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Exam One: Evolution

7/14/15 2:40 PM

Natural Selection
Five observations:
1
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All species can reproduce/population can grow
3
...

4
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Relatives resemble each other
Inferences:
1
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“struggle for existence”
2
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Survival of the “fittest”
ii
...
Unequal ability to survive and reproduce leads to changes in a
population
i
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Natural Selection
i
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Genetic Drift
i
...
Smaller the sample the greater chance of deviation
iii
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Founder effect
2
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Gene Flow
i
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Tends to reduce differences over time
4
...
Source of all inherited variation
ii
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Types
1
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Silent: same amino acid, different coding
b
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Missense: results in different amino acid
§ Insertion/deletion
§ Duplication
§ Recombination
5
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Matingà inheritable variation that affects fitness
ii
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Dissimilar sexual function/size
2
...
Female choice (inter)

Speciation
Biological Species Concept: a group of populations whose members have the
potential to interbreed in nature and produce viable, fertile offspring
Anagenesis: evolutionary change along a single evolutionary branch
Cladogensis: evolutionary divergence into two or more descendent lineages
• The ancestor may or may not change
Orthologous Genes: same gene found in different species
Paralogous Genes: gene duplication within a species

Exam Two: Eukaryotes

7/14/15 2:40 PM

Protists
• All eukaryotes except plants, fungi, and animals
• Many distantly related clades
• Most are unicellular
• Most are aquatic
• Non-monophyletic
• Energy production: photoautotrophic, heterotrophic, and
mixotrophic
Advantages of multicellularity/colonial Green Algae:
• Division of labor and differentiation/specialization of particular cells
• More efficient acquisition of nutrients
• Escape predators
o Colonies too big can be eaten (escape in size)
• Morphological complexity allows for more flexible adaptations to
environment
• Differential gene expression
Plants
• Evolved from algae
• Cooksonia is the earliest known land plant
o Fossil
o Vascular
o Early Devonian era 300-400 mya
Kingdom: Plantae
• Challenges:
o Desiccation
o Fertilization
o Dispersal of offspring
o Upright growth and water support
o Transportation of water and nutrients
o Different environmental stresses
• Preventing water loss:
1
...
Multicellular gametangia (sex organs): helped protect gametes
from drying out

3
...
Alteration of generations:
§ Plants alternate between 2 multicellular stages: haploid
and diploid
§ Gametophyte is haploid and produces haploid gametes
by mitosis
§ Fusion of gametes gives rise to diploid sporophyte,
which produces haploid spores by meiosis
o Multicellular, dependent embryos
§ Diploid embryo is retained within the tissue of the
female gametophyte
§ Land plants are called embryophytes because of the
dependency of the embryo on the parent
o Walled Spores produced in sporangia
§ Sporophyte (2n) produces spores
§ Spore walls contain sporopollenin
o Multicellular Gametangia
§ Gametes are produced within organs called Gametangia
§ Archegonia: female gametangia, produce eggs
§ Antheridia: male gametangia, makes sperm
o Apical Meristems
*Additional derived trait: STOMATA
• specialized cells that allow for gas exchange between the outside air
and the plant
Origin and Diversification of Plants:
• ~470 mya
1
...
Seedless vascular plants

i
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Vascular system:
1
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Sporophyte can grow tall
3
...
Evolution of roots
i
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Enable vascular plant to absorb water and nutrients from soil
4
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Organs that are planar surfaces, generally capturing solar
energy for photosynthesis
Evolution of Vascular Plants
• Root:
o Epidermis: outer layer
o Ground tissue: most of the stuff inside
o Vascular tissue (Stele): p and x
• Apical meristems:
o Site of cell division
o Cell division and elongation
• Secondary growth
o Evolved later than primary growth
o Growing out/lateral growth
o Originates from vascular cambiumà where new vascular cells
are being produced, creates new layers of vascular tissues
o Cork Cambium: producing periderm (cork tissue)/bark
• Cohesion-tension
o Water movement from roots to leaves
o Root absorbs water, transported to xylem
o Hydrogen bonding between water molecules creates cohesion
o Constant transpiration at leaf creates low pressure region
o Water in xylem is under tension and goes to low pressure
area, leaves
Major Plant events/evolutions:
1
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Primitive seedless plants

