Classifying different pathogens that cause disease in plants and animals

Question 1

Prions

Answer 1

→Consist only of protein; do not contain any genetic material (DNA or RNA)
→Smaller than all other pathogens
→ Pathological agent is a biologically abnormal form of a normal protein
→ Agent comes into contact with the normal form. The latter sticks to it and is forced into an abnormal folding pattern
→ Clump of abnormal protein cannot be degraded by the normal biological processes and is infectious on entering the body of an uninfected person
→ A cellular (Not living)
→ Causes: Mad cow disease
→ Microscopic

Question 2

Virus

Answer 2

→ Non-cellular particles and traditionally have not been considered living
→ Complex chemical structures consisting of nucleic acids, proteins and occasionally other biochemicals, and can be crystallised
→ Protein forms a capsid or coast, which encloses the nucleic acid
→ Lack of cytoplasm and perform no metabolic functions
→ Can invade a host cell, where its nucleic acid is replicated and translated into proteins by the host machinery
→ New particles form within the host cell, which bursts, liberating the new particles
→ Acellular
→ Microscopic
→ Causes: Influenza, Tomato mosaic virus, Covid-19

Question 3

Bacteria

Answer 3

→ Singled-cell prokaryotic organisms
→ Do not have membrane-bound nucleus or organelles
→ Larger than viruses but smaller than protozoans and vary in size from 0.2 to 20 um (Micrometres) 1 um = 10-6 m) in length
→ genetic material is a large circular chromosome
→ Most have a cell peptidoglycan wall, i.. Composed of protein and carbohydrate
→ Cellular
→ Causes: Chlorea

Question 4

Fungi

Answer 4

→ Eukaryotic organisms
→ POssess a cell wall composed of chitin
→ Do not contain chlorophyll, so are heterotropic
→ Maybe be unicellular, yeats, or multi-cellular, e.g. moulds
→ Multi-cellular forms composed of a system of microscopic tubular filaments known as hyphae branch and spread to form a structure known as mycelium
→ Reproduce asexually or sexually
→ Can be used to produce bread and alcohol with some types
→ Causes: Athletes foot, Panama disease (Banana)

Question 5

Protozoa

Answer 5

→ Single-cell eukaryotic organisms
→ possess a membrane-bound nucleus and membrane-bound organelles
→ Have a cell membrane
→ Usually reproduce by the process of binary fission
→ Most are motile and move using flagella, cilia or pseudopodia
→ Causes: Malaria (Plasmodium)

Question 6

Macroparasite - Anthropods Ectoparasitic

Answer 6

→ Multicellular eukaryotic animals
→ Have a chitinous exoskeleton that is moulted and replaced during different life stages
→ Have multiple body segments and jointed appendages
→ Macroscopic
→ Causes:
Ticks

Question 7

Macroparasite -Helminths
Endoparasite

Answer 7

→ Multicellular eukaryotic worm-like organisms
→ Generally visible to the naked eye but varies in size from a millimetre to a metre
→ Pathogenic forms commonly inhabit the gastrointestinal systems of animals
→ live on nutrients supplied by the host
→ Often have complex life cycles with multiple hosts
→ Macroscopic
→ Examples that can cause disease in humans and animals:
Nematodes (ROundworms, whipworms, hookworms)
Cestodes (Tapeworms)
Flatworms (Platyhelminths) ,e.g. flukes