Biology: 1st Semester Final Exam Study Guide
CJ09
Population
Every population tends to increase (grow larger) because individuals tend to produce multiple offspring
(children) over their lifetime.
Exponential growth curve
 this J-shaped curve shows exponential growth
 population increases very quickly
A population increases when the number of
births is greater than the number of deaths.
As a population grows and reaches its carrying
capacity, resources (such as food, water, land,
shelter, and mates) start to run out.
Population Pyramids – age-gender distribution graphs
Pyramid- shows a high
proportion of children, a rapid rate
of population growth, and a low
proportion of older people.
Onion Dome- shows a decrease
in the number of children born,
plus reduced death rates at all
ages up to old age.
Hour Glass- shows a decrease in
the population of young men and
women and a higher proportion of
children and older people.
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Ecosystems
Ecology
the study of interactions of living organisms with one another and their physical
environment.
Two types of succession:
Primary (first) succession
 a change in the environment that allows an area of land to support living things where
it never did before
 Examples: melting glacier, volcano
Secondary succession
 a major (sometimes drastic) change in the envoroment that destroys much of what was
living but allows for growth years later
 Examples: forest fire, hurricane, tornado
Food Chain
Producers capture the sun’s
energy to make food
Food Web
Consumers are those organisms
that eat plants or other organisms
to obtain energy
Trophic Levels - The path of energy through a food chain.
Decomposers break dead
organisms down and release
nutrients back into the
environment
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4 LEVELS
Fourth Level: Top carnivores (meat eaters)
Third Level: Carnivores and omnivores (meat and plant eaters)
Second Level: Herbivores (plant eaters)
First Level: Producers (plants)
Communities
Community – different species living together in a particular place
The niche is the “job” or the function of the species in the biological community.
Includes where a species lives, how it lives, what it eats…
A Jaguar’s Niche
Diet: Feeds on mammals, fish, and turtles
Reproduction: Gives birth June through August during the rainy season
Time of activity: Hunts by day and night
Symbiotic Species
Mutualism – both species benefit
Example: As the bees collect nectar to take back
to the colony to feed their larvae, they pollinate
seed producing plants.
Parasitism – one species, the parasite, benefits
from the host, which is harmed.
Commensalism - one species benefits and the
other is neither harmed nor helped
Example: The clown fish are protected by the
tentacles of the sea anemones, even though these
tentacles would quickly paralyze other fishes.
Competition - occurs when two different
organisms compete for food, space, habitat, etc.
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Example: Fleas living and feeding off a dog or
cat.
Example: Hyenas and lions complete for the
same food resources.
The Environment
The Ozone Hole
Ozone creates a protective shield in the upper
atmosphere that absorbs and reflects radiation
from the sun.
Chemistry
Atom

 everything is made up of atoms
r
Element

a pure substance made of only one kind of atom
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Covalent Bond

when two or more atoms share electrons and form a molecule
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Compounds


made up of two or more elements
represented by a chemical formula
Water
H2O two hydrogen (blue) and one oxygen (red)
pH Scale is used to determine if a compound is an acid or a base.
Acid ---------------------------------------------- Neutral -------------------------------------------- Base
Carbon Compounds
Carbohydrates
Lipids
 aka sugar (glucose, sucrose, fructose)
 aka fat
 made of carbon, hydrogen, and oxygen
 does not dissolve in water
molecules
 stores lots of energy
Proteins

made up of smaller
molecules called
amino acids

enzymes are a type of protein used to
speed up chemical reactions

enzymes operate best within certain
temperature and pH values
Nucleic Acids

genetic material of
living things

DNA and RNA

DNA stores hereditary
information
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Cells - the smallest units of life
Light microscope
 Low magnification
 can be used to examine
living cells
Electron microscope
 high magnification
 cannot be used to
examine living things
Scanning tunneling microscope
 atomic-scale images
 can be used to examine
living cells
Prokaryotic Cells


smallest and simplest cells on earth
best example: bacteria
Characteristics




surrounded by a cell wall
does not have a nucleus
DNA moves freely inside the cell
some have flagella to help them move
Eukaryotic Cells


