TEAS 7 Science flashcards
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How to describe any location on the human body
- In anatomy, whose right and left do directional terms describe?
- The subject's own right and left, not the viewer's as they face the subject.
- Which body plane divides the body into front and back parts?
- The frontal (coronal) plane. A sagittal plane makes right and left parts; a transverse plane makes upper and lower parts.
- Is the elbow proximal or distal to the wrist, and why?
- Proximal. It is closer to where the arm attaches to the trunk.
- A person lies face up. Which side of the wrist is still anterior?
- The palm side. Terms are always used as if the body were in anatomical position, however it actually lies.
- Which structure separates the thoracic cavity from the abdominopelvic cavity?
- The diaphragm, which forms the floor of the thoracic cavity.
- Which serous membrane layer covers the organ, and which lines the cavity wall?
- The visceral layer covers the organ; the parietal layer lines the cavity wall. Fluid between them reduces friction.
How air reaches the alveoli and how oxygen and CO2 trade places
- Does gas exchange happen in the trachea, the bronchi, or the alveoli?
- The alveoli, in the respiratory zone. The conducting zone only moves, cleans, warms and humidifies air.
- What is the main everyday signal to breathe faster and deeper?
- Rising blood CO2, which lowers pH. Falling oxygen becomes a strong signal only when it gets very low.
- Why does air flow into the lungs during inhalation?
- The diaphragm contracts, chest volume grows, alveolar pressure drops below atmospheric pressure, and air flows in (Boyle's law).
- Which way does carbon dioxide move in the lungs, and why?
- From blood (about 45 mm Hg) into the alveoli (about 40 mm Hg), down its partial pressure gradient.
- How is most carbon dioxide carried in the blood?
- As bicarbonate, about 70 percent. About 20 percent binds hemoglobin and 7 to 10 percent is dissolved.
- What does surfactant do in the alveoli?
- It lowers surface tension in the watery film lining each alveolus. Without it, alveoli would collapse when you breathe out.
How blood flows through the heart
- Do arteries always carry oxygen-rich blood?
- No. Arteries carry blood away from the heart. The pulmonary arteries carry oxygen-poor blood to the lungs.
- In order, which four valves does blood cross as it passes through the heart?
- Tricuspid, pulmonary, mitral, then aortic.
- Why is the left ventricle wall thicker than the right?
- It must generate far more pressure to push blood through the whole body, not just the lungs.
- Where do the pulmonary veins empty, and what blood do they carry?
- They empty into the left atrium and carry oxygen-rich blood back from the lungs.
- What does the AV node do to the heart's electrical signal, and why?
- It holds the signal about a tenth of a second so the atria finish emptying into the ventricles first.
- What causes the first heart sound, "lub"?
- The AV valves closing as the ventricles start to contract. The second sound, "dub," is the semilunar valves closing.
How food is broken down and absorbed, from mouth to colon
- Where does protein digestion begin, and which enzyme starts it?
- In the stomach, with pepsin. Pepsin is activated from pepsinogen by hydrochloric acid.
- Does bile chemically break down fat?
- No. Bile salts emulsify fat into tiny droplets so lipase has more surface. Pancreatic lipase does the chemical splitting.
- Which organ makes bile, and which organ stores it?
- The liver makes bile. The gallbladder stores it, concentrates it, and releases it when fatty chyme arrives.
- Why does pancreatic juice contain bicarbonate?
- Bicarbonate neutralizes the acidic chyme that enters the duodenum from the stomach.
- How do long-chain fat products leave the villi differently from glucose?
- Fat products enter lacteals (lymphatic vessels). Glucose and amino acids enter the villus capillaries.
- What would happen to nutrient absorption if the villi were flattened?
- Absorption would drop. Folds, villi and microvilli give the small intestine its huge surface area for absorbing nutrients.
How the nervous system sends and sorts signals
- Which ion movement causes depolarization, and which causes repolarization?
- Na+ rushing into the neuron depolarizes it. K+ flowing out repolarizes it.
- Does a stronger stimulus produce a bigger action potential?
