Bio paper 1

• All life consists of cells
• Cells can be seen with a normal light microscope, but subcellular structures are not visible
• Electron microscopes allow us to see finer details of organelles
• Magnification is equal to image size divided by object size
• Eukaryotic cells have a nucleus where DNA is found (e.g., plant and animal cells)
• Prokaryotic cells do not have a nucleus and their DNA is found in a plasmid
• Both eukaryotic and prokaryotic cells contain similar organelles
• Cell membrane keeps everything inside the cell and is semi-permeable
• Plant cells and most bacteria have an extra cell wall made of cellulose
• Cytoplasm is the liquid where most chemical reactions take place
• Mitochondria is where respiration takes place
• Ribosomes are where proteins are synthesized
• Plant cells also contain chloroplasts for photosynthesis and a permanent vacuole for storing sap
• Bacteria multiply by binary fission, doubling in number every 10 minutes
• Stem cells are found in human and animal embryos and the meristem of plants
• Diffusion is the movement of molecules from high to low concentration
• Osmosis is the diffusion of water across a semi-permeable membrane
• Active transport uses energy to move substances against a concentration gradient
• Tissues form organs, and organs work together in organ systems
• Enzymes are biological catalysts that break down larger molecules into smaller ones
• Enzyme activity increases with temperature until denaturation occurs
• Food tests can identify nutrients like starch, sugars, and proteins
• The respiratory system involves breathing and gas exchange
• The circulatory system is a double circulatory system with oxygenated and deoxygenated blood
• The heart pumps blood to the lungs for oxygenation and then to the body
• Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood towards the heart
• Capillaries have one-cell thick walls for fast diffusion of molecules
• The coronary artery supplies the heart muscle with oxygen and nutrients
• The heart is a muscle that needs its own supply of oxygen and blood to function properly
• The coronary artery delivers oxygenated blood to the heart muscle
• Blockage of the coronary artery by fatty deposits can lead to a heart attack, known as coronary heart disease (CHD)
• Stents are small tubes inserted into blood vessels to keep them open for proper blood flow
• Statins are drugs that reduce cholesterol levels, which helps reduce the buildup of fatty deposits in blood vessels
• Faulty heart valves can cause backflow, which can be replaced with artificial valves
• Blood carries red blood cells, white blood cells, and platelets
• White blood cells combat infections, platelets clot wounds to stop bleeding
• Cardiovascular disease (CVD) is a non-communicable disease caused by internal factors
• Non-communicable diseases like obesity, excessive sugar intake, smoking, lack of exercise, and alcohol consumption can lead to various health issues
• A carcinogen is a substance that increases the risk of cancer
• Cancer is the result of damaged cells dividing uncontrollably, leading to tumor formation