Chapter 4 And C

Question 1

What is a species?

Answer 1

a group of organisms that can interbreed to produce fertile offspring

Question 2

What is a sub-species?

Answer 2

a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics, but that can successfully interbreed

Question 3

What is the difference between a detritivore and a saprotroph?

Answer 3

Detritivores obtain nutrients from detritus (decaying organic material and faecal matter) by internal digestion
Saprotrophs obtain nutrients from dead organisms by external digestion

Question 4

How do you calculate population density?

Answer 4

Quadrant sampling:
- placed repeatedly in a sample area to provide reliable estimates
- placed randomly for population density
- presence/absence or % coverage can be recorded
- limitation; doesn’t work for larger organisms, (mostly just plants and small, slow moving animals)

Question 5

How is energy lost from an ecosystem?

Answer 5

Energy can be lost as heat, and can also be lost through bones, hair, faecal matter, as organism don’t consume their entire prey. Also cellular respiration.

Question 6

What limits the length of food chains?

Answer 6

Energy flow. Each trophic level receives less and less energy as the chain proceeds.

Question 7

What does a pyramid of energy show? What units are used to represent the energy transferred? (know what it means not just the symbols used).

Answer 7

Shows the relative amounts of energy flowing through each trophic level. kJ m-2 year-1 (energy per unit area per unit time)

Question 8

What is a carbon flux? Measured in?

Answer 8

Carbon flux = exchange of carbon between the atmosphere, the oceans and the biosphere. Measured in gigatons of carbon per year (Gt Cyr-1)

Question 9

What is a methanogen?

Answer 9

An Archaean microorganism that produces methane as a metabolic byproduct in anoxic conditions

Question 10

Outline the process of peat formation.

Answer 10

• Organic matter is digested by saprotrophs
• Saprotrophs assimilate some carbon for growth and release as carbon dioxide
• Organic matter is only partially decomposed
• Large quantities of organic matter build up
• Organic matter is compressed to form peat

Question 11

What are greenhouse gases?

Answer 11

gases in the atmosphere that can absorb and reflect long wave radiation back to earth, keeping earth much warmer than it otherwise would be.

Question 12

Where does carbon dioxide, water, methane, and nitrogen oxides come from?

Answer 12

Carbon Dioxide; cellular respiration, burning fossil fuels, exhausts from cars
Water; evaporation from oceans and transpiration from plants
Methane; methanogenic archaea preforming anaerobic respiration, melting of tundra
Nitrogen oxides and tropospheric ozone; combustion in the presence of nitrogen

Question 13

What has caused an increase in greenhouse gases?

Answer 13

Human activity such as burning fossil fuels.

Question 14

What is the impact of increased greenhouse gases in the atmosphere?

Answer 14

• Higher global average temperatures
• Frequent and intense heat waves
• Droughts
• Flooding
• Tropical storms
• Changes to ocean currents = colder temperatures

Question 15

What is the impact of increased CO2 levels in marine environments, in particular coral reefs?

Answer 15

Coral bleaching. Increased carbon dioxide leads to ocean acidification which kills coral polyps, meaning reefs aren’t built anymore.

Question 16

What is a niche?

Answer 16

The unique role a species plays in the community

Question 17

What is the difference between a fundamental and a realized niche?

Answer 17

Fundamental:
- The potential mode of existence of the species given its adaptations
Realised niche:
- The actual mode of existence, which results from its adaptations and competition with other species

Question 18

How does competition impact the niche of an organism?

Answer 18

If two species share a niche, this leads to inter specific competition for resources
- One species has the advantage
- Less well-adapted struggles to survive
- Will eventually be eliminated

Question 19

What is competitive exclusion?

Answer 19

”no two species can occupy the same niche for extended periods of time”

Question 20

What are the different types of relationships between species?

Answer 20

• Herbivory: primary consumers feed only on plant materials
• Predation: a consumer kills and eats another consumer
• Symbiosis: close and persistent interaction between two species (one or both can benefit)
• Mutualism: mutually beneficial symbiotic relationship, both organisms benefit from the relationship
• Commensalism: where one organism benefits and the other is unharmed
• Parasitism: symbiotic relationship. Parasite depends on host for food, host may be killed

Question 21

Describe how the relationship between Zooxanthellae and coral is mutualistic.

