2.2 Protists

Question 1

protists

Answer 1

-junk drawer of organisms
-includes all eukaryotes that do not fit “nicely” into the plant, animal or fungi kingdom

Question 2

what are protists believed to have evolved from?

Answer 2

prokaryotic bacteria

Question 3

give examples of the variety of niches and habitats protists can occupy

Answer 3

forest & ocean floors, sewage treatment plants, chlorinated swimming pools, and the atmosphere

Question 4

what are the three types of protists?

Answer 4

animal-like, plant-like and fungus-like

Question 5

example of an animal-like protist

Answer 5

amoeba and paramecium

Question 6

example of a plant-like protist

Answer 6

euglena

Question 7

example of a fungus-like protist

Answer 7

plasmodial slime mould

Question 8

structure of protists

Answer 8

-mostly unicellular (some multi)
-some are colonial
-eukaryotic
-with membrane bound organelles

Question 9

What are the 2 origin theories?

Answer 9

-could have been inward folding of membranes to create membrane bound organelles

-more likely Endosymbiosis of ancient unicellular prey by predator

Question 10

what are the different methods of motility?

Answer 10

pseudopodia, cilia/flagella or none

Question 11

describe how pseudopodia is a method of motility

Answer 11

amoeba creep by extending their cytoplasm to create ‘false feet’ (Pseudopodium, s.)

Question 12

describe how cilia/flagella is a method of motility

Answer 12

-Others swim quickly using hairlike structures called flagella and cilia

-Flagella are long hairlike projections that extend out of the cell membrane

Question 13

how do protists without a method of motility move?

Answer 13

some protists rely on water, wind currents and passing animals that they may hitch on to move them

Question 14

Heterotrophic protists with flagella are called
_____________

Answer 14

Heterotrophic protists with flagella are called
zooflagellates

Question 15

a group of protists that have an “apical complex” structure at the tip of the cell specialized for penetrating host cells are called ______________

Answer 15

apicomplexans

Question 16

apicomplexans

Answer 16

These protists release reproductive cells called spores that can enter the bodies of other
organisms and live as parasites

Question 17

what is the name of the apicomplexan that mosquitoes carry?

Answer 17

Mosquitoes carry the apicomplexan
Plasmodium, which causes malaria

Question 18

Reproduction of protists

Answer 18

-Sexual
-conjugation
-Asexual
-Or Both

Question 19

Animal-like protists

Answer 19

-heterotrophs
-endocytosis - engulfing food by extending membrane/cytoplasm
-e.g. amoeba
-ciliates sweep food into the oral groove
-e.g. paramecium

Question 20

what is endocytosis?

Answer 20

engulfing food by extending membrane/cytoplasm

Question 21

Plant-like protists

Answer 21

-autotrophs; have chloroplasts
-e.g. dinoflagellates, plankton, phytoplankton,
diatoms

Question 22

true or false: green algae is a plant-like protist

Answer 22

false

-now considered a plant

Question 23

What are dinoflagellates?

Answer 23

Unicellular protists with a cell wall made of
cellulose and two flagella are called dinoflagellates

Question 24

What are red tides and how are they caused?

Answer 24

Red Tides – Harmful Algal Bloom
-kills fish, anything that eats shellfish
-worsening due to climate change

Question 25

Fungus-like protists

Answer 25

-heterotrophs; saprophytes [feeds on dead material]
-e.g. plasmodial slime mould, cellular slime
mould, water mould

Question 26

Importance of Protists

Answer 26

1) provide aquatic consumers with food and
oxygen
2) important symbiotic relationships with other
organisms
3) cause some of the world’s most serious diseases

Question 27

give an example of a disease caused by a protist

Answer 27

E.g. Malaria

-Plasmodium, an animal–like protist needs two hosts: mosquitoes, humans

Question 28

describe the cycle of plasmodium

Answer 28

-female mosquito infected by Plasmodium
-bites human
-Plasmodium enters circulatory system, liver…
-burst RBC, cause toxins to be released
-causes chills, fever

Question 29

Explain why an amoeba and Paramecium are
considered “animal-like” protists

Answer 29

because they are heterotrophs that capture and ingest food

-amoebas use pseudopodia to capture their food

-paramecium use cilia to sweep food into their oral groove

Question 30

Explain the role plankton play in most aquatic
habitats

Answer 30

The photosynthetic organisms in plankton are called phytoplankton, and they form the
base of food chains for most other aquatic organisms.

Question 31

Identify the organism that causes malaria and
describe its life cycle

Answer 31

-plasmodium causes malaria

1) A mosquito infected with Plasmodium bites a human

2) Plasmodium infects human liver cells, which eventually burst, releasing a different form of the protist

3) Plasmodium infects red blood cells and
divides asexually. The red blood cells burst and release more Plasmodium cells

4) Another mosquito bites the infected person and
picks up Plasmodium cells.

5)Plasmodium reproduces sexually in the mosquito

Question 32

What characteristic do all protists have in
common?

Answer 32

a nucleus and membrane bound organelles

Question 33

What is HABs and how is it dangerous?

Answer 33

Harmful Algal Bloom
-HABs produce a toxin that can affect animals from fish to mammals, resulting in tissue damage and death.
-Although humans are usually alert enough to avoid the red water of HABs, we still face the
danger of eating contaminated animals, such as shellfish.

Question 34

Summarize why protists have traditionally
been placed in their own taxonomic kingdom
in the six-kingdom system

Answer 34

Biologists have a sort of taxonomic
“stuff” drawer: the kingdom Protista. Protista is a very diverse kingdom of organisms that do not fit neatly into any of the other kingdoms

Question 35

Describe three examples of structural diversity
found in protists

Answer 35

-Most protists are unicellular and free-living
(not parasitic).
-However, some protist species are colonial, organisms consisting of many similar or identical cells.
-There are even some protists, such as seaweeds like kelp, that are multicellular. These multicellular
protists have relatively complex bodies consisting of specialized cells.

Question 36

What does the theory of serial endosymbiosis
propose about how eukaryotes may have
evolved from prokaryotes?

Answer 36

Scientists hypothesize that in this process, called serial endosymbiosis, chloroplasts and mitochondria evolved from small symbiotic prokaryotes that lived within other, larger host cells

Question 37

What is the difference between the
plasmodium formed by a slime mould and
the Plasmodium that causes malaria?

Answer 37

plasmodium formed by a slime mould is a fungus-like protist

plasmodium that causes malaria is an apicomplexan

Question 38

Even though euglena lacks a cell wall, why do biologists still classify it as a plant-like protist?

Answer 38

Even though Euglena lacks a cell wall, most biologists include it in this group, because it is mostly photosynthetic