3
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Gymnosperms: naked seed plantsà not embedded in fruit
5
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Fertilization is independent of water
2
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Majority of Life is diploid
4
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Seed Coat: can with stand stress
6
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Seedling groth supported by food reserves stored in seeds
Seeds:
•
•
•

An embryo and endosperm in an enclosed seed coat
Embryo is 2n, result of fusion of egg and sperm
Endosperm=gametophyte in gymnosperm

Angiosperm:
• Flower
• Seed is surrounded by ovary, which develops into the fruit
• Advantages:
o Efficient reproduction: pollination and seed dispersal
o Extreme reduction of the gametophyte generation
o Adaptability to new and changing environments
o Efficient nutrient/ assimilate and water transport
• Monocot vs eudicot
o Monocots have one cotyledon

•

o Dicots have two
Structure:
o Male: stamenàanther (produces pollen) and filament

o Female: stigma, style, ovary
• Double fertilization:
o Pollen grain germinates on stigma, goes down style to ovary
o Pollen has 2 haploid sperm nuclei, which travels to the ovary
o One sperm nucleus germinates egg= zygote
o Other sperm nucleus unites with the 2 polar nuclei forming
the endosperm (3n)
Simple Fruit: Develop from a single ovary
• Berry: Fleshy fruits from a single ovary
o All parts fleshy, except exocarp
• Drupes: peach, fleshy with hard seed
• Pomes: endocarp enclosing seed is cartilaginous, apple
Aggregate fruit: forms from several ovaries, strawberry
Nuts: simple dry fruit with one seed
a
...
Bryophyte: land plants
• 5 derived traits of land plants
o alteration of generations
o walled spore
o multicellular gametangia
o dependent embryos
o apical meristems
Vascular +roots+ leaves
Seedless vascular
Seedsàgymnosperms
Floweràangiosperms

Exam Three

7/14/15 2:40 PM

Exam Four

7/14/15 2:40 PM

*Every organism must exchange material with its environment
*Exchanges occur at the cellular level by crossing the plasma membrane
Circulatory System
• Link exchange surfaces with body cells
• Small molecules can move between cells and their surroundings by
diffusion
• Diffusion is only efficient over small distances
o Time to diffuse is proportional to the square of the distance
• Open and closed circulatory systems have
i
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Set of interconnecting vessels
iii
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Veins: blood to heart
2
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Capillaries: site of exchange
• Blood flow is one way
• Arteries branch into arterioles and carry blood away from the heart
to capillaries
• Capillary beds are chemical exchange sites between the blood and
interstitial fluid
• Venules converge into veins and return blood from the capillaries to
the heart
• Hepatic portal vein: carries blood from the capillary beds in the
digestive system to capillary beds in the liver
Double Circulation

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•
•
•

Amphibians, reptiles, mammals
Oxygen-poor blood flows through the pulmonary circuit to pick up
oxygen in the lungs
Oxygen-rich blood delivers oxygen through the systemic circuit
Double circulation maintains higher blood pressure in the organs
than does single circulation

Four-Chambered heart
• Birds and mammals
• Two atria and two ventricles
• Most likely adaptation because of being endothermic and requiring
move oxygen than ectotherms
• Start: Right Ventricle
Mammalian Heart
• The atria have relatively thin walls and serve as collection chambers
for blood returning to the heart
• The ventricles have thicker walls and contract much more forcefully
• Four valves prevent backflow of blood in the heart
i
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Semilunar: control blood flow to the aorta and pulmonary
artery
• Cardiac Cycle: heart contracting and relaxing in a rhythmic cycle
i
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Diastole: relaxation/filling phase
Maintaining the Heart’s Rhythmic Beat:
• Some cardiac muscle cells are auto rhythmic
o Contract without nervous system signals
o Sinoatrial node- signals cardiac muscle contraction
Blood Vessels:
• Endothelium
o Epithelial layer that lines blood vessels
• Capillaries have thin walls: endothelium and basal lamina