- No. Action potentials are all-or-none: they fire fully if threshold is reached, or not at all.
- What does calcium do at the axon terminal?
- Ca2+ entering the terminal makes vesicles release neurotransmitter into the synaptic cleft.
- Which autonomic division slows the heart and favors digestion?
- The parasympathetic division (rest-and-digest). The sympathetic division raises heart rate and turns digestion down.
- Which brain region would you suspect in clumsy, uncoordinated walking?
- The cerebellum. It compares motor commands with feedback and corrects them to keep movement coordinated.
- What are the five parts of a reflex arc, in order?
- Receptor, sensory neuron, spinal cord (processing), motor neuron, effector.
How muscles contract, from nerve signal to sliding filaments
- Which muscle type is striated but involuntary?
- Cardiac muscle. Striated does not mean voluntary.
- What does calcium bind to in a muscle fiber, and what does that uncover?
- Calcium binds troponin, which moves tropomyosin off the binding sites on actin.
- Why is a muscle with no ATP stiff instead of relaxed?
- Myosin needs ATP to let go of actin. Without it, cross-bridges stay locked, as in rigor mortis.
- During contraction, do the actin and myosin filaments get shorter?
- No. They slide past each other. The sarcomere shortens as Z-discs move closer, while the A band stays the same width.
- What does acetylcholinesterase do at the neuromuscular junction?
- It breaks down ACh in the synaptic cleft so the signal does not keep firing.
- When you straighten your knee, which muscles are agonists and which are antagonists?
- The quadriceps are agonists and the hamstrings are antagonists. The roles switch when you bend the knee.
How the male and female reproductive systems make gametes and new life
- Which testis cells make testosterone, and which support developing sperm?
- Leydig cells make testosterone, responding to LH. Sertoli cells support sperm development, responding to FSH.
- Where are sperm made, and where do they mature?
- They are made in the seminiferous tubules and mature in the epididymis.
- What triggers ovulation in a typical 28-day cycle?
- An LH surge around day 14, set off by very high estrogen from the dominant follicle.
- What does the corpus luteum secrete after ovulation, and why?
- Progesterone, which prepares the endometrium for implantation.
- What happens to the endometrium if no pregnancy occurs?
- The corpus luteum breaks down, progesterone falls, and the functional layer of the endometrium is shed (menses).
- Where does fertilization usually happen?
- In the uterine tube, most often the ampulla. It does not usually happen in the uterus or ovary.
How your skin is layered and what each layer does
- Which epidermal layer is deepest, and what happens there?
- The stratum basale. Its cells divide, and new keratinocytes are pushed toward the surface.
- Does the epidermis contain blood vessels?
- No. Blood vessels are in the dermis and hypodermis.
- What do dermal arterioles do when the body is too hot, and why?
- They dilate. More warm blood flows near the surface and loses heat, and sweat also increases.
- A person's skin looks pale in the cold. What did the dermal arterioles do?
- They constricted, keeping warm blood in the core so internal organs stay warm.
- Why can a third-degree burn hurt less than a second-degree burn?
- It destroys nerve endings. Less pain does not mean a shallower burn.
- How does sunlight help the body absorb calcium and phosphorus?
- UV light lets the epidermis make vitamin D, which the liver and kidneys activate. Vitamin D is needed to absorb them.
How hormones and negative feedback keep blood glucose steady
- Which pancreatic hormone raises blood glucose, and which islet cells release it?
- Glucagon, from alpha cells. It makes the liver break glycogen into glucose and build new glucose.
- How does insulin lower blood glucose?
- It helps cells, mainly muscle and fat, take glucose out of the blood. The liver also stores extra glucose as glycogen.
- T3 and T4 levels are rising. What happens to TSH, and why?
- TSH secretion decreases. Rising T3 and T4 slow the chain, which is negative feedback.
- Which hormone shows positive feedback during labor?
- Oxytocin. Contractions stretch the cervix, which triggers release of more oxytocin.
- Where are ADH and oxytocin made, and where are they released?
- They are made in the hypothalamus. The posterior pituitary stores and releases them.
