Protists

Question 1

What is a chemoautotroph?

Answer 1

An organism that obtains energy from chemical reactions and their carbon from carbon dioxide. Example: Nitrogen fixing bacteria.

Question 2

What is a photoautotroph?

Answer 2

Organisms that carry out photosynthesis to obtain energy. Example: Tree

Question 3

What is a photoheterotroph?

Answer 3

Organisms that obtain energy from light but cannot use carbon dioxide as their sole carbon source. Instead they use biological compounds like carbohydrates and fatty acids. Example: Purple non sulfur bacteria.

Question 4

What is an heterotroph?

Answer 4

Organism that obtains hydrogen and electrons from organic substrates. Example: Humans

Question 5

Which came first? Why?

Answer 5

Chemoautotrophs, because the first things available were carbon dioxide before photosynthesis evolved.

Question 6

What is the evidence for this?

Answer 6

Rust deposits via anoxygenic photosynthesis (getting electrons from hydrogen sulfate and other molecules, seen in respiration)

Question 7

How do prokaryotes reproduce and grow?

Answer 7

They reproduce via binary fission and aggregate to form colonies. In some cases labour is given to certain prokaryotes but this is rare.

Question 8

What are the three common shapes of prokaryotes?

Answer 8

Spheres (Cocci), rods (bacilli) or helices

Question 9

Are prokaryotes capable of movement?

Answer 9

Over 50% are capable of movement via a flagella/flagellum.

Question 10

What are the two prokaryotic domains? When did we realise they differed?

Answer 10

Bacteria and Archaea, who are prokaryotes but very different as they diverged so early on in life. We discovered archaea using rRNA sequences in a lab and this was recent as they are extremophiles.

Question 11

Do viruses have a membrane?

Answer 11

Sometimes. Some have a lipid bi-layer envelope and some do not.

Question 12

Are viruses alive? Explain your answer.

Answer 12

• No energy and carbon metabolism
• No self replication
• No ancestral lineages
• Polyphyletic (no one common ancestor)

Question 13

What are the Three Great Diversification Events?

Answer 13

Prokaryotes (3.5 Bya), Unicellular Eukaryotes and Protists (2.7 Bya) and multicellularity (multiple times)

Question 14

Name as many characteristics of eukaryotes as you can.

Answer 14

Membrane enclosed nucleus, mitochondria, 80s ribosomes, chromosomes of linear DNA with histones, mitosis, meiosis, endomembrane system, flagella

Question 15

What is endosymbiosis? What did it lead to?

Answer 15

Symbiosis in which one of the symbiotic organisms lives inside the other. Led to mitochondria and plastids.

Question 16

What is a plastid?

Answer 16

Any class of small organelles in the cytoplasm of plant cells containing pigment or food.

Question 17

How did plastids evolve?

Answer 17

From endosymbiotic bacteria via endosymbiosis.

Question 18

What were the purposes of primary and secondary symbiosis?

Answer 18

Primary - Eukaryotes engulfed cyanobacteria
Secondary - Heterotrophic protists engulfed algae containing plastids, increasing algal diversity

Question 19

Are protists aerobic?

Answer 19

Yes, they have mitochondria.

Question 20

How do most protists gain energy?

Answer 20

• Photoautotrophs with chloroplasts
• But some are heterotrophs (use phagocytosis), or mixotrophs

Question 21

What are the 3 supergroups of protists?