Plant Physiology & Growth Flashcards

Photoperiodism refers to a plant's response to:

Answer: The relative lengths of day and night

Photoperiodism is the physiological response to the duration of light and dark periods, controlling flowering time in many species.

Which plant hormone is most associated with fruit ripening and senescence?

Answer: Ethylene

Ethylene is a gaseous hormone that triggers fruit ripening, leaf abscission, and flower senescence.

What is the primary function of the phloem in vascular plants?

Answer: Transport of photosynthates (sugars) from leaves to other plant parts

Phloem conducts sugars and other organic compounds produced during photosynthesis from source tissues (leaves) to sink tissues (roots, fruits).

A plant showing interveinal chlorosis on young leaves (veins remain green, tissue between yellows) most likely has a deficiency of:

Answer: Iron or Manganese

Iron and manganese are immobile nutrients needed for chlorophyll synthesis; deficiency appears first on young leaves with green veins and yellow tissue between them.

Turgor pressure in plant cells is caused by:

Answer: Water entering the vacuole via osmosis, pushing against the cell wall

When water enters the central vacuole by osmosis, it creates turgor pressure that keeps non-woody plant cells rigid and maintains wilting resistance.

C4 plants are better adapted to hot, sunny environments than C3 plants because they:

Answer: Concentrate CO2 around Rubisco, reducing photorespiration

C4 plants use a CO2-concentrating mechanism that delivers CO2 directly to Rubisco in bundle sheath cells, greatly reducing energy-wasting photorespiration.

What is vernalization?

Answer: Exposure to prolonged cold that triggers flowering in certain plants

Vernalization is the induction of flowering by a prolonged period of cold, ensuring that plants like winter wheat or biennial crops flower only after winter.