ACT Science Flashcards

Questão	Responda
Approximately -273° C; the lowest possible temperature	Absolute zero
A compound that releases hydrogen ions when dissolved in water; has a pH of less than 7	Acid
Simple, one-celled plantlike organism found in water or damp places; includes seaweeds, pond scum, and so on	Algae
A substance composed of two or more metals	Alloy
The layer of air surrounding Earth	Atmosphere
The pressure exerted by the atmosphere on every part of Earth's surface; approximately 10 newtons per square centimeter	Atmospheric pressure
The smallest part of an element that is recognizable as that element	Atom
An instrument that measures atmospheric pressure	Barometer
A compound that releases hydroxide ions in water; has a pH of more than 7; is sometimes called an alkali	Base
The temperature at which additional thermal energy causes a substance to change from a liquid to a vapor	Boiling point
A quantity of heat energy; the amount needed to raise the temperature of one gram of water 1° C	Calorie
An organic compound-like sugar or starch that contains carbon, hydrogen, and oxygen in the ratio of 1:2:1; the human body's main source of energy	Carbohydrate
A cancer-causing agent	Carcinogen
Meat-eater	Carnivore
A substance that speeds up a chemical reaction without being changed by the reaction	Catalyst
The lowest-level structure of any living organism that can perform all the functions of life, including reproduction	Cell
The main pigment in plants that captures light energy during photosynthesis	Chlorophyll
A substance composed of two or more chemically bonded elements	Compound
The exact amount of substance dissolved in a given amount of solvent; refers to a solution	Concentration
The process whereby a decrease in energy causes vapor particles to return to a liquid phase	Condensation
A material that allows heat or electricity to flow through it with minimal resistance	Conductor
A sample in which no variables are tested, thus serving as a basis for comparison	Control
A variable that stays constant in an experiment, allowing the effect of another variable to be measured	Control Variable
The circulation of fluid caused by warm fluid rising and cool fluid sinking	Convection
In a physics sense, the amount of mass per unit volume; in a more general sense, the quantity per unit area or volume	Density
The scattering of light; the spreading of a liquid or gas from areas of higher concentration to areas of lower concentration	Diffusion
Nucleic acid in the cells of an organism; contains the genes of an organism and transmits these to future generations	DNA
A sequence of changes in the plant and/or animal life of a region over time	Ecological succesion
A negatively charged fundamental atomic particle	Electron
A substance consisting of exactly one type of atom	Element
Wearing away; typically the washing away of sand or rock by running water or wind	Erosion
The changing of a fluid into gas	Evaporation
The preserved remains of a very old organism	Fossil
The number of cycles per unit time of a repeating phenomenon	Frequency
A simple sugar that is broken down to provide energy to an organism	Glucose
The part of an ecosystem where a plant or animal naturally grows or lives	Habitat
An animal that eats only plants	Herbivore
A chemical substance secreted by a gland of the body that affects other parts of the body	Hormone
The amount of water vapor in the air	Humidity
A statement that is a proposed explanation of a scientific phenomenon	Hypothesis
Electromagnetic waves whose wavelength is longer than that of visible light	Infrared radiation
A substance that blocks the flow of heat or electricity	Insulator
A molecule or atom that has become charged by either gaining or losing an electron	Ion
A variety of an element with the same number of protons per atom but a different number of neutrons	Isotope
The energy of an object due to its motion	Kinetic energy
The temperature at which additional thermal energy breaks the chemical bonds holding a substance together and causes the substance to change from the solid to a liquid state	Melting Point
The smallest unit of a chemical compound	Molecule
A fundamental atomic particle that has no charge	Neutron
A piece of rock from which metal can be profitably extracted	Ore
The movement of liquid through a membrane	Osmosis
An organism that invades another organism and feeds off it	Parasite
A numerical scale from 1-14 representing the acidity or alkalinity of a solution; 1 is very acidic, 14 is very alkaline, and 7 is neutral	pH
The process in which plants use the sun's energy to convert carbon dioxide and water into glucose	Photosynthesis
Force per unit area	Pressure
A complex molecule composed of amino acids that carries out a variety of processes in cells	Protein
A positively charged fundamental atomic particle	Proton
A complex carbohydrate found in potatoes, rice, corn, and many other vegetables	Starch
A close relationship between two organisms that is mutually beneficial	Symbiosis
Electromagnetic waves with wavelength shorter than that of visible light	Ultraviolet radiation
The gaseous form of a liquid	Vapor
Electromagnetic radiation with wavelength shorter than ultraviolet radiation	X ray
