Biology
Exam Review
Biology
• The study of life
Characteristics of Living Organisms
• Made of cell(s)
• Displays
organization
• Grows and
develops
• Reproduces
• Responds to
stimuli
• Requires energy
• Maintains
homeostasis
• Adaptations
evolve over time
Scientific Method
• Ask a question
or make an
observation
• Form a
hypothesis
• Conduct an
experiment
• Collect and
analyze data
• Draw a
conclusion
Ecology
• The study of how organisms
interact with one another and
with the nonliving part of the
environment
Levels of Organization
• Organism
• Population
• Community
• Ecosystem
• Biome
• Biosphere
Symbiotic Relationships
• Parasitism – one species benefits the
other is harmed in some way
• Mutualism – both species benefit
• Commensalism – one species
benefits the other is neither harmed
nor helped
Autotrophs or Producers
• Collect energy from sunlight to
produce food
Heterotrophs
• These organisms get energy by
consuming other organisms
What do organisms eat?
• Herbivores eat producers.
• Carnivores prey on herbivores.
• Omnivores eat both plants and
animals
Food Chain and Food Web
• A food chain is a simple model
that shows how energy flows
through an ecosystem.
• A food web is an interconnected
group of food chains.
Biogeochemical Cycle
• A cycle that involves moving a
substance (water, carbon,
nitrogen…) from the living
environment to the nonliving and
back again
Density-dependent vs. Densityindependent factors
• Density-dependent factors are
factors that depend on the number
of members in a population.
• Density-independent factors are
factors that do not depend on the
number of members in a
population.
Macromolecules
• Carbohydrates –
monosaccaharides
• Proteins – amino acids
• Nucleic acids – nucleotides
• Lipids – glycerol and 3 fatty acids
Cell
• The basic unit of life
Cell Theory
• All living organisms are composed of
one or more cells
• Cells are the basic unit of structure
and organization of all living
organisms
• Cells arise only from preexisting
cells
Prokaryotic vs. Eukaryotic
• Prokaryotic cells lack a nucleus
and other membrane-bound
organelles.
• Eukaryotic cells have a nucleus
and other membrane-bound
organelles.
Cell Membrane
• Selectively permeable
• Made of a phospholipid bilayer
• Fluid mosaic model – the
phospholipids create a “sea” in
which the other molecules can
float
Cytoplasm
• Semifluid material in which
organelles are found in a
eukaryotic cell
• This is where all prokaryotic cell
activities occur
Nucleus
• Contains the majority of the cell’s
DNA
• Surrounded by nuclear envelope
• Where chromosomes are located
Ribosomes
• The organelle that helps
manufacture proteins
• Made by the nucleolus
• Can be free-floating or attached
to the ER
Endoplasmic reticulum (ER)
• Membrane system of folded sacs
and interconnected channels
• Rough ER or Smooth ER
• Synthesizes proteins, lipids and
carbohydrates
Lysosome
• Digestive body of the cell
Centrioles
• Found in animal cells and are
used for structure during cell
division
Mitochondria
• Converts glucose into ATP
• Site of cellular respiration
• Referred to as “powerhouses” of
cell
Chloroplasts
• Found in plant cells but not
animal cells
• Site of photosynthesis
Cell Wall
• Thick, rigid, mesh of fibers that
provides protection and support
to cells
• Found in plants but not animals
Diffusion and Osmosis
• When a substance moves from an
area of high concentration to low
(DIFFUSION)
• Diffusion of water (OSMOSIS)
Facilitated Diffusion
• Diffusion with the assistance of
transport proteins
Cell Cycle
• Interphase – preparation for
nuclear division
• Mitosis – division of the nucleus
• Cytokinesis – division of the
cytoplasm
Interphase
• Gap 1
• Synthesis
• Gap 2
Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase
Cancer
• The uncontrolled growth and
division of cells
• Substances known to cause
cancer are called carcinogens
Haploid vs. Diploid
• Haploid – n - gametes
• Diploid – 2n – body cells
Meiosis
• Production of gametes, or sex
cells
• Often called reduction division
• RECALL – Crossing-over occurs
during prophase I of meiosis
Genetics
• Branch of biology focusing on
heredity
Homozygous
• Contains two of the same alleles
• AA, aa
Heterozygous
• This is when an organism has two
different alleles
• Aa, Yy
Genotype vs. Phenotype
• The genotype is the organism’s
allele pairs.
• The phenotype is the physical
appearance or outward
expression of an allele pair.
Carrier
• An individual who is
heterozygous for a recessive
disorder and shows no symptoms
of the disorder
Examples of autosomal recessive
disorders
• Cystic fibrosis
• Albinism
• Galactosemia
• Tay-Sachs disease
Examples of Dominant Disorders
• Huntington’s disease
• Achondroplasia
Sex-linked Recessive Disorders
• Red-green colorblindness
• Hemophilia
Pedigree
• A diagram that traces the
inheritance of a particular trait
through several generations
Incomplete Dominance
• The heterozygous phenotype is in
between the two homozygous
phenotypes
• A pink flowered snapdragon is
produced from parents in which
one had red flowers and one had
white flowers.
Codominance
• This is when both alleles are expressed at
the same time.
• Roan horse – both red hair and white
hair
Sex-linked Traits
• Traits controlled by genes located on the
X chromosome
• Since males have only one X
chromosome, they are affected by sexlinked recessive more often than
females.
Nucleotide
• 5-carbon sugar
• Phosphate
• Nitrogenous base
DNA
•
•
•
•
Deoxyribonucleic acid
Double helix
Five-carbon sugar - deoxyribose
Bases: adenine, thymine, guanine,
cytosine
Chargaff’s Rule
• Adenine pairs with thymine
• Guaning pairs with cytosine
RNA
•
•
•
•
Ribonucleic acid
Generally a single-strand
Five-carbon sugar is ribose
Bases: adenine, uracil, guanine,
cytosine
Three Major Types of RNA
• Messenger RNA (mRNA) – travel from
nucleus to cytoplasm and direct the
synthesis of proteins
• Ribosomal RNA (rRNA) – associate with
proteins to form ribosomes
• Transfer RNA (tRNA) – transport amino
acids to the ribosome
Semiconservative Replication
• Method of DNA replication in which
parental strands separate, act as
templates, and produce molecules of
DNA with one parental strand and one
new DNA strand.
Three Main Stages of Replication
• Unwinding – DNA helicase
• Base pairing – DNA polymerase
• Joining – DNA ligase
Transcription
• Synthesis of RNA
Translation
• The code is read and converted to
make a protein
Evolution
• Cumulative changes in groups of
organisms through time