Kingdom Protista

Question 1

What is another name for Protista?

Answer 1

Protodista.

Question 2

What does Protista comprise of?

Answer 2

They comprise mostly single-celled microorganisms but do include multicellular organisms such as seaweeds.

Question 3

Are protists eukaryotic or prokaryotic in nature?

Answer 3

All protists are eukaryotic in nature. This means that all of their cells possess a membrane-bound nucleus and membrane-bound organelles.

Question 4

What is an example of a heterotrophic protist?

Answer 4

Amoeba. They survive by capturing and ingesting prey.

Question 5

What is an example of an autotrophic protist?

Answer 5

Algae

Question 6

What is an example of a protist that is parasitic?

Answer 6

Water moulds.

Question 7

Are amoeba single-celled or multicellular?

Answer 7

Single-celled.

Question 8

Where can amoeba live?

Answer 8

They can live in freshwater streams, rivers, ponds and lakes as well as in marine habitats (seas and oceans).

Question 9

What does amoeba feed on?

Answer 9

They feed on other protists, such as algae, but also on bacteria and single-celled fungi.

Question 10

Amoeba have a definite shape, true or false?

Answer 10

False. Amoeba has no definite shape due to the constant flow of the cytoplasm.

Question 11

What is the cytoplasm of amoeba composed of?

Answer 11

The cytoplasm is composed of a thin, viscous (firm) outer layer called ectoplasm and a very fluid, watery endoplasm.

Question 12

What are pseudopods?

Answer 12

Pseudopods (false feet) are extensions of the ectoplasm and endoplasm.

Question 13

What are the sub-cellular structures/organelles contained in the endoplasm of Amoeba?

Answer 13

Mitochondria, food vacuoles, lysosomes, fat droplets and contractile vacuoles. Amoeba do not possess chloroplasts as they are not photosynthetic.

Question 14

(4 points)

What is the function of the cell membrane in Amoeba, and what is composed of?

Answer 14

• The cell membrane is made up of a phospholipid bilayer
• Responsible for retaining the contents of the cell, controlling what enters and leaves the cell, and allowing diffusion of gases (oxygen and carbon dioxide) and water.

Question 15

What is the function of the nucleus in Amoeba?

Answer 15

The nucleus controls all the metabolic activities of the cell.

Question 16

What is the function of fat droplets in Amoeba?

Answer 16

Food vacuoles store fat as an energy reserve for use during times when food is not readily available.

Question 17

What is the function of food vacuoles in Amoeba?

Answer 17

Food vacuoles secrete a mixture of acids and digestive enzymes that kill and digest the prey.

Question 18

(3 points)

What are the function of pseudopods in Amoeba?

Answer 18

• Pseudopods enable movement of Amoeba, usually in the direction of prey.
• The more fluid endoplasm flows into pseudopod as the Amoeba moves.
• Amoeba engulfs prey by extending its pseudopods around the prey; much in the same way that white blood cells engulf bacteria.

Question 19

(4 points)

What is the function of contractile vacuoles in freshwater Amoeba and why are they so important?

Answer 19

• All freshwater Amoeba have contractile vacuoles for osmoregulation.
• Water is continually moving into freshwater Amoeba by osmosis.
• This poses a serious threat to the integrity of the Amoeba.
• If the water is not removed the cell will burst.

Question 20

(2 points)

How do contractile vacuoles osmoregulate in Amoeba?

Answer 20

1. Contractile vacuoles collect the excess water that builds up in Amoeba. They do this by actively transporting the water from the cytoplasm into the contractile vacuole.
2. Eventually the contractile vacuole grows large enough to fuse with the cell membrane and the excess water is released.

Question 21

(2 points)

Why do marine Amoeba not possess contractile vacuoles?

Answer 21

• Marine Amoeba (present in the seas and oceans) do not possess contractile vacuoles as there is no osmotic gradient present between the inside and outside of the cell.
• This is due to the high salt concentration of the sea.