Biology Flashcards
What are all living things made of?
Cells
What is a eukaryotic cell?
A complex cell
What type of cells can an eukaryotic cell be?
Animal and plant cells
What are prokaryotic cells?
Smaller and simpler cells
Give an example of a prokaryotic cell
Bacteria
What is the name of an organism that is made up of eukaryotic cells?
Eukaryotes
What is the name of an organism that is a prokaryotic cell?
Prokaryote (single-celled organism)
List the subcellular structures within a animal cell
Nucleus, Cytoplasm, Cell Membrane, Mitochondria and Ribosomes
List the subcellular structures of a plant cell
Rigid cell wall, Vacuole and Chloroplasts
What do bacterial cells not contain?
A Nucleus
List the subcellular structures of a bacterial cell
Ribosomes, Chromosomal DNA, Cell Membrane, Plasmid DNA and Flagella
State the role of the human egg cell
To carry the female DNA and to nourish the developing embryo in the early stages
How is the human egg cell adapted to its function (specialised)?
Haploid Nucleus
Contains nutrients in the cytoplasm to feed the embryo
Straight after fertilisation its membrane changes structure to stop any sperm getting in so the offspring contains the right amount of dna
What is the function of the sperm cell?
Transport the male’s DNA to the females egg
How is the sperm adapted to its function (specialised)?
Long tail so it can swim to the egg (flagellum)
Lots of mitochondria in the middle section to provide the energy needed to swim
Acrosome head which stores enzymes needed to digest through the membrane the membrane into the egg
Haploid nucleus
Cilliated Epithelial Cells function?
To move substances
Where are Cilliated Epithelial Cells located?
The surfaces of organs
How are Cilliated Epithelial Cells adapted to their function (specialised)?
Beat to move substances in one direction
What do microscopes use to magnify images?
Lenses
What are the two things a microscope does?
Magnifies the image
Increases the resolution of the image
What are the two current types of microscopes?
Electron and light microscopes
When was the light microscope invented?
1590s
How does the light microscope work?
Passing light through the specimen
What can you see with a light microscope?
Nuclei and chloroplasts
When was the electronic microscope invented?
1930s
How does the electronic microscope work?
Uses electrons rather than light
What can you see with a electron microscope?
The internal structure of mitochondria and chloroplasts
What is the advantage of using light microscopes over electron microscopes?
Light microscopes can be used to study living cells, electron microscopes cannot
Why do you need to take a small slice of the specimen with a light microscope?
The specimen needs to let light through it
What must you apply to the slide before putting the specimen on?
Water using a pipette
What must you do if the specimen is transparent or colourless?
Add a drop of stain
What does methylene blue stain?
DNA
What do you place on the end of the specimen?
A cover slip
Which level objective lens do you select first?
The lowest magnitude lens
What must you do with the coarse adjustment knob?
Move it whilst looking down at the specimen until it is nearly in focus
What must you do with the fine adjustment knob?
Adjust the focus until you get a clear image
What must you do if the image is not magnified enough?
Select a higher magnitude lens and then refocus accordingly
What is the total magnification formula?
Eyepiece lens magnification x Objective lens magnification = Total Magnification
What is the magnification formula?
image size / real size = magnification
List the four small scientific prefixes and their standard form
Pico - x10^12
Nano - x10^9
Micro - x10^6
Milli - x10^3
What is an enzyme?
A biological catalyst
Why isn’t body temperature simply used to speed up reaction
Although useful reactions will be sped up, harmful/useless/unwanted reactions will be sped up aswell
What do enzymes reduce the need of?
Enzymes reduce the need of high temperatures
What is the biological name for the molecule changed in the reaction?
Substrate
Define the active site - in terms of enzymes
The part where the enzyme joins on to its substrate the catalyse the reaction
How many types of substrates do enzymes usually work with?
One
True or False? Enzymes are not said to have a high specificity for their substrate
False, they do have a high specificity for their substrate
What will happen if the substrate doesn’t fit into the enzyme?
The reaction will not be catalysed
How does changing the temperature change the rate of an enzyme-catalysed reaction?
The higher the temperature, the faster the reaction, however, if it gets too hot the protein bonds holding the enzyme together break which changes the shape of the active site, preventing the substrate from fitting in
How does changing the pH change the rate of an enzyme-catalysed reaction?
There is an optimum pH for the respective enzyme, which is where that respective reaction is at its fastest, however, if the pH gets too high or too low the protein bonds holding the enzyme together break which changes the shape of the active site, preventing the substrate from fitting in
What is usually the optimum pH of an enzyme?
7 (neutral)
What is the optimum pH of pepsin and what does it do?
It is an enzyme that is used to break down proteins
The optimum pH for pepsin is 2, which leads to it being well-suited to the acidic conditions found within the stomach
Define denature - in terms of enzymes
If an enzyme is denatured its active site is no longer functional therefore the ability to catalyse a reaction may be lost
What will cause an enzyme to denature?
A drastic change in temperature, pH or chemical environment
How does changing the substrate concentration change the rate of an enzyme-catalysed reaction?
