Praxis Science Flashcards
Nitrogen Fixation
Nitrogen fixation is when ammonia is produced from atmospheric nitrogen.
Which layer of the atmosphere contains the ozone layer?
The stratosphere contains the ozone layer, which is responsible for blocking UV rays.
Meteorite
A meteorite refers to a meteor that has made its way to Earth and has landed on its surface.
Newton’s First Law (Law of Inertia):
Definition: An object will stay at rest or move in a straight line at a constant speed unless acted upon by an external force.
Example: If you slide a book across a table, it will eventually stop because of the force of friction acting on it.
Newton’s Second Law (Law of Acceleration):
Newton’s second law of motion states the acceleration of an object is dependent on the net force acting on the object and the mass of the object.
Example: If you push an empty shopping cart, it will accelerate faster than a full shopping cart because the empty cart has less mass.
Newton’s Third Law (Action and Reaction):
Definition: For every action, there is an equal and opposite reaction.
Example: When you jump off a small boat onto a dock, the boat pushes back in the opposite direction, making it move away from the dock.
Newton’s Fourth Law (Universal Gravitation):
states that every object in the universe pulls on every other object with a force called gravity.
The reason we stay on the ground and don’t float away is because the Earth’s gravity pulls us towards its center.
What is a eukaryotic cell?
A eukaryotic cell is a type of cell that has a nucleus and other special parts called organelles.
What is the basic unit of life?
the cell
What type of organelle in the cell synthesizes proteins?
Ribosomes
What is the function of the golgi apparatus in the cell?
The Golgi apparatus helps package and secrete proteins. A sorting or distribution center for proteins. It receives proteins from the endoplasmic reticulum, or ER.
What is the difference between smooth and rough ER and what is their function within the cell?m
A rough tubular maze of membranes.
The smooth ER is smooth is not studded with ribosomes. It creates lipids/fats. Acts as a detoxification center. (Emergency room where fat lipid babies are made)
The rough ER is covered in ribosomes. Ribsomes create proteins and the rough ER “packages” them to be transported.
What is histology the study of?
The study of tissues
Name the four main types of tissues in the human body.
Epithelial tissue
Connective tissue
Muscular tissue.
Nervous tissue
What are the three types of muscular tissue?
Skeletal
Smooth
Cardiac
What are examples of connective tissue?
bone & cartilage
blood & fat ( adipose connective tissue)
Which types of muscular tissue are involuntarily controlled?
Smooth, cardiac
What type of muscle makes up the Stomach and intestines?
Smooth muscle tissue
What are plant tissues called and what are their types?
Tissue Systems
Epidermis - make up plant leaves
Vascular tissue - transport food and water to the plant via the stem and roots
Ground tissue - makes energy for the plant via photosynthesis
Specific epithelial tissues are categorized by what two things?
The individual cell shape and how many cell layers thick the tissue is.
What is the integumentary system made up of?
skin, nails, hair, subcutaneous fat
What is the main function of the human body’s integumentary system?
To protect the body.
- helps to shield the body from environmental changes and pathogens.
- help regulate temperature homeostasis.
What are the parts of the human body’s endocrine system?
all hormone producing organs or glands, thyroid, pitutatary, adrenals, pancreas etc.
What is the purpose of the human body’s endocrine system?
It acts as a messaging system, producing hormones which are sent through the body to help regulate other organ activities.
What is the correct order of biological organization of the following (from largest to smallest): Communities, population, biosphere, eyosystem.
Define each one.
Biosphere: All of Earth and its atmosphere.
Ecosystem: All of the rainforests on Earth.
Community: All communities of primates within the rainforest.
Population: All members of the community whose species is the golden tamarin.
What are the qualities that define a living thing?
made up of cells - at least one cell must exist for it to be living
movement - it must move around
use energy and get energy from a source - it must be able to get energy, convert it to a usable form, and use it
grow and develop - it must change in characteristics and get bigger
reproduction - it must make copies of itself one way or another
response to stimuli - it must react to the environment at some point
homeostasis - it must seek to maintain a stable internal environment
What is acceleration is terms of Newton’s second law?
This rate at which velocity changes is defined as acceleration. An object that changes direction or speed is accelerating. The change in speed can be increasing or decreasing to be considered acceleration. For example, a car that maintains a speed of 25mph but changes direction is considered accelerating. A car that maintains due north but either increases or decreases speed is considered accelerating.
What is velocity in terms of Newton’s second law?