- Is the pancreas an exocrine or an endocrine gland?
- Both. Digestive juice leaves through ducts; insulin and glucagon go into the blood.
How the kidneys filter blood and make urine
- After urine leaves the collecting duct, what path does it take out of the body?
- Calyces, renal pelvis, ureter, urinary bladder, urethra, then outside the body.
- Which nephron part reabsorbs the most, and what does it reclaim almost completely?
- The proximal convoluted tubule. It reclaims nearly all glucose and amino acids, plus about 67 percent of filtered water and sodium.
- What happens to urine volume if ADH secretion stops?
- Less water is reabsorbed in the collecting duct, so a large volume of dilute urine results.
- What does aldosterone do to sodium and potassium?
- It increases sodium reabsorption, and water follows. It also increases potassium loss in urine.
- Why can glucose appear in urine in uncontrolled diabetes?
- Glucose transporters in the PCT have a top speed. Very high blood glucose overwhelms them, so glucose spills into urine.
- How do reabsorption and secretion differ?
- Reabsorption moves substances from the tubule back into the blood. Secretion moves them from the blood into the tubule.
How the body defends itself: innate and adaptive immunity
- How do innate and adaptive immunity differ in speed and specificity?
- Innate is fast and nonspecific. Adaptive is slower on first exposure but specific and has memory.
- Which cells secrete antibodies?
- Plasma cells, which come from activated B cells. T cells do not secrete antibodies.
- Is a vaccine active or passive immunity?
- Artificially acquired active immunity. Your own body makes the antibodies and memory cells.
- What causes the swelling during inflammation?
- Histamine from mast cells makes capillaries leaky, so fluid seeps into the tissue.
- What happens when the body meets the same pathogen a second time?
- Memory B and T cells give a secondary response that is faster and stronger, often before symptoms appear.
- Where do B cells mature, and where do T cells mature?
- B cells mature in the bone marrow. T cells mature in the thymus.
How bones are built, remodeled, and joined
- How many bones does an adult skeleton have, and how are they divided?
- 206 bones: 80 in the axial skeleton and 126 in the appendicular skeleton.
- Which bone cells build bone, and which break it down?
- Osteoblasts build bone. Osteoclasts resorb (break down) bone. Osteocytes maintain the matrix.
- What happens to blood calcium if osteoclasts become much less active?
- Less calcium leaves bone, so blood calcium tends to fall. PTH normally raises it by increasing osteoclast activity.
- Which hormone lowers blood calcium, and which gland makes it?
- Calcitonin, from the thyroid. It inhibits osteoclasts. PTH from the parathyroid glands raises blood calcium.
- Is the sacrum axial or appendicular?
- Axial. It is part of the vertebral column even though it sits in the pelvis.
- How do ligaments and tendons differ?
- Ligaments join bone to bone. Tendons attach muscle to bone.
How a cell is built, fed, and copied
- What do prokaryotic cells lack that eukaryotic cells have?
- A nucleus and membrane-bound organelles. Prokaryotes still have DNA and ribosomes; their DNA sits in the nucleoid.
- A red blood cell is dropped into pure water. What happens, and why?
- Water moves in, so the cell swells and can burst. Pure water has less solute than the cell, so it is hypotonic.
- How does active transport differ from diffusion?
- Active transport moves substances against their gradient and uses energy, usually ATP. Diffusion moves them down the gradient with no cell energy.
- What route does a protein take when a cell exports it?
- Ribosomes on the rough ER build it, a vesicle carries it to the Golgi, which modifies it, and another vesicle releases it.
- Which division separates homologous pairs, and which separates sister chromatids?
- Meiosis I separates homologous pairs. Sister chromatids separate in mitosis and in meiosis II.
- Do plant cells have mitochondria, and what do they add?
- Yes. Plant cells add a cell wall, chloroplasts and a large central vacuole. Chloroplasts do not replace mitochondria.
How a gene in DNA becomes a protein
- What does semiconservative replication mean?
- Each new DNA molecule keeps one original strand and gets one new strand.
