Biology PDF - Key Concepts and Definitions

# Biology ## Key Terms * **Movement**: Change position or location * **Respiration**: Release energy from food * **Sensitivity**: React to the environment * **Growth**: Increase in size * **Reproduction**: Produce offspring * **Excretion**: Removal of waste * **Nutrition**: Require nutrients for g...

# Biology ## Key Terms * **Movement**: Change position or location * **Respiration**: Release energy from food * **Sensitivity**: React to the environment * **Growth**: Increase in size * **Reproduction**: Produce offspring * **Excretion**: Removal of waste * **Nutrition**: Require nutrients for growth and energy * **Eukaryotic**: Multicellular, contain a nucleus ## Categories of Organisms ### Plants * Multicellular * Contain chloroplasts for photosynthesis * Have cellulose cell walls * Store carbohydrates as starch or sucrose ### Animals * Multicellular * No chloroplasts, cannot photosynthesize * No cell walls * Store carbohydrates as glycogen ### Fungi * Cannot photosynthesize * Organized into mycelium made of hyphae (thread-like, release enzymes to absorb nutrients) * Cell walls made of chitin * Store carbohydrates as glycogen ### Protoctists * Single-celled ## Levels of Organization 1. Organelles 2. Cells 3. Tissues 4. Organ 5. Organ System ## Prokaryotic ### Bacteria * Microscopic & single-celled * Have cell wall, cell membrane, cytoplasm and plasmid * Lack a nucleus but have a circular DNA chromosome * Feed off living or dead matter ## Pathogens Microorganisms that cause a disease to its host (eg. Virus, bacteria, fungi) ### Virus * Not living organisms * Reproduce only inside living cells * No cellular structure, but have a protein coat & contain either DNA or RNA ## Cell Structures * **Nucleus**: Contains DNA and controls cell activity * **Cell wall (in plants)**: Supports the cell, prevents it from bursting * **Cell membrane**: Controls what goes in and out the cell * **Cytoplasm**: Site of metabolic reactions * **Vacuole (in plants)**: Contains cell sap, stores cell nutrients (sugar and proteins) * **Ribosome**: Sequence of amino acids where protein synthesis occurs * **Mitochondria**: Site for aerobic respiration to release energy * **Chloroplast (in plants)**: Contain chlorophyll, site of photosynthesis ## Importance of Cell Differentiation Enables tissues and organs to perform specific functions essential for complex tasks in multicellular organisms. ## Biomolecules * **Carbohydrates**: Starch and glycogen from simple sugars (carbon, hydrogen, oxygen) - CHO * **Lipids (fats and oils)**: Fatty acids and glycerol (carbon, hydrogen, oxygen) - CHO * **Proteins**: Amino acids (carbon, hydrogen, oxygen, nitrogen, sulphur) - CHONS ## Stem Cells ### Advantages of Stem Cells in Medicine * Replace damaged cells to treat diseases * Enable organ regrowth and regeneration ### Disadvantages of Stem Cells in Medicine * Risk of immune rejection * High technical and financial cost ## Tests **Glucose test (Benedict's solution)** * Heat in water bath * If present - yellow/green if amount is low, red if amount is high. * If absent - remains blue **Protein test (Biuret Solution)** * If present - turns purple * If absent - remains light blue **Starch test (Iodine solution)** * If present - blue/black colour * If absent - remains orange or yellow **Fat test (emulsion test)** * Mix sample with ethanol then add water * If present - cloudy white emulsion ## Enzymes * **Catalyst**: Chemical which speeds up a reaction without being used up itself. * **Enzymes**: Proteins that function as biological catalysts (eg. amylase) * **Substrate**: The molecule an enzyme acts on ### Lock and Key Model: 1. Substrate enters enzymes active site 2. Enzyme and substrate bind, reaction takes place and enzyme-substrate complex formed 3. Products form which leave active site 4. Enzyme is free to act on more substrate molecules ### Factors Affecting Enzymes * **Temperature**: Optimum is 27°C. As temperature increases, kinetic energy increases, number of collisions increase, more enzyme-substrate complexes formed, enzyme activity increases. If temperature rises above optimum, enzyme denatures, shape of active site changed. * **pH**: Optimum pH 7, otherwise extreme pH causes enzyme to denature. * **Substrate concentration**: High concentrations increase reaction rates until saturation occurs. * **Enzyme concentration**: More enzymes lead to higher reaction rate if substrate is available. ### Features of Enzymes * **Specific to substrate** * **Reusable** * **Sensitive to environmental conditions (eg. pH)** ### Investigating Effect of Temperature on Enzyme Activity * Add amylase to starch solution * Place in water baths at different temperatures * Test for starch presence at intervals using iodine solution ### Types of Reactions Caused by Enzymes * **Catabolic**: Breaking a large molecule into smaller ones * **Anabolic**: Building up large molecules from small ones ### Activation Energy Amount of energy required for a reaction to occur ### Energetic Reactions **Anaerobic respiration** * Glucose → ethanol + carbon dioxide * Glucose → lactic acid **Aerobic