statements below are correct or incorrect.

A. A knock-out mutation in one of the ABC genes results in a flower that lacks one of the whorls but still has the other three whorls intact and in the usual order.
B. The flower homeotic genes are all regulated by a master gene called APETAL.
C. Homeotic mutants show that petals and sepals are modified leaves, while stamens and carpels are modified thorns.
D. Flowers are composed of whorls that can differentiate into stamens, carpels, sepals, or petals, depending on which homeotic genes are active in each whorl.
E. A knock-out mutation in one of the ABC genes results in a flower that still has four concentric whorls, but in an abnormal order and with some structures duplicated.

Answer 1

Statement A is correct, stating a knock-out mutation in one of the ABC genes results in missing a flower whorl. Statement B is incorrect because flower homeotic genes are regulated by A, B, and C genes, not APETAL. Statements C is incorrect as it falsely suggests stamens and carpels are modified thorns; D is correct, affirming flower composition is dependent on homeotic gene activity in each whorl; E is incorrect, as it confuses the effects of a ABC gene knock-out mutation.

Step-by-step explanation:

Assessing the statements about flower genetics and morphology, we can clarify each point:

• Statement A is correct. A knock-out mutation in one of the ABC genes can indeed result in a flower lacking one of the whorls while maintaining the usual order of the remaining three.
• Statement B is incorrect. The master genes that regulate flower organ identity are known as A, B, and C genes, not APETAL.
• Statement C is incorrect. Homeotic mutants indicate that petals and sepals are indeed modified leaves, but stamens and carpels are not modified thorns; they are instead evolutionarily modified reproductive organs of the flower.
• Statement D is correct. Flowers consist of different whorls, and the differentiation into stamens, carpels, sepals, or petals is determined by the activity of homeotic genes in each whorl.
• Statement E is incorrect. A knock-out mutation in one of the ABC genes generally causes a transformation of one flower organ type into another rather than an abnormal order of whorls or structure duplication.