- Where do transcription and translation happen in a eukaryotic cell?
- Transcription happens in the nucleus. Translation happens at ribosomes in the cytoplasm.
- During transcription, the DNA template strand has A. Which RNA base is added?
- Uracil (U). RNA uses U where DNA would use T.
- Which codon starts translation, and which three codons stop it?
- AUG starts it and codes for methionine. UAA, UAG and UGA are the stop codons.
- How does a silent mutation differ from a nonsense mutation?
- Silent: the codon still means the same amino acid. Nonsense: the codon becomes a stop codon and the protein ends early.
- Why does deleting one base usually harm a protein more than swapping one base?
- A deletion causes a frameshift, so every codon after it is misread. A swap changes only one codon.
How traits pass from parents to children
- What ratios result from crossing two heterozygotes, Yy × Yy?
- Genotype 1 YY : 2 Yy : 1 yy. Phenotype 3 dominant : 1 recessive.
- Can you read a genotype from a dominant phenotype?
- No. YY and Yy look the same. A test cross with a recessive (yy) plant can reveal the genotype.
- How do incomplete dominance and codominance differ?
- Incomplete dominance gives a blend, like pink snapdragons. Codominance shows both alleles at once, like type AB blood.
- Can a type A parent and a type B parent have a type O child?
- Yes, if they are Iᴬ i and Iᴮ i. Type O is ii, so each parent passes i.
- Why can a father with an X-linked trait not pass it to his son?
- A son gets his father's Y chromosome. A father passes his X only to his daughters.
- Does a 3:1 ratio mean exactly 1 of every 4 children shows the recessive trait?
- No. The ratio is a probability: each child has a 1 in 4 chance, not a guarantee.
The four macromolecules of life and how cells build them
- Which reaction releases water: dehydration synthesis or hydrolysis?
- Dehydration synthesis releases water when monomers join. Hydrolysis uses water to split a polymer into monomers.
- How do plants and animals each store glucose?
- Plants store it as starch. Animals store it as glycogen, mainly in the liver and muscles.
- What is a triglyceride made of?
- One glycerol attached to three fatty acids.
- What happens to an enzyme heated far above its ideal temperature?
- It denatures. Its shape changes but its amino acid sequence stays, and the lost shape stops it from working.
- What type of molecule are almost all enzymes, and what job do they do?
- Proteins. They act as catalysts, speeding up reactions, and come out unchanged so they can be used again.
- Which sugar does DNA contain, and which does RNA contain?
- DNA contains deoxyribose. RNA contains ribose.
How microorganisms cause disease and how infections spread
- Why don't antibiotics work on viral infections?
- Antibiotics fight bacteria. Viruses have no cell of their own to attack; they borrow the host cell's machinery.
- How can harmless intestinal E. coli still cause a urinary tract infection?
- It is an opportunistic pathogen. It causes disease when it reaches a body site where it does not belong.
- Why can an antibacterial drug lead to a yeast infection?
- It kills bacteria that hold Candida back. Candida is a fungus, so the drug does not touch it and it can overgrow.
- Can a person with no symptoms spread a pathogen?
- Yes. A carrier is infected without symptoms but can still spread the pathogen.
- What are the five links in the chain of infection, in order?
- Reservoir, portal of exit, mode of transmission, portal of entry, susceptible host. Breaking any link stops spread.
- How do protozoa differ from helminths?
- Protozoa are always single-celled. Helminths are multicellular parasitic worms.
What atoms are made of and how they form ions and bonds
- What does an atom's atomic number count, and what does it identify?
- It counts protons and identifies the element. Every atom with 6 protons is carbon.
- How do you find the number of neutrons in an atom?
- Subtract the atomic number from the mass number. Carbon-14 has 14 − 6 = 8 neutrons.
- How do isotopes of the same element differ?
- They have the same protons but different neutrons. Carbon-12, carbon-13 and carbon-14 are all carbon.
- A sodium atom loses one electron. What does it become, and is it still sodium?
- A positive ion, Na⁺, with 10 electrons. It is still sodium because the protons did not change.
