Biology 4th MP Quarterly Exam
Study Guide
• Genetic drift: change in allele frequency due to
chance
• Bottleneck Effect: genetic drift after a bottleneck
event (when an event drastically reduces population
size)
– Example: Flood waters move through a forest and wipe
out any mice that were not able to climb up a tree
• Founder Effect: genetic drift that occurs after the
start of a new population (when a few individuals
start a new population)
– Example: A bird eats two out of five types of fruit in an
area and flies to another area and drops the seeds there –
the two types of fruit begin a new population in that area
• Gene flow: transfer of genetic information
from one population to another
– Makes nearby populations similar
• Natural selection: organisms that have
favorable traits that are well-suited to the
environment in which they live will be more
likely to thrive, reproduce, and pass their traits
to future generations than organisms without
favorable traits
• INCREASES species diversity (different beak
types of finches due to different food sources)
-Environment can cause an increase in the
number of individuals with beneficial
phenotypes and a decrease of individuals
without beneficial phenotypes.
-Black pocket mice increased due to phenotype
helping them blend in with new dark
environment from black hardened lava rock
-Mutations
-Combination of gametes formed by meiosis
during sexual reproduction
• Sexual reproduction. Asexual reproduction
produces genetically identical offspring with
NO variation.
• When two populations of a species can no longer
successfully mate
• Leads to speciation
-Behavioral isolation: differences in courtship or mating
behaviors
-Geographic isolation: physical barriers that divide a
population into two or more groups
-Temporal isolation: timing prevents reproduction
between populations
• Disruptive selection
• Directional selection
• Stabilizing selection
• Compare the amino
acid sequences of the
proteins – species
with more
differences are less
closely related
• Embryology compares similarities in
developmental stages of different organisms
to provide evidence that they share a
common ancestor.
Structures that had a function in an ancestor but
don’t in modern day organisms.
Ex.: Wings on flightless birds show they evolved
from ancestors that flew. They’ve since
evolved adaptations to travel efficiently in
other ways.
• Homologous structures are structures in
different organisms that share similar
structures but perform different functions provides evidence of a common ancestor. Ex.:
forelimbs of humans and cats.
1. Organism: Alligator
2. Population: 5 Alligators
3. Community: Alligators, Birds, Grass, Frogs,
Trees
4. Ecosystem: Alligators, Birds, Grass, Frogs,
Trees, Soil, Water, Sunlight
5. Biome: Temperate Deciduous Forest
Decomposers break down dead plants and
animals. This process
returns nitrogen to
the soil so that
bacteria can fix it for
plants.
They are related through photosynthesis and
respiration.
Carbon is taken in by plants through
photosynthesis.
Oxygen is given off from
photosynthesis and used
for respiration.
Similarity: A food web contains multiple related
food chains. (Both show feeding relationships)
Difference: Food chains show one feeding
relationship, food webs show multiple feeding
relationships.
A. Mutualism: Both organisms benefit from the
relationship. Ex: bee and flower
B. Commensalism: One organism benefits and
the other is neither helped nor harmed. Ex:
clownfish and sea anemone
C. Parasitism: One organism benefits from the
relationship while the other is harmed. Ex: tick
and human
• BIOTIC: Living (animals, plants, etc)
• ABIOTIC: Non-Living (water, light, soil,)
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Grass would increase
Lizards would decrease
Hawks would decrease
Rabbits and mice would increase
Snakes would increase
Mice would decrease
Grass would decrease
Competition: 2 male lions fight for a female, or
for food. 2 species of plants fight for the same
sunlight and soil.
Predation: A fox hunts, kills, and eats a rabbit.
• Approximately on Day 22
• Snakes would DECREASE because they have
nothing to eat. Locusts would INCREASE
because nothing is eating them.
• Reduce CO2 emissions to cut back on global
warming, use renewable energy like solar
energy to cut back on burning fossil fuels like
oil and gas. Recycle to cut down on waste,etc.
• They have no natural predators so they can
easily take over a new area. They take space
and food away from the native species that
lives there.