The higher the substrate concentration, the faster the rate of reaction
This is because its more likely the enzymes will meet up and react with its respective substrate
This is true to a point, as there are a limited amount of enzymes therefore if all active sites are full, adding more makes no difference
What does the enzyme amylase catalyse?
The breakdown of starch into maltose
How do you detect starch?
If starch is present, iodine will change from browny-orange to blue-black
In order to investigate the effect of pH on enzyme activity what must you do?
Put a drop of iodine into every well of a spotting tile
Place a tripod and gauze over a bunsen burner and heat the water until it reaches 35 degrees celsius
Then, using a syringe, add 3cm^3 of amylase solution and 1cm^3 of a buffer solution with a pH of 5 to the boiling tube
Next, use a different syringe to add 3cm^3 of a starch solution to the boiling tube
Immediately mix the contents, every 10 seconds take a fresh sample of the solution and when the solution remains browny-orange starch is no longer present
Why must you use a different syringe when investigating the effect of pH on enzyme activity and applying the amylase and then the starch solution?
The reaction will occur before the stopwatch is started if same syringe is used.
What do enzymes break down?
Big molecules
Give three examples of big molecules found within the body?
Proteins, lipids and some carbohydrates
Why is it important that organisms are able to break down proteins, lipids and carbohydrates?
So they can be used for growth and other life processes
But also, many of the molecules may be to big to fit through the walls of our digestive system, therefore the enzymes must break them down so they can be digested
What do plants store energy in the form of?
Starch
What enzymes convert carbohydrates into simple sugars?
Carbohydrase
Name an example of a carbohydrase
Amylase
What enzymes convert proteins into amino acids?
Proteases
What enzymes convert lipids into glycerol and fatty acids?
Lipease
What is the smaller version of a protein?
An amino acid
What is the smaller version of a lipid?
A glycerol and fatty acid
What is the smaller version of a carbohydrate?
A simple sugar
What is the chemical used to test for sugars?
Benedicts Reagent
What is the chemical used to test for starch?
Iodine
What is the test for sugars?
Add benedicts reagent, which is blue, to a sample and heat it in a water bath thats set to 75 degrees celsius
If the test is positive there will be a noticeable colour change
How does the colour of benedicts reagant change depending on the sugar concentration?
Blue -> Green -> Yellow -> Orange -> Brick Red
The higher the concentration the further the colour from blue
What is the test for starch?
Add iodine to solution, if starch present colour will change from browny-orange to a dark, blue-black colour
What is the emulsion test for lipids?
Shake the sample with ethanol until it dissolves, add solution to water
If lipid present, precipitate will form, which shows up as milky emulsion
The more lipid there is, the more noticeable the milky colour
What is the biuret test for proteins?
First, add a few drops of potassium hydroxide to make the solution alkaline
Then add some copper(ii) sulfate (CuS04) which is bright blue
If protein present, solution will turn purple
What are the three things you need for the calorimetry experiment?
Dry Food, Water, Flame
True or false? The food in the calorimetry experiment must not burn easily
False, the food must be dry and easily flammable
Describe the calorimetry experiment
Weigh a small amount of the food and then skewer it on a mounted needle
Add a known amount of water to a boiling tube
Set fire of the food, immediately hold the burning food under the boiling tube
Repeat until food no longer sets alight
Measure temperature change and use energy in food equation
What is the energy in food equation?
Energy in Food = Mass of Water x Temperature change of Water x 4.2
Define diffusion
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration
What states of matter does diffusion occur?
Liquid and Gas
Define osmosis
Osmosis is the net movement of particles across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
What is a partially permeable membrane?
A membrane with very small holes in it. So small that only small molecules can pass through them
Give an example of a tiny molecule
Water
Give an example of a large molecule
Sucrose
Which ways do water molecules pass during osmosis?
Both ways
Define active transport
Active transport is the movement of particles across a membrane against a concentration gradient using energy transferred during respiration
How is active transport different from diffusion/osmosis?
Active transport moves up a concentration gradient rather than down therefore active transport requires energy so its an active process
Give an example of active transport
Nutrients in the human gut
When theres a higher concentration of nutrients in the gut than in the blood, the nutrients diffuse naturally
When theres a lower concentration of nutrients in the gut than in the blood, active transport allows nutrients to be taken into the blood
In the investigating osmosis practical, how do you cut the potato?
Cut into the same sized pieces using a cork borer
Once potatoes are weighed and put into the solution, how long should you wait?
At least 40 minutes
What must you ensure you do once you remove the potatoes during the investigating osmosis practical?
Dry them to remove excess water
What is the only thing you change in the investigating osmosis practical?
The sucrose solution concentration
What is the percentage change equation?
Change / Orignal x 100 = Percentage Change
If a solution is isotonic, what does it mean?
Both solutions contain the same amount of water molecules
What do most human cells have?
A nucleus
What does the cell nucleus contain?
Genetic material in the form of chromosomes
What is a chromosome?
Coiled up lengths of DNA molecules
How many copies of each chromosomes do human cells usually have?
