Biology · Edexcel Paper 1
Plant Defences and Disease
How plants defend themselves against pests and pathogens using physical barriers and chemicals, how some of those chemicals are used as human medicines, and how plant diseases are detected and identified. Matches Edexcel 5.9B to 5.11B. This chapter is for separate Biology only: Combined Science students do not need it.
Lessons
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1
Physical Defences of Plants
Plants cannot run away from the animals that eat them, or from the microorganisms that infect them. This lesson is for separate Biology only: Combined Science…
9 terms -
2
Chemical Defences of Plants
Many plants make poisons, bitter chemicals and antibiotics. This lesson is for separate Biology only: Combined Science students do not need it. It explains how…
9 terms -
3
Detecting Plant Diseases
How do you tell what is wrong with a sick plant? This lesson is for separate Biology only: Combined Science students do not need it. It covers the ways of…
9 terms
Key terms in this chapter
All 27, gathered from every lesson.
- Cuticle
- The waxy layer on the surface of a leaf that reduces water loss and is a barrier to pathogens.
- Cell wall
- The rigid outer layer of a plant cell, made of cellulose.
- Physical barrier
- A structure that stops a pathogen or a pest from entering a plant.
- Epidermis
- The outer layer of cells of a plant.
- Stoma
- A tiny pore in the leaf surface, surrounded by two guard cells (plural: stomata).
- Bark
- The outer layer of dead cells that protects the trunk and branches of a tree.
- Herbivore
- An animal that eats plants.
- Mimicry
- When an organism looks like something else, which gives it protection.
- Pest
- An organism that damages a plant.
- Chemical defence
- A chemical made by a plant that protects it from pests and pathogens.
- Antibacterial
- Able to kill bacteria or stop them growing.
- Toxin
- A poison.
- Deterrent
- Something that puts an animal off eating a plant, such as a bitter taste.
- Aspirin
- A medicine developed from salicylic acid in willow bark, used for pain and fever.
- Digitalis
- A chemical from foxgloves, used to treat some heart conditions.
- Zone of inhibition
- A clear area around a disc on an agar plate where bacteria cannot grow.
- Extract
- A substance that has been taken out of a plant using a solvent.
- Control
- A part of an experiment that shows what happens without the factor being tested.
- Symptom
- A visible sign of disease in a plant, such as spots or wilting.
- Chlorosis
- Yellowing of leaves because of a lack of chlorophyll.
- Mineral deficiency
- A lack of a mineral that a plant needs, such as nitrate or magnesium.
- Distribution
- The pattern of where the affected plants are in an area.
- Diagnostic test
- A test used to identify the cause of a disease.
- Culture
- Growing microorganisms on a nutrient medium.
- Monoclonal antibody
- An antibody that binds to one specific substance, used in tests.
- Random sample
- A sample in which every individual has an equal chance of being chosen.
- Lesion
- An area of damaged or diseased tissue.