Microbiology - Outcome 2 - Protozoa

Question 1

what are protozoa?

Answer 1

unicellular eukaryotes

Question 2

how can protozoa be subdivided into their types?

Answer 2

they can be divided based on they means of locomotion

Question 3

what are the four types of protozoa?

Answer 3

• flagellates
• rhizopuds
• ciliates
• sporozoans

Question 4

what is a characteristic of flagellates?

Answer 4

move by flagella

Question 5

what is a characteristic of rhizopods?

Answer 5

form ‘pseudopodia’ - false feet

Question 6

what is a characteristic of ciliates?

Answer 6

they bear cilia

Question 7

what is a characteristic of sporozoans?

Answer 7

• include many parasitic forms
• lack organelles for locomotion

Question 8

do protozoa contain a cell wall?

Answer 8

no

Question 9

if protozoa do not contain a well wall, what does this make them more vulnerable to?

Answer 9

damage by osmotic lysis

Question 10

what is the ectoplasm and what is its function?

Answer 10

• a cytoplasm immediately under the plasma membrane that is semi-solid
• gives some rigidity to the cell

Question 11

what is the pellicle and what is its function?

Answer 11

• the cell membrane and cell structures immediately beneath the ectoplasm
• rigid to maintain shape of protozoan and to help overcome absence of cell wall

Question 12

how can the pellicle be further strengthened?

Answer 12

by depositing strips of protein below the membrane

Question 13

what is the endoplasm?

Answer 13

an inner layer of the cytoplasm containing the eukaryotic organelles

Question 14

what organelle structure is much larger in numbers in protozoa?

Answer 14

vacuoles

Question 15

what are the three types of vacuoles present in the cytoplasm of a protozoan

Answer 15

• contractile vacuoles
• secretory vacuoles
• food vacuoles

Question 16

describe the role of contractile vacuoles

Answer 16

• used for osmoregulation
• fill with water until full, then expel water to outside then
• often found in freshwater protozoa

Question 17

describe the role of secretory vacuoles

Answer 17

• contain specific enzymes which perform various functions eg. excystation

Question 18

describe the role of food vacuoles

Answer 18

• known as phagocytic vacuoles
• food taken into protozoan is surrounded by membrane forming ‘ food vacuole
• fuses with other vacuoles containing enzymes and food is digested

Question 19

what are the two distinct types of nuclei that protozoa have?

Answer 19

micronuclei and macronuclei

Question 20

what is the function of micronuclei?

Answer 20

involved in genetic recombination during reproduction

Question 21

what is the function of macronuclei?

Answer 21

trophic activities eg. responds to stimuli and day to day activities

Question 22

describe the role of pseudopodia

Answer 22

• thick extensions to the cell produced by pinching of the cell and extending the cell membrane
• act as tentacles in movement
• used by cell for feeding

Question 23

describe the reproduction process of protozoa

Answer 23

• asexual process
• binary fission

Question 24

how can some protozoa reproduce such as paramecium?

Answer 24

• reproduce asexually by binary fission
• reproduce sexually by conjugation

Question 25

what does conjugation involve?

Answer 25

involves two members of two different mating types temporarily fusing and exchanging micronuclei

Question 26

what is encystation?

Answer 26

where protozoa can develop a resting stage called a cyst

Question 27

what are cysts?

Answer 27

- dormant forms which lack cell wall and have reduced metabolic energy - multiplication occurs within cyst (excystation) so more than one organism is released

Question 28

describe the function of cysts in entamoeba hystolytica

Answer 28

- when cyst forms it has single nucleus - as cyst matures, nucleus divides producing four nuclei - at excystation, four uninucleate amoebas appear - cause dysentery

Question 29

describe the functions of cysts in Giardia lamblia

Answer 29

- newly formed cyst has same number of orangeades as original vegetative cell - as cyst matures, organelles double and two flagellated protozoa are formed - cause diarrhoea

Question 30

what are the functions of cysts?

Answer 30

- protection against adverse conditions in the environment - serve as a means of transfer between hosts in parasitic species

Question 31

what are protozoa described as in terms of temperature?

Answer 31

psychrophiles (species who inhabit human body are mesophiles)

Question 32

what are protozoa described as in terms of pH?

Answer 32

neutrophiles

Question 33

are protozoa autotrophic or heterotrophic ?

Answer 33

- heterotrophic - prey on algae and other microbes eg. bactr=eria to obtain organic sources of carbon

Question 34

what are the ways of protozoa obtaining nutrients?

Answer 34

- absorbing nutrients through cell membranes - phagocytosis, engulfing particles of food with pseudopodia - using cytosome

Question 35

what are protozoa described as in terms of oxygen?

Answer 35

obligate aerobes

Question 36

what is the rhizosphere?

Answer 36

- zone of soil surrounding the roots of plants - contains bacteria, fungi and protozoa

Question 37

how are protozoa active in the rhizosphere?

Answer 37

- they feed on bacteria - regulate bacterial populations

Question 38

explain what mineralisation is in terms of protozoa?

Answer 38

- protozoa have lower concentration of nitrogen in their cells than bacteria - obtain more nitrogen than they can utilise - release excess nitrogen in form of ammonium

Question 39

where does mineralisation occur?

Answer 39

near root system of plant

Question 40

state one beneficial effect of protozoa

Answer 40

- used as bio indicators - presence or absence of specific protozoans in environment can indicate ecological disturbances

Question 41

state one detrimental effect of protozoa

Answer 41

- malaria - plasmodium malarie - female anopheles mosquito acts as vector