Protists explained with their characteristics

len Alfred Ajibola - 29th March, 2023 @ 10:35 AM

Topics in Biology

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Academic Questions in Biology

Please click here to see all Questions and Answers

Male Reproductive System - Len Academy

From the above diagram, which of the organ below isn't a requirement for the male reproductive system?

  • A. Bladder

  • B. Ureter

  • C. Glans Penis

  • D. Testis

  • E. Bulbourethral Gland

  • F. Epididymis

A walnut shaped male accessory sex organ located between the bladder and penis is the _____.

  • A. Ductus Ejaculatorii

  • B. Bulbourethral Gland

  • C. Prostate Gland

  • D. Ductus Deferens

  • E. Seminal Vesicles

  • F. Epididymis

In a food chain, the primary consumers are classified under trophic level  _____.

  • A. Zero

  • B. One

  • C. Two

  • D. Three

  • E. Four

  • F. Five

Cold blooded animals are referred to as _____.

  • A. Homeotherms

  • B. Endotherms

  • C. Poilokitherms

  • D. Ectotherms

  • E. Thermotherms

  • F. None of the above

All reptiles are vertebrates.

  • A. True

  • B. False

_____ cells are responsible for the formation of osteoblasts.

  • A. Osteocytes
  • B. Chondrocytes
  • C. Chondroblasts
  • D. Osteoclasts
  • E. Osteoprogenitor cells
  • F. Osteoblastic

_____ is a bone that constitute the axial skeleton.

  • A. Clavicle
  • B. Scapula
  • C. Patella
  • D. Radius
  • E. Sternum
  • F. Femur

Which of the following is false concerning cartilages and bones?

  • A. Cartilage does not have a direct blood supply while bones have direct blood supply
  • B. The process of ossification replaces a cartilage to bone
  • C. The protein that makes up cartilage is called chondrin while that that makes up bone is called ossein
  • D. Cartilage grows from both ends while bones grow from one of its epiphysis
  • E. They both have living cells within them
  • F. Haversian system is absent in cartilage but present in bones

What are Protists?

Protists are neither plants, animals, fungi nor bacteria. They are simply protists belonging to the kingdom protista.

In simple terms, an organism belonging to kingdom protista is referred to as a protist; just as those belonging to kingdom plantae and kingdom animalia are called plants and animals respectively.

Please read an introduction to the classification of living organisms here.


All protists are eukaryotic organisms. Being eukaryotic imply that their cell structure has a nucleus bordered by a membrane. They also have organelles within their cytoplasm.

Generally, protists live in an aquatic, fluidly or moist habitat.

Please read on swamp forests here.


All protists do not share similar characteristics. This is because some have got 'animal-like' characteristics while others are 'plant-like'. An animal-like protist means that such protists have got some features found in animals. For instance, their cells have cell membranes, just as that of all animals. Meahwhile, recall that a cell membrane is the outermost and protective layer of the cell.

You can read on key points in biology here.


When a protist is plant-like, it means that they have cell wall and chloroplast respectively. In this regard, such plant-like protists can manufacture their own food through the use of sunlight. Also, recall that all plants have chloroplasts and a cellulose cell wall which makes them autotrophic.

Please read more on autotrophic nutrition here.


Meanwhile, understand that a few protists can be fungi-like since they may reproduce by forming spores.


Generally, protists are commonly grouped together because they do not fit specifically into any other kingdom.

Examples of protists includes: amoeba, paramecium, euglena, chlamydomonas, plasmodium, kelp, slime molds and water molds.


Some protists are single celled (unicellular) while others are colonial (form colonies) and multicellular (made up of more than one cell).

Please read on various interesting facts here.


In terms of size, a few protist can be very large. An example of a large protist is the kelp. However, most protists are microscopic in size. Examples are amoeba, paramecium and euglena.

A protist can can be free-living or parasitic. An example of a free-living protist is the amoeba. Conversely, a plasmodium is a parasitic protist. Also, understand that a few protist may be saprophytic.

You can attempt Len Academy questions in biology here.


Below is a diagram showing various protists.

Protists - Len Academy


Characteristics of Protists


1. Locomotion

This is the ability of an organism to move from one point to another.

Although some protists are non-motile (cannot move from one point to another), others exhibit locomotion via a variety of locomotary organelles.

Please read on the characteristics of living organisms here.


Below are some protists and their locomotary organelles:

Protists - Len Academy

  • Paramecium ->  Cilia

  • Amoeba -> Pseudopodia

  • Euglena -> Flagella

  • Chlamydomonas -> Flagella


Examples of non-motile protist are plasmodium and Toxoplasma gondii.

Note: Slime mold and water mold are protists that exhibit little movement.

