Explain the role of biological principles in fish harvesting and processing. Also, list two factors affecting substance movement across cell membranes.

3. a) Biological principles are crucial in fish harvesting and processing to ensure sustainability, quality, and safety. Harvesting: Population dynamics: Understanding fish life cycles, growth rates, and reproductive patterns helps set sustainable catch limits and avoid overfishing. Ecology: Knowledge of fish habitats and ecosystems allows for selective fishing methods that minimize bycatch and environmental damage. Physiology: Understanding fish stress responses helps in handling techniques that reduce injury and improve post-harvest quality. Processing: Microbiology: Applying principles of microbial growth and spoilage helps in preservation methods like chilling, freezing, salting, and smoking to extend shelf life and prevent foodborne illnesses. Biochemistry: Knowledge of enzyme activity and protein denaturation guides processing techniques to maintain texture, flavor, and nutritional value. Hygiene: Implementing sterile techniques and sanitation protocols prevents contamination and ensures food safety. 3. b) Two factors that affect the movement of substances across cell membranes are: Concentration gradient: Substances move from an area of higher concentration to an area of lower concentration. Size of molecules: Smaller molecules generally pass through the membrane more easily than larger ones. 4. a) Four significances of the fluid mosaic structure of the cell membrane are: Selective permeability: The lipid bilayer and embedded proteins allow the membrane to control which substances enter and exit the cell, maintaining internal homeostasis. Cell recognition and communication: Glycoproteins and glycolipids on the outer surface act as markers for cell-to-cell recognition and play roles in cell signaling. Flexibility and fluidity: The fluid nature allows the cell to change shape, grow, and move, and enables processes like endocytosis and exocytosis. Enzymatic activity: Some membrane proteins function as enzymes, catalyzing metabolic reactions at the cell surface. 4. b) Some organisms are said to be asymmetric because they lack any plane of symmetry. Their body parts are not arranged around a central axis or in mirror images. An example is a sponge. 5. a) Diffusion: The net movement of particles from an area of higher concentration to an area of lower concentration, down a concentration gradient, until equilibrium is reached. 5. b) Osmosis: The net movement of water molecules across a selectively permeable membrane from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration). 5. c) Active transport: The movement of molecules or ions across a cell membrane against their concentration gradient, from a region of lower concentration to a region of higher concentration, requiring energy (ATP) and specific carrier proteins. 5. d) Endocytosis: The process by which cells engulf substances from their external environment by enclosing them in a portion of the cell membrane, which then buds off to form a vesicle inside the cell. 5. e) Exocytosis: The process by which cells release substances from inside the cell to the external environment. A vesicle containing the substance fuses with the cell membrane, expelling its contents. 6. a) Biology is related to various other fields of work: Medicine: Understanding biological processes, diseases, and human physiology is fundamental to diagnosing, treating, and preventing illnesses. Agriculture: Knowledge of plant and animal biology is essential for crop improvement, livestock breeding, pest control, and sustainable farming practices. Environmental Science: Biology helps in studying ecosystems, biodiversity, conservation, and the impact of human activities on the environment. Biotechnology: Applying biological principles to develop new technologies, such as genetic engineering, drug discovery, and biofuels. Forensics: Using biological evidence like DNA, blood, and tissue samples to solve crimes and identify individuals. 6. b) Five examples of diffusion and osmosis in plants and animals: Diffusion in animals: Oxygen moving from the lungs into the bloodstream. Carbon dioxide moving from the bloodstream into the lungs. Neurotransmitters diffusing across a synapse. Diffusion in plants: Carbon dioxide entering leaves through stomata for photosynthesis. Oxygen leaving leaves through stomata as a byproduct of photosynthesis. Osmosis in animals: Water absorption in the small and large intestines. Kidneys regulating water balance in the blood. Osmosis in plants: Water uptake by root hair cells from the soil. Maintenance of turgor pressure in plant cells, preventing wilting.