Unit 4.1: Species, Communities, and Ecosystems

Question 1

Define Ecology.

Answer 1

Ecology is the study of relationships between living organisms and between living organisms and their environment.

Question 2

Define Species.

Answer 2

A species is a group of organisms which can interbreed and produce fertile (viable) offspring.

Question 3

Define Population.

Answer 3

A population is a group of organisms of the same species that live in the same area at the same time.

Question 4

Define Community.

Answer 4

A community is a group of populations living and interacting with each other.

Question 5

Define Habitat.

Answer 5

A habitat is the environment in which a species lives.

Question 6

Define Ecosystem.

Answer 6

An ecosystem is a community and its abiotic factors.

Question 7

Name the two methods of nutrition.

Answer 7

The two methods of nutrition are autotrophic and heterotrophic.

Question 8

Compare autotrophs and heterotrophs.

Answer 8

Autotrophs use an external source to produce organic materials from inorganic raw materials in the abiotic environment. They are known as producers and make up the beginning of all food chains. Heterotrophs, however, obtain energy from organic materials from other organisms.

Question 9

Name and describe the three kinds of heterotrophs.

Answer 9

Consumers: organisms that ingest other organic matter that is living or has been recently killed
Detritivores: organisms that ingest non-living organic matter
Saprotrophs: organisms that live on or in non-living organic matter, secreting digestive enzymes onto it and absorbing the products of external digestion.

Question 10

List the three requirements for a self-sustaining ecosystem. Give an example of a self-sustaining organism.

Answer 10

The three requirements for a self-sustaining ecosystem are:
-Nutrient availability
-Detoxification of waste products
-Energy availability
For example, a mesocosm

Question 11

Define Sustainability.

Answer 11

Sustainability is the quality of an ecosystem to remain diverse and productive indefinitely.

Question 12

Describe the method by which estimated size of populations is compared.

Answer 12

The method that is used to compare estimated population size is called the Quadrat Method. In the quadrat method, one chooses an area of study. He/she then marks the area with tape of a set size. Sample quadrats are randomly selected using a table or number generator. One then counts the number of each organism in each sample quadrat. Next they calculate the average number of each of the two organisms being studied. They multiply the average by the total number of quadrats that exist for each organism. (average per quadrat x Total # of quadrats for each and compare results)

Question 13

Describe a Chi-Squared test.

Answer 13

A chi-squared test is a statistical procedure for determining the goodness of fit (the difference) between observed values and those expected.

Question 14

Explain how to conduct a chi-squared test.

Answer 14

1. Find the expected values for the combination of each column and row (Group 1, Category 1; Group 1, Category 2; Group 2, Category 1; Group 2, Category 2) by multiplying the row total by the column total and dividing it by the grand total. (row total x column total / grand total).
2. Next, subtract each expected result from the observed values, square the difference, and divide by the expected. (O - E )^2/E
3. Then, take the sum of all of these numbers.