OCR A-Level Biology, Chemistry A-Level Bundled exam everything you need to pass

why do specimens need to be thin when observing them under a light microscope? - to allow light to pass through identify and explain the starch test - add iodine dissolved in potassium iodide solution to the sample - positive test = blue-black - negative test = orange-brown why is the structure...

what is water of crystallisation? - water molecules that make up part of the crystal structure of a solid define relative isotopic mass - the ass of an atom of an isotope of an element relative to one twelfth the mass of an atom of C-12 why is relative atomic mass written as a decimal? - it is a...

Magnification of light microscope - X1500 Resolution of light microscope - 0.2micrometers Magnification of a scanning electron microscope - X Resolution of scanning electron microscope - 0.002 micrometers Magnification of a transmission electron microscope - X1,000,000 Resolution of a transmiss...

Light microscope - An instrument that uses visible light and glass lenses to enable the user to objects magnified many times Compound light microscope - A light microscope which uses two lenses to magnify an object; the objective lens, which is placed near to the specimen and an eyepiece lens, th...

Classification - Arrangement of organisms into groups on the basis of shared features Taxonomy - The focus on physical similarities Species - A group of organisms that can interbreed to produce fertile offspring Why classify organisms? - To identify species, to predict characteristics, to find ev...

What two systems is the nervous system split into - - The central nervous system: made up of the brain and the spinal cord - The peripheral nervous system: made up of the that connect the CNS to the rest of the body What are the two functional systems of the peripheral nervous system? - - The som...

Abduction - Movement of the limbs away from the midline of the body. Acceleration - The rate of change in velocity. Acceleration (m/s//s) = (final velocity - initial velocity)/time. Actin-Myosin Filaments - Proteins which form the contractile units of skeletal muscle. Action Potential - Positive...

Nucleotide - Monomer that forms DNA and has a phosphate group, a sugar, and a nitrogencontaining base. DNA - A complex molecule containing the genetic information that makes up the chromosomes. RNA - A single-stranded nucleic acid that passes along genetic messages. Purines - Nitrogenous bases th...

Abiotic Factors - Rainfall pH Temperature Humidity/lack thereof Presence/level of pollution Areas with high biodiversity (7) - - Large number of successful species - Relatively benign climate with more ecological niches - Presence of many species - Few specific adaptations to enviroment - C...

What is excretion? - The removal of waste from the body that may build up and become toxic What are the main excretory products? - CO2, nitrogenous compounds and compounds such as bile pigments Why do we get rid of metabolic waste products? - They can alter the pH interfering with cell processes...

Metabolism - All of the chemical reactions that occur within an organism what is the need for specialised exchange surfaces? - multi-cellular organisms have a small surface area to volume ratio, they have increased metabolic rate, distance gases have to travel is further Specialised Exchange Surf...

What is metabolism? - The sum of all chemical reactions within cells and organisms What is an anabolic reaction? - One which builds a molecule or molecules What is a catabolic reaction? - One which breaks down a molecule or molecules Why do organisms need enzymes in their bodies? - To act as cata...

What does abiotic mean? - Non-living What does biotic mean? - living What is the definition of tropism? - Growth response to a stimulus What are some examples of an abiotic stimuli? - Light, water, gravity What are some examples of biotic stimuli? - touch, chemicals What is phototropism? - A pl...

What is the cell theory? - The cell is the basic unit of structure and function of all living organisms. Describe how to create a dry mount. - Solids are cut into thin slices (sectioning). The specimen should be placed on a slide and covered with a cover slip (small specimens can be viewed in this...