Protozoans

Question 1

Key features of protozoans

Answer 1

• Single celled
• Eukaryotic
• motile
• heterotrophic
• complex

Question 2

Locomotion in Protozoans (Flagella)

Answer 2

Some have flagellum (wave of motion propels organism forward)

Question 3

Locomotion in Protozoans
(Cillia)

Answer 3

Many move one after the other - metachronal waves

Question 4

Locomotion in Protozoans (Pseudopodia)

Answer 4

Pseudopodia (false feet)

Temporary extension of the body

Directional movement

Changes in the ectoplasm

Question 5

Food acquisition of protozoans

Answer 5

Engulf particles

Form vesicles

Receptors on the outside detect food - latch onto food and engulf

Food vesicle, lysosomes within release

Some protozoans are specialised for different forms of feeding

Question 6

Origin of Protozoans

Answer 6

Endosymbiont Theory

Question 7

Endosymbiont Theory

Answer 7

mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).

Question 8

Examples of Protozoans

Answer 8

• Amoeba
• Paramecium
• Euglena
• Trypansoma

Question 9

Amoeba characteristics

Answer 9

Free living organims
found in freshwater
some parasitic forms (Entamoeba histolytica)

Question 10

Entamoeba histolytica life cycle

Answer 10

• humans ingest cysts from food/ surfaces/water etc
• organism break down intestinal wall and make their way to blood system
• can make their way to the liver, lungs and even brain

Only amoeba that effects humans

Question 11

3 stages of the Malaria plasmodium

Answer 11

1. Exo-erythrocytic cycle (human liver)
2. Erythrocytic cycle (human blood)
3. Sporogonic cycle (within mosquito)

Question 12

What does malaria need to complete it’s lifecycle?

Answer 12

Mosquito and human host

Question 13

Malaria plasmodium - Exo-erythrocytic cycle (human liver)

Answer 13

Sporozoites injected into to human by a feeding mosquito.

carried to liver

infect liver cells (schizont)

infected cells rupture and enter blood.

Question 14

Malaria plasmodium. Erythrocytic cycle (human blood)

Answer 14

• Form trophozoites in blood cells
• Asexual cycle of immature trophozoites causes continued replication
• Sexual cycle creates gametocytes which are then passed back into mosquitos when feeding

Question 15

Malaria Plasmodium. Sporogonic cycle (within mosquito)

Answer 15

Sexual reproduction takes place within the mosquito.

Zygote (oocyte) forms in mosquito gut

Sporozoites form (cycle begins again).

Question 16

Why do humans experience a fever with malaria?

Answer 16

Trophozoites bursting out of red blood cells causes fever

Question 17

How do we treat malaria?

Answer 17

Tu Youyou - Chemical used for treating fever (sweet-wormwood)

Gene editing (Crispr) modifies double sex gene to stop females from feeding or laying.

Make males infertile

Some vaccines

Question 18

Toxoplasma gondii (cat - rodent parasite)

Answer 18

• Can manipulate hosts behaviour
• Rodent show no fear to cats when infected
• Cat must eat rodent for parasite to be transmitted
• Lack of fear - good for parasite, bad for rodent
• Parasite reproduces in cat (definitive host)

Question 19

Does toxoplasma affect humans?

Answer 19

Up to 50% of population infected due to close relationship with cats

Possible modification to human behaviour

Question 20

Trypanosoma brucei (causes sleeping sickness)

Answer 20

Hard to develop immune response because parasite can change its expression.

Relies on transmission by tsetse fly (vampire fly)

Question 21

Two subspecies of trypanosoma brucei (from tsetse fly)

Answer 21

1. Gambiense (fly-human-fly)
2. Rhodesiense (fly-game-fly)

Zoonosis (when a human is infected by rhodesiense by accident)

Question 22

Zebra theory (trypanosoma brucei)

Answer 22

Colour patterns could protect from being bitten

stripes reflect type of polarised light that tsetse flys like

Question 23

Ciliates

Answer 23

Have Cilia

Can be aquatic

free-living, symbionts or parasitic.

Question 24

what is the only parasitic ciliate that infects humans?

Answer 24

Balantidium coli