final

Question 1

Nucleomorph

Answer 1

reduced remnant nucleus from the endosymbiont

Question 2

Apicoplast

Answer 2

plastid-like organelles that some non-photosynthetic apicomplexans have

Question 3

Thylakoids

Answer 3

intracellular membranous structure that photosynthesis occurs in cyanobacteria

Question 4

Kleptoplasty

Answer 4

the behavior of taking plastids from a food source and incorporating them into the consumer’s cells

Question 5

peridinin plastid

Answer 5

plastid that most photosynthetic dinoflagellates have. Houses chlorophyll c and carotenoid peridinin

Question 6

endosymbiotic relationship

Answer 6

Relationship where one organism lives inside the cells of another organism

Question 7

symbiotic relationship

Answer 7

Relationship where 2 organisms live together but each can live on their own

Question 8

TIC-TOC system

Answer 8

Mechanism for importing proteins from cytoplasm into the plastid

TIC = translocon of inner chloroplast membrane

TOC = translocon of outer chloroplast membrane

Question 9

foundational species

Answer 9

Spatially dominant organisms that create complex habitats for other species

Are often primary producers

Provide essential services for ecosystem function, such as providing nursery space for fish

Question 10

Symbiosome

Answer 10

organelle in a host cell that houses an endosymbiont in a symbiotic relationship

When dinoflagellates end up in cell they end up inside symbiosome

Differ from lysosomes since they don’t digest the alga

Question 11

Mycobiont

Answer 11

the fungi in the symbiotic relationship that comprise lichen

Question 12

Photobiont

Answer 12

the algae in the symbiotic relationship that comprise lichen

Question 13

Zooxanthellae

Answer 13

the algal endosymbiont in endosymbiotic relationship that comprise coral

Question 14

Mutualism

Answer 14

association between organisms of different species in which they all benefit

Question 15

thermal priming

Answer 15

Technique to save kelp forests from climate change where individuals acquire a stress memory that helps them withstand subsequent exposures

Question 16

assisted evolution

Answer 16

Technique to save kelp forests from climate change where people accelerate the rate of natural evolution by introducing the genetic traits needed for survival into vulnerable populations

Question 17

epigenetic change

Answer 17

molecular modifications that alter gene expression but not underlying nucleotide sequence of the DNA
occur more rapidly than adaptive ones

Question 18

Why do phycologists call cyanobacteria algae, given that they belong to a different domain of life than all other algae? In your answer you should include: a definition of what the term “algae” means, a clear explanation of how cyanobacteria fit this definition, and a description of the main feature(s) that set cyanobacteria apart from other organisms in the eubacterial domain of life. (6 points)

Answer 18

-Algae are a diverse group of organisms that are mostly aquatic oxygen-producing photosynthetic autotrophs

-They are capable of oxygenic photosynthesis and are aquatic
-Also eukaryotic algae acquired ability to conduct oxygenic photosynthesis from cyanobacteria

-Cyanobacteria are only bacteria capable of oxygenic photosynthesis
-Photosynthesis also occurs on thylakoids in cyanobacteria and eukaryotic algae, it occurs on different structures in anoxygenic bacteria
-Pigments found in cyanobacteria photosynthetic pigments are similar to pigments in eukaryotic algae, different from other bacteria

Question 19

What does the Endosymbiont Theory propose? (2 points)

Answer 19

Proposes that eukaryotic mitochondria and chloroplasts evolved from bacterial species that existed as endosymbionts inside ancient microbial cells

Question 19

List 2 features that distinguish kelps from land plants and describe how each feature differs between kelps and plants. (4 points)

Answer 19

1.Generally speaking, algae lack adaptations to life on land
-Ex: kelp lack the structural features to hold themselves up against gravity,
-Most land plants have features that allow them to holt themselves up against gravity (ex: tree, daisy, sunflower)

2.Plants have complicated reproductive structures, algae have simple reproductive structures
-Ex: plants make flowers, seeds, and cones
-Algae tend to release propagules into water and subsequent development occurs independently from parent

