Bio Flashcards
Characteristics of living organisms
MRSGREN
Move
Respire - releases energy
Sense - are able to respond to changes in their surrounding environments
Grow
Reproduce
Excrete - they can excrete waste products such as urine
Nutrition - they are able to absorb nutrition e.g. proteins, fats and carbohydrates , provides them with energy and raw materials for growth and repair
Levels of organisation
Organelles Cells Tissues Organs Organ systems
Organelles
Organelles - parts of cells
Animals-
Nucleus: the control center of the cell, contains DNA and genetic material
Mitochondria: the site of respiration - where energy is produced
Cell membrane: controls the movement of substances in and out of the cell
Cytoplasm: where most chemical reactions within the cell take place - enzymes
Ribosomes: where protein is produced
Plants-
Cell wall: Made of cellulose, protects and supports the cell
Vacuole: contains nutrients and salts
Chloroplast: the site of photosynthesis, contains a green chlorophyll which contributes to photosynthesis
Plant characteristics
Plants- Multicellular organisms Contain Chlroplasts. They produce food through photosynthesis Contains cell wall and vacuole Stores carbohydrate as starch Examples: sunflower, roses
Animals
Multicellular organisms Can move around Stores carbohydrate as glycogen Examples: mammals and insects they have nervous coordination
Fungi
Some are unicellular
Some are made of thread like structures called mycelium that are made of hyphae
cell walls are made of chitin
Gets nutrition saprotrophic, meaning they secrete digestive juices (extracellular enzymes) onto food containing nutrients and the absorb the nutrients
Also stores carbohydrate as glycogen
Example: Yeast
Protoctist
dustbin kingdom
Unicellular and microscopic
Some are similar to plant cells, some similar to animals
Example: Amoeba, Chlorella
Bacteria
Unicellular organisms
contains circular chromosome of DNA
Some can photosynthesize but most feed off other organsims both living and dead
Example: Lactobacillus
Virus
Contains only a protein coat and a strand of DNA, no nucleus and other organelles
Even smaller then Bacteria, are particles instead of cells
Not considered a living organism as it cannot respire, excrete and can only reproduce within another living host
Examples: HIV,
What are enzymes
Enzymes are catalysts produced by living things
Catalysts are molecules that speed up reactions without being used up in the process
Enzymes need to function at an optimum temperature and pH
A substrate is a molecule that is changed in a reaction
Every enzyme molecule has an active site- the part where a substrate joins on to the enzyme
Enzymes usually only speed up one reaction and a substrate has to be the correct shape to fit into the active site for the enzyme to work
Effect of pH and temperature on enzymes
As temperature increases, the kinetic energy also increases which leads to more collisions between the substrate and the active site of the enzyme creating more enzyme-substrate complexes this speeds up reactions and makes enzymes even more efficient. However if temperature is too high, the enzyme denatures and will not be able to function properly as the shape of the active site will become different and the substrate will no longer fit properly
It’s the same for pH, if pH is too high or too low, the enzyme denatures and the active site changes shape making it unable to lock in place with the substrate
Investigating enzyme activity with hydrogen peroxide and catalase
Catalase is an enzyme which catalyses the breakdown of hydrogen peroxide into oxygen and water. You can test the effect of temperature on the volume of oxygen that is produced in a fixed time
Add set volume of hydrogen peroxide using a pipette into boiling tube, put something containing catalase eg a 1 cm^3 of potato into the boiling tube, seal the boiling tube using a bung and connect it to a gas syringe and place the boiling tube in a water bath at a temperature of 10 degrees.
Measure the volume of oxygen in the gas syringe after a minute
Repeat same process but at different temperatures 10, 20, 30 degrees…
Record volume of oxygen each time, repeat experiment 3 times and calculate an average
Control other variables
Investigating enzyme activity with starch and amylase
Add starch solution and amylase enzyme using a pipette into a boiling tube,put into water bath at temperature of 10 degrees.
after every 10 seconds put starch into a spotting tile containing wells containing iodine (turns from orange to blue-black if starch is present) and see how long it takes for all the starch to be broken down (when the iodine solution remains browny orange
Repeat this experiment at different temperatures- 10, 20, 30 degrees and record the time it takes for all the starch to be broken down
Repeat experiment 3 times and calculate average
Diffusion
The net movement of particles from an area of high concentration to an area of low concentration
Osmosis
The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane
