Phloem Tissue

What is the primary function of sieve tube elements in phloem tissue?

• To provide structural support

• To transport sucrose

• To store food

• To produce energy

What is the role of sieve plates in sieve tube elements?

• To block the flow of phloem sap

• To facilitate movement between sieve tube elements

• To store excess nutrients

• To protect the phloem tissue

Sieve tube elements lie end-to-end to form a.....

• Rack

• Pile

• Pack

• Stack

What is a characteristic feature of companion cells?

• They have a large vacuole

• They have a dense cytoplasm with many mitochondria

• They have a thick cell wall

• They have a large nucleus

Why is the metabolic activity of companion cells important?

• It helps in photosynthesis

• It maintains the activity of sieve tube elements

• It stores energy for the plant

• It provides structural support

What happens to sieve tube elements as they mature?

• They develop a thick cell wall

• They lose their nuclei and many organelles

• They become larger in size

• They start photosynthesising

What is the main component of the cell walls of sieve tube elements?

• Lignin

• Cellulose

• Chitin

• Keratin

What is the function of the sieve pores in the sieve plates?

• To store nutrients

• To allow phloem sap to flow between sieve tube elements

• To block pathogens

• To provide structural support

Why are sieve tube elements not lignified?

• The cells are not under tension

• The cells are under tension

• The cell wall has to stretch as sieve tube elements elongate

• So phloem sap can flow laterally

What is the relationship between the cytoplasm of companion cells and sieve tube elements?

• They are completely separate

• They are linked via plasmodesmata

• They share the same nucleus

• They are connected by chloroplasts