Topic 1: Key Concepts Flashcards
What are eukaryotes?
Cells which have a nuclei
What are prokaryotes?
Cells that don’t have a nuclei but do have DNA
Examples of eukaryotes?
Plant and animal cells
What 5 sub cellular structures do animal cells have?
Nucleus
Cytoplasm
Ribosomes
Cell membrane
Mitochondria
What 8 sub cellular structures do plant cells have?
Nucleus
Cytoplasm
Ribosomes
Cell membrane
Mitochondria
Cell wall
Chloroplasts
Vacuole
What is an example of a prokaryote?
Bacterial cell
What 5 sub cellular structures do bacterial cells have?
Cell membrane
Ribosome
Chromosomal DNA
Plasmid DNA
Flagellum
What is the function of the nucleus? (Plant and animal cells)
Controls activities of the cell and contains DNA
What is the function of the cell membrane? (Plant, animal and bacterial cells)
Controls what goes in and out of the cell
What is the function of the mitochondria? (Plant and animal cells)
Where aerobic respiration occurs - releases energy
What is the function of the ribosomes? (Plant, animal and bacterial cells)
Where proteins are made in protein synthesis
What is the function of the cytoplasm? (Plant and animal cells)
Where chemical reactions occur
What is the function of the chloroplasts? (Plant cells only)
Where photosynthesis happens - contains chlorophyll to absorb sunlight
What is the function of the vacuole? (Plant cells only)
Keep the cell rigid for support, contains cell sap and water and maintains the internal pressure of the cell
What is the function of the cell wall? (Plant cells only)
Made of cellulose - strengthens the cell and stops it from bursting
What is the function of the chromosomal DNA? (Bacterial cells only)
Controls cells activities and replication
What is the function of the plasmid DNA? (Bacterial cells only)
Can be be passed between bacteria and used for genetic engineering
What is the function of the flagellum? (Bacterial cells only)
Used for movement
What was the first microscope?
A light microscope with a magnification of x30
What is the most modern type of microscope?
Electron microscopes
What are properties of the most modern microscope and why is this beneficial?
Have a higher magnification and resolution than light microscopes
Allowing us to see smaller things in more detail, so we can understand sub cellular structures better now
Advantages of electron microscopes?
High resolution
Can magnify up to x500,000
Possible to investigate a greater field depth
Disadvantages of electron microscopes?
Expensive
require a specialist to use it
Specimen must be fixed in a vacuum and therefore dead
How can you calculate the overall magnification of a microscope?
Eyepiece magnification x objective magnification
Simple conversions (cm, mm, um, nm)?
cm -x10- mm -x1000- um -x1000- nm
nm -÷1000- um -÷1000mm- mm -÷10- cm
How to calculate actual size of an organism?
Actual size = image size/magnification
What is the actual size calculation triangle?
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What part of the microscope do you look through?
Eyepiece lens
What part of the microscope do you use to get a clear image?
Coarse focus nob
What is the part of a microscope that you put the specimen on?
Stage
What is a specialised cell?
A cell that has a structure adapted to its function
What does an egg cell do?
Carries female DNA and feeds the developing embryo
What are the structures of egg cells that have adapted to their function? What do they do?
Cell membrane - changes structure after fertilisation to prevent more sperm entering
Haploid nucleus - has 23 chromosomes (to form a full set of chromosomes when joined with a sperm cell) and carries genetic material
Cytoplasm - has nutrients to nourish the embryo
What does a sperm cell do?
Transports male DNA to the egg and fertilises it
What are the structures of sperm cells that have adapted to their function? What do they do?
Acrosome - contains enzymes to digest the egg membrane and break through it
Haploid nucleus - has 23 chromosomes (to form a full set of chromosomes when joined with an egg cell) and carries genetic material
Mitochondria - has a lot of it to provide energy through respiration that allows it to swim and reach the egg cell to fertilise it
Flagellum - to swim to the egg and fertilise it
What does a ciliated epithelial cell do? Example?
