B1 - Plant Cell Specialisation

What does it mean if a plant cell is specialised?

It has adaptations to carry out a specific function.

What is the process of a cell becoming specialised called?

Differentiation.

What is the function of root hair cells?

To absorb water and dissolved minerals from the soil.

How are root hair cells adapted for absorption?

They have long hairs which increase surface area.

Why do root hair cells not contain chloroplasts?

They are underground, so they cannot photosynthesise and do not need chloroplasts.

What is the function of xylem cells?

To transport water and dissolved minerals from the roots to the leaves and provide structural support.

What chemical strengthens the walls of xylem cells?

Lignin.

Why do xylem cells die when lignin builds up in their walls?

Lignin seals the cells, killing them and leaving them hollow for water transport.

Why are the end walls of xylem cells broken down?

To form a continuous tube for water and minerals to flow easily.

What internal structures are missing from xylem cells?

Nucleus, cytoplasm, vacuole, chloroplasts.

Why do xylem cells have no internal structures?

To allow water and dissolved minerals to flow easily.

What is the function of phloem cells?

To transport dissolved sugars up and down the plant (translocation).

What features of phloem vessel cells help sugar transport?

No nucleus, very limited cytoplasm, and sieve plates in end walls.

What are sieve plates in phloem vessel cells?

Pores in the end walls that allow dissolved sugars to move through.

Why do phloem vessel cells have little cytoplasm and few mitochondria?

To leave more space for dissolved sugars.

How do companion cells support phloem vessel cells?

They provide energy for sugar transport using their mitochondria.

Why do phloem vessel cells need companion cells?

Because they lack enough mitochondria and cytoplasm to release energy themselves.