ATI TEAS Science Section Practice Flashcards

Basics of Cell Theory

All living organisms are composed of cells.

The cell is the basic unit of structure and organization in organisms.

All cells come from preexisting cells.

Cells carry out the basic processes of life by:

• Taking in food and metabolizing it for energy.

• Responding to the environment.

• Growing, reproducing, and disposing of waste.

Two Main Types of Cells

There are two primary classifications of cells:

Prokaryotes

• Description: Single-celled organisms such as bacteria and algae.

• Size: Extremely small cells.

• Internal Structure: No nucleus or membrane-bound organelles.

• Genetic Material: Contains a single, usually circular chromosome located in a region called the nucleoid.

• Reproduction: Reproduces by fission (budding).

• Structural Components:   - Capsule: Sticky coating.   - Cell Wall: Provides rigidity.   - Plasma Membrane: Encloses the cytoplasm.   - Pili: Structures used for attachment.   - Ribosomes: Synthesize proteins.   - Flagella: Used for propulsion.

Eukaryotes

• Description: Can be single-celled or multicelled; includes plants, animals, fungi, and protists.

• Size: Large cells, approximately $10$ times as large as prokaryotes.

• Internal Structure: Contains a nucleus and specialized organelles.

• Genetic Material: Multiple chromosomes.

• Reproduction: Use mitosis and meiosis for reproduction and growth.

• Structural Components: Rough endoplasmic reticulum, Plasma membrane, Golgi apparatus, Ribosomes, Cytoplasm, Lysosome, Mitochondrion, Nucleolus, Nucleus, Centrioles, Microtubule, and Smooth endoplasmic reticulum.

Organelles and Their Functions

Cellular Reproduction: Mitosis

Mitosis occurs when a cell duplicates itself. This process can happen in single-cell organisms (like protozoa or bacteria) and in multicelled organisms for growth, healing, or reproduction. New cells are created with the exact same DNA as the original. When more cells are needed or a sexual stimulus is introduced, chromosomes and centrioles are replicated.

Steps of Mitosis

1. Prophase: The first phase. The nuclear membrane dissolves, allowing doubled chromosomes to float freely. Spindle fibers congregate around centrosomes to produce a spindle apparatus, which separates the floating DNA into separate poles.

2. Metaphase: Orientation of the spindle apparatus occurs, drawn by centrosomes, to push DNA to opposite ends of the cell.

3. Anaphase: Spindle fibers retract, pulled by centrosomes, pulling apart chromosomes into their v-shaped halves.

4. Telophase: A reversal of previous processes; spindle fibers dissolve and nuclear membranes form around new chromosome pairings. Mitotic division is almost complete at this stage.

Cytokinesis: Following telophase, the two nuclei are divided by cell membranes. This results in identical twin cells with the same DNA, ready for interphase.

Cellular Reproduction: Meiosis

Meiosis is a more complex process than mitosis, involving two rounds of division: Meiosis I and Meiosis II.

Meiosis I

• Prophase I: Nuclear membrane disappears. Chromosomes from each parent mingle and perform crossing-over, where similar chromosomes bundle together and alleles may be replaced, causing genetic variation.

• Metaphase I, Anaphase I, and Telophase I: These mimic mitotic steps. The chromosomal pairings, called tetrads, migrate.

• Outcome of Meiosis I: Cytokinesis creates two diploid cells containing a full but unique complement of mixed DNA ($46$ chromosomes in humans).

Meiosis II

• Prophase II, Metaphase II, Anaphase II, and Telophase II: Mirror the previous process. Centrosomes and spindle fibers push and pull chromosomes apart.

• Outcome of Meiosis II: Each daughter nucleus has only one of each pair of chromosomes ($23$ chromosomes in humans).

• Final Result: Four haploid cells, or gametes, containing $23$ chromosomes.

Organ Systems and Anatomical Planes

Cells with specialized functions join to form tissues. There are four main types:

• Connective tissue: Bone and cartilage.

• Muscle tissue: Skeletal and cardiac muscles.

• Nervous tissue: Brain cells and spinal nerves.

• Epithelial tissue: Organ surfaces, mouth lining, and skin.

Tissues join to form organs. All body systems work together to maintain homeostasis, a stable environment inside the human body.

10 Major Organ Systems

• Respiratory system

• Cardiovascular system

• Gastrointestinal system

• Neuromuscular system

• Reproductive system

• Integumentary system

• Endocrine system

• Genitourinary system

• Immune system

• Skeletal system

Anatomical Planes for Human Anatomy

• Coronal Plane (Frontal): Divides the body into front and back portions.   - Anterior/Ventral: Front.   - Posterior/Dorsal: Back.