Velocity is defined as the speed of an object in a given direction.
Two examples of velocity include a car traveling at 25 mph north or a plane flying at 575 mph in the northeast direction.
An object that changes speed or direction has a change in velocity.
What is inertia in terms of Newton’s first law?
Inertia is the resistance of an object to a change in motion.
For example, an elephant and rabbit are running at the same speed. The elephant will have greater inertia than the rabbit because the force needed to change the motion of the elephant will be greater than the force needed to change the motion of the rabbit.
What is the formula for acceleration?
What is simple harmonic motion? Give an example.
Simple harmonic motion is a repetitive, or periodic, motion where the restoring force is proportional to the displacement from an equilibrium position.
It includes things like pendulums and masses bobbing up and down on a spring. As you stretch the spring, there is a restoring force that wants to pull it back to where it began, and that force gets stronger the more you pull.
What is projectile motion? Give an example.
Projectile motion is motion that involves two dimensions, such as that which occurs in a water fountain.
When you release a projectile, like a cannonball, a bullet from a gun, or a baseball coming off a bat, it moves in an up-and-down dimension and a forwards-and-back dimension.
What are the defining characteristics of plasma as a state of matter?
Super Hot Gas: Plasma is a super hot gas where atoms are split into free-moving electrons and ions.
Glows: Plasma often glows with bright colors, like in neon signs and lightning.
Electricity: Plasma can conduct electricity, which means it can carry electric currents.
Magnetic: It can be moved and shaped by magnets.
Space Stuff: Plasma is found in stars, including the sun, and in space.
High Energy: It has a lot of energy because of the high temperatures.
Charged Particles: Plasma is made up of tiny charged particles that move around freely.
What is circular motion? Give an example.
Circular motion is, unsurprisingly, motion in a circle.
For example, imagine a ball being whirled above your head on a string or a satellite orbiting the Earth.
When an object is moving in a perfect circle at a constant velocity, we have different equations we can use to describe the motion.
What are unbalanced forces in terms of physics?
Unbalanced forces are forces on an object in opposite directions that are not equal. They cause an object to change velocity. Velocity is speed in a given direction.
What is mass in terms of Newton’s laws of physics?
Mass is defined as the quantity of matter in an object.
What is net force is terms of Newton’s second law?
Net force is defined as the sum of all forces acting on an object.
What is force in terms of Newton’s first law?
A force is a quantity with magnitude and direction. Forces are often represented by arrows. This image shows the two forces acting on the object. The size of the force is represented by arrow length. The net force on this object is zero because the length of arrows is equal in both directions representing a balanced force. According to Newton’s first law, this object will remain at rest until the net force is no longer balanced. An unbalanced force is a force applied in opposite directions that are not equal in size or magnitude.
What unit is net force measured in?
Newtons (N)
What equation represents Newton’s second law?
Newton’s second law states that the net force of an object is the product of its mass (m) and acceleration (a). This force equation relates: force mass x acceleration:
What is linear motion?
Linear motion is motion in a straight line. It’s also called 1-D motion, because you’re moving in one dimension.
Linear motion is generally the easiest to describe: you just have one graph for displacement over time, one graph for velocity over time and one graph for acceleration over time.
A car driving on a perfectly straight road is a good example of linear motion.
What is the difference between acceleration and velocity?
Velocity is how fast something is moving and in what direction, like a car going 30 miles per hour north.
Acceleration is how quickly the speed or direction of that car changes, like when it speeds up or slows down.
What is the relationship between acceleration and velocity?
Imagine you’re pushing a toy car. When you push (apply force), the car starts to move faster (it accelerates). According to Newton’s laws, the harder you push, the faster the car speeds up, changing how fast and in what direction the car is moving (its velocity). So, a force makes the car go faster or slower and changes its direction.
What does accuracy refer to in a science experiment?
how close to being correct your data is
What does reproducability/precision refer to in a science experiment?
how close together your measurements are
What is a pure substance that cannot be broken down by chemical means into simpler components?
an element
What is a molecule?
A molecule is comprised of two atoms/elements that are linked together chemically
What is a compound?
A compound is a group of molecules. Compounds can be classified by the type of bond they share with other elements – ionic or covalent.
What is translational equilibrium and how can you tell if an object is in it?
- Happens when an object moves from one point to another.
- When the sum of all the external forces acting on the object = 0 (at rest or moving constant velocity or not experiencing any acceleration)
- Sled traveling down a hill
What is rotational equilibrium and how can you tell if an object is in it?
