Comprehensive University Biology Study Guide

Principles of Biology: Life Processes and Homeostasis

The Seven Life Processes (MRS GREN): All living things perform certain functions that non-living things cannot do. * Movement: Moving to different places, moving parts of the body, or growing in certain directions (e.g., plants growing toward light). * Respiration: Releasing energy from food. This can be Aerobic (with $O_2$ ) or Anaerobic (without $O_2$ ). * Sensitivity: Sensing and feeling the conditions in your environment. * Growth: Increasing in size and producing more cells. * Reproduction: Creating copies (offspring) of the same species. * Excretion: Removing toxic waste produced by metabolism, such as $CO_2$ , urea, uric acid, and lactic acid. * Nutrition: Obtaining food. Animals eat other animals or plants; plants make their own food.
Homeostasis: Another critical process, not part of MRS GREN, which involves controlling internal body conditions to keep them constant. An example is maintaining a body temperature of $37\,^{\circ}\text{C}$ .

Cellular Structure and Function

Animal Cell Components: * Cell Membrane: Flexible, holds the cell together, is not fixed in shape. It controls what enters and leaves the cell, senses the environment, and communicates with other cells. * Cytoplasm: The liquid portion of the cell, composed mostly of water, nutrients, and waste. Most chemical reactions occur here. * Mitochondria: Perform aerobic respiration and release energy. * Nucleus: Contains genetic material (DNA). DNA is copied here and contains instructions to build proteins. * Ribosomes: Perform "Protein Synthesis" by building proteins based on DNA instructions.
Plant Cell Specific Components: * Cell Wall: Very rigid structure made of cellulose that provides a fixed shape. It prevents the cell from bursting when full of water and allows the plant to stay upright. * Chloroplast: Contains chlorophyll and performs photosynthesis to produce glucose (food). * Permanent Vacuole: Stores water and nutrients such as glucose and minerals.
Fungal Cell Components: * Includes mitochondria, a nucleus, ribosomes, cytoplasm, and a permanent vacuole. * The Cell Wall is made of Chitin. * In multicellular fungi (molds and mushrooms), cells fuse to form a structure called a Hypha (plural: Hyphae). In high concentrations, these form a network called Mycelium. * Fruiting Body: Developed from hyphae for reproduction, containing spores (single cells that spread to grow more fungi).
Bacterial Structure: * Cell Wall: Made of peptidoglycans; sometimes double. * Slime Layer: Made of proteins, fats, and sugars for protection and sticking to surfaces. * Flagellum: A protein "tail" that acts as a propeller for movement. * Cytoplasm: Contains the DNA. * DNA Chromosome: A circular strand of DNA not contained in a nucleus; much smaller than eukaryotic DNA. * Plasmids: Small, extra circular DNA chromosomes.
Viral Structure and Reproduction: * Viruses do not perform all MRS GREN processes; they are considered "semi-alive" and can only reproduce by infecting a host. * Envelope: A piece of cell membrane from a previous host used to avoid the immune system. * Protein Coat: Made of 2–3 kinds of proteins that protect genetic material. * Genetic Material: Either DNA or RNA; very small (5–10 genes). * Reproduction Cycle: 1. Virus enters a living cell. 2. DNA viruses insert DNA into the host nucleus; RNA viruses take over cell functions immediately. 3. Host cell is forced to use its energy and mechanisms to replicate viral genetic material and proteins. 4. Viral components are assembled into new viruses. 5. New viruses leave the cell to infect others.

Enzymes: Biological Catalysts

Function: Enzymes speed up chemical reactions and lower the activation energy ( $E_a$ ) required for a reaction to occur without being consumed themselves.
Mechanism of Action: 1. A Substrate binds to the Active Site of the enzyme. 2. This binding causes the enzyme to change shape slightly, forcing the substrate to react. 3. The enzyme releases the Product. 4. The enzyme returns to its original shape, ready for a new substrate.
Factors Affecting Enzyme Activity: * Temperature: Heat increases kinetic energy, increasing the rate of collisions. Every enzyme has an Optimum Temperature where it works fastest. Temperatures too far above the optimum cause the enzyme to denature (break apart), changing the active site shape permanently. * pH: Every enzyme has an Optimum pH. Deviations from this cause the enzyme to work slower or denature if the change is extreme. * Enzyme/Substrate Concentration: Affects frequency of collisions and how often reactions are catalyzed.
Properties: Enzymes are proteins, highly specific (catalyzing only one type of reaction), and act as biological catalysts.

