Download Biology End of Course Exam Study Guide

Biology End of Course Exam Study Guide:
Genetics (HEREDITY)
• Mutation is a change in the DNA sequence- increases genetic diversity.
 Gene= section of DNA that codes for a trait (ex. Eye color)
 Allele= different form a trait (brown eyes, blue eyes, green eyes)
 Traits are formed by proteins that are made from instructions on DNA.
• Homozygous refers to two identical alleles (HH or hh)
• Heterozygous refers to two different alleles (Hh)
• The principle of dominance states that some alleles are dominant and others are recessive
• Codominance is when both alleles are expressed at the same time (Red+White=Red and White spots)
• Incomplete dominance is the blending of traits (Red+White=Pink)
• Normal males have XY chromosomes; Normal Females have XX chromosomes
• Pedigrees show the pattern of inheritance with male (square symbol) and female (circle symbol) offspring
• Sex-linked traits are located on the sex chromosomes (X and Y chromosomes)
• Sexual reproduction requires two individuals; asexual reproduction requires only one single parent
• Punnett squares show the probable offspring from the cross between parents
• Mitosis- cell division (allows organisms to grow), resulting in two genetically identical cells.
-A cell with 12 chromosomes will split into 2 cells, each with 12 identical chromosomes
-Cancer is uncontrolled cell division (mitosis)
• Meiosis- cell division, resulting in 4 NON-genetically identical cells
-cell goes through 2 divisions
-results in gametes (egg & sperm with ½ the # of chromosomes)
-A cell with 12 chromosomes will split into 4 cells, each with 6
chromosomes
-Causes genetic diversity through crossing-over (chromosomes
exchange pieces) & random fertilization
EVOLUTION
• Natural selection is based on organisms with traits that allow them to
survive (adaptations), reproduce and pass on traits (genes).
*think about our birds & beaks lab.
-POPULATIONS evolve, not individuals!!!!!
• Evolution (change of time) can be explained in 4 factors:
1. there is potential for a species to increase in number
2. individuals in a population are different (variation) due to mutation & sexual reproduction
3. there is competition for limited resources (food, mates, space)
4. organisms that are better suited, survive and reproduce
• Gene pool is the combined genetic information of all members of a population
• Fitness (survival of the fittest) is the success of an organism to survive and reproduce
• Speciation is process of forming a new species through reproductive isolation (ex. Geographic, habitat, behavioral, etc)
• Species- individuals who can reproduce viable (living) and fertile offspring
• Evidence of evolution
-fossil record, observation of natural selection happening today, DNA similarities of different organisms, and
embryological evidence.
• Similarities of DNA and traits show that many different organisms share a Common ancestor.
• Homologous structures show similarities between common ancestors (Bird wing vs. mammal leg)
• Vestigial structures- body parts that no longer have a function, left over structures from an ancestor.
ECOLOGY
• Levels of Organization
-Biosphere: portion of Earth that supports life
-Biome: group of ecosystems with similar characteristics
-Ecosystem: living and non-living things in a particular area
-Community: all biotic (living) factors in a particular area
-Population: all members of the same species
-Species: individuals that can reproduce viable & fertile offspring
• Carrying capacity is the number of individuals at which the environment can support
• Limiting factors cause a population’s growth to decrease
• Density-dependent factors limit the population growth only when the density reaches a certain level
(predation, parasitism, disease, competition)
• Density-independent factors affect all populations regardless of the density (natural disasters)
• Human activities are a source for environmental change on earth
• Biogeochemical cycles move resources through the biosphere (water, carbon & nitrogen). These nutrients are reused in
the biosphere.
Carbon cycle•Carbon is used by plants to form glucose, it is released
during cellular respiration by animals and the burning of
fossil fuels.
•Nitrogen is available for plants because bacteria convert it
into a usable form.
•Animals get nitrogen from eating plants
• Predation is the interaction when one organism captures
and feeds on another (predator-prey)
• Consumers are organisms that rely on other organisms for
their energy and food supply (herbivores, carnivores,
omnivores, detritivores, decomposers)
• Producers capture sunlight to make chemical energy
• Food chains are a series of steps in which organisms
transfer energy by eating and being eaten
• Food webs are complex feeding relationships
• Symbiosis is the relationship between two closely related species (mutualism, commensalisms, parasitism)
• Abiotic factors are nonliving components of an ecosystem; biotic factors are living components of an ecosystem
• Trophic levels show the steps of energy transfer found in food webs/chains.
