Biology Final Review

Unit 5: Evolution

• Evidence of Evolution

• Fossils: The fossil record provides some of the strongest evidence for evolution, it shows that organism have evolved in a historical sequence

• Prokaryotic cells are the oldest know cells
• The oldest known fossils are about 3.5 billion years old
• Multi-cellular fossils are the more recent fossils

• Biogeography: The study of past and present distribution of organisms
• Comparative Anatomy: The comparison of different body structures in different organisms

• Homology is the similarity in characteristics that results from common ancestry
• Some homologous structures are vestigial organs,  organs that once served a purpose but no longer have any  function

• Comparative Embryology: The comparison of early stages of development among different organisms

• Most vertebrates have common embryonic structures, revealing homologies

• Molecular Biology: Comparison of DNA and amino acid sequences between different organisms reveal evolutionary relations

• All living things share a common DNA code for the proteins found in living cells
• We share genes with bacteria, yeast, and fruit flies

• Microevolution

• Evolution on a small scale within a given POPULATION.

• Population: A group of organisms that inbreed with one another. They all share the same Gene Pool
• These organisms live in the same place at the same time

• Gene Pool:

• The total collection of genes in a population at any given time
• Consists of all the alleles in all of the individuals making up a population

• Mechanisms of Microevolution

• Mutation: A Change in the DNA sequence
• Migration (Gene Flow): Gain or loss of alleles when individuals move into or out of a population
• Genetic Drift: Change in gene pool of a population due to chance
• Natural Selection : Organisms with certain inherited characteristics are more likely to survive and reproduce than organisms with other characteristics

• Hardy-Weinberg: Under certain conditions, the gene frequency will remain constant (= NO Evolution) 

• Conditions of  Hardy-Weinberg:

• Large Population
• NO migration
• NO mutation

• The Hardy Weinberg principle states that allele and genotype frequencies within a sexually reproducing, diploid population will remain in equilibrium unless outside forces act to change those frequencies
• The Hardy Weinberg Equation gives a mathematical way to calculate the rate of evolution

• If gene frequencies change, then evolution IS occurring
• If gene frequencies DO NOT change, then evolution IS NOT occurring

• Hardy-Weinberg Equations

• Allele Equation (p + q = 1)

• p = frequency if dominant allele
• q = frequency of recessive allele

• Phenotype Equation (p2 + 2pq + q2 = 1)

• p2 = Frequency of homozygous dominant
• 2pq = frequency of heterozygous
• q2 = frequency of homozygous recessive

• Three Main Causes of Evolutionary Change

• Natural Selection: If individuals differ in their survival and reproductive success, natural selection will alter allele frequencies

• Natural Selection is the only mechanism the constantly leads to adaptive evolution
• Fitness: The contribution an organism makes the gene pool of the next and subsequent generations. The fittest individuals are those that pass on the most to the next generation

• Genetic Drift: A change in a population due to chance

• Bottleneck Effect: Leads to a loss of genetic diversity when to population greatly reduced
• Founder Effect: A few individuals colonize a new habitat and the new population's gene pool is reflective of that of the original population

• Gene Flow: The movement of individuals or gametes/spores between populations. This can altar allele frequencies in a population

• Selections

• Stabilizing Selection: Favors intermediate phenotypes over extreme phenotypes, this is common in stable environments
• Directional Selection: Acts against individuals at one of the phenotypic extremes, this is common in changing environments when populations are migrating to a new and different habitat
• Disruptive Selection: Favors individuals at both extremes of the phenotypic range. This can occur in patchy habitats

• Speciation: The emergence of new species

• Speciation is the bridge between microevolution and macroevolution
• Every time speciation occurs, the diversity of life increases
• The many millions of species on Earth have all arisen from an ancestral life form that lived around 3.6 billion years ago

• Biological Definition of Species: a population or group of populations whose members have the potential to interbreed in nature and produce fertile offspring

• Reproductive isolation prevents gene flow and maintains separate species

• Allopatric Speciation: Populations of the same species are geographically separated, separating their gene pools

• Changes in the allele frequencies of each population may be caused by natural selection, genetic drift, and mutation, unaffected by gene flow from other populations
• Gene flow between populations is initially prevented by a geographic barrier
• Likelihood of allopatric speciation increases when populations are small and isolated

• A small population may have a different gene pool due to the founder effect
• Genetic drift and natural selection may have a greater effect in a small population in a new habitat

• Sympatric Speciation: When geographic isolation takes place without geographic isolation

