The Movement of Photosynthates in Plants

Which cells are responsible for the movement of photosynthates through a plant?

a) tracheids, vessel elements
b) tracheids, companion cells
c) vessel elements, companion cells
d) sieve-tube elements, companion cells

Answer:

d) sieve-tube elements, companion cells

In plants, the movement of photosynthates, which are products of photosynthesis, is facilitated by sieve-tube elements and companion cells. Sieve-tube elements are specialized cells that form the sieve tubes, which are responsible for transporting organic nutrients like sugars, amino acids, and hormones throughout the plant.

The sieve-tube elements have transverse cell walls called sieve plates that connect adjacent cells and allow for the flow of nutrients. These elements are relatively short, lack organelles, and rely on companion cells for various functions.

Companion cells are parenchymal cells that are closely associated with sieve-tube elements. They provide support and energy to the sieve-tube elements by maintaining connections, sharing nutrients, and coordinating metabolic activities. The close relationship between sieve-tube elements and companion cells is essential for the efficient transport of photosynthates.

Additionally, companion cells play a crucial role in maintaining the health and function of sieve-tube elements. When a sieve-tube element dies, its companion cell also perishes, highlighting the interdependence between these two cell types.