B3 - Infectious Diseases In Plants

Can plants be affected by infectious diseases?

Yes, plants can suffer from infectious diseases caused by viruses, fungi, and other pathogens.

Name the two plant diseases you need to know for GCSE Biology.

Tobacco Mosaic Virus (TMV) and Rose Black Spot.

What type of pathogen causes Tobacco Mosaic Virus?

A virus.

What type of plants can Tobacco Mosaic Virus infect?

A range of species including tomatoes and tobacco plants.

What are the symptoms of Tobacco Mosaic Virus?

A mosaic pattern of discolouration on the leaves.

How does TMV affect photosynthesis?

It reduces the rate of photosynthesis.

What effect does TMV have on plant growth?

It reduces the rate of growth due to less photosynthesis.

Why does TMV reduce growth?

Because the discolouration reduces photosynthesis, so the plant makes less glucose for energy and growth.

What type of pathogen causes Rose Black Spot?

A fungus.

What are the symptoms of Rose Black Spot?

Purple or black spots on leaves, yellowing of leaves, and leaves falling off.

How does Rose Black Spot affect photosynthesis?

It reduces the rate of photosynthesis.

What effect does Rose Black Spot have on plant growth?

It reduces growth due to less photosynthesis.

How is Rose Black Spot spread?

By wind and water.

Why does Rose Black Spot cause leaves to fall off?

Because it damages the leaf tissue and reduces the plant's ability to carry out photosynthesis.

Name one chemical treatment for Rose Black Spot.

Fungicides.

What do fungicides do?

They kill fungi that infect plants.

What is another way to control the spread of Rose Black Spot?

Remove and destroy infected leaves.

Why is it important to destroy infected leaves in Rose Black Spot?

To prevent the fungus from spreading to healthy plants.

Why does reduced photosynthesis lead to reduced plant growth?

Because less glucose is produced for respiration and making new cells.

Can TMV and Rose Black Spot be cured?

No, but their spread and symptoms can be managed.

How do both TMV and Rose Black Spot affect the plant similarly?

They both reduce photosynthesis, which limits the plant's growth.