Question 20

Describe the steps that scientists think occurred during chloroplast evolution in the Plantae Supergroup. (5 points)

Answer 20

-Ancient microbial cells coexisted with cyanobacteria and possibly fed on them

-A mitochondrion-containing eukaryotic cell established a endosymbiotic relationship with cyanobacterium, possibly by eating it
Once inside, the cyanobacterium somehow evaded digestion

-Loss of phagosomal membrane could have helped

-Eventually genes transferred from endosymbiont genome into the eukaryotic host’s nucleus and genes were lost from host genome

-Possibly through horizontal gene transfer
transport systems eventually evolved (many from host proteins) to allow transport in and out of plastid
So host could receive products of photosynthesis
TIC TOC system

Question 21

In your job as a research assistant you are identifying algae in plankton samples from the arctic ocean and you find an alga that you’ve never seen before. On closer inspection you find that this alga has plastids that are surrounded by 3 membranes and that the plastid has characteristics that indicate it evolved from a red algal endosymbiont.
A) Based on this data what kind of endosymbiosis do you predict gave rise to the plastid in your new alga? Provide two lines of evidence in support of your prediction and explain how the evidence supports your prediction. (5 points)

Answer 21

Secondary
Three membranes (primary only has 2 since organism it has 2 from cyanobacteria and 1 from host is lost (lecture 6 slide 13)) (secondary has additional mebranes surrounding plastid (4 (sometimes 3 total)
When it engulfs the organism it creates a phagosomal membrane over the 2 original membranes

red algae has primary endosymbiosis
which is what is and is engulfed
Secondary is engulfment of primary

Question 21

Chara vulgaris is a eukaryotic green alga. Analysis of the DNA content in the mitochondria and chloroplasts of this species indicate that the chloroplast genome contains approximately 185,000 nucleotides of DNA while the mitochondrial genome only has about 68,000 nucleotides of DNA. Why do you think the mitochondrial genome is smaller than the chloroplast genome? HINT: Think about when in evolution the respective endosymbionts were acquired and the events that happened as they evolved into organelles. (4 points)

Answer 21

Mitochondrial genome evolved first giving it more time to lose deleterious or ineffective genes within the genome

Question 21

C) Next you sequence the DNA in the new alga’s nuclear genome. From what you’ve learned in BISC 327, you know that some DNA sequences undergo very few changes during evolution while others change more rapidly. Based on this knowledge, which type of DNA sequences would you examine to determine which supergroup your alga belongs to? Choose between sequences that evolve quickly OR sequences that evolve slowly. Explain why comparing this type of DNA sequence will provide you with the answer you need. (3 points)

Answer 21

Slow evolving sequences are going to be more similar in groups that are closer taxonomically (changes take a long time for changes occur
Different supergroups split off earlier, so you can see differences
Closer related groups (within super groups) will be more similar (less time to evolve)

Question 21

6. In your job as a research assistant you are identifying algae in plankton samples from the arctic ocean and you find an alga that you’ve never seen before. On closer inspection you find that this alga has plastids that are surrounded by 3 membranes and that the plastid has characteristics that indicate it evolved from a red algal endosymbiont.

B) Based on the information given above, which of the eukaryotic supergroups do you predict this organism belongs to? Why? (2 points)

Answer 21

It either belongs to the SAR or excavata supergroup since both had secondary endosymbiosis, which involves the engulfment of either red or green algae, and the new species was found to have engulfed red algae, making it secondary

Question 22

D) Which type of DNA sequences would you examine to determine which species your new alga is most closely related to? Explain why comparing this type of DNA sequence will provide you with the answer you need. (3 points)

Answer 22

Quickly evolving genes
More differences, even between closely related ones
No difference or differences can show that they are closely related

Question 23

7. The stramenopiles that exist today belong to a monophyletic lineage that includes both photosynthetic (brown algae and diatoms) and non-photosynthetic (oomycetes) groups.