The force that attracts one object to another and is dependent on mass, is known as	Gravity
The acidity or alkalinity or a substance is measured using the ____ scale, which ranges from 1 to 14.	pH
An electromagnetic wave with a wavelength longer than that of X-rays, but shorter than that of visible light is in the ____ part of the spectrum.	Ultraviolet
The energy an object has when it is stationary is known as its ____.	Potential Energy
The changeable parameters in an experiment as the ____.	Variables
The central part of an atom, which is orbited by electrons is the ____.	Nucleus
A term which does not change its value is a ____.	Constant
A neutral particle found in the center of an atom is a ____.	Neutron
When a liquid is cooled below its freezing point, it becomes a ____.	Solid
An animal that eats both plants and meat is an ____.	Omnivore
____ orbit the nucleus of an atom.	Electrons
A compound which may induce cancer is a ____.	Carcinogen
Absolute zero is ____ degrees Celsius.	-273.15
____ is the mass per unit volume.	Density
The energy associated with a moving object is the ____ energy.	Kinetic
Conduction	Conduction is heat transfer through collisions between neighboring molecules. There are three primary means of heat transfer: conduction, convection, and radiation. Example: A pot getting heated by sitting on a hot burner is an example of conduction.
Convection	Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is moved away from the source of heat, carrying the energy with it. There are three primary means of heat transfer: conduction, convection, and radiation. Example: A convection oven is an oven that has fans to circulate air around food, which allows more heat to be transferred to the food.
Polarity	Polarity is an attribute with two possible values. In physics, it’s mainly used to describe electric charges (positive and negative) and magnets (north and south). Good to know! On the ACT, you’ll see this most often on electric circuit set-ups: electrons flow in the same circuit by starting at the negative (-) terminal and flowing through to the positive (+) terminal.
Potential Energy	Potential energy (PE) is the stored energy possessed by an object due to its position. Important to know! Gravitational potential energy is the energy stored in an object as a result of its height.
Capacitor	A capacitor is an electrical device, consisting of one or more pairs of conductors separated by an insulator, used to store electric charge when a voltage is applied. Important to know: current only flows when a capacitor is charging or discharging, not when it is fully charged.
Buoyancy	Buoyancy is the upward force on an object produced by the surrounding liquid or gas in which it is immersed, due to the pressure difference of the fluid between the top and bottom of the object. Example: It’s easier for you to stay afloat in salt water than in fresh water because salt water is denser and thus provides more buoyant force.
Radiation	Radiation is the transmission of energy in the form of waves or particles through space. There are three primary means of heat transfer: conduction, convection, and radiation. Example: warming your toes by a campfire.
Frequency	Frequency is how often the particles of the medium vibrate when a wave passes through the medium. Good to know: a typical unit of frequency is the Hertz (Hz) where 1 Hz equals 1 cycle/second.
Mechanical energy	Mechanical energy is the sum of potential energy and kinetic energy, meaning the energy an object has due to its position and/or motion. Example: Think about dropping a brick off a tall building (but don’t do it! It’s dangerous!). The potential energy of the brick’s height becomes kinetic energy as it falls. The total mechanical energy remains constant from top to bottom.
Electrical Circuit	An electrical circuit is a wired path between two or more points that carries an electrical current. A simple circuit has a source of voltage (often a battery), a conductive path that allows for the movement of charges (typically wire), and a resistor (possibly a light bulb, a motor, a speaker, etc.) Important to know! Ohm’s Law is the most frequently tested concept on electrical circuits on the ACT. It will be provided for you, but just so you know, it is V = I x R (where V is the voltage measured across the conductor in volts, R is the resistance in ohms, and I is the current measured in amperes.)
Waves	A wave is an oscillation, or disturbance, that travels through space or mass and is accompanied by a transfer of energy. Good to know! There are two main categories of waves: mechanical waves that require a medium to transmit energy (such as ocean waves, sound waves, and slinky waves) and electromagnetic waves that can transmit energy through a vacuum (such as radio waves, microwaves, UV rays, and gamma rays)
Acceleration	Acceleration is the rate at which an object changes its velocity with regards to time. Good to know! Acceleration is a vector quantity, meaning it has to do with position. Any change in the velocity, whether increasing speed, decreasing speed, or changing direction results in an acceleration.
