This definitions covers Key Definitions within Plant Diseases and Defenses for GCSE Biology. Plant pathogens, defense mechanisms, disease identification, crop protection It is section 12 of 18 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Topic position
Section 12 of 18
Practice
18 questions
Recall
20 flashcards
Key Definitions
Pathogen
A microorganism (or other agent) that causes disease in a host organism.
Cuticle
A waxy, waterproof layer covering the outer surface of leaves and stems, acting as a physical barrier against pathogen entry.
Tobacco Mosaic Virus (TMV)
A viral plant pathogen that causes a mosaic pattern of light and dark patches on leaves by disrupting chloroplast function, reducing photosynthesis and stunting growth.
Rose black spot
A fungal disease of roses (caused by Diplocarpon rosae) that produces black/purple spots on leaves, causes yellowing (chlorosis), and leads to early leaf fall.
Chlorosis
Yellowing of leaves caused by loss of chlorophyll, resulting in reduced photosynthesis. A common symptom of plant disease or nutrient deficiency.
Antimicrobial compound
A chemical produced by a plant (e.g., tannins, essential oils) that kills or inhibits the growth of bacteria, fungi, or other microorganisms.
Vector
An organism (e.g., aphid) that carries and transmits a pathogen from one host plant to another without being harmed itself.
Induced response
A defense mechanism that is activated only when a pathogen is detected, producing antimicrobial chemicals or strengthening cell walls at the site of attack.