MIDTERM Science: IB Flashcards
What is a mechanical property?
Definition
A mechanical property describes how a material will react when its is subjected to one or more mechanical constraints.
List the types of mechanical properties?
Types!
- Hardness
- Elasticity
- Resilience
- Ductility
- Malleability
- Tensile strength
What does hardness refer to?
Define
Resists penetration
What does elasticity refer to?
Define
Returns to original shape.
What does resilience refer to?
Definition
Resists physical impacts.
What does ductility refer to?
Definition
Stretches without breaking.
What dos malleability refer to?
Definiton
Flattens or bends without breaking.
What does tensile strength refer to?
Definition
Resists tension
What is a mechanical constraint?
Definition
A mechanical constraint describes the stress produced within a material when it is subjected to one or more external forces. Mechanical constraints produce various efforts inside a material.
List the 5 principle mechanical constraints:
List
- Compression
- Tension
- Torsion
- Bending
- Shearing
What is compression?
Define
Force that crushes materials.
What is tension?
Define
Force that streches materials.
What is torsion?
Define
Force that twists materials.
What is bending?
Definition
Force that bends materials
What is shearing?
Definition
A force that cuts/tears materials.
What are the mechanical properties of wood?
List
- Hardness
- Elasticity
- Resilience
- Tensile strength
What are the mechanical propeties of metals?
List
- Good conductors of electricity
- Good conductors of heat
- Malleable
- Ductile
- High melting point
Name the 3 types of projections:
List
- Isometric
- Multi-view
- Exploded view
What is an isometric view?
Define
- A 3-D representation of an object placed so that 3 sides are visble
- Visible sides are usually: Front, Top, and Side
- Visual lines in isometric projections are perpendicular to the paper.
What is a multi-view projection?
Define
- 2-D representation of a every view of an object
- Views: front, right, top (can also be bottem, back, and left)
- Mugshot views
- Must be consistent throughout and line-up
What is exploded view?
Define
Shows various parts of an object seperated from eachother.
Name the types of lines
List
- Object line
- Hidden line
- Dimension line
- Extension line
- Diameter
- Center line
What is an object line?
Define
Indicates the visible outlines of an object.
- Thick and continous
What is a hidden line?
Define
Indicates the outlines that are’t visible in the current view.
- Medium and broken
What is a dimension line?
Define
Indicate the length of an object or part of an object
- Fine, continous, arrowheads ar each end
What is an extension line?
Define
Indicates the boudries of a measurement. Always palces at the ends of a dimension line.
- Fine and continous
What is diameter?
Define
Indicates the diameter of a circular section.
- Fine, continous, arrowheads at each end
- Ø is the symbol for diamter.
What is a centerline?
Define
Indicates the center of a circle or symmetrical feature.
- Fine, has a bullseyes (dash dot, dash dot)
Types a scaling
List
- Full size
- Scale Reduction
- Scale increase
What is full-size?
Define
1:1
Dimensions of object an drawing are equal.
What is scale reduction?
Define
1:2+
Object is bigger than drawing
What is scale increase?
Define
2+:1
The drawing is bigger than the object.
Name the mechanical functions?
List
- Link
- Guide
- Seal
- Lubrication
What is a link?
Define
A link connect 2+ parts of an object
What is a guide?
Define
A gude forces a part to follow a certain motion
What is lubrication?
Define
Reduces friction by technical means.
What is a seal?
Define
Prevents a gas or liquid from escaping.
Types of guiding
Define
- Rotational
- Translational
- Helical
Name all motion transmission systems:
List
- Gear train
- Chain and sprocket system
- Friction gear system
- Belt and pulley system
- Worm and worm-wheel system
Gear Train
Components: Driver, follower, (sometimes) intermediates
Direction: In a gear train gears turn opposite to those directly beside them
Reversible? Yes
Type? Motion transmission
Lubricate? Yes
Chain Sprocket Systems
Components: Gears, chain
Direction: Gears within chain turn opposite to those outside chain
Reversible? Yes
Type? Motion transmission System
Lubricate? Yes
Friction Gear Systems
Components: Driver, follower, (sometimes) intermediates
Direction: Gears turn oppodite in direction to those directly beside them
Reversible? Yes
Type? Motion transmission
Lubricate? Not
— Extra:
Diameter = teeth (equivalence in porportion to gear train)
Belt and Pulley system
Components: Pulleys, belt
Direction: Gears within belt rotate opposite to gears outside chain
Reversible? Yes
Type? Motion transmission
Lubricate? No
Worm and Worm-Wheel system
Components: Worm, and worm wheel (screw)
— The screws motion is transmitted to one or more wheels
Direction: Sam direction for both
Reversible? No. Worm wheel (screw) is always
Type? Motion transmission
Lubricate? Yes
Name all motion transformation systems:
List
Rack and Pinion
Cam and Follower
Slider and Crank
Screw-Gear system
Name all motion transformation systems:
List
- Rack and pinion system
- Screw gear system
- Cam and follower system
- Slider-crank mechanism
Rack and pinion system
Define
Components: Pinion (gear), rack (straight, toothed bar)
Reversible? Yes
Type? Motion transofrmation system
Lubricate? Yes
Screw-gear System
Define
Components: Screw and nut
Reversible? No. Screw is always driver
Type? Motion transofrmation system
Lubricate? Yes
Extra Info:
— Nut roates into translation motion in screw
Cam and follower system
Define
Components: Cam (egg shaped piece) and follower (stick that bobs)
Reversible? No. Cam is always driver
Type? Motion transofrmation system
Lubricate? No
Extra Info:
— Cam rotates - follower translates
Slider-crank mechanism
Define
Components: crank, slider, guide
Reversible? Yes
Type? Motion transofrmation system
Lubricate? Yes
Extra Info:
— Crank rotates like wheels, slider translates like piston
Types of speed changes
- Increase
- Decrease
- No change
Describe Increase
Driver is bigger (has more teeth) than drivem
Describe decrease
Driver is smaller (has less teeth) than driven
No change
Both driver and driven have an equal (amount of teeth) size
What was the big bang?
