2.3 The protists

Question 1

Why Protists are important

Answer 1

Protists play key roles in aquatic ecosystems, some also inhabit moist terrestrial ecosystems

Some are photosynthetic and are major producers in the world’s oceans.

Question 2

Non-photosynthetic protists are important what?

Answer 2

Non-photosynthetic protists are important consumers, especially at the microscopic level, where they dominate the lowest levels of most aquatic food pyramids.

Question 3

Harmful protists

Answer 3

Some parasitic protists can cause serious disease (malaria, sleeping sickness, amoebic dysentery, beaver fever (giardiasis)

Question 4

Helpful protists

Answer 4

Nori (aka Porphyra – a multicellular protist) is a type of seaweed is used to wrap sushi

Question 5

Products from seaweed (a protist!)

Answer 5

food additives such as agar and carrageenan, also used in toothpaste, cosmetics and paints

Question 6

how did the internal membrane of prokaryotes form?

Answer 6

Internal membranes likely developed from the folded membrane of an ancestral prokaryote cell

Question 7

Mitochondria and Chloroplasts

Answer 7

Each have two membranes

Inner membranes are similar to those of their ancestral prokaryote

Have their own internal chromosomes, which are very similar to prokaryotic chromosomes

Reproduce independently within eukaryotic cells by binary fission

Based on this evidence, mitochondria and chloroplasts are thought to have originated by endosymbiosis

Question 8

Endosymbiosis

Answer 8

A relationship in which a single-celled organism lives within another organism

Question 9

The kingdom protista

Answer 9

Protists are the most diverse kingdom of eukaryotes (more than 200 000 known species)

Junk drawer

catch all

Question 10

Characteristics of Protists

Answer 10

There is no “typical” protist, since they vary greatly

Most are unicellular, but some are multicellular

Many have complex cells

Question 11

Haploid

Answer 11

Cells that contain half of the usual genetic information

Question 12

Diploid

Answer 12

Cells that contain two copies of every chromosome (normal)

Question 13

Sexual Reproduction in multicellular protists

Answer 13

some make sex cells (sperm and eggs) that are haploid

When egg and sperm fuse, resulting cell is called a zygote, most of which are diploid

Question 14

Alternation of Generations

Answer 14

A Life Cycle where diploid individuals produce spores, that make haploid individuals

The haploid individuals then reproduce sexually, producing sporophytes and completing the life cycle