Two, one from the organisms “mother”, the other from the “father”
List the phases within the cell cycle, in order
Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokenisis
What occurs during the interphase?
Subcellular structures duplicate
DNA is then duplicated to form X-shaped chromosomes with each arm of the chromosome being an exact duplicate of the other
What occurs during the prophase?
Chromosomes condense getting shorter and fatter
The membrane around the nucleus break down leading to the chromosomes lying free in the cytoplasm
What occurs during the metaphase?
The chromosomes line up at the centre of the cell
What occurs during the anaphase?
Spindle fibres pull the chromosomes apart
Then the chromatids are pulled to opposite ends of the cell
What occurs during the telophase?
Membranes form around each of the sets of chromosomes
These become the nuclei of the two new cells
What occurs during the cytokinesis phase?
The cytoplasm and cell membrane divid to form two separate cells
What is left after mitosis?
Two identical new daughter cells
How do you calculate the number of cells after multiple divisions?
Number of cells = 2^n
What is the function of spindle fibres in the cell cycle?
They pull apart the chromsomes to form chromatids
Define growth
The increase in size or mass
How do plants and animals grow and develop?
Cell Division and Cell Differentiation
Define Cell Differentiation
The process by which a cell changes to become specialised for its jobs
What does specialised cells enable an organism to do?
Work more efficiently
How else can plants grow?
Cell Elongation
Define cell elongation
The process by which a plant cell expands, making the cell bigger and so making the plant grow
When do animals grow the most?
At an early age
Why do animals still divide once fully grown?
Replace old or damaged cells
Where does cell division usually happen in plants?
The tips of the roots and shoots (meritstems)
What is a tumour?
A mass of abnormal cells
What are growth charts used to assess?
A childs growth
What are the three measurements taken for growth charts?
Length, mass and head circumference
What are undifferentiated cells called?
Stem cells
Where are human stem cells found?
The human embryo and bone marrow
What are the stem cells found within the embryo called?
An embryonic stem cell
Why are embryonic stem cells more useful than adult stem cells?
Embryonic stem cells can differentiate into any type of human cell whilst adult stem cells are much more limited
What are the only plant cells that can divide by mitosis?
The plant cells found in plant tissues called meristems
Where is meristem tissue found?
Areas of a plant that are growing
What do meritstems produce?
Unspecialised cells that are able to divide and form any cell type
In medicine what may be possible to do with stem cells?
Replace damaged tissue
What are the potential risks of using stem cells in medicine?
Tumour Development, Disease transmission and Rejection
What may cause rejection with stem cells?
If the stem cells aren’t grown using the patient’s own stem cells
What could cause disease transmission when using stem cells for medicine?
Viruses live inside cells therefore if donor cells are infected, the virus could be passed on to the patient
How could using stem cells in medicine lead to tumour development?
Stem cells divide very quickly therefore if the scientists are unable to control the rate the stem cells divide, a tumour may develop
What is one ethical issue surrounding embryonic stem cell use in medicine?
Embryos may be classed as life, therefore they shouldnt be used for experiment because each one is a potential human life
What makes up the Central Nervous System (CNS)?
The brain and the spinal cord
What is the spinal cord?
A long column of neurones that run from the base of the brain
What are three parts of the human brain?
Cerebrum, Cerebellum and Medulla oblongata
What does the cerebrum control?
Movement, Intelligence, Memory, Language and Vision
What does the cerebellum control?
Muscle coordination and Balance
What does the medulla oblongata control?
Unconscious activites, such as breathing and your heart rate
What is the largest part of the brain?
Cerebrum
What does a CT scanner use to produce an image of the brain?
X-rays
What does a CT scan show?
The main structures of the brain
What doesn’t a CT scan show?
The functions of the structures of the brain
What does a PET scanner use to produce images of the brain?
Radioactive chemicals
What does a PET scan show?
The main structures of the brain and their function
State an advantage of using a PET scan over a CT scan
A PET scan can see the brain in real time, therefore the function of the structures can be understood
Why can be treating problems in the CNS be tricky?
Hard to repair
Hard to access
Treatment may lead to permanent damage
Why is CNS damage hard to repair?
Scientists are yet to discover a way to repair nervous tissue
What does the CNS coordinate?
A response
What is the CNS made up of?
Neurones (nerve cells)
What is a sensory receptor?
A group of cells that can detect a change in your environment
What is a stimulus?
A detectable change in the environment of an organism that results in some functional activity
Name examples of different stimuli within the human body
Receptors in eyes detect light receptors in skin detect touch and temperature changes
What happens when a stimulus is detected by receptors?
The information is converted to a nervous (electrical) impulse and then sent along sensory neurons to the CNS
What happens when the CNS coordinates the response?
The impulse response travels through the CNS along relay neurones
Define an effector in terms of the CNS
Effectors are parts of the body (muscles or glands) that produce a response to a detected stimulus.
How does the CNS send the required info to an effector?
