N5 -U2 (MO) - KA5 Transport Systems - Plant

Question 1

Name the organs in plants.

Answer 1

Roots, stems and leafs.

Question 2

Why does a plant need transport systems?

Answer 2

Plants need two transport systems

1. To enable water (and essential minerals) to travel up from the roots to the leaf cells.
2. To enable sugar (produced by photosynthesis) to be transported around the plant (in an upwards and downwards fashion)

Question 3

Define photosynthesis (extra revision :-) )

Answer 3

A chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Remember photosynthesis is a ENZYME dependent reaction.

Question 4

What are root hairs?

Answer 4

Specialised cells that increases the surface area of the root epidermis to improve the uptake of water and minerals from the soil.

Question 5

How does water enter the root hairs?

Answer 5

By osmosis - water moves from the soil (area of high water molecule concentration) into root hair cells (area of low water molecule concentration) down a water concentration gradient.

Question 6

Once water is in the root hairs where does it go?

Answer 6

Water then moves from cell to cell through the root cortex by osmosis down a concentration gradient. This means that each cell has a lower water concentration than the one before it.
Once in the centre of the root the water enters the xylem vessels .

Question 7

Describe xylem vessels.

Answer 7

Narrow, hollow, dead tubes with lignin, responsible for the transport of water and minerals in plants.

Question 8

What is the role of Lignin in xylem?

Answer 8

Carbohydrate material lining the xylem vessels providing strength and support.

Question 9

After water enters xylem in the root hairs where does it go?

Answer 9

1. Water travels up through xylem cells in the stem by osmosis.
2. Water molecules move into the xylem vessels in the leaves (where it is used or lost).

Question 10

What happens to water when it leaves the xylem vessels in the leaf?

Answer 10

Water moves from the xylem vessels into the mesophyll cells where it can be used for photosynthesis, or it is lost through transpiration.

Question 11

Why are Palisade Mesophyll cells specialised?

Answer 11

The Upper Epidermis of the leaf is transparent and lets light through to the Palisade Layer beneath. The Palisade Layer consists of long, thin Palisade Mesophyll Cells. They are specialised for carrying out Photosynthesis since they contain large amounts of Chlorophyll, and their long shape maximises light absorption.

Question 12

Define Transpiration.

Answer 12

The loss of water from leaves by evaporation through the stomata.

Question 13

What factors affect the rate of transpiration.

Answer 13

Surface area of leaf exposed,
temperature,
Air humidity,
Wind Speed

Question 14

What are stomata? Whare are these loicated?

Answer 14

Tiny holes in the epidermis (skin) of a leaf. They control gas exchange by opening and closing and are involved in loss of water from leaves. Singular is stoma.
Most stomata are located on the underside of a leaf!

Question 15

How do stomata work?

Answer 15

Some of the water evaporates into the surrounding air spaces inside the leaf and then diffuses out through the stomata into the surrounding air. The opening and closing of the stomata is controlled by guard cells in the epidermis.

Question 16

How do guard cells work?

Answer 16

These are pairs of cells found on either side of the stomata (that change their shape and control gas exchange by closing stomata in darkness or when too much water is being lost).

Question 17

What are minerals? What minerals do plants need?

Answer 17

Naturally occurring, inorganic chemical substances. Minerals are necessary for both plant and animal health.

• • Nitrogen and sulphur are needed to make amino acids (to male proteins)
• • Phosphorus is needed to make ATP and Nucleic acids
• • Magnesium and Iron are needed to make chlorophyll (although iron is not part of the chlorophyll molecule)
• • Potassium is needed to keep a correct salt balance in cells.

Question 18

Describe sugar transport in cells?

Answer 18

Sugar produced by photosynthesis in the leaves is transported up and down the plant to the meristems and other tissues in living phloem cells.

Question 19

What are phloem cells?

Answer 19

The tissue in plants that transports the products of photosynthesis, including sugars and amino acids.

Question 20

Describe the differences between xylem and phloem cells.

Answer 20

• ** Xylem = Dead tissue —-> Phloem = Living tissue
• ** Xylem = Transports water & minerals —-> Phloem = transports sugar & aa’s
• ** Xylem = Transports upwards —-> Phloem = Transports up and down the plant
• ** Xylem = composed of strong lignin —-> Phloem = composed of companion cells and sieve tubes

Question 21

Describe sieve tubes

Answer 21

The cytoplasm in sieve tubes is continuous from cell to cell because the cell walls have holes in sieve plates (pores). This allows sugar to be transported to all parts of the palnt (from cell to cell). Sieve tubes lack a nucleus.

Question 22

If sieve tubes lack a nucleus what controls the cells activities.

Answer 22

Companion cells provide the energy for the sieve cells. They also control the sieve cell activities