# Unit 2 study session: Populations and Communities: Parent/Student/Teacher Study Night

```Unit 2
Parent/Student/Teacher
Study Night
Wednesday, Oct. 24
Abiotic Factors
Habitat
Biotic Factors
Population
Symbiosis
Community
Ecosystem
Biosphere
Biome
Ecology
Organism
Task 2: Organisms and
their Environment
Name 3 things a habitat provides for an organism:
Name the difference between biotic and abiotic
factors in an ecosystem:
List the levels of organization in the biosphere:
Population Size
Direct observation
Indirect observation
Sampling
Mark and Recapture
Direct Observation
Indirect Observation
A scientist counted 47 ant colonies in a yard. After
she did some research on the species of ant that lived
in the colonies she found that there are 300 worker
ants and 1 queen ant per colony. What is the
approximate ant population in the yard?
Formula: #of Ants/1 Colony X #of Colonies/1 Area
Sampling
Another biologist was studying the number of diamond willow
trees on a 11 x 12 acre plot of land. He chose six sample sites, each
one with a length of 1 acre and a width of 0.5 acres. The number of
diamond willow trees in each of the sites are: 45, 21, 58, 32, 19, 11.
What is the area of the study area?
What is the area of the sample area?
What is the average number of trees sampled?
Formula: avg #/1 sample area=X/total area
What is the approximate population of diamond willow trees in
this plot?
Mark and Recapture
When I was in high school my biology teacher asked me to
use the Lincoln-Peterson Estimate to find the approximate
population of crappies in our pond. So on day one I fished
for 8 hours and caught 31 crappies and marked their anal
fins with a hole punch. The next day I fished for 8 hours
and caught 19 crappies, of which 9 had holes in their fins.
Using the Lincoln-Peterson Estimate, approximately how
many crappies are in the pond?
N/M = S/R
N=-total population M=number in first catch that were
marked S=total number in second catch R=number in
second catch that were marked
Changes in Populations
Natality (births) Adds to population
Mortality (deaths) Decreases population
Immigration (similar species coming in) Adds
Emigration (similar species leaving) Decreases
Carrying Capacity: The maximum number of organisms a
habitat can support
Population in 2017: 5945 In 2018 there were 59 births, 87
deaths, 157 immigrants and 39 emigrants. What is the
population for 2018?
Population Density
How tightly packed or spread out organisms are in an
area
A city has 48,568 people and it has an area of 29.5
square miles. What is the population density?
Between Organisms
Natural Selection: The theory that more organisms are
born/hatched than can survive and those with the right
adaptations are more likely to survive. Also known as
survival of the fittest.
Niche: The role an organism plays in its environment. Ex.
Predator, prey, decomposer, producer, parasite, host.
Symbiosis: A close relationship between two or more
organisms where at least one is benefitted.
Ex. Parasitism, Mutualism, Commensalism, Amensalism
Task 5: Changes in
Communities
Primary succession is the process in which plants and animals
first colonize a barren habitat. This happens after a lava flow,
new sand dunes form or new landforms arise from the ocean.
Pioneer species are the first plants to arrive and begin to grow.
When they die, their materials begin to form soil allowing larger
plants to take root and grow.
Secondary succession is the series of community changes which
take place on a previously colonized, but disturbed or damaged
habitat. Examples include areas which have been cleared of
existing vegetation (such as after logging in a woodland) and
destructive events such as fires.
Primary Succession
Secondary Succession
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