Plant Transport Mechanisms and Functions

Vascular plants produce nutrients like sucrose in their leaves, which are transported to other parts of the plant. Leaves act as the source, while shoots and roots are the sink. Xylem and phloem are the two main vascular tissues, with phloem responsible for sugar transport. Phloem loading increases sugar concentration, causing water to move from xylem to phloem, creating pressure that drives sugar and water from source to sink. Sucrose is actively transported at the sink, facilitating continuous water flow from xylem to phloem and back, primarily driven by transpiration.

What is the primary role of a 'source' in vascular plants?

• To store excess nutrients

• To produce more sugars than it requires

• To consume sugars for growth

• To transport water and minerals

Which tissue in plants is responsible for conducting water and dissolved minerals?

• Phloem

• Xylem

• Sieve plates

• Companion cells

What is the main function of phloem in plants?

• Conducting water

• Storing nutrients

• Providing structural support

• Conducting carbohydrates

How are phloem cells connected to facilitate sugar transport?

• Via companion cells

• Through xylem vessels

• By sieve plates

• Through tonoplasts

What process causes water to move from xylem to phloem?

• Transpiration

• Active transport

• Osmosis

• Diffusion

What happens to the water potential in phloem cells near the source during phloem loading?

• It remains constant

• It decreases

• It increases

• It fluctuates

How is sucrose removed from the sink cell?

• Via osmosis

• By passive diffusion

• By transpiration

• Through active transport mechanisms

What role does ATP play in the transport of sucrose into the vacuole?

• It provides energy for active transport

• It increases water potential

• It facilitates osmosis

• It acts as a transport protein

What primarily causes water to move upward in the roots?

• Water potential differences

• Transpiration

• Phloem loading

• Active transport

What is the function of a tonoplast in plant cells?

• To transport sucrose into the vacuole

• To increase turgor pressure

• To conduct water and minerals

• To connect phloem cells