A) Provide two alternative hypotheses explaining how a single common ancestor could have given rise to this mixture of photosynthetic and non-photosynthetic groups. (4 points)

Answer 23

1. One hypothesis is that a common ancestor had photosynthetic abilities derived from red algae that were passed down.
   - The non-photosynthetic organisms lost the plastids required for photosynthesis through evolution
   Energetically expensive to keep plastid if its not contributing

2.Other hypothesis is that each group individually acquired ability to photosynthesize

Question 23

Describe the primary, secondary, and tertiary endosymbiotic events that gave rise to plastids in eukaryotic algae. In each case, state the kinds of algae that were engulfed (cyanobacterium, red, green, or stramenopile) and list the groups of algae that have each type of plastid. (6 points)

Answer 23

Primary endosymbiosis:
- cyanobacteria were engulfed and evolved into a plastid
- Mitochondrion-containing eukaryotic cell established a endosymbiotic relationship with cyanobacterium
- Cyanobacteria that were normally taken as food by ancient microbial cells evaded digestion and took up residence inside cell
- Evolves into chloroplasts
- Archaeplastida group has plastid from primary endosymbiosis

Secondary endosymbiosis:
- eukaryotic cell with a cyanobacterial-derived plastid was taken up by a eukaryotic host and these eukaryotic endosymbionts evolved into plastids
- Engulfed red algae or green algae
- SAR and excavata supergroup has plastids from secondary endosymbiosis

Tertiary:
- eukaryotic cell engulfs another eukaryotic cell that has plastid from secondary endosymbiosis
-Engulfed stramenopiles
-Occurred in some dinoflagellates

Question 23

What can scientists look for in the genomes of the non-photosynthetic stramenopiles in an attempt to distinguish between the above hypotheses? Explain why this evidence is not conclusive. (3 points)

Answer 23

–If had photosynthetic ancestor and lost the ability to photosynthesize
=There would be similar genes between non-photosynthetic individuals
-Specifically ones that are of cyanobacterial origin (acquired photosynthetic ability from them)
= photosynthetic past
-They could have apicomplexans = plastids that lost photosynthetic abilities
Has more than 2 membranes = from secondary endosymbiosis

2. If photosynthetic abilities were acquired individually
   They would likely not have similar plastids (that could have lost photosynthetic abilities)

Why is it inconclusive:
Since ancestors are no longer here so we can’t study them directly/know for sure

Question 24

A graduate student is studying a newly discovered species. She has determined that the organism is a ciliate. Surprisingly, she found several genes encoded in the nucleus that appear to be of red algal origins. She thinks that her findings might provide information about the ancestral species that gave rise to the entire Alveolate clade. Do you agree? Why or why not? Use evidence we discussed in lecture to support your argument. (4 points)

Answer 24

I agree
Red algal genes in ciliates could suggest that the alveolate ancestor had red algal plastid
Follows chromalveolate hypothesis
Proposes that stramenopiles and alveolates descended from photosynthetic ancestor

Question 25

Scientists are acquiring information on how plastids evolved by studying organisms that belong to the genus Paulinella. Why are species in this genus of interest to scientists? Give two reasons and for each reason explain what it is that scientists are hoping to learn. (4 points)

Answer 25

A species in the Palinella genus has a photosynthetic organelle called a chromatophore that is derived from a cyanobacterium
Only known organism to have acquired a photosynthetic organelle from a cyanobacteria apart from ancient microbial ancestor that gave rise to other algae
Gives validity to theory that algae acquired photosynthetic abilities by engulfing a cyanobacteria

A species in Paulinella feeds on cyanobacteria but is not photosynthetic
Genes of cyanobacterial origins have been found in the species genome
Suggests that organisms can acquire genes from prey they feed on

Question 26

At the cellular level, what are 3 of the main impacts of stressfully high temperatures on algae? (3 points)

Answer 26

Reactive oxygen species
Heat shock proteins
Membrane fluidity changes

Question 27

How do cells mitigate the above impacts (stressfully high temperatures)? Explain how each response helps to counteract each of the above impacts.