Please read on some amazing facts in biology here.


2. Nutrition

Certain protists are photosynthetic autotrophs (that is, they can manufacture food by utilizing the energy from sunlight). Examples are euglena and algae.

Conversely, some are heterotrophic (that is, they cannot produce their own food and hence rely on readymade food). Examples are amoeba and paramecium.

The protist plasmodium is the causative agent of malaria. (It is sometimes referred to as the malaria parasite). It undergoes a parasitic kind of nutrition; which is a type of heterotrophic mode of nutrition.

Please read on micro-organisms causing food, water and air borne diseases here.

Some protists are both autotrophic and heterotrophic. Euglena is an example.


3. Cell Structure

Most are unicellular. Amoeba, paramecium, euglena, chlamydomonas and plasmodium are examples of unicelluler protist.

A few protists are multicellular. Examples include kelp, slime molds and algae.


4. Reproduction

Reproduction in a protist is typically asexual but sometimes, sexual reproduction does occur.


Plasmodium falciparum may undergo sexual reproduction at some stages in it's life cycle.

You can read on the male reproductive system here.


5. Habitat

They generally live in an aquatic habitat and this is typically a fresh water. Fresh water habitat include ponds, lakes, rivers and streams.

Note: Seas and oceans are salt water.

Please read on tropical rainforest and savanna here.


6. They are eukaryotic organisms

Being eukaryotic implies that their cell structure have a well defined nucleus and cell membrane.

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Amazing facts in Biology

Russia is home to the largest area of forest in our world with a land mass of 815 million hectares

Giant Squid - Len Academy

Giant squid lives deep in the ocean and they have the largest eyes in the world

The movements of the fingers are controlled by muscles of the palms and forehands

Platypus - Len Academy

Platypus (sometimes referred to as the duck-billed platypus) is an egg-laying, semiaquatic mammal found in eastern Australia. It has no stomach and as such, its food goes from the mouth through the esophagus and directly to their intestines.

Pufferfish - Len Academy

Pufferfish contain a toxin called tetrodotoxin. This makes them foul tasting and poisonous to predators. Tetrodotoxin is about 1,200 times more poisonous than cyanide, and there is enough toxin in one pufferfish to kill 30 adult humans. Unfortunately, there isn't any known antidote to this poison.

Interestingly, a delicacy in Japan (called fugu) is made from pufferfish. This meal is very expensive, and must be prepared by trained and licensed chefs. An improper preparation of fugu may lead to the customer's death. Sadly, such deaths are recorded annually

Wombat - Len Academy ​​​​​​

Wombats are the only animal with a cube-shaped poo. They can stack up these cube-shaped poo, marking their territory with it

Robert Waldow - Len Academy

Robert Wadlow (1918–1940) remains the tallest man ever recorded in the Guinness World Records. He was an American who stood at 8 feet, 11 inches.

An abnormally enlarged pituitary gland had resulted into Robert Wadlow's giant size.

Cockroach is the fastest land animal on six legs

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Like humans, all apes laugh when tickled

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An ostrich's eye is bigger than its brain

Notable points in Biology

Layers of an Artery - Len Academy

An artery is composed of three layers:

  • The outermost layer is termed tunica adventitia (or tunica external). It consist mainly of collagen fibres and connective tissues that anchors the arteries to other nearby tissues.

  • The middle layer is named tunica media. It is made up of smooth muscles and elastic fibres that supports the artery in conveying blood at high pressures.

  • The inner layer is called tunica intima (or tunica internal). It is lined by a smooth tissue called endothelium, and is made up of a fine network of connective tissues.

Please read on the layers of an artery here

All living organisms possess various features in order to survive in their environment. This is the concept of adaptation. As an instance, a fish is able to live in water because it has gills and fins.

Also, a camel is able to survive in the desert because it has large feet to aid walking on sand without sinking. It also has long eyelashes to help protect it from the blowing sand and wind.

Plants are also able to live in different habitats because they have the required adaptive features towards that habitat. For instance:

  • Plants that live in/on water are termed hydrophytes.

  • Plants that live on land with moderate amount of water are termed mesophytes.

  • Plants that live on deserts or arid lands are termed xerophytes.

The point is:

All organisms have various features on them that enables them adapt in their habitat

For a thing to be considered living, it must possess all the basic characteristics of life. These include:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

Please read the explanations on all the basic characteristics of life here

During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.

This is the concept of anaerobic respiration

Food Chain - Len Academy

A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.

Note: Habitat is a place where an organism live. It is of three types:

  • Terrestrial (Land)
  • Aquatic (Water)
  • Arboreal (Treetops)

You can read on food chain here