1. Protists
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2. Plant-like protists all contain chlorophyll, the pigment found in plant cells, which is involved in the process of photosynthesis.
Most plant-like protists are able to produce their own food.
However, some are heterotrophic and ingest materials from their surrounding.
There are six phyla within the plant-like protist group.

3. Euglenophyta
In the past, euglenids have been classified as both plants and animals because in the presence of light they are photosynthetic.
However, in the absence of light they become heterotrophic. The Euglena is one of the most studied plant-like protists.
The image on the right shows some features of the Euglena.
The dark spot on the bottom represents the eye spot which is used to detect light.
One feature of the Euglena which is not shown is its flagellum. Most species contain two flagella which allow for movement. Similar to animal-like protists, the euglenids reproduce asexually.

4. Rhodophyta (Red Algae): Phaeophyta (Brown Algae) and Chlorophyta (Green Algae)
The protists in these phyla all contain chloroplast which means they too photosynthesize.
In addition to containing chlorophyll, they also contain other pigments that allow them to absorb additional wavelengths of light.
These algae are multicellular and they generally inhabit moist to wet environments.
Reproduction varies greatly amongst this group. The most common form of reproduction is through binary fission.
However some algae reproduce sexually.

5. Green algae play an important role in providing oxygen through photosynthesis; algae are also part of the aquatic food chain.
You may have noticed green algae forming in ponds or in shallow rivers and lakes.
Fertilizer run-off may lead to excessive growth of green algae causing an imbalance in the natural environment.

6. Chrysophyta
Diatoms provide much of the nourishment for aquatic organisms.
These protists are unicellular and each species has a very unique shape.
Structurally, they are composed of two halves that fit perfectly together.
This is an image of various diatoms showing circular and triangular shapes.

7. When they reproduce asexually, they split and separate into two.
Then each original part grows into a new half.
After several generations of reproducing asexually, the size of the diatom reduces significantly.
When this occurs, the diatoms reproduce sexually by producing a zygote.
While diatoms do not contain flagella, many other protists in this phylum are flagellated.

8. Pyrrophyta
Have you ever had the opportunity to watch the ocean light up from within its depths?
This phenomenon is the result of dinoflagellates, a protist from this phylum. When water containing large amounts of dinoflagellates becomes agitated, bright flashes of light are visible.

9. In response to excessive nutrients or elevated water temperatures, dinoflagellates experience rapid growth called a bloom.
In addition to tinting the water red, dinoflagellates produce toxins.
These toxins accumulate in the bodies of fish which can then affect humans who consume the toxic fish.
Dinoflagellates are photosynthetic, but they can also ingest materials from their environment.
They are generally unicellular, contain two flagella and reproduce asexually.

10. Fungus-like Protists
These protists are generally referred to as slime moulds and are classified in the phylum Gymnomycota.
These protists are heterotrophic and generally feed on dead organic materials.
The characteristics of slime moulds vary greatly during their lifecycle.
They begin their life as a single cell.
By extending its cytoplasm, similar to an amoeba, slime moulds are able to move and unite to form multicellular masses. These masses shrink in size and eventually produce spores.

11. Quiz – True or False? Protists can be prokaryotic or eukaryotic.
Animal-like protists contain chlorophyll.
An amoeba moves by extending its cytoplasm and producing pseudopods.
Flagella provide locomotion for protists in the phylum Ciliophora.
Parasitic protists are responsible for disease in humans.
Plant-like protists have no need to move, therefore do not contain flagella.
Euglena is a plant-like protist that is both autotrophic and heterotrophic.
Global warming and will have an effect on green algae growing in lakes and rivers.
Slime moulds show the potential for complex speciation.
The Protist kingdom is very diverse.

12. Answers
False – The classification of protists is based on the fact that they all contain a nucleus and therefore are eukaryotic. They cannot be classified in the animal or plant kingdom because they lack specialized tissues.
False – Only plant-like protists contain chlorophyll. Remember this is the pigment that allows these protists to photosynthesize.
True – The false feet produced by the extension of cytoplasm provide mobility to an amoeba. In addition, the pseudopods also allow amoeba to engulf their food by phagocytosis.

13. 4. False – Protists in the phylum Ciliophora contain tiny hair-like structures called cilia that surround their cell body. The motion of these structures provides movement for these protists. 5. True – Parasitic organisms rely on a host for survival. Some protists cause serious illnesses such as malaria and have been responsible for outbreaks like the Irish potato famine in the mid 1800's. 6. False – Many plant-like protists contain flagella including Euglena and dinoflagellates. 7. True – Euglena contain chlorophyll and will photosynthesize when light is available. In dark conditions, Euglena will feed off of organic material.

14. 8. True – Elevated water temperatures increase the growth rate of green algae. This causes an imbalance in the ecosystem. The overgrowth of the algae inhibits the growth and survival of other organisms. 9. True – Unicellular slime moulds uniting to form a multicellular mass illustrates the potential for specialization. Soon, cells may become specialized to carry out a specific task. 10. True – There is great variation in reproduction; from asexual fragmentation to sexual conjugation. Protists can be autotrophic or heterotrophic or a combination of both. Locomotion may involve a flagellum or cilia. Finally, protists may be free living or parasitic.

15. Homework Take a look at the links below