Resistor	A resistor is an electrical component that consumes electrical energy when current flows through it. Important to know: resistance is measured in ohms (Ω).
Four States of Matter	The states of matter observable in everyday life are solids, liquids, gases, and plasma. Solids have a stable shape and definite volume. Liquids take the shape of their container and have a definite volume if temperature and pressure are constant. Gasses and plasmas have no definite shape or volume.
Amplitude	Amplitude is the “height” of a wave measured from its equilibrium position; the maximum displacement or distance moved by a point on a wave. Image: Large Desktops (binary/octet-stream)
Volt	A volt is a unit of both voltage and electric potential. It refers to the energy that could be released if electrical current is allowed to flow.
Velocity	Velocity is the rate at which the position of an object changes in a certain direction. Good to know! Velocity is a vector quantity and speed is a scalar quantity. Speed refers to how fast an object is moving. Vector has to do with a position: if a person took one step forward and one step back to the original position, velocity would be zero.
Density	Density is the compactness of an object, measured in mass per unit volume, in other words, density = mass/volume. Important to know: If an object weighs more than an equal volume of water it will sink; if it weighs less, it will float.
Work	Work is done when a force is applied to an object resulting in a displacement of the object in the direction of a force. Example: when a brick is dropped from a building, the work done on the brick as it falls is equal to the weight of the brick multiplied by the distance it falls (the displacement).
Electrical Current	Electrical current is the flow of electric charged particles. In electric circuits, this charge is typically carried by electrons in a wire.
Charge	A charge is a characteristic of a unit of matter that expresses the extent to which it has fewer or more electrons than protons. A negatively-charged atom has more electrons than protons; a positively-charged atom has more protons than electrons. Important to know! Like charges repel each other; opposite charges attract.
Wavelength	A wavelength is the distance from a particular height on a wave to the next spot on the wave where it is the same height and going in the same direction. Image: Large Desktops (1) (binary/octet-stream)
Ampere	An ampere, often shortened to amp, it is the unit of electric current.
Kinetic Energy	Kinetic energy (KE) is the energy possessed by an object due to its motion. Translational kinetic energy, KE = ½ x mass x velocity²
Potential Energy	Potential energy (PE) is the stored energy possessed by an object due to its position. Important to know! Gravitational potential energy is the energy stored in an object as a result of its height.
Condensation	Condensation is the change of a gas or vapor to a liquid, either by cooling or by being subjected to increased pressure.
Molar Mass	Also known as molecular weight, molar mass = grams/mole. It is the sum of the total mass in grams of all the atoms that make up a mole of a particular molecule. Good to know: You don’t need to memorize this for the ACT, but a mole is approximately equal to 6.02 x 1023 atoms.
Atom	An atom is the smallest unit in a chemical element. Each atom consists of a nucleus, which consists of protons and neutrons, and a set of electrons that move about the nucleus. Image: Large Desktops (2) (binary/octet-stream)
Ion	An ion is an electrically charged atom (or group of atoms) formed by the loss or gain of one or more electrons.
Freezing Point	The temperature at which a liquid phase of a substance begins to turn into a solid. Important to know! The freezing point is the same as the melting point. For example, think about water. The temperature at which ice begins to melt is the same at which water begins to freeze into ice.
Endothermic	A system that absorbs energy from its surroundings, usually in the form of heat, is endothermic. Examples of endothermic processes: baking cookies, melting ice, photosynthesis
Reactant	A reactant is a substance participating in a chemical reaction that is consumed during the reaction to make the products.
Solute	A solute is a substance that is dissolved in another substance (the solvent), usually the component of the solution present in the lesser amount. Example: If you mix a spoonful of salt in a glass of water, the salt is the solute.
Evaporation	Evaporation is the change of a liquid to a gaseous state due to an increase in temperature and/or pressure.
Solvent	A solvent is a substance that dissolves a solute (a chemically different liquid, solid, or gas, resulting in a solution. Example: If you mix a spoonful of salt in a glass of water, the water is the solvent.
