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Biology: Combined Science - Coggle Diagram
Biology: Combined Science
Diffusion and Osmosis
Diffusion :
diffusion is the spreading out of the particles of a gas, or of any particles in a solution.
net movement - movement is from an area of higher concentration to lower
it takes place because of the random movement of the particles. The motion of the particles cause them to bump into each other, and this move them all around
Rates of diffusion
if there is a big difference in concentration between two areas, diffusion will take place quickly.
If there is a small difference in concentration the net movement by diffusion will be quite slow.
Diffusion in living organisms
dissolved substances move into and out of your cells by diffusion across the cell membrane.
these include simple sugars, such as glucose, gases such as oxygen and carbon dioxide, and waste products such as urea from the breakdown of amino acids in your liver
Osmosis
this is when only water moves across a partially permeable membrane from a dilute solution to a concentrated solution.
A dilute solution of sugar contains a high concentration of water. it has a low concentration of sugar.
A concentrated sugar solution contains a relatively low concentration of water and a high concentration of sugar.
Cells
Animal cells
structure and function
the nucleus - controls all the activities of the cell and is surrounded by the nuclear membrane.
the cytoplasm - a liquid cell that is where most of the chemical reactions happen.
the cell membrane - controls the passage of substances such as glucose and mineral ions into the cell. Also controls the movement of substances such as urea or hormones out of the cell.
the mitochondria - where aerobic respiration takes place, releasing energy for the cell.
the ribosome - where protein synthesis takes place.
Plant cells
Plant cells have all the features of a typical animal cell and 2 more
All plants and algal cells have a
cell wall
made of cellulose that strengthens the cell and gives it support.
chloroplasts - allow the plant to make food by photosynthesis.
Permanent Vacuole - space in the cytoplasm filled with cell sap. this is important for keep the cells rigid to support the plant.
Cell Division
The cell cycle and mitosis
stage 1: longest stage in the cell cycle. the cell replicates their DNA to form two copies of each chromosome ready for cell division.
stage 2: mitosis: in this process one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides.
stage 3: this is the stage during which the cytoplasm and the cell membranes also divide to form two identical daughter cells.
The Digestive System
Main organs of the human digestive system
Mouth
gullet
diaphragm
stomach
liver
gall bladder
pancreas
duodenum
bile duct
large/small intestine
appendix
rectum
anus
glands such as the pancreas and salivary glands make and release digestive juices containing enzymes to break down your food.
the stomach and small intenstine are the main organs where food is digested. in the small intestine, soluble food molecules are absorbed into your blood , once there they get transported around your body.