Populations: Prokaryotic and Eukaryotic Domains

Question 1

What are keystone species?

Answer 1

Species that have very strong influences in ecosystems , despite having relatively low abundances

Question 2

What is a trophic cascade?

Answer 2

When a change own the species community at one trophic level affects the species community at a trophic level that is not directly above or below the altered trophic level

Question 3

What is molecular phylogenetics?

Answer 3

Where the differences in nucleotide sequences in DNA are used to see how closely related a species are.

Question 4

What is genetic drift?

Answer 4

Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

Question 5

What is metagenomics?

Answer 5

The study of genetic material recovered directly from environmental samples

Question 6

What is the difference between gram positive and gram negative bacteria?

Answer 6

Gram positive-

• Thick layer of peptidoglycan and a single membrane
• Stains violet

Gram negative-

• Two membranes and thin layer of peptidoglycan
• Loses violet stain and is stained instead by safranin (a counter stain which makes it pink/red)

Question 7

What are the three types of bacteria called that live in moderate to very high temperature conditions?

Answer 7

• Mesophiles- moderate temperature (15-60 degrees)
• Thermophiles- 60-80 degrees
• Hyperthermophiles- >80 degrees

Question 8

How have thermophilic bacteria adapted to survive in such high temperatures?

Answer 8

• More H bonds, disulphide bridges, metal binding, electrostatic and hydrophobic interactions = more thermally stable proteins
• DNA thermostability (proteins that hold DNA together- not known much about yet)

Question 9

What are bacteria called that live in very low temperatures (0-10 degrees)? How do they overcome these conditions?

Answer 9

Psychrophiles. Mobile and flexible proteins that overcome the freezing molecular motions.

Question 10

What are halophiles? How do they withstand these conditions?

Answer 10

Can withstand high salt concentrations.

To prevent an exodus of water from the cell they offset the high salt in their surroundings by accumulating intercellular potassium and glycine betaine

Question 11

How do acidiophiles survive their conditions?

Answer 11

Pump all the hydrogen ions back out- they have a normal intercellular pH of about 7

Question 12

How do radiation resistant bacteria withstand their conditions?

Answer 12

Cells have chromosomes which are tightly packed so that broken DNA ends do not diffuse

Broken ends annealed to other chromosomes. Use undamaged copies by putting pieces together.

Question 13

How is species diversity determined if there is no niche overlap?

Answer 13

Species diversity determined by niche breadth.

Question 14

What is niche partitioning?

Answer 14

This is the idea that natural selection drives competing species into different patterns of resource use and therefore different niches

Question 15

Give some explanations for he existence of niches.

Answer 15

• Current competition= find niche to reduce interspecific competition
• Evolutionary avoidance of competition
• Species have evolved differently and independently in response to natural selection

Question 16

What are mutualism, amensalism, and commensalism?

Answer 16

Mutualism- both organisms benefit

Amensalism-one organism harmed, the other unaffected

Commensalism- one organism benefits, the other is unaffected

Question 17

What is net and gross primary production?

Answer 17

Net-net available energy available to organisms that eat plants

Gross- amount of accumulated energy

Question 18

What are the most three common adaptations for animals living further north?

Answer 18

• Shorter extremities so blood travels less far from the core
• Lighter pigmentation so less heat is radiated
• Smaller surface area to volume ratio to minimise heat transfer to the environment