Along a motor neurone
State two examples of a effector responding accordingly
A muscle contracting or a gland secreting it’s respective hormone
Define reaction time in terms of the CNS
How long it takes for you to respond to a stimulus
True or false? Neurones have a cell body with a nucleus?
True, they also have cytoplasm and other subcellular structures
What are the names of the extensions of a neurone that connect to other neurones?
Dendrites and Dendrons
What is the role of dendrites and dendrons?
To carry the nerve impulses towards the cell body
What are the names of the extensions of a neurone that carry nerve impulses away?
Axons
What is the role of an Axon?
To carry the nerve impulses away from the cell body
What are some axons surrounded by?
A myelin sheath
What is the role of a myelin sheath?
An electrical insulator, which speeds up the impulse
Is a smaller neurone faster than a longer one?
No, the longer the neurone, the faster the impulse is
Why is a longer neurone faster than a longer one?
No time wasted on the impulse travelling between to another neurone
Name the 3 types of neurones
Sensory, Motor and Relay Neurone
Describe the shape of a sensory neurone
One long dendron from receptor cells to the cell body which is located in the middle
One short axon carriers nerve impulses from the cell body to the CNS
Describe the shape of a motor neurone
Many short dendrites carry nerve impulses from the CNS to the cell body
One long axon carriers nerve impulses from the cell body to effector cells
Describe the shape of a relay neurone
Many short dendrites carry nerve impulses from sensory neurones to the cell body
An axon carries nerve impulses from the cell body to motor neurones
Which neurone has its axon surrounded in myelin sheath?
The Motor Neurone
Describe the order of the neurones
Sensory Neurone -> CNS -> Relay Neurone -> Motor Neurone
What do synapses connect?
Neurones
What do we call the connection between two neurones?
A synapse
What is the name of the chemicals which carriers the nerve signal across a synapse?
Neurotransmitters
What is a Neurotransmitter
A chemical which transfers a nerve signal across a synapse
Explain why the nervous impulse is slowed down a bit by a synapse?
It takes time for the neurotransmitters to diffuse across the gap
Define a reflex
Automatic and rapid response to a stimuli
What is the goal of a reflex?
To reduce the chances of being injured
Define reflex arc
The passage of information in a reflex (receptor to effector)
Why is a reflex quicker than a conscious activity?
With a reflex, no time is spent on thinking about the response
Give an example of a reflex within the human body
The human eye contracting and dilating depending on the light intensity
What is the human eye contracting and dilating depending on the light intensity an example of?
A reflex
How does the eye reflex work?
Light receptors in eye detect very bright light and send a message along a sensory neurone to the brain
Message travels along a relay neurone to a motor neurone which tells the circular muscles in the iris to contract making the pupil smaller
State all the parts of a human eye
Cornea, Iris, Lens, Retina, Rods / Cones and the optical nerve
What is the role of a cornea within a human eye?
The cornea refracts / bends the light into the eye
What is the role of an iris within a human eye?
The iris controls how much light enters the pupil
What is the pupil in a human eye?
The hole in the middle
What is the role of a lens within a human eye?
The lens refracts light, focusing it on the retina
What is the role of a retina within a human eye?
The retina is the light sensitive part and its covered in receptor cells
What is the role of the rods within a human eye?
The rods are more sensitive to dim light but can’t sense colour
What is the role of the cone within a human eye?
The cones are sensitive to different colours but are not so good in dim lights
What is the role of a optical nerve within a human eye?
The optical nerve is the nerve that carries the information from light (which was converted into electrical impulses) to the brain
What is the light sensitive part of a human eye?
The retina
What part of the eye can detect light but not colour?
Rods
What part of the eye can detect colour but not light?
Cones
True or false? The lens is elastic?
True
Why is the lens elastic?
So the eye can focus light onto the retina by changing the shape of the lens
What happens to the cillary muscles when looking at distant objects?
It relaxes
What happens to the cillary muscles when looking at close objects?
It contracts
Why does the cillary muscle relax when looking at distant objects?
To pull the suspensory ligaments to pull tight which pulls the lens into a less rounded shape so light is refracted less
Why does the cillary muscle contract when looking at close objects?
To slacken the suspensory ligaments which turns the lens into a more rounded shape so light is refracted more
What happens when a human is long-sighted?
The lens is the wrong shape and doesn’t bend the light enough so the light is brought into focus behind the retina
What two things cause being long-sighted?
The lens being the wrong shape or the eyeball being too short
What type of lenses corrects long-sighted humans?
Convex / Converging
What happens when a human is short-sighted?
The lens is the wrong shape and bends the light too much so the light is brought into focus in front of the retina
What two things cause being long-sighted?
The lens being the wrong shape or the eyeball being too long
What type of lenses corrects short-sighted humans?
Concave / Diverging
What causes a human to be colour blind?
The cones not working properly
What is a cataract in the eye
A cloudy patch on the lens
What does a cataract stop?
Light from being to enter the eye
Why can’t we cure colour blindness at the moment?
Cone cells can’t be replaced
Can we cure a cataract?
Yes
How do we cure a cataract?
