Chapter 23: Protists

Question 1

Protists are found in a wide variety of → ____

Answer 1

habitats

• All require → water
• Most are free living and inhabit freshwater or marine
environments

Question 2

Some act as saprophytes

Answer 2

obtain nutrients from dead
organic material (chemoorganoheterotrophs)
• Release degrading enzymes and absorb products
through osmotrophy

Question 3

Others have holozoic nutrition, ___

Answer 3

which involves the
ingestion of solid nutrients through → phagocytosis

Question 4

Protist morphology and physiology is the
same as ________

Answer 4

plants and animals

• But they are mainly unicellular,
so a lot of function occurs in
just a single cell

Question 5

Plasmalemma

Answer 5

plasma membrane of protists

• Identical to multicellular organisms

• Ectoplasm (outer gel) and endoplasma
(inner fluid) are found under the
plasmalemma

Question 6

Ectoplasm

Answer 6

(outer gel)

Question 7

endoplasma

Answer 7

(inner fluid)

Question 8

Pellicle

Answer 8

is a rigid layer beneath the plasmalemma
• Acts as a supportive layer or cuticle

Question 9

Vacuoles are usually found in a
protist’s _____

Answer 9

cytoplasm

Question 10

Contractile vacuoles

Answer 10

osmoregularity organelle for
freshwater protists
• Constantly expelling water

Question 11

Phagocytic vacuoles

Answer 11

sites of food ingestion in protists that
perform phagocytosis

• Some phagocytes have a
cytosome (cell mouth) and a
cytoproct (anal pore) to aid
in the entrance and exit of
phagocytized materials

Question 12

Cilia or flagella are found
on many _____ at some
point in their
→ life cycle

Answer 12

protists

• Allow for
→ motility
• Generate water
currents for feeding and
respiration

Question 13

Trophozoites

Answer 13

actively growing and
reproducing protists

Question 14

Encystsment

Answer 14

formation of a → dormant cyst
• Simple structure with a → cell wall
• Form in aquatic and parasitic protists

Question 15

Cysts protect against

Answer 15

harmful changes in the environment
(pH, low O2, desiccation, loss of nutrients)
• Acts as sites for nuclear reorganization and cell division
• For parasitic species, a cyst is the infectious stage

Question 16

Excystment

Answer 16

is the process where a protist escapes from
the cyst
• May be triggered by better environmental conditions

Question 17

Protists have both ___ and ___ reproduction in
their life cycles

Answer 17

asexual ; sexual

Question 18

Binary fission

Answer 18

is the most common method of asexual
reproduction

• Nucleus divides, then cytoplasm divides during
cytokinesis
• Two identical cells form

Question 19

Sexual reproduction involves _____

Answer 19

gamete formation

Question 20

• Gametes are called ____ in protists

Answer 20

gamonts

Question 21

Haploid gamonts fuse in a process called → _____

Answer 21

syngamy

Question 22

Conjugation

Answer 22

involves the exchange of genetic material
between two individuals

• Creates a genetically distinct nucleus

Question 23

Classification of protists
was historically done
based on morphology
and locomotion into four
groups:

Answer 23

Flagellates, ciliates,
amoebae, and
stationary

Question 24

Phylogenomics

Answer 24

involves the analysis of genes across
many species to determine evolutionary relationships

• Lead to the creation of → supergroups

Question 25

Euglenozoa

Answer 25

• Primitive eukaryotes • Free-living and parasitic flagellates • Chemoorganotrophs or photoautotrophs • Euglena spp. • Elongated cell bound by plasmalemma • Stigma – helps organism orient to → light

Question 26

Stigma

Answer 26

helps organism orient to → light

Question 27

Trypanosomes

Answer 27

– pathogenic Euglenozoa • Leishmania causes → leishmaniasis • Trypanosoma cruzi causes → Chagas’ disease • Transmitted by “kissing bugs” • T. brucei cause → African sleeping sickness

Question 28

Metamonada

Answer 28

• Giardia intestinalis • Diarrhea from contaminated water • Members are flagellated and lack mitochondria • Mitosomes – mitochondria-like double-bounded membrane organelles • Most metamonads are harmless symbionts with a few exceptions

Question 29

Mitosomes

Answer 29

mitochondria-like double-bounded membrane organelle

Question 30

Giardia – causes

Answer 30

diarrhea

Question 31

• Hexamita salmonis

Answer 31

fish parasite

Question 32

H. meleagridis

Answer 32

turkey pathogen

Question 33

Pseudopodia

Answer 33

used for locomotion and feeding

Question 34

Lobopodia

Answer 34

rounded

Question 35

Filopodia

Answer 35

long and narrow

Question 36

Reticulopodia

Answer 36

netlike mesh

Question 37

Naked amoebae

Answer 37

lack cell wall and are surrounded only by a plasma membrane

Question 38

Testate amoeba

Answer 38

plasma membrane is covered by → material

Question 39

Entamoebida

Answer 39

• Lack mitochondria but contain mitosomes • May possess 20 mitochondrial proteins • Parasites or commensals • Entamoeba histolytica • Causes amoebic → dysentery • Third leading cause of parasitic death worldwid

Question 40

Eumycetozoa “Slime Molds”

Answer 40

• Distinctive stage when the organisms exist as streaming masses of colorful protoplasm • Protoplasm creeps along in amoeboid fashion over moist, rotting logs, leaves, and other organic matter, which it degrades

Question 41

Ciliophora

Answer 41

found in both benthic (sediments) and planktonic communities in water and soil systems • Use many cilia as locomotory and feeding (Paramecium) • Cilia longitudinal rows or spirals around the body • Precisely coordinated movement

Question 42

Apicomplexans

Answer 42

are distinguished by the apical complex at one end of the cell • Plasmodium genus in this group that causes → malaria