paper 1 bio

• multicellular organisms require new cells for growth, development and repair
• the spongy mesophyll is a tissue
• a microorganism is a very small organism. they include: bacteria, fungi, protists, and viruses
• a stem cell is an undifferentiated cell, capable of becoming any other type of cell
• a root hair cell has: a large surface area to absorb water and mineral ions, mitochondria to provide energy for active transport and protein channels to transport water and mineral ions to the cell
• smoking increases the risk of: lung, mouth, stomach and breast cancer
• differentiation is the process by which cells become specialised. it can involve the cell changing shape, size and changing the combinations of organelles in contains
• widespread vaccination can result in herd immunity, which helps prevent outbreaks of disease. This means the disease is very unlikely to spread from an infected person to someone who is not vaccinated because almost everyone else is vaccinated
• PH is a measure of the hydrogen ion concentration or a measure of acidity
• The upper epidermis is transparent to allow light to pass through and reach the palisade mesophyll cells - which is where photosynthesis happens
• 'Against the concentration gradient' means movement from lower concentration to higher concentration.
• the larger the organism, the lower the surface area to volume ratio will be
• object size = image size/magnification
• an STD is a sexually transmitted disease
• aspirin is a painkiller. it is effective at reducing fevers
• protists are eukaryotic organisms, and are mostly unicellular
• electron microscopes have a higher magnification than light microscopes and can see subcellular structures
• replacement valves can be: mechanical or biological
• a biological heart valve may be rejected because the immune system may identify biological material as 'foreign'
• anaerobic respiration in plants and fungi: glucose -> ethanol + carbon dioxide
• ventricles have thicker muscular walls as the have to pump the blood around the lungs or body, whereas the atria only have to pump blood to the ventricles
• the phloem tissue is made of elongated cells which form long tubes
• digitalis treats heart failure
• osmosis: the movement of water molecules from a region of high water concentration to a region of low water concentration
• region of an enzyme that binds to the substrate is active site
• unicellular organisms are made of just one cell
• proteins are made from carbon, hydrogen, oxygen and nitrogen
• stents are tube-shaped devices that are placed inside the coronary arteries and then expanded to keep the arteries open.
• cm to mm: 1 cm = 10 mm
• transpiration refers to the evaporation of water from the surface of a plant
• natural resting heart rate: 70 bpm
• an element is a substance that cannot be broken down into simpler substances by chemical means.
• a molecule is an atom or group of atoms which have combined chemically
• the human body is mostly composed of water (65%)
• a compound is a substance formed when two or more elements chemically combine.
• xylem tissue transports water and mineral ions from the roots to the leaves
• multicellular organisms consist of multiple cells
• induced fit model enzymes: the active site is slightly altered to fit the substrate
• osmosis is a passive process because it doesnt require any energy from the cell
• most human cells have 23 pairs of chromosomes