- The most widely accepted theory regarding the origins of the universe
- When matter began expansion
What is an astronomical unit?
Symbol: Au
Measures… Distances within our solar system
Approximately: 150 million kilometers
Average distance between earth and sun
What is a Light Year?
Symbol: Ly
Use: Measures distances out our solar system
Approximately 9460 billion kilometers
Represents average distance travelled by light per year
List the conditions conducive to life:
- Water
- Ideal mass
- Lithosphere
- Atmosphere
- Habitable zone
- A circular orbit
Explain Habitable zone
- A planet must orbit at a particular distance called the habitable zone
- Varies depending on size and strength of star
- Allows water to stay in liquid form
What is a circular orbit?
- The shape of a planets orbit determine the quantity of energy the planet receives thus influencing the tempreture
What is atmosphere?
- A planet atmosphere must be able to protect life forms from dangerous solar radiation.
- A planet must also have an atmosphere that allows the water cycle to take place.
What is the ideal mass?
Mass determine strength of a planets gravity.
In a small planet
- Low mass
- Low gravity
- Doesn’t absorb neccessary particles for life to develop.
In a big planet
- High mass
- Strong gravity
- Absorbs to many particle, harmful toxins etc.
Why is water essential?
A planet needs liquid water because it is essential to the development of the first molecules.
What is a lithosphere?
A planet needs a solid surface for simple molecules to develop into more complex life forms.
What are layers of strata?
- Layers/strata are sedimentary rock that usually arrange in layers
- A stratigraphic layer is made of sedimentary deposits with the same charachteristics (colour, particle size, type of rock, etc.)
- Stratigraphy is iomportant because it allows science to piece together various event that opccured in earths history
What are the 3 methods of dating?
- Superposition
- Relative dating
- Absolute dating
What is superposition?
The principle that the oldest layer is always found at the bottem and the the youngest layer is always found at the top. That means fossils found in lower layers come from eras previous to those above them.
When there is no fault.
What is relative dating?
Relative dating is based on the concept of superposition. It is used to determine the order of events but not prove an exact age. When a fault is running through.
What is absolute dating?
Absolute dating or carbon dating involves measuring the amount of uranium or carbon-14 in a fossil or rock layer.
Carbon-14 decays at a predictable rate.
Most precise of the 3 methods.
What is evolution?
Evolution is the result of small changes in DNA over a long period of time. Its the idea of fittest to survive not strongest, smartest etc. Best suited to environment
What were the 4 eras?
- Precambrain
- Paleozoic
- Mesozoic
- Cenozoic
What were the events of the precambrian era?
Last 4 billion years!
- During the first 1000 million years the earth and solar system were formed
- Rodinia becomes the first continent
- Appearance of Prokaryotes, cells with no nuclei and bacteria
- Appearance of bacteria that can do photosynthesis, and release oxygen into the atmosphere
- Appearance of eukaryotes, cells with nucleus (worms, soft coral, jellyfish)
- Appearance of Ediacaran Fauna; animals capable of reproduction and digestion
What were the events of the paleozoic era?
Lasted 300 million years?
- Earth seperates into 4 continents
- Hot climate and shallow oceans !LIFE!
- Appearance of animals with spine, pikaia, nautilus
- Appearance of land plants
- Cold causes mass extinction
- Jawed fish
- Trees
- Mass extinction causes 70% of marine species to disapear
- Appearance of reptiles
- Largest mass extinction caused by glaciation, volcanic eruptions, acid rain, and destruction of ozone layer
Events of mesozoic era
185 million years
- warm -> large reptiles
- Appearance of dinosaurs
- Mass extinction due meteorite impact and volcanoes causes dissapearnace of some sea life.