Respiration and ATP

Definition: The process of releasing energy from food (primarily glucose). Cells can also convert fats and proteins (in emergencies).
Types of Respiration: * Aerobic Respiration: * Uses oxygen ( $O_2$ ). * Provides more energy (efficient). * Occurs in the mitochondria. * Word Equation: $\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + (\text{Energy})$ * Chemical Equation: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + (30-36\, \text{ATP})$ * Anaerobic Respiration: * Without oxygen ( $O_2$ ). * Provides little energy but is simple and fast. * Occurs in the cytoplasm. * Lactic Acid Fermentation (Animals): $\text{Glucose} \rightarrow \text{Lactic Acid} + (\text{Energy})$ * Alcohol Fermentation (Yeast/Plants): $\text{Glucose} \rightarrow \text{Ethanol} + \text{Carbon Dioxide} + (\text{Energy})$
ATP (Adenosine Tri-Phosphate): A chemical substance used by cells to carry energy. When energy is needed, ATP adds water ( $H_2O$ ) and breaks down into ADP (Adenosine Di-Phosphate) and a free phosphate group ( $P$ ). The breaking of this bond releases energy used for cell functions. * Reaction: $ATP + H_2O \rightarrow ADP + P + \text{Energy}$ * Recharging: $ADP + P + \text{Energy (from respiration)} \rightarrow ATP + H_2O$

Biological Transport and Cell Specialization

Transport Mechanisms: 1. Diffusion: Movement of substances from high to low concentration without using energy until particles are spread evenly. 2. Active Transport: Movement of substances using energy (ATP), often from low to high concentration or for large molecules that cannot pass the membrane. 3. Osmosis: Movement of water across a semi-permeable membrane from high water concentration (low solute) to low water concentration (high solute) without using ATP.
Factors Affecting Rate: Large surface area, short distance, large concentration gradient, and high temperature increase rates. * SA:V Ratio: As organisms get larger, their surface-area-to-volume ratio ( $SA:V$ ) decreases, making diffusion less efficient.
Osmotic Environments: * Hypotonic: Concentration of water is higher outside; water moves in. Animal cells may burst (lyse); plant cells become Turgid. * Hypertonic: Concentration of water is lower outside; water moves out. Animal cells shrivel; plant cells become Plasmolyzed. * Isotonic: Water concentration is equal; no net movement. Plant cells are Flaccid.
Cell Differentiation: The irreversible process where cells change shape and structure (expressing different proteins) to perform specific functions.
Stem Cells: Unspecialized cells that produce more cells via mitosis before specializing. * Totipotent: Can specialize into any cell type. * Pluripotent: Can specialize into most cell types. * Multipotent: Can specialize into some cell types.
Organization: Cells $\rightarrow$ Tissues $\rightarrow$ Organs $\rightarrow$ Organ Systems $\rightarrow$ Organisms.

The Respiratory System and Gas Exchange

Functions: 1. Ventilation: Inhaling and exhaling air. 2. Gas Exchange: $O_2$ diffusing into blood and $CO_2$ diffusing into lungs.
Anatomy: * Nose/Mouth: Filter (hair), warm (blood), and moisten (mucus) air. * Trachea: Walls reinforced with cartilage rings to prevent collapse; lined with ciliated epithelial cells and mucus. * Alveoli: Small air sacs where gas exchange occurs. They are one-cell thin, surrounded by capillaries, and have a large surface area.
Ventilation Mechanism: * Inhaling: Intercostal muscles contract, ribcage moves up and out, diaphragm flattens, lung volume increases, pressure decreases, and air moves in. * Exhaling: Intercostal muscles relax, ribcage moves down and in, diaphragm becomes dome-shaped, lung volume decreases, pressure increases, and air moves out.
Diseases: * Bronchitis: Airways blocked by mucus. * Asthma: Alveoli surface covered in mucus; walls thicken, increasing diffusion distance. * Emphysema: Alveoli lose elasticity and become smooth, reducing surface area. * Carbon Monoxide Poisoning: $CO$ replaces $O_2$ in red blood cells permanently.

Digestion and Nutrition

Food Categories: * Carbohydrates: Quick/slow energy. Simple (glucose, fructose), double (sucrose, maltose, lactose), and polysaccharides (starch, glycogen, cellulose). * Lipids (Fats): Long-term energy, protection, insulation. Digested into glycerol and fatty acids. * Proteins: Growth and repair. Made of amino acids. * Nucleic Acids: DNA/RNA. Made of nucleotides. * Minerals/Vitamins: Essential for functions like bone strength (Calcium), $O_2$ transport (Iron), and immune health (Vitamin C/D). * Fibre: Undigestible cellulose used to prevent blockages in the intestines.
Digestive Functions: Ingestion, Digestion (mechanical and chemical via enzymes), Absorption (in villi/microvilli), and Egestion (feces removal).
Digestive Enzymes: * Amylase/Carbohydrase: Starch $\rightarrow$ Maltose/Glucose. * Protease (e.g., Pepsin, Trypsin): Proteins $\rightarrow$ Amino acids. * Lipase: Lipids $\rightarrow$ Fatty acids and glycerol.
Calorimetry: Measuring energy content. Energy (Joules) = $(\Delta \text{Temp}) \times \text{Mass of Water} \times 4.2 / \text{Mass of Food}$ .