• Sagittal Plane: Divides the body into left and right portions.

• Transverse Plane: Divides the body into top and bottom portions.   - Superior: Head.   - Inferior: Feet.

Anatomy of the Respiratory System

The primary function is to provide oxygen ($O_2$) to body cells for energy creation through gas exchange, which also removes carbon dioxide ($CO_2$) as waste.

Gas Exchange Process

Air is inhaled through the nose and passes through the nasal cavity, pharynx, and larynx.

• Pharynx: Cavity behind the nose and mouth connecting to the esophagus.

• Larynx: Hollow muscular organ holding vocal cords.

• Trachea: Cartilage-lined tube. The epiglottis is a flap covering the trachea to prevent solid/liquid material from entering during swallowing.

• Bronchi and Bronchioles: The trachea divides into two bronchi, which branch into narrower bronchioles inside the lungs.

• Alveoli: Small sacs at the end of bronchioles where gas exchange occurs via diffusion between the alveoli and blood.

• Surfactant: Fluid coating the alveolar membranes that reduces the pressure required for inflation by lowering surface tension.

• Diaphragm: Flattens to draw air in and expands to force air out.

Anatomy of the Cardiovascular System

The function is to transport materials to and from body cells using blood as the major carrier.

• Materials Transported To Cells: Nutrients, oxygen, hormones (e.g., insulin), and immune cells.

• Materials Transported Away From Cells: Waste products (excreted as urine), carbon dioxide (exhaled), and excess salts.

Vessels and Chambers

• Arteries: Thick-walled vessels carrying oxygenated blood away from the heart. Branch into arterioles then capillaries.

• Veins: Thinner-walled vessels carrying deoxygenated blood back to the heart. Capillaries merge into venules which form larger veins.

• Heart Structure: Four chambers: left atrium, right atrium (top); left ventricle, right ventricle (bottom).

Circulation Loops and Heart Cycle

• Pulmonary Loop: Transports deoxygenated blood from the right ventricle to the lungs and oxygenated blood back to the left atrium.

• Systemic Loop: Transports oxygenated blood from the left ventricle to the body and deoxygenated blood back to the right atrium.

• Systole: Contraction of heart muscles.

• Diastole: Relaxation of heart muscles.

• Sinoatrial node (Pacemaker): Located in the upper wall of the right atrium; controls contractions via electrical signals.

Components of Blood

• Plasma: Liquid component (constitutes $52$ to $62$ percent) that moves blood cells and proteins.

• Erythrocytes (Red Blood Cells): Constitute $38$ to $48$ percent. Contain hemoglobin to carry oxygen and return carbon dioxide.

• Leukocytes (White Blood Cells): Less than $1$ percent. Five types that fight infection.

• Platelets (Thrombocytes): Less than $1$ percent. Cell fragments facilitating blood clotting.

• Lymphatic System: Network of capillaries and veins carrying interstitial fluids and wastes through a fluid called lymph.

Anatomy of the Gastrointestinal System

Functions to break down food physically and chemically through digestion. Digestion starts in the mouth with chewing and salivary enzymes.

• Saliva: Moistens food; enzymes begin chemical digestion. Food is shaped into a bolus.

• Stomach: Secretes gastric juice ($pH = 1$ to $2$), containing hydrochloric acid, the enzyme pepsin (digests proteins), and mucus. Food mixed with water and juice creates chyme.

• Peristalsis: Muscular squeezing action moving food through the system.

• Small Intestine: Chyme enters the duodenum via the pyloric sphincter. Proteins break into amino acids; starches break into simple sugars. Nutrients are absorbed here into the blood.

• Large Intestine (Colon): Undigested food passes from the cecum to the colon. Water and salt are reabsorbed to create feces, stored in the rectum, and eliminated through the anus.

Anatomy of the Nervous System

Central Nervous System (CNS)

Includes the brain and spinal cord. Controls thought and movement.

• Neurons: Basic nerve cells.   - Axon: Long extension sending impulses.   - Dendrites: Shorter extensions receiving stimuli.

• Communication: Done electrically along fibers and chemically across the synapse using neurotransmitters.

Peripheral Nervous System (PNS)

Connects to the CNS. Consists of:

• Somatic (Voluntary): Motor neurons relay signals to muscles. At the muscle, the signal releases acetylcholine, stimulating contraction.

• Automatic (Involuntary).

Regions of the Brain

• Frontal Lobe: Movement, intelligence, reasoning, behavior, memory, personality. Controls executive function and decision-making.

• Temporal Lobe: Speech, behavior, memory, hearing, vision, emotions.

• Parietal Lobe: Intelligence, reasoning, language, sensation, reading.