- Occurs when a rigid body revolves/orbits and axis.
- when the sum of all the external torques acting on the object are equal zero (at rest or moving at constant angular velocity or not experiencing any acceleration)
- Bike wheel spinning, ceiling fan turning
What unit of measurement do we use to measure rotational equilibrium?
Torques
What is work as defined by physics?
Work is the displacement (movement from one point to another) due to force (N) , depends on distance (m) object is moved
Work (J) = force (N) x distance (m)
How much work is done when you HOLD a 10 N object 10 m above the ground?
Since the object is not being moved, there is no work done.
What unit is WORK in physics measured by?
joules (j), equal to newtons-meter (nm)
What does displacement mean in terms of physics?
Displacement in physics is how far and in what direction an object has moved from its starting point.
What is a vector within physics?
A vector is a way to show both the direction and how far something moves or points.
What is the physics equation for WORK?
Work = force x distance
amount of force (N)
the distance displaced (distance - m)
the cause of the displacement
What three conditions must be met for WORK (work = force x distance) to happen?
What is the definition of POWER in physics and how does it relate to WORK?
The power definition in physics is how much work is done in the time it takes to do it; work measures how much force is moved a certain distance.
Thus power is how much force is moved a certain distance over time.
Power (w) = work (j) / time interval (s)
What is ANGULAR VELOCITY in physics?
Angular velocity is how fast something is spinning around a point or axis.
What is the physics equation for POWER?
What unit is POWER measured in?
Watts
(Remember work is measured in joules)
What is ENERGY?
Energy is the ability to do work. It makes the things around us move or change.
Where does the majority of energy on earth come from and what is it called?
The sun, known as radiant energy or solar radiation
What are the three types of fossil fuels?
Coal, natural gas, and oil
End product of animal and plant remains stewing deep beneath the earths surface
What is a closed system refer to within the transfer of energy?
A closed system is one where energy can be transferred within the system but cannot enter or leave the system itself.
What is the law of the conservation of energy?
Energy cannot be created or destroyed.
It can:
- Transfer from one obj to another (i.e., quarterback throwing a football)
- Change from one form of energy to another (i.e., process food to fuel body)
What are the three ways that energy TRANSFERS from one object to another?
Movement of waves (i.e., sound
Movement of heat
Movement of objects
What is mechanical energy?
moving matter and energy moving through a medium (the matter that waves travel through)
What are examples of electromagnetic energy?
UV rays, microwaves, radiowaves
Does electromagnetic energy require a medium to travel through like mechanical energy?
No
What is thermal energy?
Thermal energy is the energy created by moving, vibrating atoms that make up matter
(i.e., heat will flow from hotter object to cooler one - adding hot water to cold tub warms up water)
What are the three types of “manmade” energy?
electrical
nuclear (i.e. when atoms are split/combined)
chemical (i.e. chem reactions inside batteries)
What is a photon?
A photon is a tiny particle of light. It has no mass and travels at the speed of light, carrying energy. For example, the light from the sun is made up of countless photons that travel to Earth and make it bright.
What happens if an atom absorbs a photon?
When an atom absorbs a photon, the energy from the photon is transferred to the atom, causing one of its electrons to jump to a higher energy level or orbit. This makes the atom excited. For example, when sunlight hits your skin, atoms in your skin cells absorb photons, leading to changes that can cause a tan.
What causes acid rain?
Acid rain is caused by pollutants like sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) released into the atmosphere from burning fossil fuels in factories, cars, and power plants. These pollutants mix with water vapor in the air to form acids, which then fall to the ground as acid rain, harming plants, animals, and buildings.
What is the difference between mitosis and meiosis?
Mitosis and meiosis are both processes of cell division, but they serve different purposes and have distinct differences:
Mitosis:
Purpose: To create two identical daughter cells for growth and repair.
Number of Divisions: One division resulting in two cells.
Chromosome Number: Daughter cells have the same number of chromosomes as the parent cell (diploid).
Example: Skin cells dividing to heal a cut.
Meiosis:
Purpose: To produce sex cells (sperm and eggs) for reproduction.
Number of Divisions: Two divisions resulting in four cells.
Chromosome Number: Daughter cells have half the number of chromosomes as the parent cell (haploid).
Example: Formation of eggs in the ovaries or sperm in the testes.
