Science notes
Levels of organisation-
Cell→ Tissue→ Organ→ Organ systems→ Organism
A cell is the smallest functional unit (before development: stem cells)
A tissue is a group of specialised cells
Types of tissues:
Epithelial - forms the skin
Connective - transports substances
Muscle - contracts and relaxes
Nerve - transmits information
Organ is a structure made up of two or more tissues
Organ system is made up of an organ along with tissue (like blood)
Digestive system-
Obtains nutrients and energy from food
Chemical digestion is when the body uses chemicals to break down food (this occurs in the stomach, mouth and small intestine)
Mechanical digestion is when the body churns to break down the food (this occurs in the mouth, oesophagus, stomach)
Ingestion → Propulsion → Mechanical → Chemical → Absorption → Defecation
Specialised cells and disease:
Epiglottis - covers the trachea and opens to let food in
Villi - is used to absorb food and nutrients in the small intestine
Acid reflux is when food and chemicals move back up the trachea into the throat and mouth from the stomach
Respiratory system-
Responsible for breathing
Cellular respiration: glucose + oxygen → carbon dioxide + water
Organs used in the system: Nose, mouth, pharynx, larynx, trachea, lungs, bronchi, alveoli, diaphragm, bronchi
Specialised cells and disease:
Alveoli act as the primary state for gas exchange, moving inhaled oxygen into the blood stream and trading it for waste carbon dioxide to be exhaled
Bronchi are the main air passages of the lower respiratory system that branch off the windpipe trachea and carry air inro the left and right lungs
Asthma is when your airway is inflamed and sensitive causing bronchoconstriction with excess mucus production
Circulatory system-
Transports oxygen and products to cells
Organs used in the system: heart, veins, arteries, lungs, capillaries
Specialised cells and disease:
Blood cells- red blood, white blood, plasma and platelets
Coronary heart disease occurs when cholesterol plaques build up in the heart’s arteries reducing blood and oxygen supply
Blood vessels:
Arteries- carry blood away (thick walls)
Veins- carry blood into the heart (thin walls with a flattened tube)
Capillaries- blood distribution (thin and small)
Excretory system-
Process of getting rid of waste
Organs used in the system: kidney, uterus, bladder, urethra
Nephrons help maintain blood pressure and PH balance in the kidney
Disease:
Kidney stones are hard mineral and salt deposits that form inside your kidneys when urine becomes to concentrated
All body systems
Digestive, muscular, integumentary, lymphatic, endocrine, nervous, skeletal, reproductive, respiratory, urinary, circulatory
Plants-
Photosynthesis: carbon dioxide + water → oxygen + oxygen
Cellular respiration: oxygen + glucose → carbon dioxide + water
The 4 major organs of a plant:
Roots- provide anchorage and support
Leaves- photosynthesis to create glucose and oxygen
Stem- important for transportation of nutrients and oxygen
Reproductive- allows for pollination and reproducing
Plant tissues:
Epidermis- the tissue of the outer skin
Ground- uses photosynthesis to make nutrients
Vascular- transports fluids throughout the plant
Merismatic- responsible for the plants growth
Roots have two different types. Tap roots are large roots with thin branches. Fibrous roots have a small mat like root shape.
Osmosis is the process of water absorption in root hairs. It goes through the semipermeable tissue and goes from low to high concentration of salt.
Shoots and stems have two different parts to transport different things. The Xylem moves water to the top and only moves in one direction. The Phloem transports glucose up and down through the plant.
The leaves take in carbon dioxide through the stomata which are controlled by guard cells.
Pollination is the transfer of pollen from one plant to another. There are two main types:
Self-pollination is the transfer of pollination from the anther to the stigma within the same plant
Cross-pollination is two plants within the same species reproduce with each other
An ecosystem is a group of abiotic (non-living) and biotic (living) things that interact with one another to stay alive and support each other.
Energy pyramids have different trophic levels. 10% of the energy moves from the previous organism each level. It moves up like this:
Producer
Primary consumer
Secondary consumer
Tertiary
Apex predator
Periodic table-
A pure substance cannot be separated by physical methods. An impure substance can be separated by physical and chemical methods.
Elements are a pure substance and can combine into a compound. All matter is made up of tiny atoms which are made of negative and positive particles. Protons are positively charged, neutrons are neutral and electrons are negatively charged.
A molecule is a group of two or more atoms that are chemically bonded together.
80% of the elements on the periodic table are metals
Metals: (located on the left side of the table)
Metallic
Good conductors of heat and electricity
Flatten when hit (malleable and ductile)
High melting point
Most are solid at room temp
Non-metal:
Dull
Poor conductors
Break when hit
Low melting point
Often gases at room temperature
Metalloids are a group of elements that have the same properties of metals and non-metals (semi-conductors)
Metals rust and oxidise when exposed to oxygen for a long time
Malleable means that it is flexible whereas ductile means that it can be made into thin wire.
Carbon allotropes can exist in multiple forms.
An alloy is a mixture of metals. Each type of metal has the same size atoms so when mixing in another metal with larger particles it can create a stronger alloy and reduce the amount of sliding.