- Appearance of first birds and mammals
- Pangea breaks up into todays configuration
- Mass extinction of dinosaurs caused by meteroite impact in Yucatan, Mexico.
Events of cenozoic era
65 million years and counting!
- Age of the mammals
- Appearance of primates and hominids
- Some extinctions cause by (hunting, fire, disease spread by humans)
- Appearance of mega fauna
What is pasteurization?
Pasteurization is the partial sterilization of liquids such as:
- Milk
- Cheese
- Wine
- Orange juice etc.
Pasteurization is the process or rapidly heating and cooling a substance in order to kill bacteria.
What are the 4 types of tissues?
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nerve tissue
What are tissues
When embryos develop cells that are similar divide to form a tissue. A tissues is a set of identical or different cells that work together to preform a common function in an organism.
Define epithelial tissue:
This tissue lines the outer surfaces of the body and the interior surfaces of organs.
Define connective tissue:
This tissue connects, supports and protects other tissues.
Define muscle tissue:
This tissue is made up of elongated cells that can contract.
Define muscle tissue:
This tissue is made up of elongated cells that can contract.
Define nerve tissue:
This tissue is made up of neurons.
What are cell cultures?
A cell cultutre is the process in which cells are grown outside of the organsim that they come from.
What can a cell culture do?
- We can cultivate cells like bacteria (uni-cellular) and plant&animal cells (multi-cellular)
- Cell cultures are done to better understand how cells work
- Test medication and beauty products, reducing the need for animal testing
- Develop vaccines
- Create tissues like skin to treat burns
How do cell cultures work?
When a tissue is extracted…
- Scientists seperate targeted cells
- Depending on the type of cell, cell are put into test tubes, flasks, and petri-dishes to cultivate
- Containers are filled with a liquid or a solid medium that contains the conditions needed to allow the cell to thrive: must be maintained, tempreture, humidty, pH etc.
- Must be done in a sterile ennvironment, anti-biotics can be added.
What does DNA stand for?
Deoxyribonucleic Acid
Where do you find DNA?
In the nucleus of all living organisms.
What does DNA contain?
The genetic code of an organism. Based on the parents’ code.
DNA is shaped like…
A double helix
The side of DNA that twists to form a double helix are made of
2 different types of nucleotides.
A sugar and a phosphate group.
These molecules alternate.
The steps of a DNA ladder are made from
A line pf nitrogen bases.
How many nitrogen bases are there?
4
A, T, C, G
Adenine.
Thymine.
Cytosine.
Guanine
Which bases connect?
A and T
C and G
What is a gene?
A gene is a segemnt of DNA thatdetermine a specific genetic characteristic.
How are genes passed on?
Genes are passed on through heredity.
What is our entire set of genes called?
The human genome.
What is a chromosome?
A chromosome is a structure that contains DNA (genes) of an organism. When a cell is dividing DNA coils up to form a chromosome. Each DNA molecule in the nucleus of a cell is a chromosome.
How many chromosome exist in the nucleus of a cell?
23 pairs. (46 chromosomes)
Which chromosomes are different in men and women?
The sex chromosome.
Women: xx
Men: xy
22 other pairs of chromosomes are the same.
What does a karyotype show?
A kayotype shows the chromosomes of an individual displayed from largest to smallest.
What is mitosis?
Mitosis is a type of cell division used to make identical copies of cells.
Mitosis is a cell division that results in ___ ___ daughter cells.
TWO
IDENTICAL
In mitosis the daughter cells each contain ____ ____ chromosomes.
23
PAIRS OF
What is the purpose/function of mitosis?
Growth and repair of damaged tissues:
- Replace
- Grow
- Repair
- Neurons are the onlu cells incapable of divsion or repair
What are the 5 steps in the process of mitosis?
- DNA coils up into chromosomes, cell membrane dissolves
- Chromosomes duplicate (DNA replication) centriole move towrds poles
- Chromosome line up in middle of cell
- The spindle fibres pull half of the chromosome pair to one pole and the other half to the opposite pole of the cell.
- The cell membrane pinches off in the center to ‘seperate into 2 new cells (cytokinesis). Chromosome decondenses and nuclear membrane form. The result in 2 identical daughter cells, each containing 23 pairs of chromosomes.
What is meiosis?
Meiosis is a type of cell divison that produces for different from the original mother cell. Reproductive cells are also called gametes; sperm cells (spermatozoa) and egg cells (ova) that unite during fertilization.
Meiosis in females happens in the ____ (in the ____) and ________ (____) are only mature enough to be fertilized starting at ____.
