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parasite

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Definition

A parasite is an organism that lives in or on another organism, called the host, and gets its food from the host. Parasites are not able to produce their own food, so they must rely on their hosts for survival.

Parasites can be divided into two main types:

  • Endoparasites: Endoparasites live inside their hosts. Examples of endoparasites include tapeworms, heartworms, and malaria parasites.
  • Ectoparasites: Ectoparasites live on the outside of their hosts. Examples of ectoparasites include ticks, fleas, and lice.
  • Parasites can cause a variety of problems for their hosts, including:
  • Disease: Parasites can transmit diseases to their hosts. For example, malaria parasites are transmitted by mosquitoes.
  • Weight loss: Parasites can cause weight loss in their hosts. This is because the parasites are taking food away from the host.
  • Death: In some cases, parasites can kill their hosts. This is especially true for young or elderly hosts.

Parasites are a major problem for humans and animals. There are many different ways to control parasites, including:

  • Medication: Medication can be used to kill parasites.
  • Prevention: Prevention is the best way to avoid parasites. This can be done by avoiding contact with parasites, using insect repellent, and practising good hygiene.

How can the word be used?

An organism that carries a parasite from one host to another.

parasite

Different forms of the word

Noun:

  • parasite (an organism that lives in or on another organism and benefits at the other organism's expense).
  • parasitism (the relationship between a parasite and its host organism).

Adjective:

  • parasitic (of or relating to parasites or parasitism).

Etymology

The word "parasite" is derived from the Greek word "parasitos", which means "one who eats at another's table". The first recorded use of the word "parasite" in English was in the 14th century.

Question

What is a parasite?

AQA Science Exam Question and Answer

Question:

Explain the relationship between parasites and their hosts in the context of biology. Provide examples of different types of parasites and the adaptations they have developed for survival within their host organisms.

Answer:

Parasites are organisms that live off another organism, called a host, often causing harm or inconvenience to the host in the process. This relationship can be classified into different types: endoparasites live inside the host, while ectoparasites reside on the host's external surface.

Examples of endoparasites include tapeworms and malaria parasites. Tapeworms attach to the host's intestines, absorbing nutrients directly from the host's digested food. Malaria parasites, on the other hand, invade red blood cells, causing the host to experience fever and fatigue.

Ectoparasites like ticks, fleas, and lice remain on the host's surface, feeding on blood or other bodily fluids. Ticks, for instance, pierce the host's skin to extract blood, potentially transmitting diseases in the process.

Parasites often exhibit specialised adaptations to survive within their hosts. Some have evolved hooks, suckers, or adhesive structures to maintain their position. Others have developed complex life cycles, utilizing different hosts at various life stages to ensure successful reproduction and dispersal.