- How does an ionic bond differ from a covalent bond?
- Ionic bonds transfer electrons so opposite ions attract (usually metal + nonmetal). Covalent bonds share electrons (usually nonmetals).
- Why is boron's atomic mass listed as about 10.81 when no single atom weighs that?
- The periodic table value is a weighted average of the element's natural isotopes, not the mass number of one atom.
How matter changes state, and what stays the same
- What is the difference between sublimation and deposition?
- Sublimation is solid to gas, like dry ice. Deposition is gas to solid, like frost.
- What does a thermometer in a pot of melting ice read, and why?
- It stays at 0 °C until all the ice has melted. The added energy pulls particles apart instead of raising temperature.
- Does cutting a brick in half change its density?
- No. Mass and volume are both halved, so density stays the same.
- Is dissolving sugar in water a physical or a chemical change?
- Physical. The sugar is still sugar, so its chemical identity has not changed.
- A reaction in an open container seems to lose mass. Was matter destroyed?
- No. A gas product likely drifted away. In a closed container the total mass stays the same.
- Why does ice float on liquid water?
- Ice is less dense (about 0.92 g/cm³) than liquid water (about 1.0 g/cm³).
How to read, balance, and classify a chemical reaction
- Why can't you balance an equation by changing a subscript?
- Subscripts define the substance. Changing H₂O to H₂O₂ turns water into a different substance. Change coefficients instead.
- Is 2H₂ + O₂ → 2H₂O balanced even though molecules go from 3 to 2?
- Yes. Atoms must balance, not molecules. Each side has the same number of each kind of atom.
- How do single replacement and double replacement differ?
- Single: a lone element replaces another in a compound. Double: two compounds swap partners.
- What does a negative ΔH tell you about a reaction?
- The reaction is exothermic. It releases heat to its surroundings.
- Why does an instant cold pack feel cold on your skin?
- The process inside is endothermic and absorbs heat. Your skin loses heat to the pack; no "cold" is added.
- What forms when methane burns completely, and what type of reaction is it?
- Carbon dioxide and water, with heat released. It is combustion: a fuel reacting rapidly with oxygen.
What makes a chemical reaction faster or slower?
- What two conditions must a collision meet to cause a reaction?
- The particles must hit in the right orientation and with at least the activation energy.
- How does a catalyst speed up a reaction?
- It gives a different pathway with a lower activation energy. It is not used up and gives the same products.
- Why does iron powder react with acid faster than one iron nail?
- Smaller pieces have more surface area, so more of the iron is exposed to the acid.
- Does equilibrium mean reactants and products are present in equal amounts?
- No. It means the forward and reverse rates are equal. Concentrations stay constant but are usually not equal.
- A product is removed from a system at equilibrium. Which way does it shift?
- Toward the products, by Le Châtelier's principle. The system shifts to counteract the stress.
How solutions work: what dissolves, how much, and why cells swell or shrink
- Why can a warm soda hold less carbon dioxide than a cold one?
- Raising temperature decreases the solubility of gases, so the gas escapes from the warmer liquid.
- What does diluting a solution change, and what stays the same?
- Adding solvent lowers the concentration. The amount of solute stays the same.
- What does "like dissolves like" mean?
- Polar solvents such as water dissolve polar and ionic solutes. Nonpolar substances such as oil do not mix with water.
- How does a supersaturated solution differ from a saturated one?
- It holds more solute than the solubility limit and is not at equilibrium. A seed crystal can make the extra crystallize.
- Why is isotonic saline used to prepare IV fluids?
- An isotonic solution causes no net water movement, so cells keep their size. Physiological saline is 0.9% m/v.
How acids, bases, pH and buffers work
- How much more H+ does a pH 3 solution have than a pH 4 solution?
- Ten times more. Each pH unit is a tenfold change in hydrogen ion concentration, and a lower pH means more H+.
- Does a strong acid mean a concentrated acid?
- No. Strong means the acid ionizes completely in water. It does not describe how much acid is in the solution.
- What is the general pattern of neutralization?
- Acid + base → salt + water. Milk of magnesia reacting with stomach acid is an example.
