Download Biology EOCT Review

Biology EOCT Review
“All wish to possess knowledge, but few,
comparatively speaking, are willing to pay
the price.”
Ecology
 The study of interactions
between organisms and their
physical environment
 Ecosystem – natural unit that
includes all living things within
an area, their interactions with
each other and all of the nonliving features in the area
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Biotic factors – all living things
Abiotic factors – non-living,
water, air, temperature, soil,
rainfall, sunlight, etc
Ecology cont.
 Levels of organization within
ecosystems
 From smallest to largest
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Organism –> Population (1
species) -> Community (different
species) ->Habitat -> Ecosystem > Biome -> Biosphere
Ecology cont.
 Major Land Biomes
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Tundra
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Taiga
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Great biodiversity of species, heavy rain, always warm, infertile soil
Grasslands
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We live here, moderate rain, cold winters, warm summers, deciduous
trees (drop leaves)
Tropical Rainforest
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Coniferous forest (pines, spruce), long cold winters, soil thaws in
spring and summer
Temperate Deciduous Forest
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Permafrost, cold, lichens, mosses, grasses
Prairies, windy, rainfall and temperature vary throughout year
Desert

Little rain, hot temps in the day, cold temps at night, drought resistant
plants
Biology cont.
 Populations
 Population density - # of
individuals living in a given area
 Exponential growth – J-shaped
curve, rapid growth rate
 Logistical growth – S-shaped
curve – usually present in
natural populations – top of S
represents the population
reaching its carrying capacity
 Carrying capacity – maximum
# of individuals a specific
environment can support
Exponential
Logistical
Ecology cont.
 Energy Flow Through an Ecosystem
 Ultimate source of energy is the SUN
 Producers – make their own food
(autotrophs) then transfer the energy to
consumers
 Consumers – heterotrophs, eat
producers
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Primary – herbivores
Secondary – carnivores
Omnivores – eat plants and animals
Decomposers / Saprophytes – break
down dead organic matter
Ecology cont.
 Energy Flow through
Ecosystem
 Food chain – shows transfer of
energy from one organism to
another
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Each step is a trophic level
Always starts with a producer
(plant) and ends with a
decomposer
 Food web – all the food chains
in a community connected
together
 A food chain is one part of a
food web
Ecology cont
 Cycles
 Energy flows through a community in 1 way,
from the sun to the top of the food chain.
Only 10% of energy is passed on to the next
trophic level.
 Matter is recycled in an ecosystem.
Decomposers convert matter back into a
usable form for other living things.
Ecology
 Carbon-Dioxide-Oxygen Cycle
 Plants take carbon dioxide out of
atmosphere and put oxygen into
atmosphere through photosynthesis
 Heterotrophs take oxygen out of
atmosphere and put carbon dioxide into
the atmosphere through respiration.
 Water cycle – evaporation, condensation,
precipitation, transpiration
 Nitrogen cycle – nitrogen fixing bacteria
convert nitrogen gas into nitrates to be
used by plants
Ecology
 Succession in an Ecosystem –
gradual steps taking place until
an ecosystem reaches a
mature and stable community
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Pioneer species – first to
inhabit an area – makes soil
for other vegetation to inhabit
Climax community – mature
community
Primary
 Types
 Primary – occurs in area that
was previously unihabited
(rock, lava flows)
 Secondary – a disrupted area
that still has some soil and
vegetation
Secondary
Ecology
 Humans and the Environment
 Non-renewable resources – cannot be replaced
in a short amount of time (oil, coal, natural gas,
nuclear)
 Renewable resources – can be replaced
naturally in a relatively short amount of time
(hydroelectric, solar, wind, wood)
 Greenhouse effect – trapping of heat being
released by the earth by the atmosphere (keeps
us warm at night)