Moves substances along internal surfaces e.g. mucus in airways
What are the structures of ciliated epithelial cells that have adapted to their function? What do they do?
Cilia - hair like projection to sweep the substances and move them
Nucleus - contains genetic material
Examples of specialised cells?
Egg cell
Sperm cell
Ciliated epithelial cell
What is an enzyme?
It acts as a biological catalyst and speeds up the rate of breakdown
What does each enzyme have that’s unique?
A unique active site
Where do enzymes and substrates bind?
Substrate binds to the active site of an enzyme
What do enzymes and substrates form when they bind?
Enzyme substrate complex
What is the lock and key model?
Compares the binding of enzymes and substrates at the active site as if they’re a key and a lock
What are the key words relating to enzymes and substrates?
Specific and complimentary
Why do we need enzymes?
Used for digestion and protein synthesis
What are the factors that affect enzyme activity?
Temperature
pH
Substrate concentration
What is denaturing?
When the shape of an active site changes as bonds in the enzyme break
Description of the trend between temperature and enzyme activity?
As temperature increases, so does the rate of reaction until the optimum temperature then the rate of reaction decreases as the enzyme denatures
Description of the trend between pH and enzyme activity?
As pH increases, so does the rate of reaction until the optimum pH where the rate of reaction begins to decreases as the enzyme denatures
What is the average optimum temperature?
Around 37°C
What is the average optimum pH?
8
Description of the trend between substrate concentration and enzyme activity? Why?
As substrate concentration increases, so does the rate of reaction until it plateaus then the rate of reaction doesn’t change as there comes a point where the enzyme is fully saturated and no more molecules can fit into it
What enzyme breaks down proteins and what are the products?
Protein is broken down by protease into amino acids
What enzyme breaks down lipids and what are the products?
Lipids are broken down by lipase into glycerol and fatty acids
What enzyme breaks down carbohydrates (e.g. starch) and what are the products?
Carbohydrates (e.g. starch) are broken down by carbohydrases (e.g. amylase) into simple sugars (e.g. glucose)
What is diffusion?
Diffusion - the net movement of particles from an area of higher concentration to an area of lower concentration down the concentration gradient
In what states does diffusion occur?
Liquids and gases
What is osmosis?
Osmosis - the net movement of water molecules from an area of higher water concentration, to an area of lower water concentration down the concentration gradient, through a partially permeable membrane
What is active transport?
Active transport - the net movement of particles from an area of lower concentration to an area of higher concentration against the concentration gradient, it requires energy
What is a hypertonic solution?
A substance with a higher concentration of solute particles but a lower concentration of water
What is a hypotonic solution?
A substance with a low concentration of solute particles but a higher water concentration
What is calorimetry?
A process used to find the amount of energy in food
What is the process of calorimetry?
- Weigh your food sample and put it on a mounted needle
- Add a set volume of water to a boiling tube and record its temperature
- Set fire to the food, hold it under the boiling tube until it goes out, repeat until the food no longer catches fire
- Record the temperature of the water
- Find the energy per gram of food
How to calculate the energy per gram of food?
Energy per gram of food:
(Mass of water x temperature of water x 4.2) / mass of the food
The calculation in brackets is simply the energy in the food
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the test for reducing sugars called?
Benedict’s test
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the test for starch called?
Iodine test
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the test for proteins called?
Biuret test
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the test for lipids called?
Emulsion test
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the process of the test for reducing sugars?
- Add blue Benedict’s reagent to a food sample and leave it in a water bath at 75°C
- If the food sample turns green, yellow or red, reducing sugars are present
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the process of the test for starch?
- Add iodine solution to a food sample and mix
- If the sample changes from orange to blue-black, starch is present
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the process of the test for proteins?
- Add potassium hydroxide solution to a food sample and then some copper(II) solution
- If the solution changes from blue to purple, proteins are present
TESTING FOR FOOD MOLECULES CORE PRACTICAL: What is the process of the test for lipids?