By replacing the faulty lens with an artifical one
What is the W.H.O definition of good health?
The state of complete physical, mental and social well-being and not merely the absence of disea or infirmity
If someone is very physically fit, but has mental health issues are they healthy according to the W.H.O definition?
No
Define disease
A condition where part of an organism doesn’t function properly
What are the two types of disease?
Communicable and non-communicable
What is a communicable disease?
A disease that can be spread between individuals
What is a non-communicable disease?
A disease that can’t be spread between individuals
Give an example of a communicable disease
Cholera, Malaria or Tuberculosis
Give an example of a non-communicable disease
Cancer, Diabetes or CVD
What is a pathogen?
A disease causing organism
What are examples of types of pathogens?
Bacteria, fungi, viruses and protists
What is a protist?
A eukaryotic single-celled organism
What type of pathogen causes cholera?
A bacterium (Vibrio Cholerae)
What are the symptoms of cholera?
Diarrhoea
How does cholera spread?
Contaminated water sources
What are methods to reduce cholera transmission?
Ensuring people have access to clean water supplies
What type of pathogen causes tuberculosis?
A bacterium (Mycobacterium Tuberculosis)
What are the symptoms of tuberculosis?
Coughing and lung damage
How does tuberculosis spread?
Through the air when infected individuals cough
What are methods to reduce tuberculosis transmission?
Good hygiene
What type of pathogen causes malaria?
A protist
What are the symptoms of malaria?
Damage to red blood cells and even liver damage
How does malaria spread?
Mosquitoes (the vector) pass on the protist to humans
What are methods to reduce malaria transmission?
Mosquito nets and insect repellent
What type of pathogen causes stomach ulcers?
A bacterium (Helicobacter pylori)
What are the symptoms of stomach ulcers?
Stomach pain, nausea and vomiting
How does stomach ulcer spread?
Oral transmission (swallowing contaminated water/food)
What are methods to reduce stomach ulcer transmission?
Having clean water supplies and hygienic living conditions
What type of pathogen causes ebola?
A virus (Ebola virus)
What are the symptoms of ebola?
Haemorrhagic fever (Fever + Bleeding)
How does ebola spread?
Bodily fluids
What are methods to reduce ebola transmission?
Isolating infected individuals and sterilising any areas where the virus may be present
What type of pathogen causes chalara ash dieback?
A fungus
What are the symptoms of chalara ash dieback?
Leaf loss and bark lesions
How does chalara ash dieback spread?
Through the air/wind
What are methods to reduce chalara ash dieback transmission?
Removing young, infected ash trees and replanting with different species or restricting imports/movement of ash trees
What is a vector, in terms of disease transmission?
A vector is an organism which passes on a pathogen without getting the respective disease (showing symptoms)
What are viruses?
Usually a protein coat around a strand of genetic material
What must viruses do in order to reproduce?
Infect other living cells
Name the two types of virus pathways?
Lytic and lysogenic
What is the lytic pathway?
Virus attaches to host cell and injects genetic material
Genetical material uses proteins and enzymes in cell to replicate its material
Viral components assemble
Host cell splits open, releasing new viruses, which infect more cells
What is the lysogenic pathway?
Genetic material becomes incorporated into the genome of the cell (DNA)
As the cell divides, the viral genetic material divides aswell. However, the virus is dormant and no new viruses are made
Eventually a trigger causes the material to leave the genome and enter the lytic pathway
Give an example of a trigger within the lysogenic pathway
The presence of a chemical
In which virus pathway is the virus dormant for most of the cycle?
The lysogenic pathway
What does the virus use in the lytic pathway to replicate?
The host cells proteins and enzymes
State two STI’s
Chlamydia and HIV
What type of pathogen causes Chlamydia?
A bacterium
How is the chlamydia bacterium different to a normal bacterium?
The bacterium acts in a similar way to a virus as it can only replicate in host cells
What are the symptoms of Chlamydia?
Sometime’s causes infertility
What are methods of preventing Chlamydia transmission?
Wearing a condom during sex and screending individuals so they can be treated for the infection
What type of pathogen causes HIV?
A virus
What does the HIV virus kill?
White blood cells
What does HIV infection eventually lead to?
AIDS (Acquired Immune Deficiency Syndrome)
What is AIDS?
When the infected person’s immune system deterioates and eventually fails
Why is AIDS so bad?
Because the immune system is extremely weak or non-existent the person becomes very vulnerable to opportunistic infections by other pathogens
How is HIV spread?
Bodily fluids
What are methods of preventing HIV transmission?
Wearing a condom, avoid sharing needles and medication can be used to reduce the risk of an infected indivudals passing the virus on to others during sex/pregnancy
What are examples of physical defenses within plants?
Waxy cuticle on leaves and stems and the cells are surrounded with cell walls
Why is a waxy cuticle a defense within plants?
Acts as a barrier to stop pathogens entering whilst laos stopping water collection on the leaf which could reduce infection
Why is a cell wall a defense within plants?
Acts as a barrier preventing pathogens that make it past the waxy cuticle
What is a plant cell wall made of?