Solution	A solution is a homogeneous mixture composed of two or more substances. In a solution, a solute is the substance dissolved in another substance, known as the solvent. Example: mixing salt into water to create a solution of salt water (gargle it for a sore throat!)
Acid	Acids have various defining characteristics that distinguish them from bases including having a pH of less than 7, tasting sour, and producing a piercing pain in a wound. Examples: lemons, vinegar, sulfuric acid
Atomic Number	the number of protons in the nucleus of an atom. The higher the atomic number, the heavier the atom is. Important to know! Atomic number is crucial because it determines the chemical properties of an element and its place on the periodic table. Elements are ordered according to their atomic numbers. Important to know! Atomic mass is approximately equivalent to the number of protons and neutrons in the atom (the mass number).
Electron	An electron is a negatively-charged subatomic particle found in a “cloud” around the nucleus of an atom. Electrons are extremely small compared to the other parts of an atom and can be gained or lost.
Melting Point	The melting point is the temperature at which the solid phase of a substance begins to change to a liquid. Important to know! The melting point is the same as the freezing point. For example, think about water. The temperature at which ice begins to melt is the same at which water begins to freeze into ice.
Neutrons	A neutron is a subatomic particle in the nucleus of an atom with about the same mass as a proton, but without an electric charge.
Nucleus	The nucleus is the positively charged central core of an atom, consisting of protons and neutrons.
Product	The substance that results from the combination of the reactants in a chemical reaction.
Molecule	A molecule is a group of two or more atoms linked together by sharing electrons in a chemical bond.
Base	Bases have various defining characteristics that distinguish them from acids including a ph greater than 7, a bitter taste, and a slippery feel. Examples: baking soda, Tums, ammonia.
Viscosity	Viscosity is the extent to which a fluid resists the tendency to flow. Examples: molasses and toothpaste have a high viscosity; milk and oil have a low viscosity.
Atomic Mass	Atomic mass is the measurement of the size of an atom. Atomic mass is closely approximated by adding the number of protons and neutrons. Measured in atomic units (u).
pH	Ph is a numeric scale used to specify the acidity or alkalinity (basicity) of an aqueous solution. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Did you know? Pure water is neutral, neither an acid nor a base.
Proton	A proton is a positively-charged subatomic particle in the nucleus of an atom.
Exothermic	A system that releases energy, usually in the form of heat, but also in the form of light, electricity, or sound is exothermic. Examples of exothermic processes: starting a fire, nuclear fission, rusting iron
Boiling Point	The boiling point is the point at which a liquid phase of a substance begins to change into a gas or vapor. Example: Think about a boiling pot of water and the water turning into the water vapor steaming from the pot.
Isotope	An isotope is a form of the same element that contains an equal number of protons as the primary form of the element, but a different number of neutrons. Example: hydrogen-3 (tritium) is a radioactive isotope of hydrogen. Its nucleus has one proton and two neutrons, resulting in triple the mass of ordinary hydrogen.
Phenotype	Phenotype is an individual's observable trait, such as height, eye color, or hair color. Did you know? Lots of people get genotype and phenotype confused. Genotype is the genetic code that influences many of an organism’s traits, but is not wholly responsible. Phenotype is the visible or expressed trait; it depends on the genotype but can be influenced by environment.
Prokaryotic Organism	A prokaryotic organism is a single-celled organism that lacks a nucleus. Team Prokaryote: bacteria (such as E. coli and streptococcus, which causes strep throat) and archaea.
Genotype	Genotype is an individual’s collection of genes. Genotype can also mean the two alleles inherited for a particular gene. Examples: You might remember genotypes from Mendel’s pea plant experiments: genotype determines flower color, pod shape, seed shape, pod color, etc.
Digestive System	The digestive system contains the organs and glands in the body that are responsible for the ingestion, digestion, and absorption of food. Starring organs: mouth, esophagus, stomach, intestines, liver, gallbladder, pancreas, rectum, anus
Nucleobases	The building blocks for the double helix of DNA and RNA. Important to know! In DNA, cytosine (C) always pairs with guanine (G) and thymine (T) always pairs with adenine (A).
