SP1 Key Concepts in Biology Flashcards
Define an electron microscope
uses electrons to see smaller things in much more detail - has a higher magnification and resolution
Define a light microscope
pass light through the specimen to show us things like nuclei and chloroplasts
Define resolution
How well a microscope distinguishes between two points that are close together. A higher resolution means that the image can be seen more clearly
Why can some cells be seen with an electron but not a light microscope?
Electron microscopes see things in more detail
Formula for total magnification
total magnification = eyepiece lens magnification x objective lens magnification
Formula for sizes and magnification
magnification = image size / real size
Formula triangle with image size on top
List the units and conversions
Millimetre (mm) x1000 = Micrometre (um) x1000 = Nanometre (nm) x 1000 = Picometre (pm)
List 5 parts to an animal cell
Nucleus, Cytoplasm, Cell membrane, Mitochondria, Ribosomes
List 3 additional parts to a plant cell
Rigid cell wall, Vacuole, Chloroplasts
Define ribosomes
these are involved in the translation of genetic material in the synthesis of proteins
Define large vacuole
contains cell sap and maintains the internal pressure to support the cell
Define mitochondria
where most of the reactions for respiration take place
Define chloroplasts
where photosynthesis occurs - they contain a green substance called chlorophyll
Define cytoplasm
gel-like substance where most chemical reactions occur in the cell - it also contains enzymes
Define nucleus
contains genetic material that controls the activities of the cell
How are sperm cells adapted to their function?
- has long tail to help it swim
- lots of mitochondria to provide it with energy to swim
- acrosome at front of head, where it stores enzymes needed to digest its way through membrane of egg
- haploid nucleus
How are egg cells adapted to their function?
- contains nutrients in cytoplasm to feed embryo
- haploid nucleus
- straight after fertilisation, its membrane changes structure to stop any more sperm getting in. This makes sure the offspring has the right amount of DNA
How are ciliated epithelial cells adapted to their function?
Cilia are on the top surface of the cell; the cilia beat to move substances upwards, moving mucus up to the throat where is can be swallowed and doesn’t reach the lungs
List 5 parts to a bacterial cell
Chromosomal DNA, Ribosomes, Cell membrane, Plasmid DNA, Flagellum
Define plasmid DNA
small loops of extra DNA that aren’t part of the chromosome. Plasmids contain genes for things like drug resistance, and can be passed between bacteria
Define flagellum
hair-like structure that rotates to make a bacterium move away from harmful substances or towards beneficial things like nutrients
Define eukaryotes
complex cells
Define prokaryotes
smaller, simpler cells that make single-celled organisms
Define enzymes as biological catalysts
Enzymes are catalysts in the body used to speed up chemical reactions
Why are enzymes important as catalysts for life processes?
Enzymes speed up chemical reactions in the body, and reduces the need for high temperatures
Test for Starch
Add iodine : if starch is present, the sample will turn from browny-orange to a dark blue-black colour
Test for Sugars
Use Benedict’s Reagent : higher conc. of sugar, the further the colour change will go from blue - green - yellow - orange - brick red
Test for Proteins
Use the Biuret Test : add some potassium hydroxide to make solution alkaline. Then add some copper sulfate. If there is protein, the solution will turn purple. No protein = stays blue
Test for Lipids
Emulsion Test : shake test substance with ethanol and pour into water. If lipids are present, they will precipitate and show up as a milky emulsion