In short, mitosis creates identical cells for body functions, while meiosis creates cells with half the genetic information for reproduction.
What is nitrification?
Nitrification is a process in which certain bacteria in the soil convert ammonia into nitrites and then into nitrates. This is important for plants because nitrates are a form of nitrogen that plants can easily absorb and use to grow.
For example, when farmers add fertilizer to their fields, it often contains ammonia that gets turned into useful nitrates through nitrification.
What is carbon sink?
A carbon sink is anything that removes more carbon from the atmosphere than it gives off.
Three sources of carbon sink are the ocean, soil, and plants.
When should a scientist use a scientific experiment to study a problem?
A scientist should use a scientific experiment to study a problem when they want to test a hypothesis and determine cause-and-effect relationships. This method allows them to control variables, collect data, and make observations under controlled conditions to see if their predictions hold true.
For example, if a scientist wants to know if a new fertilizer helps plants grow faster, they would set up an experiment comparing plants with and without the fertilizer.
When should a scientist use an observational study to study a problem?
A scientist should use an observational study to study a problem when they want to gather data and identify patterns or correlations without interfering with the subjects or environment. This method is useful when it’s not possible or ethical to manipulate variables.
For example, studying the behavior of animals in the wild or observing the health effects of smoking in a population are situations where observational studies are appropriate.
What are the steps of the scientific method?
Olivia’s quirky hamster eats all cookies.
Who is John H. Ostrom and what is his impact on paleontology?
John H. Ostrom was an influential American paleontologist best known for his groundbreaking work on the relationship between dinosaurs and birds. His impact on paleontology includes:
- Dinosaur-Bird Connection: Ostrom’s study of the dinosaur Deinonychus in the 1960s led to the revolutionary idea that some dinosaurs were more closely related to birds than to reptiles. This challenged the traditional view and provided evidence that birds are the modern descendants of theropod dinosaurs.
- Feathered Dinosaurs: His work laid the foundation for the discovery of feathered dinosaurs, supporting the theory that feathers and other avian characteristics evolved in theropod dinosaurs before the appearance of modern birds.
- Revising Dinosaur Biology: Ostrom’s research contributed to a new understanding of dinosaur behavior and physiology, suggesting they were active, warm-blooded creatures rather than the sluggish, cold-blooded reptiles they were once thought to be.
Ostrom’s contributions significantly advanced our understanding of dinosaur evolution and bridged the gap between dinosaurs and birds, transforming the field of paleontology.
What are the stages of the water cycle?
Evil crooks pay cash.
- Evaporation: Water from oceans, rivers, lakes, and even plants turns into water vapor and rises into the air due to the heat from the sun.
- Condensation: The water vapor cools down as it rises and turns back into liquid water droplets, forming clouds.
- Precipitation: The water droplets in the clouds become heavy and fall back to the Earth as rain, snow, sleet, or hail.
- Collection: The water collects in bodies of water like rivers, lakes, and oceans, and the cycle starts again.
What happens if the binding energy of an atom is high?
If the binding energy of an atom is high, it means that the nucleus is very stable. Binding energy is the energy required to separate all the protons and neutrons in the nucleus. A high binding energy indicates that the nucleus is tightly bound and less likely to break apart or undergo radioactive decay.
For example, iron-56 has one of the highest binding energies per nucleon, making it very stable compared to other elements.
In what eon did earth’s atmosphere begin to become oxygenated?
Earth’s atmosphere began to become oxygenated during the Proterozoic Eon. This significant change, known as the Great Oxygenation Event, occurred around 2.4 to 2.3 billion years ago when cyanobacteria started producing oxygen through photosynthesis, gradually increasing the oxygen levels in the atmosphere.
What is a mantle plume?
A mantle plume is an upwelling of abnormally hot rock within the Earth’s mantle. This hot rock rises from deep within the mantle, possibly from near the core-mantle boundary, and can cause volcanic activity when it reaches the Earth’s surface.
An example of a mantle plume is the one beneath Hawaii, which creates the volcanic islands in the middle of the Pacific Ocean.
What are the different types of biodiversity? Describe each.
What are infrared waves?
Infrared waves are a type of electromagnetic radiation with wavelengths longer than visible light but shorter than microwaves. They are often associated with heat, as objects emit infrared radiation based on their temperature.
For example, infrared waves are used in remote controls for TVs and in thermal imaging cameras to see heat patterns.
What is an angiosperm?
