topic 1- key concepts in bio Flashcards
Difference between Eukaryotes and Prokaryotes
- eukaryotic cells are complex and include animal and plant cells
- prokaryotic cells are smaller and simpler e.g bacteria ( they’re single celled organisms)
What is found in Eukaryotic cells ( animal and plant)
Animal and plant cells
- Nucleus ( contains genetic information– DNA– of the cell and controls activities of cell)
- Cytoplasm (liquid substance in which chemical reactions occur and contains enzymes)
- Cell membrane (controls what enters and leaves the cell)
- Mitochondria (where aerobic respiration takes place - provides energy for a cell)
-Ribosomes ( Where protein synthesis occurs)
ONLY IN PLANT CELLS
- chloroplast ( Where photosynthesis takes place and contains chlorophyll that harvests light needed for photosynthesis)
- Permanent Vacuole ( contains cell sap, improves rigidity)
-Cell wall ( made from cellulose and strengthens cell
What is found in bacterial cells
- Cytoplasm
- Cell membrane
- Cell wall
- Chromosomal DNA ( bacterial cells have no nucleus- floats in cytoplasm)
- Plasmid ( small rings of DNA and code for extra genes)
- Flagellum ( Long, thin tails attached to bacteria that allows them to move)
What is a specialised cell?
- cell gaining new sub-cellular structures to be suited to its role
How sperm cell is specialised ?
-carry male’s DNA to the egg for reproduction
-Streamlined head and long tail to aid swimming
-Many mitochondria to supply energy to
allow cell to move
How egg cell is specialised ?
- specialised to accept single sperm cell and develop into embryo
- lots of mitochondria to provide energy source for developing embryo
- Large size and cytoplasm to allow quick, repeated division as embryo grows
How root cell is specialised ?
- have large surface area due to root hairs, meaning more water can move in
- large permanent vacuole affects the speed of movement of water from soil to the cell
- mitochondria provide energy from respiration for active transport of mineral ions into the root hair cell
How phloem cell is specialised ?
- Cell walls of each cell form structures called sieve plates when they break down, allows movement of substances from cell to cell
- lose many sub-cellular structures, energy cells need to be alive is supplied by mitochondria of the companion cells.
What are the two main types of microscopes ?
-light and electron
Magnification equation
magnification = image size/ actual size
Converting from milli, micro, nano and picometers
Milli x10^-3 divide by 1000 to get micrometers and etc.
Micro x10^-6
Nano x 10^-9
Pico x 10^-12
What is an enzyme ?
- biological catalyst speeds up rate of reaction
- fit in lock and key method– active site and substrate are complimentary
- form enzyme-substrate complex
What happens to an enzyme when it exceeds its optimum temp. ?
-becomes too hot bonds that hold enzyme together will break.
changes the shape of the active site, so the substrate can no longer ‘fit into’ the enzyme.
- denatured
What happens to an enzyme when pH is too high or low?
- forces that hold amino acid chains that make up the protein will be affected.
-change shape of active site, substrate can no longer
fit in. - denatured
Practical- when starch is present
- Place drop of iodine solution on each well of a tray.
- Label test tube with pH to be tested. Place in water beaker w/ 50ml water place above Bunsen Burner for 3 minutes.
3. 2cm3 amylase solution, 2cm3 starch solution and 1cm3 of buffer pH solution in test tube and start stopwatch. - After 10 seconds, use pipette to place a drop the solution into one well containing iodine solution if mixture turns blue-black starch is present & hasn’t yet been broken down.
- Repeat Step 4 after another 10 seconds, repeat until solution remains orange –record time taken
- control conc. and vol. of amylase solution
use of enzymes in carbohydrase, proteases and lipase
carbohydrase– convert carbohydrate to simple sugar
proteases – convert proteins to amino acids
lipase– convert lipids( fats ) to fatty acids & glycerol
How to test for reducing sugars ( Benedict’s solution )
- Presence of reducing sugar indicated by colour
change to reddish-brown
Test for protein (Biuret test)
- add drops of potassium hydroxide (KOH) to make it alkali, then add copper (II) sulfate
- observe colour change if protein is present blue to violet
Test for lipids (Emulsion test)
- add ethanol to food sample and shake then add water
- If lipids present, will be indicated by formation of white emulsion layer at top of sample.
- more white emulsion, the more lipids
what 3 ways does transport occur?
- osmosis
- diffusion
- active transport
Why do we use Bunsen burner and water beaker in practical testing for starch
- keep solution at relatively constant temperature throughout reaction (temperature is a control variable in this experiment).
Why does transport occur in and out of cells ?
- carry substance like oxygen, glucose and waste products in and out to support life processes
What is diffusion ?
- net movement of particles from high concentration to low concentration
Properties of diffusion
- all particles possess Kinetic energy
- random movement
- passive process
What is osmosis?
Movement of water particles from a higher concentration to a low concentration through a partially permeable membrane
- form of passive transport ( requires no energy)
What is active transport?
- requires energy
- move molecules against concentration gradient from low concentration to high concentration
Osmosis potato practical
Cut potato equal size
- remove excess water.
- Measure initial mass of potatoes
- put potatoes in sucrose solutions w/ different concentrations
- clean w/ tissue paper again & record new mass.
- Find difference in mass & calculate percentage gain or loss of mass
What are independent, dependant & control variable in Osmosis potato experiment
Independent variable:
-Conc. of sucrose solution
Dependant variable:
- measuring change of mass in potatoes
Control variable:
- potato size