•

Arteries and veins: endothelium, smooth muscle, and connective
tissue
o Arteries have thicker walls than veins to accommodate the
high pressure of blood pumped from the heart

Blood Pressure:
• Blood flows from areas of higher pressure to areas of lower
pressure
• Blood pressure is the pressure that blood exerts in all directions,
banging against arteries
• Pulse is the rhythmic bulging of artery walls with each heart beat
1
...
Diastolic Pressure
§ Pressure when the heart is relaxing and filling back up
with blood
Regulation of Blood Pressure
• Homeostasis mechanisms regulate arterial blood pressure by
altering the diameter of arterioles
• Vasoconstriction: contraction of smooth muscle in the arteriole
walls, increased blood pressure
• Vasodilation: relaxation of smooth muscles in the arterioles,
decreases blood pressure
*Thin endothelial walls of capillaries allows exchange between blood and
interstitial fluid
*Blood pressure drives out of capillaries
*Osmotic pressure drives fluids into capillaries at the venule end
Lymphatic System: fluid return
• Returns fluid that leaks out from capillary beds
• Lymph: fluid lost by capillaries
o Drains into veins in the neck

•

Lymph nodes: organs that filter lymph and play an important role in
the body’s defense

*Most of blood is plasma (55%)
Erythocytes/Red Blood Cells:
• Most numerous blood cell
• Contain hemoglobin (millions/cell)
o Hemoglobin: iron-containing protein that transports oxygen,
each hemoglobin contains 4 oxygen molecules
Gas Exchange
*Gas exchange supplies oxygen for cellular respiration and disposes of CO2
Partial Pressure
• Pressure exerted by a particular gas in a mixture of gases
• Gases undergo net diffusion from higher partial pressure to lower
partial pressure
Respiratory surfaces
• Animals require large, moist respiratory surfaces for exchange of
gases with air or water
• Gas exchange across respiratory surfaces takes place by diffusion
• Respiratory surfaces vary by animal and can include gills, tracheae,
and lungs
1
...
Tracheal System:
§ Tracheal tubes supply oxygen directly to body cells
3
...
Barrier Defenses
§ Include skin and mucus membranes of the respiratory,
urinary, and reproductive tracts
§ Mucus traps and allows for the removal of microbes
§ Many body fluids including saliva, mucus, and tears are
hostile to many microbes (lysozymes)
§ The low pH of skin (<5) and the digestive system (~2)
prevents growth of many bacteria
2
...
Inflammatory Response
§ Initiated by mast cells
§ Mast cells:
ú Connective tissue
ú Release histamine: dialates blood vessels and
increases permeability
ú Phagocytes release cytokins that increase immune
response
• Blood flow increases, neutrophils
congregate
§

*Vertebrates also have adaptive immunity
Adaptive Immunity:
• Acquired immunity
• Develops after exposure to foreign agents
o Example: microbes and toxins
• Involves a very specific response to pathogens

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•

•
•
•

Pathogen specific recognition
Relies on two types of lymphocytes/WBC
1
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mature in thymus
II
...
these antigen fragments are bound to cell-surface
proteins called MHC Molecules
a
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Host cells transport antigen fragments to MHS
2
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mature in Bone Marrow
Antigens: substances that can elicit a response from a B or T cell
T or B cells bind to antigens via antigen receptors specific to part of
one molecule of that pathogen
Each individual B or T cell only recognizes a specific type of
molecule (aka only one pathogen)