Effect is increased by man’s burning of fossil
fuels – puts more carbon dioxide in the air –
causes global warming
DNA and Genetics
 Genetics – study of heredity
and variation of traits in
organisms
 Trait – specific characteristic
of an organism that is
inherited
 Gene – segment of DNA on
a chromosome that
determines the
characteristics of a particular
trait
DNA and Genetics
 DNA deoxyribonucleic acid
 Found in every cell of an organism
 Located with the chromosomes in
the nucleus
 Double helix shape
 Nucleic acid made of long strands
of nucleotides
 Nucleotides – nitrogen base,
sugar, and phosphate group


Adenine pairs with thymine
Guanine pairs with cytosine
DNA and Genetics
 The genetic code – (sequences
of nucleotides) determines with
amino acids are coded for and
hence which proteins
 DNA replication – self-
duplicating process

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Double helix unwinds and unzips
Each single strand serves as a
template for a new complimentary
strand
Enzyme binds nucleotides to the
template to form the new strand
DNA and Genetics
 RNA - Ribonucleic Acid
 Nucleic acid
 3 differences from DNA
 Sugar is ribose instead of deoxyribose
 Nitrogen bases: adenine, uracil,
guanine, and cytosine
 Single stranded
 3 types of RNA
 Messenger RNA – carries DNA nucleotide sequence
out of the nucleus to the ribosomes
 Transfer RNA – transports amino acids to the
ribosomes for protein assembly
 Ribosomal RNA – makes up the structure of the
ribosome
DNA and Genetics
POLYMERASE
DNA
mRNA
 DNA Transcription – mRNA molecule is synthesized
from the DNA molecule in the nucleus
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DNA unwinds and unzips
Complementary RNA nucleotides pair with one of the
DNA template strands
mRNA strand detaches from the DNA and goes out to the
ribosomes in the cytoplasm to carry out protein synthesis
DNA and Genetics
 DNA Translation – takes place in the ribosomes
 Translates the genetic code into a protein by
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assembling a chain of specific amino acid
sequence
3 nitrogen bases = a triplet codon = a specific
amino acid
Order of codons determines order of amino
acids which determine the protein that is
synthesized
tRNA brings in anti-codons to attach to the
complementary codon
When anti-codons pair with codons, amino
acids are attached together in a chain
Assembly ends when a “stop” codon is reached
and the protein is released to the cell for use
Genetics and Gregor Mendel
 Mendel studied inheritance in pea
plants
 Mendel = father of genetics
 Hybrid = offspring of cross between
a homozygous dominant parent and
a homozygous recessive parent
 Concluded that offspring have two
genes form each trait, one from
each parent
 Alleles = different forms of the same
gene
segregation
Mendelian Genetics
 Law of Dominance- when 2 different alleles are
inherited, one is expressed (dominant) and one
is hidden (recessive)
 Law of Segregation – the two different forms of
an allele randomly separate during meiosis –
during fertilization new combos of the alleles
come together
 Laws of Independent Assortment – genes for
different traits sort out separately from one
another during meiosis
Incomplete
Dominance
Mendelian Genetics
 Genome – genes present in an
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organism
 Human genome – project
mapping out locations of
genes (and the traits they
code for) in the 23 pairs of
chromosomes
Phenotype – physical
appearance of a trait (tall plant)
Genotype – allele combonation in
an organism (TT, Tt)
Homozygous – alleles are the
same
Heterozygous – alleles are
different (hybrid)
Mendelian Genetics
 Probability – likelihood that an
event will occur
 Punnet Square – chart that shows
all the possible combinations of
gametes and their probabilities
when two organisms are crossed
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Monohybid cross – two alleles for
one trait crossed
Dihybrid cross – two pairs of
different traits at one time
Genetics
 Sexual reproduction –
male and female sex
cells (gametes) fuse
during fertilization
 Gametes are haploid (1
set of chromosomes) =
n
 Zygotes are diploid (2
sets) = 2n
Mitosis
Meiosis
And
fertilization