Unit B - Chapter 4

Question 1

Explain the differences between a population and a community.

Answer 1

A population contains members from the SAME species, a community is the collection of different species.

Question 2

What is an ecotone and why do they contain greater diversity?

Answer 2

An ecotone is the area that contains both terrestrial and aquatic organisms. It has a higher bio-diversity because it supports two kinds of organisms (terrestrial and aquatic).

Question 3

Describe a taiga biome (include location, main plants, etc)

Answer 3

Taiga biomes are located in Northern Alberta and their main plants are called ‘Conifer Trees’. The taiga biome has the 2nd most precipitation, 2nd coldest temperature, and 3rd in diversity of organisms.

Question 4

Describe a muskeg biome (tundra).

Answer 4

Also located in Northern Alberta. The ground is swampy and boggy because the rain/melted snow does not drain, due to the permafrost below soil that never melts. The muskeg is 3rd in precipitation, 1st in cold temperatures, and 4th in diversity of organisms.

Question 5

Describe a grassland biome.

Answer 5

Grasslands are located in central and southern Alberta. Their main plants are rough fescue, wheat grass and spear grass. The grassland has rich, fertile soil and receives a lot of sunlight. The grassland is 4th in precipitation, 4th in cold temperatures, and 2nd in diversity of organisms.

Question 6

Describe a deciduous forest biome.

Answer 6

Also located in central and southern Alberta. Also has rich, fertile soil and warm temperatures. The deciduous forest is 1st in precipitation, 3rd in cold temperatures, and 1st in diversity of organisms.

Question 7

Name and describe the three zones in a lake ecosystem.

Answer 7

1. The Littoral Zone - area from the shore of a lake to the area where no more plants grow in the lake bottom.
2. The Limnetic Zone - the area of the lake in which there is open water and sufficient light for photosynthesis.
3. The Profundal Zone - the region of the lake where there is low oxygen and insufficient light for photosynthesis. (below the limnetic zone)

Question 8

List the four factors that affect TERRESTRIAL ecosystems.

Answer 8

1. Soil
2. Available Water
3. Temperature
4. Sunlight

Question 9

List the four factors that affect AQUATIC ecosystems.

Answer 9

1. Chemical Environment
2. Temperature/Sunlight
3. Water Pressure
4. Seasonal Variations

Question 10

State what happens to lake ecosystems during winter.

Answer 10

The ice forms at the top of the lake. The water underneath is arranged according to its density (the least dense is at the the top and the most dense is at the bottom at 4 degrees). The thick ice limits sunlight access which lowers the oxygen levels underneath.

Question 11

State what happens to lake ecosystems during spring.

Answer 11

The ice at the top melts and now oxygen can spread throughout the water. The water warms to 4 degrees then sinks through the less dense water, carrying oxygen with it. This is called the spring turnover.

Question 12

State what happens to lake ecosystems during summer.

Answer 12

Layers of water are again set up with the densest water at the bottom. As soon as the water warms above 4 degrees, it stops sinking and rises up above all the less dense water. The upper level is called the epilimnion, the lower level is called the hypolimnion. Organisms in the hypolimnion must rely on oxygen brought down from the spring turnover. The epilimnion experiences a problem where the warmer it is, the less oxygen it can hold. So during a hot spell, it loses a lot of oxygen.

Question 13

What are the four main factors that limit populations and communities?

Answer 13

1. Biotic Potential
2. Limiting Factors
3. Carrying Capacity
4. Limits of Tolerance

Question 14

Describe the four factors that determine biotic potential.

Answer 14

1. Birth Potential: The maximum number off offspring per birth.
2. Capacity for Survival: The number of offspring that reach reproductive age.
3. Breeding Frequency: The number of times that a species reproduces each year.
4. Length of Reproductive Life: The age of sexual maturity and the number of years an individual can reproduce.

Question 15

Define carrying capacity.

Answer 15

The maximum number of individuals of a species that can be supported at the time by an ecosystem.

Question 16

State the two laws in relation to the limits of tolerance.

Answer 16

Law of the Minimum: The nutrient in least supply is the one that limits growth.
Law of Tolerance: An organism can survive with a certain range of an abiotic factor; above and below the range it cannot survive.

Question 17

State the three forestry practices.

Answer 17

1. Slash-and-burn: Clearing of forests for agriculture.
2. Clear-cutting: Removal of all treas in an area for use in timber or pulp.
3. Selective Cutting: Selectively removing trees from an areas, leaving others to regenerate the area.

Question 18

What are the two kinds of lakes?

Answer 18

1. Oligiotrophic: Deep and cold lakes (low oxygen levels).

2. Eutrophic: Shallow and warm lakes (high nutrient levels).

Question 19

What is biological oxygen demand (BOD)?

Answer 19

The BOD is a measure of the amount of dissolved oxygen need by decomposers to break down the organic matter in a sample of water over a five-day period at 20 degrees.