The Circulatory System

Components: Heart, blood vessels (arteries, veins, capillaries), and blood (plasma, RBCs, WBCs, platelets).
Heart Anatomy: Includes Vena Cava (bringing deoxygenated blood), Right Atrium/Ventricle (pumping to lungs), Pulmonary vessels, Left Atrium/Ventricle (pumping to body), and Aorta. The Septum prevents mixing of oxygenated and deoxygenated blood.
Cardiac Cycle: 1. Atria fill; atrioventricular valves closed. 2. Atria contract; valves open; ventricles fill. 3. Ventricles contract; semilunar valves open; blood exits via arteries.
Blood Vessels: * Arteries: High pressure, thick muscled walls, narrow lumen. * Veins: Low pressure, thin walls, wide lumen, valves to prevent backflow. * Capillaries: One-cell thin for diffusion.
Blood Cells: * RBCs: Biconvex, no nucleus, contain haemoglobin for $O_2$ transport. * WBCs (Innate/Acquired): Phagocytes eat pathogens; Lymphocytes (B and T) produce antibodies and remember pathogens. * Clotting: Platelets convert Fibrinogen to sticky Fibrin to form a scab.

Coordination and Control

Nervous System: * Pathway: Stimulus $\rightarrow$ Receptor $\rightarrow$ Coordination (CNS) $\rightarrow$ Effector $\rightarrow$ Response. * Neurons: Sensory (to CNS), Intermediate (processing), and Motor (to effector). * Structure: Cell body, dendrites (receive), axon (carry signal), axon terminals (send), and myelin insulation. * Synapse: Signal crossing the gap via neurotransmitters stored in vacuoles and released via exocytosis.
Reflex Arc: Rapid, involuntary response involving the spinal cord to allow faster action than the brain could process.
The Eye: * Iris Reflex: Circular/radial muscles control pupil size to regulate light entry. * Accommodation Reflex: Ciliary muscles and suspensory ligaments change lens thickness to focus near or far.
Endocrine System: Uses hormones (chemical signals) in blood. * Pancreas: Insulin (lowers blood glucose) and Glucagon (raises it). * Pituitary Gland: ADH (water control), FSH/LH (reproduction). * Adrenal Gland: Adrenaline (fight-or-flight). * Thyroid: Thyroxine (metabolic rate).

The Urinary System and Homeostasis

Nephron Function: 1. Ultrafiltration: Occurs in the Glomerulus inside the Bowman's Capsule. Small molecules (water, urea, glucose, minerals) are filtered out under high pressure. 2. Selective Reabsorption: Occurs in the tubules. Glucose is fully reabsorbed; water and minerals are reabsorbed as needed for homeostasis.
Water Control (Negative Feedback): If blood water is low, the Hypothalamus informs the Pituitary to release ADH. ADH makes the kidney's collecting ducts more permeable, reabsorbing more water back into the blood.
Thermoregulation: * Hot: Vasodilation (more blood to skin), sweating (evaporative cooling), and hairs laying flat. * Cold: Vasoconstriction, shivering (muscle respiration heat), and hairs standing up (insulation).

Human Reproduction

Gestation: Lasts 40 weeks (9 months). The embryo (to 8 weeks) then foetus is supported by the Placenta (diffusion of nutrients/ $O_2$ ) and Amniotic Sack (protection).
Gametogenesis: * Egg Cell: Large, nutrient-rich cytoplasm; Zona Pellucida (jelly coat) becomes impermeable after one sperm enters. * Sperm Cell: Small, mobile (tail), many mitochondria, acrosome containing enzymes to digest the egg's jelly coat.
Hormonal Regulation: * FSH: Stimulates egg maturation and oestrogen secretion. * LH: Triggers ovulation and progesterone secretion. * Oestrogen: Thickens uterus lining. * Progesterone: Maintains uterus lining.

Scientific Skills and Tests

Experimental Design (CORMS): Change (variable), Organism (standard), Repeat (reliability), Measure (dependent variable), Same (controlled environmental variables).
Accuracy vs. Reliability: Accuracy is how close values are to reality; Reliability is consistency through repeats (at least 3) and excluding anomalies.
Chemical Indicators: * $CO_2$ : Limewater turns cloudy; Hydrogencarbonate indicator turns yellow. * Starch: Iodine turns blue-black. * Glucose: Benedict's turns brick red (needs heat). * Protein: Biuret turns violet. * Lipids: Ethanol emulsion turns white/cloudy.