• Occipital Lobe: Vision.

• Cerebellum: Balance, coordination, fine muscle control.

• Brain Stem: Breathing, blood pressure, heartbeat, swallowing.

• Cortex: Performs the most sophisticated functions.

The Muscular and Skeletal Systems

Muscular System

• Skeletal Muscle: Attached to bones; only type under conscious control.

• Smooth Muscle: Involuntary; moves substances through organs (e.g., digestive system).

• Cardiac Muscle: Involuntary; walls of the heart.

• Mechanics: Muscles only contract; they are arranged in antagonistic pairs (e.g., biceps and triceps).

• Connections: Tendons connect bone to muscle; Ligaments connect bone to bone at joints.

Skeletal System

Consists of $206$ bones categorized as long, short, flat, or irregular. Bones synthesize blood and immune cells.

• Compact Bone: Dense, hard outer layer/shaft. Contains nerves and blood vessels.

• Spongy Bone (Cancellous): Irregularly shaped sheets inside ends of long bones and centers of others (pelvis, skull, etc.). Filled with red bone marrow (creates blood stem cells, RBCs, WBCs, and platelets).

• Yellow Bone Marrow: Found in centers of long bones; consists mostly of fat.

Anatomy of the Reproductive System

Female System

• Ovaries: Produce ova (eggs).

• Fallopian Tube (Oviduct): Path from ovary to uterus.

• Uterus (Womb): Development site for embryos. Fertilized eggs attach to the endometrium.

• Vagina: Birth canal. The fetus passes through the cervix (mouth of the uterus) into the vagina.

Male System

• Testicles (Testes): Male gonads; sperm produced in seminiferous tubules. Contained in the scrotum.

• Epididymis: Coiled tube for sperm storage and mobility development.

• Seminal Vesicles: Glands secreting mucus, fructose, and prostaglandin during ejaculation.

• Prostate Gland: Secretes semen (milky alkaline fluid containing sperm) into the urethra.

Reproduction and Development

Fertilization occurs when sperm penetrates the egg, fusing nuclei to form a zygote. The zygote undergoes mitosis to become an embryo. If unfertilized, the egg dissolves within the fallopian tube. Hormones like testosterone, estrogen, and progesterone govern these processes.

Anatomy of the Endocrine System

Network of glands producing chemical messengers (hormones) that travel through the bloodstream.

Anatomy of the Genitourinary System

Involved in excretion (eliminating wastes). Includes kidneys, ureters, bladder, and urethra.

• Kidneys: Key organs for excretion. Divided into cortex and medulla.

• Nephrons: Tiny filtering tubes ($1,000,000$ per kidney). Three processes: filtration, secretion, and reabsorption.

• Glomerulus: Capillary cluster acting as a filter in the nephron.

• Urine Path: Tubule $\rightarrow$ Ureters $\rightarrow$ Bladder $\rightarrow$ Urethra.

• Homeostasis: Maintained by eliminating waste, regulating blood acidity, and controlling levels of metabolites and electrolytes.

Anatomy of the Integumentary System

Consists of skin (largest organ), hair, nails, glands, and nerves.

Skin Layers

• Epidermis: Outermost layer. $90$% keratinocytes (keratin provides water resistance); <10% melanocytes (melanin pigment protects from UV).

• Dermis: Middle layer; dense connective tissue, nerves, and blood vessels.

• Hypodermis (Subcutaneous): Inner layer; connects skin to muscle/bone.

Glands

• Sudoriferous (Sweat) Glands: Secrete water and $NaCl$ to lower temperature and remove trace wastes (ammonia).

• Sebaceous Glands: Produce sebum (oil) for lubrication/elasticity.

• Ceruminous Glands: In ear canals; secrete cerumen (wax) to protect the eardrum.

Anatomy of the Immune System

Three Lines of Defense

1. First Line (Nonspecific): Physical barriers like skin and fluids (tears, mucus, saliva, waxes, stomach acid).

2. Second Line (Nonspecific): Attempts to limit spread.     - Inflammation: Swelling/redness signal WBCs and Natural Killer (NK) cells.     - Phagocytes: Swallow bacteria identified by helper T cells.     - Interferons: Combat viruses and block cell-to-cell infection.

3. Third Line (Specific):     - B Lymphocytes: Antigens bind to them to produce specific antibodies (Humoral/Antibody-mediated response). Creates memory cells.     - T Lymphocytes: Mature in the thymus. Cell-mediated response.     - Killer T Cells (Cytotoxic): Kill unknown cells.     - Helper T Cells: Help B and Killer T cells recognize invaders.

Macromolecules

Large organic molecules containing carbon. Most are polymers made of repeating monomers.

