Xylem and Water Uptake

Question 1

The xylem transports:

Accepted Answer

Water and mineral ions — Xylem carries water and dissolved mineral ions from the roots up to the rest of the plant.

Question 2

How does water enter a root hair cell?

Accepted Answer

Osmosis — Water moves by osmosis from the dilute soil solution, across the partially permeable membrane, into the root hair cell.

Question 3

Mineral ions are usually absorbed by roots by:

Accepted Answer

Active transport — Ions often move from a lower concentration in the soil to a higher concentration in the cell, so active transport, using energy from respiration, is needed.

Question 4

Which feature adapts a root hair cell for absorbing water?

Accepted Answer

A long, thin extension giving a large surface area — The long, narrow root hair greatly increases the surface area in contact with the soil solution, speeding up absorption.

Question 5

Xylem vessels are made of:

Accepted Answer

Dead, empty cells with no cross-walls — Mature xylem vessels are dead and hollow, with their end walls broken down to form continuous tubes for water flow.

Question 6

In which direction does water move in the xylem?

Accepted Answer

Upward from roots to leaves — Xylem carries water in one direction, upward from the roots through the stem to the leaves.

Question 7

What is the role of lignin in xylem vessels?

Accepted Answer

To strengthen and support the vessels — Lignin thickens and strengthens the xylem walls, supporting the plant and preventing the vessels from collapsing.

Question 8

Which pathway correctly shows the route of water into and up a plant?

Accepted Answer

Soil → root hair cell → root cortex → xylem → leaf — Water is absorbed from the soil by root hairs, crosses the cortex, enters the xylem and is carried up to the leaves.

Question 9

Which statement about xylem and phloem is correct?

Accepted Answer

Xylem is made of dead cells; phloem is made of living cells — Xylem vessels are dead and hollow, while phloem is made of living cells that transport sugars and amino acids.

Question 10

Active transport of mineral ions into root cells requires energy from:

Accepted Answer

Respiration — Active transport moves ions against a concentration gradient and uses energy released by respiration in the root cells.

	Xylem	Phloem
Carries	Water + mineral ions	Sucrose + amino acids
Direction	Upward only	Up or down
Cells	Dead	Living

Taking up water and minerals

The xylem