• New species arise within the same area as the parent species

• Reproductive Barriers 

• Reproductive barriers act serve to isolate a specie's gene pool and prevent inbreeding
• Reproductive barriers are categorized as pre-zygotic or post-zygotic, depending on whether they function before or after zygotes form

• Rates of Speciation

• Punctuated Equilibrium: New species appearing after long periods of little to no change 
• Gradualism: Species diverging gradually over long periods of time

Unit 6: Ecology

• Ecology: The scientific study of how organisms interact with their environment

• Ecological Hierarchy

• Organism: The one individual living thing
• Population: A group of individuals of the same species living in the same geographic area
• Community: A collection of all the populations of organisms living close enough together for potential interaction
• Ecosystem: Includes all BIOTIC and ABIOTIC factors in an environment

• Biotic Factors: Living factors
• Abiotic Factors: Non-living factors

• Biomes

• Tropical Forest:

• Located in regions near the equator
• High amounts of rainfall
• Complex and diverse vegetation

• Savanna:

• Located in Africa and South America
• 30 - 50 cm of annual rainfall
• Vegetation includes scattered trees, grasses, and forbs

• Desert

• Located in large regions of Australia and North Africa
• Extremely low rainfall amounts
• Vegetation includes small shrubs, cacti, and small trees

• Chaparral

• Small coastal regions along the Mediterranean region
• Mild wet winters and hot dry summers
• Vegetation includes spiny shrubs

• Temperate Grassland

• Found in cooler regions
• 25 - 75 cm of annual rainfall with periods of drought
• Vegetation includes scattered trees

• Temperate Forest

• Located in Eastern Regions of the U.S., Central Europe, Asia, and Australia
• Very high rainfall amounts, 75 - 150 cm of annual rainfall
• Vegetation includes oak trees, maple trees, hickory trees, and birch trees

• Taiga

• Located in regions of Asia, Western North America, and regions near the arctic circle
• Receives 40 -  200 cm of annual rainfall
• Vegetation include sparse trees

• Tundra

• Located in the Northernmost regions of earth
• Receive 15 - 25 cm of annual rainfall
• No vegetation due to permafrost

• Survivorship Curve: Plots survivorship as the proportion of individuals from an initial population that are alive at each age.

• Type I: species that produce few offspring (ex humans), but give them good care, increasing the chance that they will survive to maturity.
• Type II: Survivorship is constant over the lifespan (ex: lizard, rodents)
• Type III: species that produce very large #s of offspring (ex: many invertebrates) but provide little care for them.

• Carrying Capacity: The maximum population size that an environment can sustain

• Factors That Limit a Population

• Density Dependant Factors

• Competition for limited food supply
• Competition for territory
• Influence on health, disease transmission, health

• Abiotic Factors

• Weather
• Environmental Factors

• Interspecific Relations: Interactions with other species within the community

• Competition: A relation where two different species compete for the same limited resource

• Niche: The sum total of a specie's use of biotic and abiotic factors

• Mutualism: A relation in which both species benefit
• Predation: A relation where one species eats the other
• Herbivory: A relation where species eat plants
• Parasitism: A relation where parasites benefit off other organisms

Unit 7: Plants

• Angiosperm: A flower producing plant

• Monocot: Embyos have a SINGLE seed leaf\

• Veins run parallel
• Vascular bundles are in a complex arrangement
• Flowers are generally in multiples of THREE
• Has a fibrous root system  

• Dicot: Has TWO embryonic seed leaves

• Veins are usually branched
• Vascular bundles are arranged in a ring
• Flowers are generally in multiples or FOUR or FIVE
• Has a tap root

• Types of Growth

• Primary Growth: Growth in HIGHT
• Secondary Growth: Growth in WIDTH

• Plant Structures

• Sepals: Enclose and protect the flower bud
• Petals: Attract pollinators
• Stamen (Male Reproductive Part): Produces pollen, consists anther which are elevated by filaments

• Anther: Sacs in which meiosis occur and in which pollen is produced

• Carpel (Female Reproductive Part): Consists of a stalk with an ovary at the base and stigmas at the tip.

• Ovary: Contains ovules, the ovules contain developing eggs and support cells
• Stigma: Acts to trap pollen

• Root Hairs: Hold plants into the ground and absorb nutrients

• Transpiration-Cohesion-Tension Mechanism: A transportation mechanism that drives the upward movement of water in plants

Unit 8: Regulation

• Vocabulary

• Hormone - A CHEMICAL signal that travels through the bloodstream.
• Endocrine Gland - An organ that makes and secretes hormones. 
• Target Cell - Cells that respond to a particular hormone.
• Endocrine System - Communication and Regulation.

