Practice Question

1. Describe and explain one structural adaptation of a root hair cell.

Root hair cells have a long, thin extension called a root hair) which will provide a large surface area. This will increase the rate of absorption of water and mineral ions from the soil.

2. Why do root hair cells contain many mitochondria?

They contain many mitochondria to release energy, by aerobic respiration  for active transport of mineral ions into the root hair cell.

3. What advantage does having a thin cell wall provide to root hair cells?

A thin cell wall provides a short diffusion distance, allowing water and mineral ions to move into the cell quickly.

4. Describe two structural adaptations of xylem cells that allow for efficient water transport.

Xylem cells are dead and hollow with no cytoplasm or organelles, allowing free flow of water upwards.

Xylem vessels lack end walls, to form a continuous vertical tube, and their cell walls are thickened with lignin, to strengthen and waterproof the xylem vessel.

5. Give two structural adaptations of phloem cells that for  the transport of sugars and amino acids.

Sieve tube elements are joined end-to-end with sieve plates (porous end walls) to allow easy flow of dissolved sugars.

The phloem cells have very few structures within the cell, allowing the sugar solution to travel freely through phloem cell.

7. How do companion cells support sieve tube elements?

Companion cells have lots of mitochondria to carry out respiration to release energy (ATP) needed for the active loading and unloading of sugars into and out of phloem cells(sieve tube elements.)

Q7. State three differences between xylem and phloem vessels.

Any of the following 3:

Xylem transports water and minerals in an upwards direction; phloem transports sugars and amino acids upwards or downwards (source to sink).

Xylem cells are dead, phloem cells are living.

Xylem cells lack internal cell structures and end walls; phloem cells contain few structures and have sieve plates.

Xylem walls are reinforced with lignin; phloem walls are not.