- Add ethanol to a food sample and shake for a minute
- Pour solution into water
- If there’s a milky emulsion, lipids are present
TESTING FOR EFFECT OF pH ON AMYLASE ACTIVITY CORE PRACTICAL: What is the process of testing the effect of pH on enzymes?
- Heat 3cm³ of amylase solution, 1cm³ of pH buffer solution MAKE SURE THAT THE WATER IN THE BEAKER REMAINS AT A CONSTANT TEMPERATURE OF 35°C USING A THERMOMETER throughout the whole experiment
- 5 min later, add 3cm³ of starch solution to the mixture and continue to heat
- The amylase enzyme breaks down the starch
- Add a drop of the mixture to a drop of iodine solution that’s in a spotting tile using a dropping pipette
- Record the time when iodine solution remains orange after sample is added to the iodine
- Repeat steps 1-5 with different pH buffers
TESTING FOR EFFECT OF pH ON AMYLASE ACTIVITY CORE PRACTICAL: How can the rate of reaction be calculated?
Rate of reaction = 1000/time
TESTING FOR EFFECT OF pH ON AMYLASE ACTIVITY CORE PRACTICAL: What are the independent and dependent variable in this experiment?
Independent: pH of solution
Dependent: time taken for amylase to break down starch
How can you remember what each variable in an experiment means?
CID SAM
Control Same
Independent Alter
Dependent Measure
MAGNIFICATION CORE PRACTICAL: How can the magnification of an image be found? Equation triangle?
Magnification = image size/real size
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MAGNIFICATION CORE PRACTICAL: What are all 6 of the parts of the microscope?
- Eyepiece
- Objective lens
- Stage
- Coarse adjustment knob
- Fine adjustment knob
- Lamp
MAGNIFICATION CORE PRACTICAL: What is the process of using a microscope?
- Put the specimen on a slide, and put a cover slip on the specimen, then place the slide onto the stage
- Start with the lowest powered lens then move the stage up using the coarse adjustment knob
- Look down the eyepiece and adjust the focus with the adjustment knobs (use the coarse one first)
- To see the slide with a greater magnification, swap to a higher powered lens and refocus
OSMOSIS CORE PRACTICAL: What are the steps done to investigate osmosis in potatoes?
- Cut a potato into identical cylinders of the same mass
- Divide the cylinders into groups of three and measure the mass of each group
- Prepare beakers that contain different concentrations of sucrose solution and one beakers with pure water (control), put one group of cylinders into each beaker
- Leave each beaker and group out for 40 minutes, then take out the cylinders, dry them gently with a paper towel and measure the mass of each group again
OSMOSIS CORE PRACTICAL: How can the % change in mass be calculated?
% change in mass = change in mass/initial mass x 100
OSMOSIS CORE PRACTICAL: What are the independent and dependent variables?
Independent: concentration of sucrose solution
Dependent: potato cylinder mass
OSMOSIS CORE PRACTICAL: What are the conclusions to this experiment?
The potatoes that are in the less concentrated sucrose solutions and in the pure water, will increase in mass BECAUSE THE WATER PARTICLES ARE GOING FROM AN AREA OF HIGHER WATER CONCENTRATION (THE LESS CONCENTRATED SUCROSE SOLUTION) TO AN AREA OF LOWER WATER CONCENTRATION (THE POTATOES)
The potatoes that are in the more concentrated sucrose solutions, will decrease in mass BECAUSE THE WATER PARTICLES ARE GOING FROM AN AREA OF HIGHER WATER CONCENTRATION (THE POTATOES) TO AN AREA OF LOWER WATER CONCENTRATION (THE HIGHLY CONCENTRATED SUCROSE SOLUTION)
What is a control? What does it do?
It’s an experiment or observation designed to minimize the effects of variables other than the independent variable - increases the reliability of results