• 10% of energy is available for the next trophic (feeding) level. The other 90% is used from bodily functions & heat.
• Energy is NOT recycled.
DNA
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All cells contain DNA
Know the main difference between DNA and RNA
o DNA-double stranded, contains ATCG, stays in nucleus
o RNA- single stranded, contains AUCG, found in nucleus/cytoplasm/ribosomes
DNA is shaped as double-helix
A pairs with T, C pairs with G.
Nucleotide (subunit of DNA): made up of a nitrogen base, sugar & phosphate
Ribosomes are used for the site of protein synthesis (where proteins are made)
A gene contains the information for making a protein.
DNA replication
o Occurs before cell division
o Takes place in the nucleus
o Results in two identical double helixes (each with an original & new strand)
Transcription & Translation
o RNA is copied in the nucleus
o RNA leaves nucleus to the ribosome
o Amino acids are linked together (in order of the RNA message) and folds into a functional protein.
o The structure of the protein determines its function!
Cells & Biomolecules
•Prokaryotes lack a nucleus; Eukaryotes have a nucleus
• The cell is the smallest unit of life.
• Cells remain small in order to move nutrients in & out efficiently (quickly.
*Then how do we grow?.....Mitosis (cell division)!
• Diffusion- movement of molecules from an area of high concentration to an area of low concentration (molecules will
spread out until they are evenly spaced).
• Osmosis is the movement of water across a membrane from high to low concentration.
• When a cell is placed in salt water (hypertonic), water within the cell will leave and the cell will shrink.
• The movement of molecules is regulated by a selectively permeable cell membrane.
• Passive transport does NOT require energy to move molecules (ex. Diffusion & osmosis).
• Active transport DOES require energy to move molecules against the concentration (like pushing a rock uphill).
• The successful functioning of the cell is determined by its structure (organelles).
• Know the following parts of the cell (organelles)
-Nucleus: stores DNA
-Cell Wall: only occurs in plants, creates a rigid structure
-Cell membrane: controls what enters and exits cell
-Lysosome: contains digestive enzymes to breakdown wastes
-Mitochondria: site of cellular respiration (converts sugar to energy…ATP!)
-Chloroplasts: site of photosynthesis (concerts carbon dioxide into sugar)
•Know the following Biomolecules
-Carbohydrates: sugars, used from energy (broken down during cellular respiration)
-Lipids: fats, oils, steroids, used from long-term energy storage
-Proteins: made of a chain of amino acids, responsible for all processes in an organism
-Nucleic acids: DNA and RNA
• Enzymes are proteins that speed up chemical reactions (end is the suffix –ase)
Photosynthesis & Cellular Respiration
•Photosynthesis transforms light energy into stored chemical (bond) energy by converting carbon (CO2) + water into
sugar (glucose) and releases oxygen.
• Photosynthesis occurs in producers (plants and some bacteria)
• How do plants grow? Where does plant mass comes from?
-the CARBON in the air, is converted to biomolecules.
• Matter in the form of food is broken down through cellular respiration into
energy (ATP) and oxygen.
• When you lose weight, is fats & sugars being broken down into CARBON and
released by breathing out CO2.
• Cellular Respiration occurs in the Mitochondria in a cell.
• Cellular respiration releases energy because energy is released when sugar/fat
bonds are broken.
Skills & Essential Concepts
•Scientifically testable experiments require a method to gather specific
measurements and data (ex. Measuring height & mass)
•Unintended consequence- unplanned problem
•Constraint- limitation, restriction, obstacle,
• Sustainable- can be maintained for a long period (forever)
• Valid experiments: contain controls
-example: test a stream at 2 ft deep, 4 ft deep, & 6 ft deep
• Reliable experiments: multiple trials
-Repeat experiment, collect data multiple times
•Independent (manipulated) variable- variable that you change in an experiment
•Dependent (responding) variable- what you measure, the data you collect
•Homeostasis- the process by which organisms keep their internal conditions relatively stable
•Feedback mechanisms help organisms maintain homeostasis.
•Know the 2 types of feedback:
1. Positive feedback- encourages body process
Ex. Contractions during birth
2. Negative feedback- discourages body process
Ex. Sweating to decrease body temperature