The members of kingdom Protista are mostly unicellular eukaryotes that have chloroplasts and cellulose.

C. unicellular eukaryotes

An amoeba has no definite shape since it can stretch out its body when it tries to engulf a food.

C. They have a definite shape

A trichocyst is an organelle that is found in a ciliate or a flagellate. It serves as their defense mechanism by ejecting long thin threads in response to stimuli.

C. trichocysts

**Conjugation** is the process in which a bacterial cell can transfer genetic material to another bacterial cell through the use of pili or direct contact. During the process, the bacterial cell that gives off its genetic material is called the **donor** cell and the other who receives the genetic material is called the **recipient** cell. From the given choices, the correct answer is **b**

B

**Algae** are plantlike protists that contain chlorophyll pigments in order for them to accomplish photosynthesis. They are aquatic in nature and hydroponically in fresh and saltwater environments. Moreover, these species contain accessory pigments which give them their wide range of color appearances. Hence, the correct answer is D.

D

Phytoplankton, which are usually found near the surface of the water, are tiny organisms that drift or wander in the water. They make their own food through photosynthesis.

C. phytoplankton

Autotrophs are self feeding organisms such as plants and algae. They undergo the process of photosynthesis to produce their own food. Both plants and algae have a cell wall.

A. photosynthetic pigments and cell wall composition

The alternation between the diploid and the haploid stages are under the process of alternation of generations.

d. diploid and haploid cells

Slime molds are commonly found on deciduous logs, rotting wood, and soil.

B. rotting wood or compost piles

The hyphae, which resemble a fungus, appear like a long, thread-like, and branching structure that is released by water molds.

D. hyphae

These categories are not adequate in classifying a protest. Because the following characteristics are very common among other organisms. It would be best to use genetic methods to further characterize and classify protist species.

The protist engulfs its food directly into its body through the process of endocytosis. Therefore, it will also take in some extra water or fluid as it ingests the food, which is extracted by contractile vacuoles.

The ciliates uses its cilia, which are hair like structures around it to move around. the cilia functions like thousands of fish fins. The sarcodines move in a worm like projection, by adjusting its body fluidly.

conjugation is when two paramecia bind and interact in order to exchange genetic information. This is not a form of reproduction, because no new cells are formed

see explanation for solution

**Algae** are plant-like, unicellular protists that have **chlorophyll** and other accessory pigments that help them manufacture their own food through the use of sunlight. Similar to plants, they can undergo photosynthesis.

**Euglenophytes** are plant-like protists that are distinguished by having no cell wall and a presence of an *eyespot* in their cell. These species contain chloroplast and can utilize the process of photosynthesis for food production but most of the time, they are like zooflagellates acting as heterotrophs.

Plant-like protist serves as the source of food for aquatic animals in the aquatic food chain. They as the primary producers like plants.

**Red algae** are plant-like protists that can live at great depths because of their ability to harvest light efficiently. These species have chlorophyll *a* and a reddish accessory pigment called **phycobilins** that are good in harvesting blue light. Because of this pigment, it enables this alga to thrive on deeper levels of seas and oceans. An example of this is the **coralline algae**

**Brown Algae** are plant-like protists that have chlorophyll *a* and *c*, and a brown accessory pigment called **fucoxanthin**. The presence of this accessory pigment and chlorophyll *c* makes algae appear dark yellow to brown in color. These species are mostly found in shallow waters and the most common example of this is **kelps**.

**Green Algae** are plant-like protists that share the most characteristics with plant species, including the presence of photosynthetic pigments and cellulose as the main cell wall component. These species can be found in both fresh and salt water and can be unicellular or multicellular. Examples of these are *Chlamydomonas* (unicellular algae), and *Ulva* (multicellular species).

**Alternation of generation** is the process in which the algal species can switch from haploid to diploid, and vice versa. This process makes the life cycle of algae include both haploid and diploid generations and enables them to have sexual and asexual reproduction.

Termites have a symbiotic relationship with a microbiota that plays a significant role in the digestion of lignin and cellulose that are found in the cell wall of woody plants. The microbiota, which is a group of microorganisms that include the protists and bacteria that are living inside the termite’s gut, produces digestive enzymes to decompose those compounds to convert it into an energy that the termites can use. This is why when the termites were fed off with an antibiotic, it caused the bacteria living inside the body of the protists to die. Because of this, the enzymes which are needed by the termites to digest food are now gone. Eventually, this event led to their starvation.