B and T Cell Development
• Adaptive immune system has four major characteristics
1
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Self-tolerance; lack of reactivity against an animal’s own
molecules
3
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Activated B and T cells undergo multiple cell divisions
(clonal selection)
II
...
Memory Cells: long-lived, become effector cells if the
same antigen is encountered again
4
...
The first exposure to a specific antigen represents the
primary immune response

a
...
Secondary Immune Response: memory cells facilitate a
faster, more efficient response
Antibody function
• Antibodies don’t kill pathogens; instead they mark pathogens for
destruction
• In neutrophils:
o Antibodies bind to viral surface proteins, preventing infection
of a host cell
o Antibodies may also bind to toxins in the body fluids and
prevent them from entering body cells
• Opsonization:
o Antibodies bind to antigens on bacteria, triggering
phagocytosis
• Antigen
o antibody complexes may bind to a complement protein
§ Complement protein: ultimately forms a pore in the
membrane of the foreign cell, leading to its lysis
Active and Passive Immunity:
• Active immunity:
o Primary or secondary immune response to pathogen invasion
o Can be induced by immunization, introduction of antigens into
the body
• Passive immunity:
o Provides immediate, short-term protection
o Maternally inherited (through placenta or milk)
Blood Groups
• Antigens on red blood cells determine whether a person has A (A
antigen), B (B antigen), AB (both antigens), or 0 (neither)
• Antibodies to nonself blood types exist in the body
• Transfusion with incompatible blood leads to destruction of the
transfused cells

Excretory System
• Removal of metabolic waste AND osmoregulation
• Controls solute concentrations and balances water gain and loss
• Renal or urinary system
• Animals nitrogenous wastes reflect its phylogeny and habitat
o The type of quantity of an animal’s waste products can
greatly affect water balance
o Nitrogenous breakdown products of proteins and nucleic acids
often results in toxic ammonia (NH3)
§ NH3: interferes with mitochondrial ATP formation
o Some animals convert ammonia to less toxic compounds prior
to excretion
Forms of Nitrogenous Waste:
• Animals excrete nitrogenous wastes in different forms
• Differ in toxicity and the energy costs of producing them
• Depend on an animal’s evolutionary history and habitat, especially
water availability
a
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Uric Acid
o Insects, snails, birds, and many reptiles
o Relatively nontoxic
o Secreted as a pasteà little water loss
o
c
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Evelyn Hutchinson
• niches are “n-dimensional hypervolumes”
• Robert MacArthur
*Species interactions are defined by the effects on the species involved

Mutualism:
• Two organisms from different species rely on one another for
nutrition, protection, or other life functions
• Examples:
o Pollination of angiosperms
o Seed dispersal
o Protection
o Parasite cleaning
o Reciprocal resource exchange
Consumer-Resource Interactions:
• “predator-prey”
• consuming part or all of an individual or another species
• may or may not result in the death of the consumed species
• consumer benefits, consumed detriment
o herbivore-plant
o predator-prey
o parasite, pathogens-host
Competition
• the use or defense of a resource by an individual that reduces the
availability of that resource to others
• competition among individuals may be
o intraspecific: within species
o interspecific: between different species
• Competitive Exclusion Principle: two species cannot coexist in the
same place if they’re competing for the same resource (very similar
niche)
• Mechanisms:
i
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Competition occurs through mutual effects on shared
resources (scramble)
o Interference:
§ Competition occurs through direct antaganostic
interactions

§ Deny resource to competitor
o Apparent:
§ Competition occurs through indirect interactions
elsewhere in the food web
§ Usually by modifying a shared predator’s interactions
ú Allelopathy: interference competition in plants via
chemical warfare
*species interactions can be direct or indirect
*more than one tropic level is a tropic or food chain
Tropic Cascade: effects felt further down food chain
*predation can maintain diversity
Keystone Predator: attack dominant competitor, increasing diversity



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