- What happens to blood pH if a person breathes out less CO2 than usual?
- Less acid is removed, so blood pH falls and blood becomes more acidic. Breathing out more CO2 raises blood pH.
- In the blood's carbonic acid-bicarbonate buffer, which partner picks up extra H+?
- Bicarbonate (HCO3-) picks up extra H+ and becomes carbonic acid. Carbonic acid is the partner that neutralizes extra base.
- What is the normal range of arterial blood pH?
- 7.35 to 7.45. Below 7.35 is acidosis and above 7.45 is alkalosis.
How to measure like a scientist: units, prefixes, tools and readings
- Where do you read the volume in a graduated cylinder?
- At the bottom of the meniscus, with your eye level with it.
- How do you convert degrees Celsius to kelvins?
- Add 273.15: K = °C + 273.15. The 9/5 factor is only for Fahrenheit.
- A sample warms from 20 °C to 45 °C. By how many kelvins?
- 25 K. A Celsius degree and a kelvin are the same size.
- How do accuracy and precision differ?
- Accuracy is closeness to the true value. Precision is closeness of repeated measurements to each other. Results can be precise and still wrong.
- An object goes from Earth to the moon. What happens to its mass and weight?
- Mass stays the same. Weight changes because the pull of gravity changes.
- Which is smaller, 1 mg or 1 µg?
- 1 µg. A microgram is 0.000001 g and a milligram is 0.001 g.
How to use logic and evidence to judge a scientific claim
- How does a scientific theory differ from a scientific law?
- A theory explains why things happen. A law describes or predicts what happens. A theory does not turn into a law.
- Can an experiment prove a hypothesis?
- No. Results can support or refute it, but science does not claim to prove it.
- What makes a hypothesis falsifiable?
- Some possible result could show it is wrong. A claim that no test could rule out is not scientific.
- Sunscreen sales and lifeguard rescues rise together. Does sunscreen cause rescues?
- No. A confounding variable, hot sunny weather, drives both. Correlation alone does not show cause.
- What kind of study can test whether one variable causes a change in another?
- A controlled experiment that changes one variable, keeps the rest the same, and ideally uses random assignment.
- How do inductive and deductive reasoning differ?
- Inductive goes from specific observations to a general conclusion, which may be wrong. Deductive goes from a general principle to a specific prediction.
How to read a trend and predict what happens next
- How do direct and inverse relationships differ?
- In a direct relationship both variables rise or fall together. In an inverse one, one rises while the other falls.
- A line rises steadily but crosses the y-axis at 5. Is it directly proportional?
- No. It is a direct relationship, but a directly proportional line must pass through the origin.
- At constant temperature, gas pressure doubles. What happens to the volume?
- It halves. Volume and pressure are inversely proportional (Boyle's law).
- Why is a prediction far beyond the last data point risky?
- That is extrapolation, and the pattern may not hold outside the range tested. Predictions inside the range are reasonable.
- In a negative feedback loop, what happens if the effector cannot act?
- Nothing pushes back against the change, so the change keeps going.
- In the simple breathing chain, what happens to airflow if the diaphragm cannot contract?
- The chest cavity does not get bigger, lung pressure does not drop, and air does not flow in.
How to read an experiment: variables, controls and valid conclusions
- In "Does caffeine dose affect reaction time?" which variable is independent?
- Caffeine dose, which the researcher changes on purpose. Reaction time is the dependent variable, which is measured.
- How does a control group differ from controlled variables?
- A control group is a set of subjects that does not get the tested change. Controlled variables are conditions kept the same for every group.
- Why is it a flaw to change two things at once in an experiment?
- You cannot tell which change caused the result. Repeating the flawed test does not fix this.
- Why use random assignment to groups?
- It makes it likely the groups start out alike, so hidden differences spread out evenly.
- What do repeated trials add to an experiment?
- They show whether a result is consistent or just a fluke, which makes it more reliable.
- What makes a conclusion valid?
- It answers the original question, stays within the conditions tested, and says the data support or do not support the hypothesis.
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