Biology Paper 1 Flashcards
Electron microscopes
Allow you to visualise finer details including organelles( sub cellular structures) due to their greater resolving power and higher resolution
Light Microscope
Allow you to see outlines of cell
-Cheap
Magnification Equation
Image size divided by object (cell) size
Eukaryotic cells
E.g. Animal and plant cellls
- Cell membrane (semi-permeable, controls what enters and leaves)
-Nucleus (DNA)
-mitochondria (respiration)
-cytoplasm (chemical reactions)
-Ribosome (protein synthesis)
Plants only:
-chloroplast (chrolophyll, photosynthesis
-cell wall (cellulose)
Prokaryotic cells
e.g. Bacteria
No nucleus= plasmid (loop of DNA)
Mitosis
All human cellls have 23 pairs of chromosomes (diploid) except gametes (eggs or sperm) that have just 23 (haploid)
New diploid cells are made for growth and repair
1.Nucleus dissolves, and genetic material is duplicated
2. the two sets of chromosomes mover to opposite sides of the cells
3.Other sub-cellular structures duplicate
4. the cell divides producing two genetically identical diploid cells
Specialisation
Stem cells can specialise to perfrom specific functions. they are found in animal embryos and plant meristems.
Some stem cells are still made in your bone marrow, but these can only specialise into blood cells.
Embryo clones
Can be made of a person to harvest stem cells from these can be used to treat conditions without them being rejected by the patients body.
Diffusion
The movement of particles from an area of high concentration to that of a low concentration across a concentration gradients. Requires energy. the rate can be increases by increasing
SA
Temperature
Difference in concentrations
Osmosis
The diffusion of water across a semi-permeable membrane to balence the conventrations of solution inside and outside a cell. Water must move, as larger molecules cannot fit through the holes. Water moves in if the concentration is higher outside.
Osmosis RP
-Weigh, and place identical cylinders from same vegetable in sugar solutions of varying concentrations
- After set time, remove excess water and reweigh, calculate % change in mass= final mass - initial mass divided from intital mass times 100
Active Transport
The movement of particles through a membrane via carrier proteins, this requires energy, and so can move them against the concentration gradient
Digestive system
-Teeth break down food mechanically’ saliva contains amylase (an enzyme)
-The liver produces bile stored in gall bladder before going to small intestine. Bile emulsifies lipids to form droplets. increasing their SA
-The stomach contains hydrochloric acid and enzymes that chemically break down food
-The pancreas secreates amylase which breaks down starch into glusose in Small intestine
-Small intestine has Villi that absorbed nutrients
-Water is absorbed into by blood in large intestine
Enzymes
Special protiens that ac as biological catalysts, often breaking down molecules into shorter ones
They are specific to subtrates that fit their active site
Activity (rate of reaction)
Increases with temperature until enzyme denatures (active site changes shape) the same is true for too high or low ph
Enzyme examples
Carbohydrases break down carbohydrates ino simple sugars
Proteases break down protiens into amino acids
Lipases break down lipids into glycerol and fatty acids
Enzyme practical
-Mix amylase with starch and start timer
-remove a few drops from the mixture every 10 seconds and add to iodine
-record time taken for no starch to be detected (remain orange)
-repeat at diff temps with diff ph buffer solutions added
Food tests
Starch:
Turns iodine from orange to black
Sugars:
turn benedicts solution from blue to orange
Protien:
turns biuret reagant from blue to purple
Lipids(fats):
turn cold ethanol cloudy
Respiratory system
Structures:
Trachea bronchi aveoli bronchioles
-Aveoli (air sacs) have a large surface area to allow gas exchange to occur at a fast rate
Doule circulatory system
Blood enters heart twice every time it is pumped round body
