b1-cell biology

• eukaryotic cells have a nucleus, mitochondria, ribosomes, and a cell membrane - plant and animal cells
• prokaryotic cells are smaller than eukaryotic cells and have a single circular chromosome - they do not have a nucleus and are a simple cell e.g bacteria
• aerobic respiration occurs in the mitochondria in sub-cellular structures
• a fine adjustment knob is used to focus the lens until a clear image is displayed on a light microscope
• electron microscopes have a higher resolution and higher magnification than light microscope
• resolution is the ability to distinguish between two points
• magnifications is the process of making something bigger
• root hair cells are specialised for absorbing water and minerals from the soil
• the function of a sperm cells is to transport the male DNA to the female DNA in eggs for reproduction
• chromosomes are found in pairs
• chromosomes are coiled up in lengths of DNA, which carry a large number of genes
• binary fission is a type of simple cell division used by bacteria to multiply
• mean division time is the average amount of time it takes for one bacterial cell to divide into two bacterial cells
• zone of inhibition is the clear area that forms around a disk on an agar plate when bacteria die
• cultures are incubated at no higher that 25 degrees Celsius to decrease the risk of harmful bacteria growing
• a stem cell is an undifferentiated cell which has the ability to become one of many different types of cell or more stem cells
• stem cells are found in the bone marrow of an adult human and they turn into specific cells such as blood cells.
• plant stem cells are found in the meristem tissue
• oxygen and carbon dioxide can diffuse through the cell membrane
• the bigger the concentration gradient, the faster the rate of diffusion
• osmosis requires a partially permeable membrane
• osmosis is the movement of water
• active transport is the movement of substances from a low concentration to a high concentration using energy from respiration
• active transport need energy osmosis does not
• active transport can move many substances, osmosis only moves water
• the larger an organism the smaller the surface area to volume ratio
• single-celled organisms with a large surface area to volume ratio can easily exchange substances with he environment without adaptions
• oxygen, water vapour and carbon dioxide are included in gas exchange in a leaf
• alveoli allow the efficient/rapid transfer of oxygen to the blood and the removal of waste carbon dioxide from the blood