A-Level Biology - Ocr Already Passed

What is a laser scanning confocal microscope used for? {Ans: Creating a high resolution, high contrast image, at different depths of the specimen.}Give four features of meristematic cells that means they can differentiate easily {Ans: Thin walls with very little cellulose; no chloroplasts; no large vacuole; divide by mitosis and have the ability to differentiate into many cell types}Describe the effects of ethanol on membrane structure {Ans: Non-polar ethanol molecules can insert themselves into the bilayer disrupting the structure, meaning the bilayer becomes more fluid and permeable}Why are there so many mitochondria in cardiac muscle? {Ans: Supply energy for contraction}Describe how the charge inside a RBC is maintained when hydreogencarbonate ions diffuse into the plasma {Ans: Chloride ions move into the RBCs from the plasma (chloride shift)}Explain the orientation of phospholipids within the bilayer {Ans: Hydrophilic phosphate heads are orientated outwards (towards water); hydrophobic fatty acid tails are orientated inwards (away from water)}Define bulk transport and give two examples {Ans: The movement of large molecules that are too big to pass across the plasma membrane. Endocytosis (phagocytosis or pinocytosis) brings large molecules INTO the cell, enclosed in a vesicle. Exocytosis transports large molecules