Key Concepts In Biology Flashcards
Example of prokaryotic cell
Bacteria
What are eukaryotic cells
Plant and animal cells, have nucleus, complex and contain their DNA in a nucleus
Function of nucleus
To enclose genetic materia
What is the cytoplasm
A gel-like substance where chemical reactions take place
What is a cell membrane
Controls the molecules that can enter and leave the cells
What are mitochondria
Where aerobic respiration occurs
How much is one order of magnitude?
10X
What do plant and animal cells have in common
Nucleus, mitochondria, ribosomes, cytoplasm, cell membrane
What do plants have that animals cells dont
Chloroplasts, cell wall, vacuole
What are chloroplasts
Contain chlorophyll and are sites of photosynthesis
What is a cell wall
Made from cellulose, strengthens the cell
What is the vacuole
Filled with a fluild called cell sap, helpd give plant its shape
What is differentiation
When cells become specialised
What happens during fertilisation
The genetic info of the ovum and sperm combine
What are the adaptations of a sperm cell
Long tail - allows them to swim to ovum(streamlined), mitochondria - gives them energy to swim, enzymes - allows them to digest their way through the outer layer of the ovum
What is the job of a nerve cell
To send electrical impulses around the body
What does an axon do
Carries the electrical impulses from one part of the body to another
What is an axon covered in and what does it do
Myelin, insulates the axon and speeds up the transmission of nerve impulses
What do the ends of axons have
Synapses
What are synapses
Junctions which allow the impulse to pass from one nerve cell to another
What do dentrites do
They increase the surface area so the other nerve cells can connect more easily
Why are muscle cells packed with mitochondria
To provide them with energy
What do muscles contain
Muscle fibres
What do muscle fibres do
Can change the length of the muscle cell, when a muscle cell contracts these protein fibres shorten, decreasing the length of the cell
What do enzymes break down
Big molecules - proteins, lipids, some carbohydrates
What do digestive enzymes break down
The food we eat so it can be diegested
What are carbohydrates
Enzymes called carbohydrases convert carbohydrates to simple sugars e.g amylase breaks down starch
What are proteins
Proteases convert proteins to amino acids
What are lipids
Lipases convert lipids into glycerol and fatty acids
How are carbohydrates synthesised
By joining together simple sugars
How are proteins synthesised
Joining amino acids
How are enzymes synthesised
Catalyse the reactions needed to do this
What is the equation for rate of reaction
1000/time
What is resolution
How well a microscope distinguishes between 2 points that are close together
Higher resolution =…
Clearer image, more detail
When were light microscopes invented
1590s
How do light microscopes work
Passing light through the specimen
What do light microscopes allow us to see
Living cells, nuclei, chloroplasts
When was the electrom microscope invented
1930s
What do electron microscopes have
Higher magnification and resolution than light microscopes
Equation for total magnification
Eye piece lens magnification x objective lens mag.
Equation for magnification
Image size/real size
What are enzymes
Catalysts produced by living things
What is the substrate
The molecule chnaged in the reaction
What is the active site
The part the substrate joins to, to catalyse the reaction
What is osmosis
The net movement of water across a partially permeable membrane from a region of high concentration to low concentration
What is a partically permeable membrane
A membrane with small holes in
What is diffusion
The net movement of particles from an area of high concentration to low concentration
What particles does diffusiom happen in
Gases, liquids
What can diffuse through cell membranes
Small molecules - glucose, amino acids, water, oxygen
What is active transport
The movement of particles across a membrane against a concentration gradient using energy transferred during respiration
Equation for percentage change
(Final mass - initial mass / initial mass) x 100
What is amylase
An enzyme
What does amylase do?
Break down starch to maltose
What do u use to detect starch
Iodine
What happens to iodine when starch is present
It will change from browny-orange to blue-black
What are the control variables in the reaction of effect of pH on enzyme activity
Concentration, volume of amylase solution
What does increasing the temperature do
Increases the rate
What happens if the temperature gets too hot
Some of the bonds holding the enzymes together break, changing the shape of the enzymes active site = denatured
What is the optimum
pH enzymes work at
7
What is a enzyme that doesn’t work best at pH7
Pepsin - breaks down proteins in the stomach - pH2
What does higher substrate concentration mean
Fast ror
Investigating osmosis experiment steps using potato cylinders
1) prepare sucrose solutions of different concentrations from pure water to very concentrated sucrose solution
2) use a cork bored to cut a potato into same sized pieces
3) divide the cylinders into groups of 3 and use a mass balance to measure mass of each group
4) place 1 group in each solution
5) leave potato in solution for about 40 mins
6) remove potato and pat dry gently with paper towel-removes excess water=accurate measurement of final mass
7) weight each group again
How to work out percentage change
(Final mass - initial mass / initial mass) x100
Units of measure table
Millimetre(mm) x1000>< ÷1000 micrometer(um) x1000>
Units of measure in standard form
mm = x10(-3)m um = x10(-6)m nm = x10(-9)m pm = x10(-12)m
Steps on investigating the effect of on pH on enzyme activity
1) Put a drop of iodine solution into every well of a spotting tile
2) Put a beaker of water on a tripod over a Bunsen burner and heat till 35°c
3) Use a syringe to add 3cm(3) of amylase solution and 1cm(3) of a buffer solution with a pH of 5 to a boiling tube, put the boiling tube into the water for 5 mins
4) Use a diff. Syringe to add 3cm(3) of starch solution to boiling tube
5) Immediately mix contents of boiling tube and start stop clock
6) Use continuous sampling, to record how long it takes for the amylase to break down all the starch, use a dripping pipette to drop a bit of solution from boiling tube into some iodine in a well every 10 seconds until the iodine becomes a browny-orange colour
7) Repeat these steps with different pH of buffer solution to see how pH effects time taken for starch to be broken down