UTERUS
WOMB
EGG CELLS
OVA
PUBERTY
Meiosis in males starts at _ _ _ in the _ _ _ and continues until _ _ _.
PUBERTY
TESTICLES
DEATH
Each _ _ _ produced during meiosis contains only _ _ _ chromosome(s) of each _ _ _ so they combine during fertilization to produce a _ _ _ _ _ _ of chromosomes.
DAUGHTER CELL
ONE
PAIR
COMPLETE
PAIR
Process of meiosis
- DNA coils to form chromosomes
- Chromosomesd duplicate (DNA replication)
- Nuclear membrane dissolves; centrioles move towards poles; Spindel fibres are formed; Genetic cross over: exchange of maternal and paternal DNA between chromosommes that code for the same traits
- Chromosomes line up in center of cell
- Spindle fibres pull a complete pair of chromosomes to each pole
- Cytokinesis
- Result: 2 non-identical cell (23 pairs of chromosomes/each)
- Chromosomes line up in cell center
- Spindel fibres pull half of each chromosome to pole.
- Cytokinesis
- Result: 4 different daughter cells. Only 1 chromosome/each (not 2). In order to unite with opposite sex gamete fertilization.
What are GMO’s
A genetically modified organism is an organism whose genetic material has been altered by the mean or inserting new genes into their DNA in order to obtain new characteristics.
Benefits of GMO’s
- Resistant to pesticides
- Decrease glabal warming
- Better crops
- Food with more nutrional value
- Medincinal studies
Concerns with GMO’s
- Mess up the food chain
- Cross pollination
- Profit driven-compagnies
- Can eb used by the wrong people
What is assisted reproduction?
This describes all medical producedures that help in the union of the ova and the spermatozoa for the purpose of achieving fertilization.
What is the purpose of assisted reproduction?
Aiding an infertile couples in concieving a child.
What is infertility?
Infertility is a term to describe a couples inability to reproduce after one year or sexual relations.
Causes for infertility:
- Poor quality of gametes
- Poor quantity of gametes
- Malformations of the reproductive system
- Malformations in the reproductive system cause by STBBIs
In order list the 4 types of assisted reproduction:
- Hormonal treatments
- Artificial insemination
- In-vitro fertilization
- Intracytoplasmic sperm injection
How do hormonal treatments work?
Subject takes hormonal based drugs that can help trigger ovulation. Taking horomone can cause the ovaries to produce more than one egg and can results in multiple carriges.
How does artificial insemination work?
> Where do fertilization occur?
Introduction of spermatozoa directly into the uterus of a woman.
- During ovulation
- Uses a cather
- Fertilization occurs in fallopian tubes and pregnancy assuems its natural course.
How does in-vitro fertilization work?
- Ova and spermatozoa are fertilized in a labratory
- The embryos obtained are transplanted into a womans uterus to continue development
- Treatment is recommended when fallopian tubes are block or when artificial insemination attempts have failed
What is intracytoplasmic sperm injection?
- Forces spermatozoa into ovum
- Used when not enough sperm cell are available for fertilization
1. Ova are collected
2. Spermtozoa are injected into ova
3. Ova are inserted into ovum
4. Embryos are implanted into uterus
Benefits of assisted reproduction:
- Might be free
- Single person can reproduce
- Infertile couples can reproduce
- Homosexuals can reproduce
Concerns of assisted reproduction:
- Expensive
- Disposing embryos… ethically questionable
- Multiple carriages
- Success rates are average
What is a pure substance
Composed of only one type of particle (atom, or molecule)
What are the 2 types of pure substances?
- Element (1 type of atom)
- Compound (1 type of molecule)
What are the 2 types of mixtures?
Homogeneous and Heterogeneous
Define a homogeneous mixture?
The particles are uniformly distributed.
- You can only see one part or phase (it looks like one substance)
Define a heterogeneous mixture:
The particles are not uniformly distributed.
You can see different parts or phases
- It looks like a mixture
What is a solution?
A homogenous mixture of one or more solutes dissolved in a solvent.
Signs of a chemical change:
- Effervesence
- Precipitation
- Tempreture change
- Colour change
- Produces a light
Types of chemical changes
- Synthesis
- Decomposition
- Oxidation
What is synthesis?
- 2+ reactants combine to form a new product
- Reactants and product can be in all different states
- Reactants are more than the product(s)
What is decomposition
- When a compound breaks down into 2+ substances
- The opposite of synthesis
- Product(s) are more than reactant(s)
What is oxidation?
- One of the reactants is an oxygen gas
- Look for O2 all by it’s self as a reactant
Characteristic properties:
- Density
- Boiling point
- Melting point
- Electrical conductivity
Non-characteristic properties
- Mass
- Colour
- Odour
- Volume
