Question

Phase change is O A. the transition to flowering competence B. transition from season to season C. the transition from growth to dormancy D.germination E. opening of guard cells QUESTION 29 Floral organs are thought to have evolved from A. roots OB. shoots C. leaves OD.gametes E. fruits

Answer 1

Q1) Phase change is _______.

Correct option: option A. The transition to flowering competence.

Explanation: Phase change is the phenomenon that plants undergo to prepare to respond to the stimuli needed for flowering. Thus, it may also be considered as a change from vegetative (growth) to the reproductive stage of a plant. Hence, option A. i.e. the transition to flowering competence is CORRECT.

Option B. Transition from season to season: Although changes in season may cause changes in the flowering patterns of a plant, it is merely a cue or a factor that influences the flowering. It is not the 'phase change' phenomenon itself. Hence option B is incorrect.

Option C. Transition from growth to dormancy: Plant dormancy is the state of arrested plant growth. Thus, there is no change in the vegetative or reproductive phase of a plant. It merely goes into a hibernating mode, which may be influenced by environmental cues such as temperature and water availability, or by internal physiological cues. Hence, option C is incorrect.

Option D. Germination: Germination is a process of formation of a plant from a seed. Hence option D is incorrect.

Option E. Opening of guard cells: Guard cells are the cells surrounding the stomatal opening in plants. They regulate transpiration in plants by controlled opening and closing. Thus, option E is incorrect.

Q2) Floral organs are thought to have evolved from _______.

Correct option: Option C. Leaves

Explanation: Floral organs which are also called floral whorls are made up of speak (calyx), petal (corolla), stamen and carpels. A flower is thought to have evolved from leaves as it fits the theory. Flowers are thought to have begun as an elongated stem with slightly modified leaves that acted as primordial whorls, present in a spiral pattern. Initially, sepals and petals are thought to have been similar, only later differentiating into individual whorls. Gradually, the space between the nodes that held the leaves is thought to reduce to give rise to a clustered arrangement, forming a flower. Thus, option C is correct.

Since options A, B, D, and E do not fit into this theory, they are incorrect.