An angiosperm is a type of plant that produces flowers and seeds enclosed within a fruit. Angiosperms are the largest group of plants and include a wide variety of species, from grasses and trees to flowers and shrubs.
For example, apple trees, roses, and wheat are all angiosperms.
What is a sporophyte?
A sporophyte is the diploid, spore-producing phase in the life cycle of plants and algae that undergo alternation of generations. It develops from the fertilized egg, or zygote, and produces spores through meiosis, which can then grow into the haploid gametophyte phase.
For example, in ferns, the leafy plant that we commonly see is the sporophyte.
What do haploid and diploid mean?
Haploid and diploid refer to the number of sets of chromosomes in a cell:
Haploid (n): A cell with one complete set of chromosomes. This is typically seen in sex cells (gametes), such as sperm and eggs in animals, and spores in plants. For example, human gametes each have 23 chromosomes.
Diploid (2n): A cell with two complete sets of chromosomes, one from each parent. Most body cells (somatic cells) are diploid. For example, human body cells have 46 chromosomes, 23 pairs.
What is transpiration?
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant.
What is subduction?
Subduction is a geological process where one tectonic plate moves under another and sinks into the mantle as the plates converge. This process typically occurs at convergent boundaries where an oceanic plate is forced below a continental plate or another oceanic plate. Subduction zones are associated with volcanic activity, earthquakes, and the creation of deep ocean trenches.
An example of a subduction zone is the area along the Pacific Ring of Fire, where the Pacific Plate is being subducted beneath other surrounding plates.
What is the order of taxonomic classifications?
The order of taxonomic classifications, from the broadest to the most specific, is:
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
A handy acronym for remembering the order of taxonomic classifications is:
“Dear King Philip Came Over For Good Soup.”
What is precession?
Precession is the slow, gradual change in the orientation of an astronomical body’s rotational axis. For Earth, this means that the axis slowly traces out a cone over a period of about 26,000 years. This movement affects the position of the celestial poles and the timing of the seasons over long periods.
For example, due to precession, the star Polaris will not always be the North Star; eventually, another star will take its place.
What is atmospheric turbidity?
Atmospheric turbidity refers to the haziness or cloudiness in the atmosphere caused by the presence of suspended particles and pollutants, such as dust, smoke, and aerosols. These particles scatter and absorb sunlight, reducing the clarity and brightness of the sky. High atmospheric turbidity can lead to reduced visibility and affect weather and climate by influencing the amount of solar radiation that reaches the Earth’s surface.
Under what circumstances might vasodilation occur?
Vasodilation occurs under several circumstances, primarily as a response to increased body temperature, low oxygen levels, or the presence of certain chemicals and hormones. Here are some specific situations:
- Increased Body Temperature: When you’re hot, blood vessels near the skin surface dilate to help release heat and cool the body down. For example, when you exercise, your face might turn red due to vasodilation.
- Low Oxygen Levels: If tissues need more oxygen, blood vessels dilate to increase blood flow and deliver more oxygen. This can happen at high altitudes where the air has less oxygen.
- Chemical Signals: Certain substances like nitric oxide, produced in the body, cause blood vessels to dilate. Medications like nitroglycerin, used to treat chest pain, also cause vasodilation.
- Inflammation or Injury: During an inflammatory response or injury, vasodilation occurs to increase blood flow to the affected area, bringing immune cells and nutrients for healing.
These processes help regulate body temperature, ensure sufficient oxygen supply, and facilitate healing and immune responses.
Under what circumstances might vasorestriction occur?
Vasoconstriction, the narrowing of blood vessels, occurs under various circumstances to regulate blood flow and maintain blood pressure. Here are some specific situations:
- Cold Temperatures: When you’re cold, blood vessels constrict to conserve heat and maintain core body temperature. For example, your fingers might turn pale when you’re in a cold environment.
- Stress or Fear: During a “fight or flight” response, stress hormones like adrenaline cause vasoconstriction to redirect blood flow to essential organs and muscles.
- Low Blood Pressure: To increase blood pressure, the body can constrict blood vessels, ensuring that vital organs receive enough blood and oxygen.
- Dehydration: When the body is dehydrated, blood volume decreases, and vasoconstriction helps maintain blood pressure and ensure blood flow to critical areas.
- Medications: Certain medications, such as decongestants, cause vasoconstriction to reduce swelling and congestion in nasal passages.
These processes help the body adapt to various conditions, maintaining homeostasis and ensuring that critical organs function properly.