larger and more complex
animal and plant cells
Characteristics




cell membrane
has nucleus
cytoskeleton
organelles
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Organelles
Cell Membrane - selectively permeable,
meaning it allows only certain substances into
and out of a cell
Cell Wall – very thick layer of cellulose that
gives plants protection and support to stand
upright
Nucleus
Endoplasmic Reticulum
– stores DNA
– tells cell what to do
– network of cables
– holds ribosomes
Ribosomes
Mitochondria
– makes and stores energy
(ATP)
– time microscopic
structures
– makes protein
Lysosomes
Golgi Apparatus
– breaks down and digests
substance
–“packages” protein with a
molecular layer that allows
the protein to leave the cell
Vacoule
Choloplasts
– stores excess water in plant
cells
– conducts photosynthesis
– captures energy from the
sun to make food
– gives plants green color
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Cell Membrane Transport
Passive Transport- does not use the cells energy
Diffusion
 movement of a substance from an area of high
concentration to low concentration
Osmosis
 the diffusion of water molecules across selectively permeable membrane
 (remember the egg experiment)
Facilitated diffusion
 membrane proteins that helps bring in or carry out substances
 a carrier protein molecule that carries amino acids and sugars across the cell membrane
Active Transport- requires the cell to use energy (ATP)
Endocytosis – when the cell
takes in solid substances
(cell eating)
Exocytosis - when the cell needs
to get rid of large amounts of
waste (cell burping)
Pinocytosis – when the cell
takes in liquid substances
(cell drinking)
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Mitosis
Eukaryotic Cell Reproduction

23 chromosomes from the egg (haploid cell) combine with the
23 chromosomes from the sperm (another haploid cell) to
produce a fertilized egg cell (diploid cell), which then has 46
chromosomes
A karyotype is a diagram that shows a cell’s chromosomes arranged in order from largest to smallest.
Two of these chromosomes determine sex



Karyotype of a male with Downs Syndrome (right)
Chromosomal abnormalities often result from the failure of
chromosomes to separate properly during meiosis.
Trisomy is an abnormality in which a cell has an extra
chromosome. This means the cell contains 47 chromosomes
instead of 46. Downs syndrome, or trisomy 21, is a
chromosomal abnormality that results from having an extra
number 21 chromosome.
The offspring always inherits an X
chromosome from the mother.
If the father also gives an X
chromosome, the offspring will be
female or XX.
If the father gives a Y chromosome,
then the offspring is male or XY.
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Cell Cycle
Stages of Mitosis
Cells reach certain size then divide into
two cells.
The chromosomes copies in the nucleus of a dividing cell are
separated into two nuclei.
Prophase
- Chromosomes become visible
- The nuclear envelope dissolves and spindle forms
Metaphase 3
- Chromosomes line up along equator
Anaphase I
- Centromeres divide
- Chromotids (now called chromosomes)
move to opposite poles
A cell spends 90% of its time in the first
three phases of the cycle, which is called
interphase.
Telophase I and Cytokinesis
- Nuclear envelopes form
- Chromosomes uncoil
- Spindle dissolves
- Cytokinesis begins
Stages of Meiosis
Four cells are produced, each with half as much genetic material as the original cell.
Prophase I
Metaphase I
Anaphase I
Chromosomes
become visible.
The nuclear
envelope breaks
down. Crossing
over occurs.
Pairs of
homologues
chromosomes
move to the
equator of the cell.
Homologous
chromosomes
move to the
opposite poles of
the cell.
Telophase I &
Cytokinesis
Chromosomes
gather at the poles of
the cell. The
cytoplasm divides.
Prophase II
Metaphase II
Anaphase II
A new spindle
forms around
the
chromosomes.
Chromosomes
line up at the
equator.
Centromeres
divide.
Chromatids
move to the
opposite poles of
the cell.
Telophase II &
Cytokinesis
A nuclear envelope
forms around each set
of chromosomes. The
cytoplasm divides.
Haploid offspring cells.
Crossing over: the exchange of genetic material between chromosomes during meiosis
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Heredity
Heredity
 The passing of characteristics or traits from
parents to offspring
DOMINANT
 THE EXPRESSED FORM OF A TRAIT
 REPRESENTED BY CAPITAL LETTERS
 EXAMPLE: PURPLE FLOWER = B
recessive
 the trait not expressed in an offspring
 represented by lower case letters
 example: white flower = b
Homozygous
 Two alleles of a particular gene that are the same
 Example: BB or bb
Heterozygous
 Two alleles of a particular gene that are different
 Example: Bb
Genotype
 The set of alleles that an individual has for a character or trait
 Example: (three possible types) BB, bb, or Bb
Phenotype
 The physical appearance of any given character or trait
 Example: Purple flower or white flower
Punnett Square: (each square = 25% of the offspring)
Genotype:
50% Tt , 50% tt
Phenotype:
50% tall, 50% short
Practice…
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Multiple Alleles


More than two alleles exist for a trait.
Example: Blood type exists as four possible phenotypes: A, B, AB, & O
GENOTYPES
IAIA
IAi
IB IB
IB i
IAIB
ii
RESULTING PHENOTYPES
Type A
Type A
Type B
Type B
Type AB
Type O
Pedigree Studies





Each generation is represented by a roman numeral
Each person is numbered
Males are squares
Females are circles
Affected individuals are shaded