Unit 1 - Key Concepts In Biology Flashcards
What does a magnification on x30 mean?
It appears 30 times bigger
How do you work out a microscopes magnification
You multiple the magnifications of the two lenses together
What does resolution mean
The smallest distance between two points that can still be seen as two points
What is the highest magnification and resolution that today’s best light microscopes can produce
x1500 with resolution of 0.0001 mm
What is different about an electron microscope compared to a light microscope
Beams of electrons pass through a specimen to build up an image
What do electron microscopes allow
Better magnification and resolution
Between each prefix, what is the multiplayer?
X1000
What is the order of prefixes starting from millimetres?
Milli, micro, nano, pico
What is a cell with a nucleus called?
Eukaryotic
What is the role of a cell membrane? (2)
To control what enters and leaves the cell, separates each cell
What is the role of the nucleus
To control the cells activities and contains the DNA
What is the role of cytoplasm
A watery jelly where most of the cells activities occur
What is the role of Mitochondria
Where aerobic respiration occurs
What is the role of ribosomes
To make new proteins.
What is the field of view
The circular area you see in a light microscope
What is the role of a cell wall
It supports and protects the cell
What is the role of a vacuole
It stores sap and helps keep the cell rigid
What is the role of the chloroplasts
They contain chlorophyll used for photosynthesis
Explain the core practical - using microscopes
Understand how to use a microscope
Collect a small specimen of your choice e.g cheek cells or onion tissue
Add a drop of stain to your microscope slide
Place the specimen on the stain
Lower a coverslip using a toothpick
Examine under a microscope starting with the lowest magnification
Draw and annotate a cell diagram
Why are bacteria difficult to see with light microscopes
They are small and mostly colourless
What is a flagellum
Part of a bacteria cell that spins, allowing it to move
What is the name for cells that do not have a nuclei
Projaryotic
In prokaryotic cells, where is the DNA stored (2)
In a large loopsof chromosomal DNA or smaller loops called plasmids
How do bacteria get their energy?
They release digestive enzymes into their surrounding and absorb the digested food into their cells
What do digestive enzymes do in humans?
They turn large molecules into smaller subunits which are small enough to be absorbed by the small intestine
What are polymers?
Molecules made up of monomers that are joined as a chain
Why does synthesis happen very slowly?
The sub units rarely collide with enough force to form a bond
Why does the break down of large molecules happen very slowly?
The smaller subunits need enough energy to break the bonds
What is a biological catalyst?
An enzyme that increases the rate of reactions
What are substrates?
The substances that enzymes work on
What are the substances that are produced by enzymes?
Products
Where is amylase found and what reaction is catalysed
In the salvia and small intestine
Breaks down starch into small sugars
Where is catalase found and what reaction is catalysed?
Most cells, especially liver
Break down hydrogen peroxide to water and oxygen
Where is starch synthase found and what reaction is catalysed
In plants
Synthesis of starch from glucose
Where is DNA polymerase found and what reaction is catalysed
Nucleus
Synthesis of DNA from its monomers
What are chemical reagents?
Substances used to identify certain changes
What does iodine solution show and what happens
Identifies starch and turned from yellow to black
What are reducing sugars
All of the smallest sugars e.g glucose and fructose
What does Benedictus coalition show and what happens
It shows reducing sugars
Equal amount of food as solution is placed in hot water bath. Turns from blue to red (lots of sugars)
What is the buried test (what does it show and how)
Shows protein
Potassium hydroxide solution is mixed with food, two drops of copper sulphate is added, turns from blue to purple
What is the ethanol emulsion test? (What does it show and how)
It shows fats and oils (lipids)
Food is mixed with ethanol and shaken, some is poured into water and shaken again, the fats and oils will form a cloudy foam on top
What is a calorimeter used for
To measure the amount of energy in a food by burning it
How is the amount of energy in a food calculate using a calorimeter?
From the temperature of the water
What types of sugars does the Benedictus test react with?
Reducing sugars
Explain the core practical - testing foods
Carry out different investigations using the solutions and food samples to see what is in it
E.g iodine solution to find starch
What are qualitative food tests?
They only show if a substance is present or not
What is quantitative information
Data that shows values such as the mass
What is the structure of a protein
A 3D molecule formed from a folding chain of amino acids
What is the active site of an enzyme
Where the substrate of the enzyme fits at the start of the reaction
Why can only certain enzymes work for specific substrates
The active sites are all different shapes
What is the lock-and-key model?
A model that shows how enzymes work (2 substrates fit onto the active site of an enzyme where they have a bond formed between them making one product molecule)
What can affect how he protein folds up? (2)
Changes in pH or temperature
What happens when a protein is denatured
The enzymes has been changes affecting the shape of the active site so the substrates no longer fit
For a graph showing the temperature and how long it takes for 100g of a substrate to be broken down, how do you work out the rate of reaction
100/ minutes ( it equals how much was broken down per minute)
Why does the enzyme react faster at a higher temperature?
There is more energy so the molecules move faster, making it a higher chance of slotting into the active site
What is the optimum temperature
The temperature in which the reaction happens the fastest
What can affect the rate of enzyme-controlled reactions? (3)
Concentration of substance
pH
Temperature
Why is the change of concentration in the substance cause a different change in the enzyme reaction than the other factors
It has an optimum concentration but any higher won’t make the rate less
Explain the core practical - pH and enzymes
Set up a tripod, gauze, heat resistance may, Bunsen burner and beaker with water (40C)
Use the Bunsen burner to keep the water at this temperature
Place a drop of iodine solution in a spotting tile
Measure 2cm^3 of amylase solution 1cm^3 of a solution with a known pH and 2cm^3 of starch solution into a tube and place in water bath
Every 20s put a drop into an iodine solution drop
Repeat with different pHs
What causes body odour?
Bacteria living on your body
What is a concentration gradient formed from
A difference between two concentration
What is diffusion
The spread of particles
Which direction do particles diffuse on a concentration gradient
Down
What causes a faster diffusion
A larger difference between the two concentrations
What is a semi-permeable membrane?
A membrane that allows some particles through it but not all
What type of membranes are cell membranes?
Semi-permeable
What molecules can diffuse through cell membranes?
Water molecules
What is osmosis
The diffusion of water molecules through semi-permeable cell membranes
When does the overall movement of particles down a concentration gradient stop
When the concentration of solutes is the same on both sides
What does osmosis cause to tissues
To gain or loss mass
What is the word equation for a percentage change he in mass
Final mass - initial mass / initial mass x 100
What does active transport allow? (2)
Molecules to be transported against a concentration gradient or molecules that are too large for the cell membrane
What part of a cell is used for active transport?
Transporter protein
What happens in active transport?
The proteins capture the molecules that fit and carry them across the membrane
What are passive processes?
Processes that do not require energy
Explain the core practical - osmosis in potato slices
Label different boiling tubes with different concentrations of sucrose solution
Cut similar sized potato slices
Blog each one dry and record its mass
Put one into each boiling tube for 15 mins
Take out, blot and record it’s mass again
Why are different sucrose concentrations used for osmosis practical?
Higher sucrose concentration means less water molecules which means slower osmosis
Why is a sucrose solution used for osmosis practical?
The sucrose molecules are too big for the cell membrane so only the water is let in
