18. Protista

Question 1

Main features of Protista

Answer 1

Single celled or multicellular 
Eukaryotic
Feeding method: taking in organic substances or some can photosynthesis.
Can be microscopic- except algae
Found in water

Question 2

Main features of amoeba

Answer 2

Single celled
A consumer- it feeds on small plants, animals and bacteria.
Lives in freshwater ponds on top of mud at bottom.

Question 3

Amoeba diagram

Answer 3

Ectoplasm and Endoplasm
Fat droplets
Nucleus
Waste products
Pseudopod
Contractile vacuole
Food vacuole
Cell membrane

Question 4

Function of following in amoeba
Cell membrane
Nucleus
Cytoplasm

Answer 4

Semi permeable
Controls the parts of the cell
Holds everything.

Question 5

Endoplasm and Ectoplasm appearance.

Answer 5

Endoplasm: inner layer, fluid like, has grainy appearance-because of waste and food vacuoles

Ectoplasm: where the Endoplasm becomes soft in places at edge. Transparent.

Question 6

Pseudopod function and how it moves

Answer 6

Referred to as false foot.

1. For movement- extends in direction it wants to move in.
2. Also used to engulf prey, for feeding.

Moves when ectoplasm softens and moves forward and the Endoplasm moves in to replace it.

Question 7

Feeding in an amoeba

Answer 7

It surrounds it’s prey with its pseudopod.
Food then digested and stored in food vacuole.
Waste products moved into the cytoplasm and excreted.

Question 8

Contractile vacuole function

Answer 8

It is responsible for osmoregulation. ie. Keeps the water balance constant, stopping the amoeba filling with water and bursting.

Question 9

Steps of osmoregulation

Answer 9

1. Excess water enters the contractile vacuole.
2. The contractile vacuole swells with water and moves to the edge.
3. It bursts and expels the water.

Question 10

What is osmoregulation?

Answer 10

Amoebas cytoplasm has a higher salt concentration than the surrounding fresh water. As a result water constantly rushes in by osmosis. Therefore the amoeba cell can become full with water, burst and die.

Question 11

Importance of amoeba

Answer 11

Entamoeba histolytica causes contamination of fresh water. Known as a parasite as it harms other organisms in the water.