• Endocrine System VS. Nervous System

• Endocrine System

• Types of Signals: Chemical signal which travels through blood
• Speed of Signals: Slow
• Duration of Response: Long lasting.

• Nervous System

• Types of Signals: Electrical signals which travel through neurons
• Speed of Signals: Rapid
• Duration of Response: Short lived.

• Neurosecretory  Cells

• Perform functions of BOTH the endocrine and nervous system.
• Conduct nerve signals AND make/secrete hormones into the blood.

• When Nerve Signals reach the end of a nerve cell:

• Neurotransmitters are released

• Neurotransmitters DO NOT travel via blood.

• Neurotransmitters travel in the space between neuron and reach the next neuron, where the electrical signal continues.

• Water Soluble VS. Lipid Soluble (Steroid) Hormone

• Water soluble hormones bind to receptors on the plasma membrane, whereas steroid hormones bind to receptors inside the cell.
• Steroid hormones always affect gene expression & other hormones have this or other effects.

• Stereroids

• Adrenal glands, testes, and ovaries, are the only organs that produce stereroids.
• Stereroid hormones can enter the target cell and have a direct effect on the target cell's nucleus.

• Targets and Actions of Hormones

• Development of sex characteristics
• Regulation of blood sugar
• Maintenance of Circadian rhythyms
• Stimulation of T cell development
• Maintenance of water/sugar balance
• Regulation of blood calcium levels

• The Hypothalmus and the Pituitary Gland

• The Pituitary gland is located at the base of the hypothalmus
• Posterior Pituitary Gland - An extension of the hypothalmus, stores and secretes hormones from the hypothalmus. Neuosercretory cells connect the hypothalmus and posterior pituitary gland (Makes ADH and Oxytocin) 

• Oxytocin - Targets mamary glands to stimulate milk produciton  and uterine muscles to enable contraction of the uterus during childbirth.
• ADH - Targets kidney tubules to resorb water, decreasun urine volume when the body needs to maintain water.

• Anterior Pituitary Glad - Makes and secretes hormones into the blood. (Makes TSH, ACTH, FSH, LH, Prolactin, Growth Hormones, and Endorphins.

• TSH - Stimulates the thyroid and the release of thyroxin into the blood, increasing metabolism
• ACTH - Stimulates the adrenal cortex
• FSH - Stimulates production of ova and sperm
• LH - Stimulates ovaries and testes
• Prolactin - stimulates milk production in females
• Growth Hormones - Stimulates growth and metabolic functions.
• Endorphins -Target pain receptors in the brain and act as natural pain killers

• The Thyroid Gland

• Located just under the voice box
• Produces thyroxin and triiodothyronine

• These glands play a crucial  role maturation and development
• In humans, thyroid deficiency results in stunted skeletal growth and slow mental development. This is called hypothyroidism

• Hypothyroidism

• Insufficient T3/T4 due to defective thyroid or severe iodine deficiency.
• Symptoms include; weight gain, lethargy, intolerance to cold, goiter.

• Hyperthyroidism

• Excess T3/T4. Most commonly caused by Grave's Disease/
• Symptoms include; weight loss, profuse sweating, irritability, and high blood preasure.

• The Pancreas

• Located near the upper part of the digestive tract, where the stomach, liver, and small intestine meet.
• Produces glucagon and insulin to regulate blood sugar levels. 
• Theses two hormones are antagonistic hormones
• What Happens When Glucose Levels get too High:

1. Rising Glucose stimulate Beta Cells
2. Beta Cells secrete more insulin
3. Insulin stimulates body cells to take up glucose from the blood, the liver takes of glucose and stores it as glycogen
4. Blood Glucose levels decrease

• When blood glucose levels fall to a set limit, beta cells loose their stimulus to secrete insulin.

• What Happens When Glucose Levels get too Low

1.        Low blood sugar stimulates Alpha Cells

2.        Alpha cells secrete more glucagon

3.        Glucagon signals the liver cells to break down glycogen into         glucose

4.        Blood glucose levels increase

• When blood glucose rises to set limit, alpha cells lose their stimulus to secrete glucagon

• Neurons: Nerve signals that carry signals from one part of the body to another

• Cell Body: Contains the neuron's organelles
• Dendrites: Receive information from other neurons and relay information to the cell body
• Axon: Long extension of the cell body that transmits signals to other neurons
• Terminal: The end of an Axon
• Schwann Cells: Insulates the axon and speeds the conduction of the signal
• Nodes of Ranvier: Spaces between the Scwann cells, leaky points of the signal