Plant Disease Practice Questions

Give two signs the student could look for that would suggest a lettuce plant has a disease.

The student wants to find out which disease the lettuce plants have.

Describe one way the student could identify the disease.

Figure 1 shows a section through a leaf.

Figure 1

Name layer X and explain how it helps to defend the leaf against microorganisms.

Table 1 shows three plant defences.

Identify whether each defence is a physical, a chemical or a mechanical response.

Tick (✓) one box in each row.

Table 1

Plant defence	Physical	Chemical	Mechanical
Cellulose cell wall around each cell
Antibacterial chemicals made in the leaves
Stiff hairs on the surface of the stem

Complete Table 1 to show the type of organism that causes each problem.

Choose your answers from:

fungus insect virus

Table 1

Problem in the plant	Type of organism
Tobacco mosaic disease
Rose black spot
Sap being removed from the phloem by a pest

Aphids feed by taking sugars from the phloem of a plant.

Suggest why a large number of aphids on a plant reduces the growth of the plant.

Give the reason why the student grew seedlings in solution A.

Explain the mean height of the seedlings grown in solution B.

The leaves of the seedlings grown in solution C were yellow.

Explain why.

Calculate the percentage increase in mean dry mass per plant when the concentration of nitrate ions is increased from $0$ mmol dm$^{-3}$ to $8$ mmol dm$^{-3}$.

Percentage increase = __________ %

Explain why plants grown in soil containing more nitrate ions had a greater dry mass.

Increasing the concentration of nitrate ions from $8$ mmol dm$^{-3}$ to $16$ mmol dm$^{-3}$ made almost no difference to the mean dry mass.

Suggest one reason why.

Give two ways the grower could identify the disease affecting the strawberry plants.

The grower decides to use a testing kit containing monoclonal antibodies.

Give one advantage of using this kit rather than sending plants away to a laboratory.

Suggest why it is important for the grower to identify the disease quickly.

Suggest a cause for the appearance of each plant.

Use Table 1.

Describe how the gardener could check that the suggested cause for plant A is correct.

Explain how the data in Table 1 support the conclusion that a thicker waxy cuticle helps a tomato plant to produce a greater mass of tomatoes.

Variety A makes a poisonous chemical in its leaves that deters insect pests.

Suggest one advantage and one disadvantage of this to the grower.