Osmosis	Osmosis is the movement of molecules through a semipermeable membrane from a less concentrated solution into a more concentrated one to cause equilibrium. Did you know? Pruned fingers after sitting in a bathtub are an example of osmosis: your fingers are not shrinking, they are swelling because the water is trying to get into your body to cause equilibrium.
Mitosis	Mitosis is the part of the cell division cycle in which the chromosomes in a cell’s nucleus are separated into two identical sets of chromosomes, and each set ends up in its own nucleus. Important to know! There are four stages to mitosis: prophase, metaphase, anaphase and telophase.
Eukaryotic Organism	A eukaryotic organism is an organism with a complex cell or cells. Has a nucleus, unlike a prokaryotic organism. Team Eukaryote: humans, cats, palm trees, mushrooms, yeast, and pretty much anything that’s not bacteria or archaea.
RNA	RNA is a molecule made up nucleotides that acts as a messenger between DNA and ribosomes to make proteins. Good to know! Like DNA, RNA carries hereditary genetic information. Unlike DNA, which is double-stranded, it exists in a single-stranded form.
DNA	Deoxyribonucleic acid stores hereditary biological information. DNA molecules carry the instructions for the development, functioning, and reproduction of all known living organisms and many viruses. Important to know! The structure of DNA is a “double helix”: two strands coiled around each other made up of nucleotides.
Genes	A gene is a region of DNA that act as instructions to make proteins. They are important because they determine hereditary traits: each person has two copies of each gene, one from each parent. Examples: humans have genes that determine blood type, eye color, certain genetic disorders, and body type.
Ribosome	A ribosome is a complex machine found in all living cells that serves as the site where proteins are made. A helpful image: DNA and RNA are the planning managers of a cell and the ribosome is its factory, manufacturing the proteins essential to life.
Respiratory System	The respiratory system includes the organs that allow the body to breath and exchange oxygen and carbon dioxide throughout the body. Starring organs: nose, mouth, trachea, lungs, bronchi
Pollination	Pollination is the transfer of pollen from the stamen (male reproductive organ) to the pistil (female reproductive organ) in plants to start the production of seeds. Hint: this is why your parents told you about the “birds and the bees”: these creatures often accidentally move pollen from one part of the flower to another.
Proteins	Proteins are large molecules consisting of chains of amino acids. They do most of the work in a cell and are required for the function of the body’s tissues and organs. Did you know? The body does not store protein; that’s why we must ingest it to build that muscular beach body.
Meiosis	Proteins are large molecules consisting of chains of amino acids. They do most of the work in a cell and are required for the function of the body’s tissues and organs. Did you know? The body does not store protein; that’s why we must ingest it to build that muscular beach body.
Stages of Cellular Division	During interphase, the cell grows and makes a copy of its DNA. During the mitotic phase, the cell separates its DNA into two sets and divides its cytoplasm, forming two new cells. The mitotic phase is further divided into mitosis (the division of chromosomes in the nucleus) and cytokinesis (the division of the cytoplasm).
Circulatory System	The network of organs and vessels responsible for the flow of blood, nutrients, hormones, oxygen, and other gases to and from cells in the body. Also goes by the name, “cardiovascular system.” Starring organs and vessels: the heart, lungs, arteries, and veins.
Allele	An allele is a form of a gene. Some genes have a variety of different forms. Humans have two alleles at each genetic locus, with one allele inherited from each parent. Example: your hair color is determined by which alleles of a gene you inherit.
Chromosomes	Structures located inside the nucleus of animal and plant cells. Chromosomes contain most of the DNA of an organism. Important to know! females have two of the same sex chromosomes (XX); males have two distinct ones (XY). The presence or absence of the Y chromosome determines the sex of mammals and many other animals.
Metamorphosis	Metamorphosis is a state change. In an insect or amphibian, the process of transformation from an immature form to a mature form. Example: caterpillars become butterflies through metamorphosis.
Mitochondrion	A mitochondrion is an organelle found in most cells, where respiration and energy production occur. Good to know! Mitochondria generate ATP, which is used as a source of chemical energy.
Photosynthesis	Photosynthesis is the process used by plants and other organisms to convert light energy (generally the sun), into sugars that can be converted into fuel for living things. Chlorophyll (the green pigment in plants) is essential for photosynthesis. Hint: “photo” means light and “synthesis” means putting together.