Answer 27

Changes in membrane (make it more gel-like) caused by lipids…
fluidity of membranes depends on the lipid composition
Cold conditions reduce fluidity and make membranes more gel like
Warmer conditions disorder the phospholipid tails in the membrane, making membrane loose thickness

Heat shock proteins produced
Act as molecular chaperones
Bind to denatured proteins and aggregations and prevent them from interfering with cellular activities by targeting them for refolding or degradation

ROS (reactive oxygen species) scavenging machinery is hyper-activated
Chloroplasts and mitochondria are primary site of ROS production is cells
Processes that strip electrons from oxygen-containing molecules
Occur in chloroplasts (photosynthesis) and in mitochondria (respiration)
ROS are highly reactive and cause cellular damage when they reach high levels
Under normal conditions they are at low levels
Stressful conditions (high heat) ROS production becomes excessive
So ROS scavenging machinery is activated to prevent cell damage

Question 28

Why is bull kelp a foundational species? In your answer, include a definition of what a foundational species is and describe how bull kelp fits this definition. (6 points)

Answer 28

A foundation species is a spatially dominant organisms that create complex habitats for other species
Bull kelp are a dominant habitat- forming seaweed in BC, creating dense habitats for an abundance of organisms
They provide functions necessary for ecosystem function in many ways such as providing nursery spaces for fish
The loss of a foundation species drastically changes the community, which would happen with loss of bull kelp, since they are the only underwater large canopy forming species, so no other species could take over and recreate these environments, that bull kelp is the foundation of

Question 29

Many people are concerned that ocean warming is occurring faster than foundational species, like forest-forming kelps and coral reefs, can adapt. Scientists are investigating ways to provide foundational species with the traits they will need to survive into the future. Describe two methods, discussed in lecture, that scientists are working on that could provide foundational species with these traits. (4 points)

Answer 29

assisted evolution: Technique to save kelp forests from climate change where people accelerate the rate of natural evolution by introducing the genetic traits needed for survival into vulnerable populations
Ex: moving resilient individuals into vulnerable populations

thermal priming: Technique to save kelp forests from climate change where individuals acquire a stress memory that helps them withstand subsequent exposures
Involves epigenetic mechanisms that affect expression of genes after first stress exposure (alter gene expression, not underlying nucleotide sequence)

Question 30

In reef-forming corals, a mutualistic relationship exists between an alga and an invertebrate. Why is this relationship a mutualistic one? In your answer you should define what a mutualistic relationship is, describe the relationship that exists between the alga and the invertebrate polyp, and explain how this relationship fits the definition of a mutualistic one. (6 points)

Answer 30

A mutualistic relationship is one where all organisms in the relationship benefit.
Corals are an example of a mutualistic relationship since both the coral and the algae benefit from the partnership
The algae feeds the coral through products from photosynthesis
. The coral provides the zooxanthellae with a protected environment and compounds they need for photosynthesis

Question 31

15. What happens when corals bleach? (6 points)

Answer 31

Corals have a symbiotic relationship with algae, which are their primary food source and gives them their colour. When the water conditions are unfavourable (ex: too warm) the zooxanthellae living in the coral secrete a toxin forcing the coral polyp to expel the zooxanthellae. Losing the algae causes the coral to lose its colour (turns white) and also its main food source. This bleached coral also becomes more susceptible to disease,

Question 32

How are F. distichus embryos affected by acidic seawater? (4 points)

Answer 32

Embryo growth is impaired at acidic conditions
Embryo growth depends on maintenance of a proton gradient along the growth axis
in acidic conditions, proton expulsion at the base of the pH gradient more difficult, impairing growth

Question 33

Using the traditional definition, explain what a lichen is. (2 points)

Answer 33

A lichen are a symbiosis between algae and fungi, where the cells of each coexist next to each other

Question 34

Why is this relationship a mutualistic one? In your answer, describe what each partner in the relationship contributes to the relationship. (4 points)

Answer 34

Algae produce sugars through photosynthesis which the fungi eats

Fungi produce the thallus structure of the lichen which provides shelter for the algae, providing favorable conditions protecting it from UV radiation, desiccation, and other outside threats to the algae

Question 35

What is the problem that scientists interested in studying lichen development have not yet been able to overcome? (2 points)