Cellulose
What are examples of chemical defenses within plants?
Quinine and Aspirin
In the field, how are plant disease usually detected?
Observations
How can plant pathologists identify the pathogen involved?
Different pathogens are spread in different way
How do plant pathologists detect antigens?
Monoclonal antibodies can be used to detect the antigens present from a particular pathogen within a cell tissue
The pathogen can then be used to identify the disease
How do plant pathologists detect DNA?
If a pathogen is present, it’s DNA will be present in the plants tissue
Techniques can be used to identify the DNA
What are examples of physical barriers within human body?
Skin, Hairs and Mucus and Cells in the tranchea
Why is skin a defense within humans?
Acts as a barrier to prevent pathogens entering
Blood will also clot to quickly seal cuts
Why does hair and mucus in your nose act as a defense within humans?
They trap particles that could contain pathogens
Why do cells in your trachea and bronchi act as a defense within humans?
They produce mucus which traps pathogens
Also occasionally have cillia on them
What are examples of chemical barriers within human body?
HCL in stomach and lysosomes in tears
Why does hydrochloric acid in the stomach act as a defense within humans?
It kills most pathogens that are swallowed
Why does lysosomes in tears act as a defense within humans?
It kills bacteria on the surface of the eye
What destroys pathogens within the human body?
The immune system (eg. Lymphocytes and Phagocytes)
What do white blood cells use to travel around the body?
The blood (Circulatory System)
What does every pathgogen have on it’s surface?
Antigens
Where is the antigen located on a pathogen?
The surface
What is a pathogens antigen usually made from?
Protein
What happens when the b-lymphocytes locates an antigen?
The b-lymphocytes begins to produce antibodies (proteins)
What do the antibodies to do the antigens?
Bind to them so other white blood cells can destroy them
True or False? The antibodies produced are specific to that pathogen so they won’t lock on to any other pathogens?
True
What is also produced alongside the antibodies?
Memory lymphocytes
Why is the response to a pathogen slow at first?
No b-lymphocytes that can make the respective antibody
When is the person “immune” to a specific antigen?
When the b-lymphocytes have produced memory lymphocytes for that specific antigen
How is the secondary response different to the first, in terms of pathogen infection?
The secondary response is not only faster but also stronger
Why is the secondary response faster and stronger?
Memory lymphocytes are present to quickly produce antibodies for the specific antigen
What does immunisation usually involve injecting into the body?
Dead or inactive pathogens
What must the pathogens be that are injected into the body during immunisation?
Antigenic (carry antigens)
What do the antigenic pathogens cause to be made?
Memory lymphocytes
Why does immunisation help prevent infection?
Memory lymphocytes are produced because of the dead/inactive antigenic pathogens
On infection of live pathogens of the same type, fast response due to memory lymphocytes
What are the pros of immunisation?
Herd Immunity and disease eradication
What are the cons of immunisation?
Doesn’t always work and a bad reaction may occur (rejection)
What is herd immunity?
If a certain percentage of the population are immune to a pathogen, there are fewer people to pass on the pathogen
Name a disease that has been virtually wiped out by vaccines?
Smallpox
What are examples of a bad reaction to a vaccine?
Swellin, fever or even seizures
What are monoclonal antibodies?
Identical antibodies
What produces antibodies?
B-lymphocytes
Why is a tumour cell fused with a b-lymphocyte?
Although tumour cells don’t produce antibodies, they do rapidly divide
What type of tumour cell is most oftenly used for monoclonal antibodies?
A myeloma cell (tumorous white blood cell)
What is the name of the cell produced when a myeloma cell is fused with a monoclonal antibody?
A hybridoma cell
Why are monoclonal antibodies useful?
They can be made to bind to anything you want, therefore they can be used to target a specific cell or chemical found within the body
What hormone is found within the human urine only when a woman is pregnant?
HCG
Which hormone do pregnancy testing sticks test for?
HCG
What is found on the area of the pregnancy stick you urinate on?
Antibodies that will bind to HCG, with blue beads attached
What is found on the test strip on the pregnancy stick?
Antibodies that will bind to HCG. However, they are stuck onto the strip
Why are the antibodies stuck to the test strip?
So they don’t move
What would happen to the pregnancy stick if you’re pregnant and urinate on it?
The hormone will bind to the antibodies on the blue beads
The urine will move up the stick, carrying the hormone and the beads
The beads and hormone bind to the antibodies on the strip
The blue beads get stuck, leading to the blue colour change
What would happen to the pregnancy stick if you’re not pregnant and urinate on it?
The urine will move up the stick, carrying the beads
The blue beads don’t get stuck, leading to no colour change
What do cancer cells have that allow them to be targeted by monoclonal antibodies?
They have proteins on their cell membranes that aren’t found on normal body cells. These are called tumour markers
When using monoclonal antibodies to diagnose cancer what must you do first with the antibodies?
Label them with a radioactive element
How are the labelled monoclonal antibodies given to the patient?
