ATI TEAS Version 7 Science Comprehensive Study Guide
Cell Biology and Microbiology
Totipotent cells are characterized by their unique functional capacity to develop into any kind of cell within an organism. This level of potency allows them to give rise to both embryonic and extraembryonic cell types. In contrast, specialized cells perform distinct roles, such as carrying electrical impulses in the nervous system or fighting infectious diseases within the immune system.
Cellular structures vary significantly between different domains of life. Both prokaryotic and eukaryotic cells share a fundamental structure: the cell membrane. This phospholipid bilayer acts as a selective barrier for the cell. However, other organelles like the Golgi apparatus, chloroplasts, and the endoplasmic reticulum are membrane-bound structures typically found only in eukaryotes.
Genetic information that determines the characteristics of an organism is stored within the nuclei of eukaryotic cells. Proteins, which include large classes of molecules such as enzymes, are essential for biological functions. When analyzing the monomers that constitute an enzyme macromolecule, the covalent bonds linking these monomers are specifically identified as peptide bonds.
In the context of cellular respiration, the mitochondrial inner membrane performs a role analogous to the thylakoid membrane of chloroplasts during photosynthesis. Both structures are integral to energy conversion processes and the movement of electrons across membranes.
When the body's immune system identifies target cells for destruction, specialized molecules known as perforins are utilized. Perforins function by creating holes in the cell membranes of their target cells, which leads to cell death. Other immune responses involve different classes of molecules, such as cytokines, lymphotoxins, or interferons.
Pathogens that cause illness are treated differently based on their biological nature. For example, a patient suffering from a cold and sore throat caused by a virus will not be prescribed antibiotics, as antibiotics are only effective against bacteria. Other types of pathogens include protists and fungi, each requiring specific medical interventions.
Human Anatomy and Physiology
The biological hierarchy of organization in the human body progresses from the simplest units to increasingly complex structures. The correct order from simple to complex is atoms, leading to cells, then tissues, and finally organs. Major body cavities house specific organ systems; for instance, the thoracic cavity contains the heart and lungs, making these organs particularly vulnerable to severe blunt trauma in that region.
The integumentary system serves several protective and excretory functions. The epidermis is the specific layer of skin that lacks blood vessels (it is avascular). Within the skin, apocrine glands are responsible for the secretion of pheromones. Sweat glands also play a role in excretion, specifically releasing urea in response to the breakdown of proteins and the formation of ammonia.
The cardiovascular system operates through a specific cardiac cycle. The term used to describe the relaxation of the chambers of the heart during this cycle is diastole. Conversely, systole refers to the contraction phase. Glands within the body are categorized as endocrine or exocrine; the parotid gland is an example of an exocrine gland, whereas the pituitary, pineal, and parathyroid glands are classified as endocrine.
In the digestive system, both digestion and absorption of nutrients occur simultaneously within the small intestine. Specifically, lipids absorbed in the small intestine first enter lacteal vessels, which are part of the lymphatic system. The esophagus and gallbladder do not participate in both processes, and the stomach primarily focuses on digestion.
The urinary system utilizes the kidneys to filter excess solutes from the blood. For gas exchange, the respiratory system relies on the alveoli. Emphysema, characterized by damage to the alveoli from toxins and pollutants, severely hinders the body's ability to exchange oxygen and carbon dioxide. This movement of carbon dioxide from the blood into the alveoli occurs via diffusion down a concentration gradient.
The skeletal system provides structural support and serves as a site for the storage of minerals, such as calcium and phosphorus. In terms of regional anatomy, the tibia and fibula are located in the crural region of the body (the lower leg), distinguished from the coxal (hip), antecubital (elbow), or tarsal (ankle) regions.
Neurophysiology and Neuromuscular Function
Nerve cells, or neurons, rely on specific structures and ion movements to function. The myelin sheath provides vital insulation for nerve cells, increasing the speed of impulse conduction. Efferent neurons, specifically motor neurons, are responsible for releasing neurotransmitters that stimulate muscle cells to contract.