respiration** * Glucose + oxygen → carbon dioxide + water * H12O6 + 6O2 → 6CO2 + 6H2O ## Cell Transport * **Diffusion**: Movement of particles from high to low concentration, down the gradient * **Osmosis**: Movement of water molecules through a semi-permeable membrane (dilute → concentrated) * **Active transport**: Movement of substances against the concentration gradient, requires energy (ATP) ### Factors Affecting the Rate of Movement * **Surface area to volume ratio**: Smaller cells diffuse more efficiently * **Distance**: Shorter diffusion distance increases the rate * **Temperature**: Higher temperatures speed up movement ## Photosynthesis Converts light energy into chemical energy stored in glucose * Carbon dioxide + water → glucose + oxygen * 6CO2 + 6H20 → C6H12O6 + 6O2 ### Factors Affecting Rate of Photosynthesis * **CO2 concentration**: More CO2 increases the rate * **Light intensity**: More light increases the rate * **Temperature**: Rate increases with temperature due to faster enzyme activity ## Cellular Respiration Breaks down glucose to release energy * **Cellulose**: Carbohydrate made of glucose, used to strengthen cell walls * **Starch**: Carbohydrate used for long term storage ### Uses of Glucose * Produce cellulose * Make amino acids * Cellular respiration ## Transpiration Evaporation of water (loss) through the stomata of the leaves ### Transpiration Pull 1. Roots take in water by osmosis 2. Water passes up the stem through the xylem 3. Water moves from cell to cell by osmosis 4. Water leaves through stomata by transpiration ### Function of Carbohydrates * Glucose used as fuel * Form cell wall * Store energy ## Leaf Adaptations for Photosynthesis * Large surface area to absorb more light * Thin structure to reduce diffusion distance for gases * Chloroplast concentrated in cells near light source * Stomata for regulated gas exchange ## Mineral Requirements * **Magnesium**: Production of chlorophyll * **Nitrates**: For plants to synthesize amino acids, needed for growth and repair * **Phosphate**: Makes DNA and other compounds * **Potassium**: Needed for enzymes of respiration and photosynthesis ## Investigating the Effect of a Variable on an Organism * **Change**: Independent variable * **Organism**: What organisms will be involved? Species control * **Repeat**: Repeat at least 3 times. How will you make sure it is reliable? * **Measurement 1**: What to measure? What equipment is used? * **Measurement 2**: How and how long to measure? * **Same**: Control variables to ensure a fair test ## Palisade & Spongy Mesophyll * **Palisade mesophyll**: Consists of tightly packed columnar cells * **Spongy mesophyll**: Has a random arrangement of irregularly shaped cells ## Water Potential * **Hypotonic**: High number of solutes, low water potential. Water moves out, causing it to shrink. Plasmolysis in plant cells, crenation in animal cells. * **Hypertonic**: Low number of solutes, with high water potential. Water moves in. Animal cells expand & burst, plant cells become turgid/normal. * **Isotonic**: Equal number of solutes and water potential, equal moving in and out, equilibrium. Plant cells are flaccid, animal cells are normal ## Graphs of Photosynthesis Rates * **Light intensity**: The rate of photosynthesis increases as light intensity increases until reaching a plateau. * **CO2 concentration**: The rate of photosynthesis increases as CO2 concentration increases until reaching a plateau. * **Temperature**: The rate of photosynthesis increases until reaching an optimum temperature, then decreases. ## Cell Structure Comparison Table | | Animal | Plant | Fungi | Bacteria | |---|---|---|---|---| | Nucleus | ✓ | ✓ | ✓ | X | | Cell membrane | ✓ | ✓ | ✓ | ✓ | | Cell wall | X | ✓ | ✓ | ✓ | | Cytoplasm | ✓ | ✓ | ✓ | ✓ | | Ribosomes | ✓ | ✓ | ✓ | ✓ | | Mitochondria | ✓ | ✓ | ✓ | X | | Chloroplast | X | ✓ | X | X | | Vacuole | X | ✓ | ✓ | X | | Plasmid | X | X | ✓ | ✓ | ## Digestive Enzymes 1. **Amylase**: Salivary glands and pancreas, breaks carbohydrates into simple sugars. Substrate is starch. 2. **Lipase**: Pancreas & small intestine, breaks down fat for energy. Substrate is lipids (fats & oils). 3. **Protease/Pepsin**: Stomach lining, begins protein digestion. Substrate is proteins ## Carbohydrates * **Monosaccharides**: One sugar (eg. glucose, fructose) * **Disaccharides**: Two sugars (eg. sucrose, lactose) * **Polysaccharides**: Many sugars (eg. starch, cellulose) ## Diagram of a Yeast Cell The image shows a typical yeast cell with the following labeled structures: cell wall, cell membrane, cytoplasm, nucleus, ribosomes. ## Diagram of a Plant Cell The image shows a typical plant cell with the following labeled structures: cell wall, cell membrane, cytoplasm, nucleus, ribosomes, chloroplasts, vacuole. ## Diagram of a Bacteria Cell The image shows a typical bacterial cell with the following labeled structures: cell wall, cell membrane, cytoplasm, bacterial chromosome, plasmid, ribosomes. ## Diagram of an Animal Cell The image shows a typical animal cell with the following labeled structures: cell membrane, cytoplasm, nucleus, mitochondria, ribosomes.