Through a drip (which goes into the blood and is carried around the body)
What happens when the labelled monoclonal antibodies come into contact with the cancer cells?
They bind to the tumour markers
What is used to find the labelled monoclonal antibodies?
A radio-sensitive camera
What are the results from the radio-sensitive camera show?
The location of the cancer, the size of the cancer and whether it’s spreading or not
When treating cancer, what is attached to the monoclonal antibodies?
An anti-cancer drug
How is the monoclonal antibodies given to the patient when treating cancer?
Through a drip (which goes into the blood and is carried around the body)
Why do the monoclonal antibodies target only the cancer cells?
Because they only bind to the unique tumour markers
True or False? The drug attached to the monoclonal antibody kills the cancer cells and body cells?
False, only the cancer cells are killed
Why is using monoclonal antibodies better than methods such as radiotherapy?
Monoclonal antibodies only kill cancer cells, whereas, radiotherapy kills all the cells within a given area
True or False? The side-effects of monoclonal antibodies for treating cancer are lower than radiotherapy?
True
True or False? Monoclonal antibodies can’t be used to find blood clots as they don’t have antigens?
False
How come monoclonal antibodies can be used to find blood clots?
When a blood clot forms, proteins in the blood join together to form a solid mesh
Monoclonal antibodies can be used to bind to these proteins
What must you attach to a monoclonal antibodies when finding blood clots?
A radioactive element
How do you use a labelled monoclonal antibody to find blood clots?
Inject the labelled monoclonal antibodies into the body
Take a picture using a radio-sensitive camera, if on the photo there is an area with a really bright spot, there is a blood clot in that location
Why is finding blood clots useful?
You can easily find a potentially harmful blood clot and get rid of it before it harms the patient
How do antibiotics work?
They inhibit processes in bacterial cells - but not in the host cells
What is an example of an antibiotic preventing processes within bacterial cells?
Some antibiotics work by destroying the cell wall which prevents the cell from dying, therefore the cell will die without any daughter cells
Why is it important to be treated with the right antibiotic?
Different antibiotics kill different types of bacteria
True or False? Antibiotics kill viruses
False, they don’t as viruses reproduce using your body cells therefore they are resistant to the antibiotics as antibiotics won’t target host cells
Why can’t antibiotics kill viruses?
Viruses reproduce using your body cells therefore they are resistant to the antibiotics as antibiotics can’t target host cells without killing them
What are the two phases of testing for antibiotics?
Preclinical and clinical testing
What is the first stage of preclinical testing?
Drugs are tested on human cells and tissues
What is the second stage of preclinical testing?
Drugs are tested on live animals
What is the goal of the second stage of preclinical testing?
To test that the drug works, whether it produces the effect you’re looking for) and to find out how toxic it is
What is the first stage of clinical testing?
The drug is tested on healthy volunteers
What is the goal of the first stage of clinical testing?
To ensure there aren’t any harmful side effects when the body is working normally
What is the second stage of clinical testing?
The drug is tested on volunteers who are infected with the disease respective to that antibiotic
What is the goal of the second stage of clinical testing?
To find the optimum dosage
What occurs once the drug passes clinical testing?
It must be approved by a medical agency to be used
What is a disadvantage of testing drugs on human cells and tissue?
You can’t test drugs that affect whole or multiple body systems
True or False? The first stage of clinical testing involves testing the drug on infected individuals?
False, it is first given to healthy volunteers
Define the optimum dose, in terms of antibiotics?
The dose of drug that is the most effective and has the fewest side effects
Define placebo, in terms of antibiotics?
A substance that looks like the drug being tested but doesn’t do anything (eg. A sugar pill)
What does using a placebo account for when testing for drugs?
The placebo effect which is when the patient expects the treatment to work so they feel better, even though the treatment isn’t doing anything
Define a blind trial, in terms of drug testing?
The patient in the study doesn’t know whether they’re getting the drug or placebo
Define a double blind trial, in terms of drug testing?
The patient nor the doctor know who has a placebo and who has the drug
Why is a double blind trial sometimes done?
So the doctors analysing the results aren’t subconsciously influenced by their knowledge
What are the two types of solution that can be used for a growth medium?
Nutrient broth solution or solid agar jelly
What is used to transfer the microorganisms to the agar jelly after it’s been poured into a petri dish?
An inoculating loop (wire loop)
What temperature are the petri dishes keep at in school?
25 degrees Celsius
What does antiseptic kill?
Bacteria outside the body (eg. the skin)
What’s the difference between antiseptics and antibiotics?
Antibiotics kill bacteria within the body where as antiseptics kill bacteria outside the body
What is the name for the bacteria that aren’t affected by the antibiotic?
Antibiotic-resistant bacteria
What is the control on an agar plate?
A paper disc
Why is a control used on an agar plate?
Ensure the bacteria are killed due to the antibiotic, not to a property of the paper discs which are soaked with the antibiotic
How do you tell how effective an antibiotic is when using agar plates?
The larger the inhibition zone, the more effective the antibiotic against the specific bacteria
When using agar plates, what is the impact of contamination of unwanted microorganisms?