Red tides are caused by a harmful algal bloom. Low salinity, warm temperature, and high nutrient in the water cause the red tide to form. When the wastes from farms and factories are wash by the runoff and groundwater discharge, a high concentration of nitrite, nitrate, and phosphate are carried by the rivers to the ocean. If a high level of nutrient goes into the sea, millions of algae will grow in clusters. Their growth are often seen in a shade of red, or brown. This kind of algal bloom has microscopic algae that produce toxins which causes the death of fishes. This also makes the fishes and shellfishes dangerous to eat.

The process of sexual production through conjugation enables the species of *Paramecium* to undergo genetic exchange. This genetic exchange is beneficial for natural selection and adaptation, and thus can create a positive impact on the evolution of species

Not all small organisms are beneficial in life, environment, and society. In fact, some of these microscopic organisms act as parasites and cause most diseases in plants, animals, and humans. An example is the Plasmodium protozoa that causes malaria. In humans, malaria is caused by four different species of Plasmodium. These species are P. falciparum, P. malariae, P. ovale and P. vivax. This parasite, which is transmitted by a female Anopheles mosquito, reproduces itself in the intestines of the mosquito. Once it reaches the red blood cells of a human, it begins to multiply rapidly and causes serious complications and in worst cases, mortality. There were severe cases in some places wherein a malaria outbreak has occurred. This has already killed thousands of people.

Clearly, it is not only a problem for the entire human race but its effect has caused a disruption in the ecosystem. The insecticides such as dichlorodiphenyltrichloroethane (DDT) that were used to kill the mosquitoes and the spread of malaria have caused a fatal effect to other life-forms including those plants, animals, and humans that are exposed to high levels of DDT. In addition, the parasites have become resistant to the effect of DDT and in turn, they have even spread to new places.

The question asked to identify and classify the given sample organisms based on their phenotypic appearance. Let us first list down the given observations for each protist.

Protist A: The protist used **pseudopods as their locomotor organ**, and they do not have cell walls nor they can photosynthesize.

Protist B: The protist does not have a cell wall, and the **presence of two flagellar structures** is evident.

Protist C: The cells look like an amoeboid structure, it has no chlorophyll or any photosynthetic pigments and it contains many nuclei, and **sporangia, and germinate through flagellated cells**.

Protist A: This sample organism is under **Phylum Sarcodina**. The species under this phylum is described as animal-like protists and use pseudopods as their feeding and locomotor organ.

Protist B: The sample organism is under **Phylum Euglenphyta**. Euglenophyte species are identified to the presence of their two flagellar structure and the presence of eye post and chlorophyll pigments in their cell.

Protist C: The sample organism is under **Phylum Acrasiomycota**. These protists are described as “fungus-like”, as they only feed on dead organisms for their nutrients. Slime molds (*their common name*) play an important role in nutrient cycling.

As long as food is plentiful, slime – mold cells exist independently as tiny amoebas They move around, feed on bacteria in the environment, and reproduce simply by dividing into two. But when the food becomes scarce, the slime – mold behavior changes dramatically

The slime – mold cells stop reproducing and move towards another, forming a cluster (called a “Pseudo plasmodium”) with tens of thousands of cells, at this point, the slime – mold cells start acting as a unified whole, rather than lots of unicellular creatures, they act as a single multi cellular creature, and produce spores. Spores are better able to survive in harsh conditions, and when the conditions improve, the spores develop into new slime mould So, its one way of perpetuating the species

At one time, the classification of organisms was done based on their ability to move and ingestion of food. The organisms which have the ability to move and feed on other organisms were called animals and the ones which are stationary and prepare their own food are called plants.

However, such criteria for classification cannot be used to classify Protists. This is because **Protists** form a diverse group of species. They are neither animals nor plants nor fungi. They are eukaryotes that resemble either of the groups. There are several Protists in Kingdom Protista.

They are classified into various groups based on their characteristics. The groups are named according to the name of the organisms which they resemble. These groups are: Animal-like protists, plant-like protists, and fungi-like protists.

The ozone layer is mainly responsible for absorbing harmful ultraviolet radiation from the sun. It acts as an umbrella to all the life-forms on our planet since we cannot be exposed to high levels of UV radiation. A continuous exposure to UV radiation will damage the cells and cause the death of most life-forms including the photosynthetic organisms such as plants, algae, and phytoplankton. For an instance, if the phytoplankton would be exposed to high levels of UV radiation, it would cause damage to their DNA and other organelles. It will impair their cell processes including photosynthesis and growth rate. As a result, the marine ecosystem will be disrupted due to the diminishing population of phytoplankton.

The answer is yes. Since the malaria parasite is usually found in the red blood cells of an infected human, the disease can also be potentially transmitted through blood transfusion, organ transplant, or even the use of contaminated needles or syringes.