The mass number means the number of protons + neutrons. The atomic number means the number of protons. A neutral atom has the same number of protons and electrons. To figure out the number of neutrons, minus the atomic number from the mass number.
The nucleus is in the middle of the atom shell and holds all the protons and neutrons. The first shell holds 2 electrons, the second and third shell hold up to 8 electrons.
The history of the atom model:
Aristotle believed in the four elements
Democritus believed in particles called Atomos
Dalton believed in the small invisible particle
Thomson believed in a positive ball with negative electrons
Chadwick believed in the nucleus with shells surrounding
Rutherford believed in a positive nucleus with empty spaces
Schrofinger had an electron cloud around a singular nucleus
Bohr had an electron with energy shells
Rows of the period tables are named periods and show how many electrons shells each element has. Columns which are called groups are grouped into the columns with the same number of electrons for each element.
Change-
Energy
Mechanical
Potential (stored energy)
Kinetic (movement energy)
Nuclear
Chemical
Light
Sound
Electrical
Radiant
Conduction occurs in solids where energy is transmitted through a substance via direct physical contact between neighbouring atoms.
Radiation occurs in empty space with the transmission of energy in the form of waves or particles through a space or physical medium.
Convection occurs in fluids with the transfer of heat through physical movement and circulation of fluids driven by temperature and density differences.
Thermal conductor is a material that allows heat energy to move through it quickly. Thermal insulator is a material that resists the flow of thermal energy, by slowing down the heat transfer through conduction, convection or radiation.
Open systems exchange MATTER and ENERGY. In closed systems, ENERGY can go in but matter cannot. Isolated systems have neither energy or matter moving in or out. Input is the energy that is added to a system, and output is the matter and energy that comes out of a system.
Particle model of matter is that all matter is made up of tiny particles that are always moving. These tiny particles have spaces between them and when you add heat it causes the particles to move faster.
The Law of the Conservation of Energy states that energy cannot be created for destroyed, meaning that the amount of energy in the world constantly stays the same.
Energy transformation is when an energy changes from one form into another. An energy transfer is the movement of energy from one location to another.
Solar cookers use radiant energy to heat an object or food. There are three main elements to a solar cooker:
Insulator- keeps the heat in and on the black object
Black target- absorbs the heat so food can cook
Reflector- brings more sunlight towards the black object
There are 4 main types of solar cookers:
Panel cooker which uses reflective panels to focus the radiant energy on the black target
Box cooker traps solar radiation into a box to cook the food
Tube cooker has double layers of glass to trap heat and insulates the black object
Parabolic cooker uses a concave reflective surface to focus solar rays on the target
There are two types of changes of an object. There is a physical change which is reversible and is usually a change of state, temperature, size and the appearance or disappearance of a substance. A chemical change is when a new substance has formed.
Exothermic means that energy is being generated within a system and endothermic means that energy is being absorbed.
Structure of the earth
The inner core is a solid, with high temperature and pressure. It is the iron-nickel centre of the Earth, being around 1200km thick and 5,000 - 6,000 degrees Celsius.
The Outer core is molten, with high temperatures and pressures. It is the iron-nickel layer that surrounds the inner core, being around 2200km thick and 2,700-4,200 degrees Celsius.
The mantle is solid, with high temperature and pressure. It is located under the crust, made of silicon, oxygen, magnesium, iron, aluminium and calcium, causing convection currents and movement of tectonic plates. It is around 2400km thick and 500-4,000 degrees Celsius based on location.
The crust is a solid and is the thinnest part of the Earth. It is the outer surface that is composed of basalt and granite, being around 5-10 km thick and 200-400 degrees Celsius.
The plate tectonic theory is that all plates are constantly moving due to the convection currents of magma in the mantle. This is seen in the evidence of fossils and the super continent Pangea. Each plate moves around 1-2 inches per year.
The lithosphere contains the plates, and the asthenosphere is the hot magma surface with convection currents.
Fossils
4 types of fossils:
Body fossils- the remains of an organism’s body
Trace fossils- the indirect evidence of life (footprints)
Amber fossils- an organism being trapped in resin
Opalised fossil- water floods the trace and evaporates, leaving an exact replica of the organism
The 3 types of rocks:
Igneous rock which is formed when magma cools down and cements into a rock. This mainly happens due to the heat and cooling in volcanoes.
Sedimentary rock is formed when sediment compacts into a new rock through compaction and cementation.
Metamorphic rock forms when an already formed rock into a new one through the application of heat and pressure.
A mineral is a pure, naturally occurring solid with a fixed chemical structure. A rock is the mixture of one or more minerals together.
Normal skills and information-
Validity- variable
Reliability- repeated
Accuracy- bullseye
Scientific report:
Introduction
Aim
Variables
Hypothesis
Materials
Method
Risk assessment
Results
Discussion
Conclusion
COWS MOO SOFTLY IN DARK CORNERS
Independent variable is the ONE variable that is changed throughout an experiment
Dependent variable is the variable you MEASURE
Controlled variables are the factors you keep the SAME throughout all tests
Crosses
Units
Title
Line
Axis
Scale
Size