• Dehydration Reaction (Condensation): Joining monomers by removing a water molecule.

• Hydrolysis: Breaking bonds by adding water.

Types of Carbohydrates and Lipids

• Monosaccharide: Simple sugar ($C_6H_{12}O_6$).

• Disaccharide: Two sugars joined by glycosidic linkage ($C_{12}H_{22}O_{11}$). Examples: sucrose, lactose.

• Polysaccharide: polymer. Examples: starch, cellulose, glycogen.

• Lipids: Hydrophobic.   - Triglycerides: Fatty acids + glycerol.   - Phospholipids: Cell membrane ingredient.   - Steroids: Cholesterol and hormones.

Chromosomes, Genes, and DNA

• DNA: double helix nucleic acid in chromosomes. Bases: Adenine ($A$), Thymine ($T$), Cytosine ($C$), Guanine ($G$). Pairs: $A-T$ and $C-G$.

• RNA: Transcribed from DNA. Bases: $C$, $G$, $A$, and Uracil ($U$). Ribosomes use RNA to build proteins.

• Codon: Trinucleotide sequence corresponding to a specific amino acid.

• Mutations: Mistakes in copying DNA.

Mendel’s Laws of Heredity

Gregor Mendel studied pea plants, crossing purebred tall ($TT$) with purebred short ($tt$).

• F1 Generation: All tall (heterozygous $Tt$).

• F2 Generation: Created by crossing $Tt \times Tt$.   - Genotype Ratio: $1/4\,TT$, $2/4\,Tt$, $1/4\,tt$ ($1:2:1$).   - Phenotype Ratio: $3/4$ tall stems, $1/4$ short stems ($3:1$).

Basic Atomic Structure and Periodic Table

• Atoms: Composed of a central nucleus ($positive$ protons and $neutral$ neutrons) surrounded by $negative$ electrons.

• Atomic Number: Number of protons; determines chemical properties.

• Atomic Mass: Number of protons + number of neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Compound: Substance with two or more elements (e.g., $H_2O$, $C_6H_{12}O_6$).

Physical and Chemical Characteristics of Substances

Physical Properties

Measured without altering the substance.

• Volume: Space occupied.

• Viscosity: Resistance to motion.

• Density: Mass per unit volume.

• Phase Changes:   - Melting: Solid to liquid (Endothermic).   - Vaporizing: Liquid to gas (Endothermic).   - Sublimation: Solid to gas (Endothermic).   - Condensing: Gas to liquid (Exothermic).   - Freezing: Liquid to solid (Exothermic).   - Deposition: Gas to solid (Exothermic).

• Triple Point: Temp/pressure where all three states exist.

• Critical Point: Temp/pressure where liquid and gas phases become identical.

Chemical Properties

Measured by altering the substance.

• pH Scale: Measures acidity ($0$ to $14$).   - Acid: pH < 7; higher concentration of $H^+$ ions.   - Alkaline (Base): pH > 7; donate $OH^-$ ions.   - Neutral: $pH = 7$ (Water).

• Solubility: Ability to dissolve in a solvent.   - Solute: What is dissolved.   - Concentration: Ratio of solute to solvent.

Passive Transport and Water

• Osmosis: Solvent moves from low solute concentration to high solute concentration across a semipermeable membrane.

• Diffusion: Particles move from high to low concentration to reach equilibrium.

• Water ($H_2O$): Polar molecule (asymmetrical electron distribution). High heat capacity and high heat of vaporization. Ice is less dense than liquid water.

Chemical Reactions

• Ionic Bond: Electron transferred; attraction between positive/negative ions. Usually between metals (cations) and nonmetals (anions).

• Covalent Bond: Electrons shared.   - Nonpolar: Shared equally.   - Polar: Shared unequally.

Reaction Types

• Enzymes (Catalysts): Speed up reactions by lowering the required energy. Act on a substrate (e.g., amylase breaks down amylose).

Scientific Reasoning and Metrics

Metric System Conversions

• Length (Meters): $1000\,mm = 1\,m$, $100\,cm = 1\,m$, $1\,km = 1000\,m$.

• Mass (Grams): $1000\,mg = 1\,g$, $1\,kg = 1000\,g$.

• Volume (Liters): $1000\,ml = 1\,l$.

• Volume of Solid: $Length \times Width \times Height$ (measured in cubic meters).

Scientific Method

• Hypothesis: Educated guess that can be tested.

• Independent Variable: Manipulated variable (the presumed cause).

• Dependent Variable: Outcome variable (the effect).

• Control Variable: Variable that stays constant.

• Validity: Accuracy of results.

• Reliability: Reproducibility of results.