Answer 21

Zooxanthellae lives in the tissue of the coral and gives it its colour. The coral provides a protected environment and compounds needed for photosynthesis. Zooxanthellae provides oxygen, help with removing waste, and supplies coral with nutrients.

Question 22

What is biomagnification? Discuss an example (in detail, not dates etc but scientific detail).

Answer 22

Bio magnification is the process in which chemical substances become more concentrated at each trophic level. For example, DDT, this chemical can be washed into waterways and travel up the food chain starting with a zooplankton, small fish, large fish, and then fish-eating birds.

Question 23

What are micro plastics? What is their effect on organisms? Discuss specific examples.

Answer 23

Micro: plastic debris that is less than 5mm (exfoliants, abrasives).
- Organisms such as lugworms consume sand and digest the microorganisms found on the surface of sand particles.
- Seeing as micro plastics as incredibly small, they can mix in with the sand that is eaten by the lugworms.
- The lugworms then become vulnerable to pathogens.
- Cause them to have less energy for churning up the bottom sediments
- One of their most important functions in the ocean ecosystem.

Question 24

What are macroplastics? What is their effect on organisms? Discuss specific examples.

Answer 24

Macro: large, visible plastic debris larger than 5mm (bottles, nets, bags)
- Albatrosses skim the surface of the ocean to catch fish.
- They can pick up floating plastics in the water
- They feed this mix of plastics and fish to their chick
- Adults can regurgitate the plastic they’ve swallowed
- The chicks can’t so their stomachs become full
- The chicks may feel full – and not want to eat actual food
- They end up starving due to lack of nutrients

Question 25

What is the richness and evenness?

Answer 25

Richness: the number of different species present
Evenness: if a habitat has similar abundance for each species present, the habitat is said to have evenness

Question 26

How the Simpson’s reciprocal index be used to assess the biodiversity of an ecosystem? How do you interpret the values?

Answer 26

• Takes into account richness and evenness
• Lowest possible defined value of D is 1
• The higher the D value, the more bio diverse

Question 27

What is in situ conservation? Ex situ conservation?

Answer 27

In situ: preservation of plant and animal species within their natural habitat
Ex situ: preservation of plant and animal species outside their natural habitats

Question 28

What is a population growth curve?

Answer 28

Shows the numbers of a population over time
3 phases:
- Exponential: number of individuals increase at a faster rate (high natality, low mortality/ high immigration, low emigration)
- Transitional: growth rate slows down, population still increasing (increasing mortality, increasing emigration)
- Plateau: numbers of individuals have stabilised, no more growth.
(Natality = mortality, emigration = immigration)

Question 29

How can the rates of natality, mortality, immigration and emigration be used to explain the shape of the sigmoid growth curve.

Answer 29

• Natality: the number of new individuals after successful reproduction/number of births
• Mortality: the number of deaths
• Immigration: the number of individuals arriving from other places
• Emigration: the number of individuals leaving a population

Question 30

What is the role of bacteria in the nitrogen cycle? Give specific examples for the 3 bacteria species discussed.

Answer 30

Bacteria helps recycle the nitrogen through the environment
- Rhizobium: nitrogen fixing bacteria lives in root nodules. Convert nitrogen gas to ammonia
- Nitrobacter : lives in well oxygenated soils. Converts nitrites into nitrates
- Nitrosomonas: converts ammonia into nitrites (unusable to plants)

Question 31

Describe the flow of energy through a food web

Answer 31

• food web shows how food chains are linked together into more complex feeding relationships
• food webs are more detailed/accurate;
• organisms can occupy more than 1 trophic level
• organisms can have more than one food source
• organisms can have more than one predator

Question 32

What methods can be used to estimate population numbers of marine species?

Answer 32

• capture-mark-release-recapture: this sampling involves collecting a sample of animals, marking them, and then releasing them. Later collect another sample and from the number of marked ones recaptured an estimate of the pop can be calculated
• the Lincoln index can be used to estimate the pop using recapture data

Question 33

How does effective management work to conserve species within national parks?

Answer 33

• in situ conservation
• biological control (living organisms or virus), chemical control (toxins), physical control (removal)
• designation of protected areas of land
• ecological monitoring of species
• interventions may be require to prevent competition from an invasive species

Question 34

What does a niche include?

Answer 34

• where the organism lives (spatial habitat)
• what and how it eats (feeding activities)
• interactions with other species