Neuronal signaling involve the movement of ions across the cell membrane. Repolarization of a neuron is achieved through the opening of potassium channels, which allows potassium to leave the neuron ( efflux). This process restores the negative internal charge of the cell following depolarization. Sensory perception and nutrition are distinct from these electrical signaling processes.
Chemistry and Physical Science
The pH scale is a logarithmic measure of the acidity or alkalinity of a substance. Because the scale is logarithmic, each whole number change in pH represents a tenfold change in hydrogen-ion concentration (). For instance, a substance with a is times more acidic than a substance with a . When comparing a solution with a to one with a , the difference is five units, meaning the hydrogen-ion concentration at is or times stronger than at . Blood pH is maintained by buffer systems; when blood pH rises (becoming more alkaline), carbonic acid acts as a buffer by donating ions.
Chemical reactions can be modified by catalysts. The result of using a catalyst is that the reaction is completed in a shorter amount of time because the catalyst lowers the activation energy required. In chemical terminology, an oxidation reaction is specifically characterized by the removal of electrons () from a substance.
Atoms can become ions by changing their electron count. A chloride ion () possesses a negative charge because it has gained an electron. Soap acts as an emulsifier because of its dual polar and nonpolar nature, which allows it to bond with both oil and water to remove grime.
Matter undergoes changes in order and energy during phase transitions. As a solid turns into a liquid, the particles become less ordered and their mobility increases. The triple point of a substance refers to the specific temperature and pressure at which the substance exists simultaneously in solid, liquid, and gas phases.
Genetics and Inheritance
Mutations are changes in the DNA sequence. If a mother's germ cell contains mutated DNA, that mutation can be passed on to her offspring. Mutations in somatic cells or stem cells are generally not heritable. Cancer is a specific condition resulting from genetic mutations that lead to the uncontrolled division of a single cell within the body.
DNA strands consist of complementary base pairs. Nitrogenous bases follow specific pairing rules (Adenine with Thymine, and Cytosine with Guanine). If a portion of a DNA strand reads , the sequence of bases on the complementary strand, read from the end, would be .
Genetic inheritance can be predicted using a Punnett square. In a cross where an unknown genotype is paired with a recessive trait (), and the resulting offspring are approximately half and half , the unknown genotype is determined to be .
Biological processes related to reproduction include oogenesis and ovulation. Ovulation is the specific process in which an ovarian follicle matures and releases a reproductive egg. Menstruation and fertilization represent different stages of the reproductive cycle.
Scientific Method and Laboratory Practice
The scientific method requires that hypotheses be testable and falsifiable. A hypothesis that has not been falsified by experimentation remains provisional, as experiments can never truly "validate" a hypothesis in an absolute sense, only fail to disprove it. Scientific theories and hypotheses are subject to modification based on new evidence. For example, if research discovers that parasitic worm infestations reduce the severity of certain autoimmune disorders, the original hypothesis that such infestations are purely damaging must be modified to reflect that worm infestation reduces the severity of certain autoimmune disorders.
Research integrity depends on methodology. If a researcher gathering data on bird wing strength excludes large birds because of equipment limitations (such as a small net), the data should be rejected because the results are biased by the methodology. Furthermore, repeating published work is a standard scientific practice because it provides independent confirmation of results.
Data analysis involves distinguishing between correlation and causation. If a study finds that Process A and Process B are correlated, the study does not indicate a causal relationship between the processes. In physical experiments, multiple variables must be considered. In a study of falling objects, the following data was collected:
- Object A: Mass , Time of Fall
- Object B: Mass , Time of Fall
- Object C: Mass , Time of Fall
- Object D: Mass , Time of Fall
From this data, it can be concluded that air resistance is greater for Object A than for Object B, given they have the same mass but different fall times.
Specific laboratory tools are required for various measurements. To accurately measure the density of small irregular solids, a student needs a weighing balance to find mass and a graduated cylinder with water to find volume via displacement. Density is calculated using the formula:
A spectrophotometer is a tool used to measure the turbidity of a liquid by measuring the transmission of light through the sample. Other tools like centrifuges or microdensitometers serve different analytical purposes.