Parasites and Pathogens in Biology

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Questions and Answers

What is a characteristic of a pathogen?

It is a type of parasite that does not consume host resources.

It is a type of endoparasite that lives inside organisms.

It is a type of parasite that causes infectious disease. (correct)

It is a type of ectoparasite that lives on the outside of organisms.

What is the primary advantage of an endoparasite living inside an organism?

It is subject to less grooming.

It is easier to feed. (correct)

It is less likely to be removed by other organisms.

It is easier to move around.

What is the primary disadvantage of an ectoparasite living outside an organism?

It is subject to grooming. (correct)

It is harder to feed.

It is more likely to be removed by the host's immune system.

It is less likely to be able to move around.

What is the purpose of the carpenter ants' behavior after being infected with the Zombie ant fungus?

To spread the fungus's spores to other ants. Signup and view all the answers

What is the main reason why ectoparasites are often arthropods?

Because they are able to move easily and feed on the host's surface. Signup and view all the answers

What is the primary advantage of a parasite not killing its host?

It allows the parasite to establish a longer-term relationship with the host. Signup and view all the answers

What is the primary purpose of the mistletoe's roots?

To absorb nutrients from the host plant. Signup and view all the answers

What is the primary reason why the varroa destructor mite has significant economic consequences?

It causes significant damage to bee colonies and affects honey production. Signup and view all the answers

What is the primary purpose of the fungal infection in the Zombie ant fungus?

To produce spores that infect other ants. Signup and view all the answers

What is the primary difference between ectoparasites and endoparasites?

Ectoparasites live on the outside of organisms, while endoparasites live inside. Signup and view all the answers

What is the term for the ability of a host to minimize harm from infection?

Infection tolerance Signup and view all the answers

What is the rate of transmission between susceptible and infected individuals in the Susceptible-Infected-Resistant model?

S x I x b Signup and view all the answers

What is the result when the reproductive ratio R0 is greater than 1?

The infection will spread Signup and view all the answers

What is an example of a host adaptation to combat parasites?

All of the above Signup and view all the answers

What is the term for the process of two or more species continuing to evolve in response to each other's evolution?

Coevolution Signup and view all the answers

What is the term for a parasite whose host is also a parasite?

Hyperparasitism Signup and view all the answers

What is the name of the parasitic wasp that lays a single egg in the host, and the egg divides into a polyembryonic mass?

Copidosoma floridanum Signup and view all the answers

What is the percentage of insects that are parasitoids?

10% Signup and view all the answers

What is the term for the strategy of preventing further development of the host after immobilising it?

Idiobiont Signup and view all the answers

What is the relationship between the abundance and richness of parasitoid hymenoptera and overall arthropod taxon richness?

Strong relationship Signup and view all the answers

What is the primary mode of transmission of the prion endoparasite?

Through consumption of infected dead animals or their faeces Signup and view all the answers

What is the term for a newly discovered or rare disease that increases in abundance?

Emerging infectious disease Signup and view all the answers

What is the term for the ability of a host to prevent infection from occurring?

Infection resistance Signup and view all the answers

What is the name of the fungus that lives in the outer layer of amphibian skin and causes ion imbalance?

Batrachochytrium dendrobatidis Signup and view all the answers

What is the term for an organism that disperses a parasite between hosts?

Vector Signup and view all the answers

What is the term for the process by which a parasite is transmitted from a parent to its offspring?

Vertical transmission Signup and view all the answers

What is the term for the ability of a host to reduce the negative impacts of an infection?

Infection tolerance Signup and view all the answers

What is the term for the fluctuations in the populations of hosts and parasites over time?

Parasite-host dynamics Signup and view all the answers

What is the term for the species that carry a parasite but do not succumb to disease?

Reservoir species Signup and view all the answers

What is the term for the process by which a parasite avoids detection by incorporating into the host's chromosomes?

Genetic integration Signup and view all the answers

Study Notes

Parasites

A parasite is an organism that lives in or on another organism, consumes its resources, and causes harm to the host.
Not all parasites kill their hosts; some have evolved to coexist with their hosts without causing harm.

Types of Parasites

Ectoparasites: live on the outside of organisms, examples include arthropods, leeches, lampreys, and nematodes.
Endoparasites: live inside organisms, examples include viruses, prions, protozoans, bacteria, fungi, and helminths.

Endoparasites

Viruses: consist of genetic material surrounded by a protective protein coat, important in agriculture and human health.
Prions: begin as beneficial brain proteins, replicate on contact with other proteins, and transmit through consumption of infected dead animals or their faeces.
Protozoans: unicellular eukaryotic organisms, examples include malaria, Giardia maris, and Giardia lamblia.
Bacteria: single-celled prokaryotes, examples include shot hole plant bacteria, crown gall, anthrax, plague, pneumonia, and salmonella.
Fungi: devastate many plant species, examples include Dutch elm disease, chestnut blight, and ash dieback.
Helminths: parasitic worms, examples include hookworms, lungworms, echinostomes, liver flukes, and threadworms.

Parasite and Host Dynamics

Populations of hosts and parasites fluctuate over time, with dynamics similar to predator-prey relationships.
Parasites often have a higher reproductive rate than their hosts and do not often kill their hosts.

Mechanisms of Parasite Transmission

Horizontal transmission: when a parasite moves between individuals other than parents and offspring.
Vertical transmission: when a parasite is transmitted from a parent to its offspring.
Mode of entering the host: piercing tissue, reliance on a vector.
Ability of parasite to jump between species: a lethal parasite that specialises on one host may face extinction, solution is to infect multiple species.

Parasite Adaptations

Parasites can evolve adaptations that increase the probability of transmission, examples include zombie snails and Entomophthora muscae.
Host adaptations: hosts have developed a range of responses to combat parasites, including immune system responses, production of antibacterial/antifungal compounds, and mechanical/biochemical defences.

Coevolution

Coevolution occurs when two or more species continue to evolve in response to each other's evolution, examples include the invasive rabbit population in Australia and the parasitic worm Acanthocephalus dirus.

Parasitic Hymenoptera

Parasitic Hymenoptera: more than 150,000 species, rival beetles, many parasitic, mostly endoparasites.
Parasitoid developmental strategies: Koinobiont, Idiobiont, and Hyperparasitism.
Example: Copidosoma floridanum, a parasitic wasp that produces soldiers to eliminate competitors.

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Description

Learn about parasites, their relationships with hosts, and how pathogens cause infectious diseases. Explore examples like carpenter ants and the Zombie ant fungus.