Tensile strength in plant fibers

Question 1

What is tensile strength?

Answer 1

The maximum stretching force that can be applied to a tissue before it breaks.

Question 2

What fibres are found in plants?

Answer 2

Vascular tissues (phloem and xylem), sclerenchyma fibres (lignified support tissues)

Question 3

Outline the procedure to test the tensile strength of plant fibres.

Answer 3

1. Use forceps to separate the fibres.
2. Cut fibres into equal lengths with equal diameters.
3. Hold the fibre rigid using two clamps.
4. Add weights to the fibre, 10g at a time until it breaks. Record the mass added before the fibre broke.
5. Repeat steps 3 and 4 and take a mean of the mass.

Question 4

What are the controlled variables of this practical?

Answer 4

Number of fibrous strings tested per plant.
Diameter/length of fibrous strings.

Question 5

What is the tensile strength of plant fibres determined by?

Answer 5

The chemical composition of the plant eg. cellulose and lignin content.