Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Flowering in plants involves a change in gene expression in the shoot apex, triggered by abiotic factors like the length of the dark period (photoperiodism).
Phytochromes are pigments used by plants to detect light. They exist in two forms: (inactive, absorbs red light at ) and (active, absorbs far-red light at ).
In Long-Day Plants (LDP), flowering is induced when levels remain high at the end of a short night. acts as a promoter of flowering in these species.
In Short-Day Plants (SDP), flowering is induced when levels fall below a critical threshold due to a long night. acts as an inhibitor of flowering in these species.
Sexual reproduction in flowering plants depends on three distinct processes: pollination (transfer of pollen from anther to stigma), fertilization (fusion of male gamete with female ovule to form a zygote), and seed dispersal.
Most flowering plants have a mutualistic relationship with pollinators (such as bees, birds, or bats) where the plant receives reproductive assistance and the pollinator receives food (nectar/pollen).
Germination of seeds requires specific conditions: (to rehydrate cells), (for aerobic respiration), and an ideal temperature (for enzyme activity).
The metabolic process of germination involves the hormone gibberellin, which stimulates the production of -amylase to catalyze the hydrolysis of starch into maltose.
📐Formulae
💡Examples
Problem 1:
A researcher exposes a Short-Day Plant (SDP) to a long night, but interrupts the darkness with a brief flash of red light. Predict the effect on flowering and explain why using phytochrome theory.
Solution:
The plant will not flower.
Explanation:
In Short-Day Plants, acts as an inhibitor of flowering. During a long night, slowly converts back to . If a flash of red light occurs, is rapidly converted back into . This raises the concentration above the critical inhibitory threshold, preventing the transition of the shoot apex to a floral meristem.
Problem 2:
Describe the internal chemical sequence that leads to the emergence of the radicle during the germination of a starchy seed.
Solution:
uptake Gibberellin Amylase Maltose Glucose Respiration.
Explanation:
- The seed performs imbibition (takes up ). 2. The embryo releases the hormone gibberellin. 3. Gibberellin triggers the synthesis of -amylase in the aleurone layer. 4. Amylase breaks down starch stored in the endosperm into maltose. 5. Maltose is converted to glucose for use in aerobic cell respiration to produce for growth.