Answer 35

They have not been able to conclude exactly how lichens form since studies with just algae and fungi partners in labs do not proceed very far in terms of lichen development

This suggests that there are other microorganisms associated with lichens, through their roles are unknown

It is also unknown how symbiont partners find each other and how lichen formation is initiated and what happens as it proceeds

Question 36

What is a biocrust and why are they important in dryland areas like deserts? (4 points)

Answer 36

Biocrusts are communities that include mosses, lichens, algae, fungi, and bacteria
They are important to dryland areas since they increase soil fertility by fixing carbon and nitrogen and stabilize the soil and influence the movement of water.

Question 37

Why are declines in lichen abundance in the Canadian arctic concerning? (2 points)

Answer 37

Declines are concerning since lichens are a major component of many animals, such as caribou’s diets.
In winter lichens are most important component of their diet
It is unknown whether caribou and other animals can transition to other food sources

Question 38

Consider two populations of bull kelp, one growing in an area where ocean temperatures warm to stressfully high levels every summer and another growing where ocean temperatures stay cool all summer long. At the cellular and molecular (gene expression) levels, list 3 differences you predict would be present between the two populations in the summer months and explain how these differences would help the kelp growing at the warmer temperatures survive. (6 points)

Answer 38

Heat shock proteins produced
Act as molecular chaperones
Bind to denatured proteins and aggregations and prevent them from interfering with cellular activities by targeting them for refolding or degradation
Would still be present in kelp in cool water, just at much lower levels
Because heat denatures proteins

Composition of lipids in cellular membranes is altered to make them more stable under warmer conditions
fluidity of membranes depends on the lipid composition
Cold conditions reduce fluidity and make membranes more gel like
Warmer conditions disorder the phospholipid tails in the membrane, making membrane loose thickness - double check to see if produce lipids to make membrane stronger

ROS (reactive oxygen species) scavenging machinery is hyper-activated
Chloroplasts and mitochondria are primary site of ROS production is cells
Processes that strip electrons from oxygen-containing molecules
Occur in chloroplasts (photosynthesis) and in mitochondria (respiration)
ROS are highly reactive and cause cellular damage when they reach high levels
Under normal conditions they are at low levels
Stressful conditions (high heat) ROS production becomes excessive
So ROS scavenging machinery is activated to prevent cell damage

Question 39

In your own words, define an extremophile and give 2 examples of environments these organisms might inhabit. (2 marks)

Answer 39

Extremophiles are organisms that live under extreme conditions, such as environments with high or low salinity, temperatures, pressures, and acidity. An example of a habitat that these organisms might inhabit are hydrothermal vents which have very high temperatures and pressures. Another example is the Dead Sea which has a very high salinity.

Question 40

Biofilms are found in many of our planet’s ecosystems and are characterized by the mucus mats they produce. Name and describe the two primary functions these mucus layers play in the ecology of biofilms. (4 marks)

Answer 40

Ecosystem services
Sediment stabilization - preventing erosion
Food source
Feeds a diverse range of organisms - bivalves, mollusks, gastropods, birds, etc…

Question 41

How might algal biofilms be directly or indirectly linked to the habitat and survival of the Western Sandpiper? (2 marks)

Answer 41

Major nutritional source for western sandpiper during spring when migrating
Migrate very long distance - between peru and alaska
So need to fatten up
biofilm is very nutritious and provides bird with enough energy for journey

Question 42

In Andrew’s lecture we touched on extremophiles and the extreme places they inhabit. Briefly discuss the difference between psychrotolerant and psychrophilic organisms and explain why the green algae discussed are classified as one of the two. (3 marks)

Answer 42

A psychrotolerant organism able to survive below 0℃ but grows optimally at 20-25℃

A psychrophilic organism requires cold conditions, growing optimally at less than 15℃, upper survival limit at 18 - 20℃

Chlamydomonas
Psychrophile
Because it grows optimally at 10℃ and Psychrophiles grow optimally at less than 15℃
so not psychrotolerant since it grows optimally at 20-25℃