Dominant and Recessive Traits	The terms dominant and recessive describe the inheritance patterns of certain traits, meaning how likely it is that a certain phenotype gets passed on to offspring. Dominant traits are more likely to be inherited. Important to know! individuals who have one dominant and one recessive allele will typically have the dominant phenotype, but they are carriers of the recessive allele and can pass it on.
Osmosis	Osmosis is the movement of molecules through a semipermeable membrane from a less concentrated solution into a more concentrated one to cause equilibrium. Did you know? Pruned fingers after sitting in a bathtub are an example of osmosis: your fingers are not shrinking, they are swelling because the water is trying to get into your body to cause equilibrium.
Hypothesis	The claim that is tested in a study or experiment. If the question is “Does UV radiation cause skin cancer?”, a hypothesis might be: UV radiation causes skin cancer because it damages the DNA in your skin cells, which causes cells to grow out of control.
Control	The control is the group that is treated in the same way as the experimental group except that it does not receive the treatment of the independent variable. It “controls” for all other variables that might affect an experiment other than the independent variable. variable in the experiment group. Example: in an experiment testing which fertilizer works best for daffodil growth, the control would be the plants that were not treated with any fertilizer at all.
Matter	Matter is the substance that composes all observable physical objects and gives them mass. Observable matter can exist in four states: solid, liquid, gas, and plasma. A vacuum is the absence of matter.
Air Resistance	The frictional force air exerts against a moving object. Also called “drag.” Example: When you are trying to run into a headwind and it feels soooo much harder to get anywhere.
Three Primary Layers of the Earth	Chemically, the Earth can be divided into three layers: the crust (which is solid), the mantle (which can be divided into the upper and lower mantle and is solid/plastic), and the core (which can be divided into the outer core which is liquid, and the inner core, which is solid). Did you know? Scientists determine the composition of the Earth through seismic monitoring (measuring earthquake waves) as well as measurements of gravitational and magnetic fields of the Earth. Image: Large Desktops (3) (binary/octet-stream)
Gas Giant	A gas giant is a giant planet composed mainly of hydrogen and helium. Examples: Jupiter, Saturn, Uranus, and Neptune
Dependent Variable	The dependent variable is the variable in a science experiment that depends on the independent variable. It is the variable scientists watch to see how it responds to changes made with the independent variable. Example: in an experiment testing which fertilizer works best for daffodil growth, the dependent variable would be the respective heights of the plants treated with different fertilizers.
Terrestrial Planet	A terrestrial planet is a planet that has a solid surface and other “Earth-like” features. Examples: Mercury, Venus, Earth, Mars
Mass	Mass is the amount of matter in an object. Gravitational mass is a measurement of how much gravity an object exerts on other objects. Mass differs from weight in that the mass of an object never changes, but weight changes based on the force of gravity. On Earth, weight = mass * the force of earth’s gravity (9.8 m/s2)
Altitude	Altitude is the height of an object or point in relation to either sea level or ground level. Example: The altitude of Mount Everest is 8,848 meters above sea level.
Five Primary Layers of the Atmosphere	From lowest to highest, they are the troposphere (where most of the clouds live), stratosphere (where the ozone layer is), mesosphere, thermosphere, and exosphere. Did you know? A sixth layer, the ionosphere, overlaps other atmospheric layers. The air is ionized by the sun’s ultraviolet rays, which affects the transmission of radio waves.
Orbit	An orbit is the gravitationally curved path of an object around a point in space. Orbits typically refer to planets moving around a star or moons going around planets in an elliptical shape. Example: The earth chugs around its orbit around the sun approximately once every 365 days.
Erosion	Erosion is the breakdown of the soil, rock, or other surface material due to processes such as water flow or wind that move material from one location to another. Example: the Grand Canyon in the US was formed by the water flowing through it that eroded the rocks.
Independent Variable	The independent variable is the variable in a science experiment that is changed by the scientist. Example: in an experiment testing which fertilizer works best for daffodil growth, the independent variable would be the fertilizers tested.
Metamorphism	Metamorphism is the change of minerals or texture in rocks, usually due to heat, pressure, or chemicals. Example: marble is metamorphosed limestone; it is limestone that has been recrystallized, resulting in a change in color and texture.

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	Criado por Luisa Villardi mais de 6 anos atrás