Chapter 7 Self-test questions

. Plant diseases can spread to crops in a field in a number of different ways. Which of the following ways in which a disease might reach a crop would normally be outside of the control of a farmer?

Infected seed sown in the field.

Spread by insects as they feed on the crop.

Air currents from distant crops.

Plants left in the ground from the previous crop.

. Some fungi produce harmful products in the food making them unsuitable for human or animal consumption - what are they called?

Microflora.

Mycotoxins.

Microtoxins.

Mycospores.

. Which of the following is not an example of how knowledge about a pathogen such as Septoria can be used to change the way a crop is grown?

Being aware of conditions likely to increase the risk of disease.

Changing the crop sowing time to make it harder for the disease to infect.

Using another fungus to suppress the levels of Septoria in the crop.

Changing the crop rotation by increasing the gap between growing susceptible hosts to reduce fungal spore levels.

. Which of the following elements and products were used in the 1800s of ways of reducing pests and diseases in crops?

Chlorine gas and mercury.

Nicotine and sulfur.

Arsenic salts and mercury.

Nicotine and mercurous chloride.

. Why are plant viral diseases so difficult to control?

Viral diseases spread too quickly to make chemical treatments viable.

Products that used in the past have been found to be toxic to humans.

There are no chemical treatments currently available against viral diseases.

They are so rare that companies do not research products to cure such diseases.

. What is the success rate in getting a new chemical product registered compared to potential products researched?

<1 in 5000

< 50000

<1 in 150000

<1 in 1.5 million

. Which of the following is NOT a factor in the decision of when to apply a fungicide?

The colour of the fungicide.

Cost vs benefit.

The stage of the infection.

The weather forecast.

. Insecticide spraying is often carried out very early in the morning or late in the evening. Why?

Because farmers like to work early and late.

Because the chemicals work best in low light levels.

To minimise the effect on pollinating insects such as bees.

To maximise the number of insects killed.

. Which of the following techniques is not used in the UK to introduce mutations in the DNA of a plant to change its resistance to a disease?

Traditional plant breeding.

Exposing seed to nuclear radiation.

Exposing seed to chemicals such as ethyl methanesulfonate.

Genetic modification.

. The technique which is increasingly used by plant breeders to edit the original DNA of a plant and so improve the characteristics of the crop is called:

Genetic engineering.

CRISR-Cas.

Gene splicing.

DNA replication.

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