Structures and Functions in Living Organisms Flashcards
What are the levels of organisation?
Organelles-> Cells-> Tissues-> Organs-> Systems
What does a nucleus do ?
Controls the activity of the cell and contains genetic materials.
What happens in a cytoplasm ?
Where all the cell’s reactions take place
What does a cell membrane do ?
Holds the cell together and controls what goes in and out.
What does a mitochondria do ?
Generates energy in the form of ATP
What three organelles do plants have that plants don’t and what are their functions
Cell wall- made of cellulose, gives support to cell (no skeletons)
Vacuole- contains cell sap, weak solution of sugars and salts.
Chloroplasts- contains chlorophyll needed for photosynthesis.
What are carbohydrates made of
Carbon
Hydrogen
Oxygen
Monosaccharides
e.g. Glucose/fructose
simple one unit sugars that taste sweet when dissolved in water.
Disaccharides
E.g. Maltose, lactose and sucrose
Dissolve in water
Maltose= glucose + glucose
Polysaccharide
E.g. Starch or cellulose in plants
Glycogen= animals
Complexed molecules used for storage
Don’t break up easily
Don’t easily dissolve in water
Sources and function of carbs
Cereals, rice, wheat, barley, maize, fruits and veg.
Main source of energy and also stores energy.
Used for structures in plants.
What are lipids made of
Carbon hydrogen and oxygen
3 fatty acids and 1 glycerol
What enzyme breaks down starch
Amylase
Starch –> maltose
Sources of lipids
Cheese, milk, eggs nuts and seeds
Functions of lipids
Provides energy
Insulates important organs
Forms parts of the cell membrane
Uses cholesterol to make steroid hormones
What enzyme breaks down lipids
Lipase
Lipids–> fatty acids and glycerol
What are proteins made up of
Carbon, hydrogen, nitrogen, oxygen (+ sulphur)
Long and thin= keratin.
Spherical= haemoglobin
What are sources of proteins
Meat, fish, eggs, nuts and seeds
What is the function of protein ?
Growth and repair of muscles
Catalysts
Hormones
Antibodies
What enzyme breaks down protein
Protease
Protein–> amino acids and peptides
How do you test for glucose
Liquefy food sample
Dissolve in Benedict’s solution
Heat in water bath
Glucose= brick orange ppt
Test for starch
Liquefy food sample
Add iodine solution
Yellow= no starch
Blue/black= starch
What are enzymes
Biological catalysts that catalyse many different metabolic reactions. They are specific.
They speed up reactions but remain chemically unchanged.
What is the optimum temperature for enzymes in humans
37 degrees Celsius
What are enzymes sensitive to
Heat and ph.
Temp too high, then the enzyme will be denatured= active site shape changes so the substrate is no longer complementary to the active site.
Ph too high= bonds holding enzymes structure are broken..denatured.
What is diffusion
The net movement of particles from areas of higher concentration to areas of lower concentration until a uniform composition is achieved.
What is osmosis
The net movement of water molecules for, areas of high water molecule conc. To lower water molecule conc. Across a partially permeable membrane.
What is active transport
The transport of dissolved molecules against the concentration gradient by using energy in the form of ATP.
Why can plants be turgid or flaccid?
Osmosis.
If water enters, volume of cytoplasm increases, exerting pressure outwards. This means that the cell is stronger and has support to grow upwards.
What factors affect the rate of substances going in and out and why?
SA: a large surface area means that molecules have more space to diffuse through, increasing the rate of movement.
Temp: the higher the temp, the higher the KE there is, making more molecules collide with the cell membrane= movement more likely.
Conc. Grad: the bigger the different in conc. Gradient, the re opportunities particles have to diffuse= quicker.
Diffusion experiment
Put a coloured substance in water
Time how long it takes for a uniform composition
Repeat experiments at different temperatures= compare times
- higher temp= higher KE= more collisions = substance moves through liquid quicker
Osmosis experiment
Cut two potato cylinders of the same size.
Put on in water and one in salt water
Salt water= potato loses mass as water diffuses out by osmosis to area of lower water molecule conc.
Water= potato gains mass as water diffuses in by is moms to area of Lower water molecule conc.