Results will be affected and could result in the growth of pathogens
What does an autoclave use to kill any microorganisms present?
Steam at high pressure and high temperature
List ways of steralising equipment
Gamma rays, autoclave or heat (bunsen burner)
How is the inoculating loop steralised?
Passing it through a hot flame
Why is the inoculating loop steralised?
So any unwated microogranisms are killed
Why are liquid bacterial cultures kept in a culture vial with a lid?
To prevent other microbes getting in
What is the liquid bacteria kept in?
A culture vial with a lid
True or false? The petri dish should be stored upside down?
True, this is to avoid drops of condensation falling onto the agar
Which way is the petri dish stored?
Upside down
Why is the petri dish stored upside down?
To avoid drops of condensation falling onto the agar
Define a risk factor, in terms of non-communicable disease
A factor that is linked to an increase in the likelihood that a person will develop a certain disease during their lifetime
List risk factors that are unavoidable
Age or gender
List risk factors that are avoidable
Smoking, drinking alcohol, diet or obesity
How is smoking a risk factor for cardiovascular disease?
Nicotine, in smoke, increases the heart rate which increases blood pressure
Blood pressure damages artery walls, which contributes to the build up of fatty deposits in the arterys which restricts blood flow therefore increasing the risk of a heart attack/stroke
What disease could too few, much nutrients lead to?
Scurvy (lack of vitamin c)
How does excessive alcohol consumption act as a risk factor?
Alcohol is broken down by enzymes in the liver and some of the products are toxic
Therefore, drinking too much alcohol will cause an excessive amount of those toxic products which can cause permanent liver damage
What non-communicable disease can excessive alcohol consumption lead to?
Cirrhosis
List risk factors associated with cardiovascular disease
Obesity, lack of exercise, too much alcohol and a diet high in saturated fat
How do non-communicable diseases affect the NHS at a local level?
Wastes money, beds and staff
How do non-communicable diseases affect the NHS at a national level?
Wastes money, beds and staff but also puts a strain on the economy with less able workers
How do non-communicable diseases have an affect at a global level?
Can hold back developing countries as cardiovascular disease is the number one cause of death worldwide
What is cholesterol?
A fatty substance that the body needs to make things like cell membranes
What does too much cholesterol cause?
Blood flow restriction as the fatty deposits build up in the arteries
Where do the deposits occur?
Area’s where the artery wall have been damaged
What is usually recomended first to treat cardiovascular disease?
Lifestyle changes
Why are lifestyle changes recomended first when treating cardiovascular disease?
There are not really any downsides
Why must people with cardiovascular disease eat less saturated fat?
Saturated fat can increase blood cholesterol level
What are examples of drugs that can reduce the risk of cardiovascular disease?
Statins, anticoagulants and antihypertensives
How do statins reduce the risk of cardiovascular disease?
Statins reduce the amount of cholesterol in the bloodstream which slows down the rates of deposits forming
What are the side-effects of using statins to reduce the risk of cardiovascular disease?
Aching muscles or potentially liver damage
How do anticoagulants reduce the risk of cardiovascular disease?
Anticoagulants make blood clots less likely to form
What are the side-effects of using anticoagulants to reduce the risk of cardiovascular disease?
Excessive bleeding, if in an accident
What is an example of an anticoagulant?
Warfarin
How do antihypertensives reduce the risk of cardiovascular disease?
Antihypertensives reduce blood pressure, this helps to prevent damage to blood vessels which reduces the risk of fatty deposits forming
What are the side-effects of using antihypertensives to reduce the risk of cardiovascular disease?
Headaches and fainting
What is an example of an antihypertensives?
Beta blockers
Why are surgical procedures the last opportunity when treating cardiovascular disease?
Any type of surgery is a major procedure and there is a risk of bleeding, clots and infection
Name 3 examples of surgical procedures to treat cardiovascular disease
Stents, coronary bypass surgery (CBS) and donor heart replacement
Where are stents inserted?
Inside arteries
Why are stents used to treat cardiovascular disease?
They keep the vessel open, allowing blood through lowering the risk of a heart attack
What is a disadvantage of using stents to treat cardiovascular disease?
Overtime, the artery can narrow again as stents can irritate the atery and make scar tissue grow
How is coronary bypass surgery used to treat cardiovascular disease?
A healthy vessel will enable blood to flow better, reducing blood pressure therefore the risk of cardiovascular disease decreases
What are some disadvantages of using a donor heart?
New heart may not always start pumping properly and drugs have to be taken to prevent rejection (these drugs may also increase the vulnerability to infection)
Why does cells need oxygen?
For aerobic respiration
How do oxygen and carbon dioxide move between cells?
Diffusion
How is urea produced by animals?
From proteins
Where does urea diffuse from?
The cells to the blood plasma
Why do single-celled organisms not require exchange surfaces?
They have a large enough SA:V so enough substances can be exchanged across the membrane to supply the volume of the cell
Why do multi-cellular organisms require exchange surfaces?
They have a small SA:V so it makes it harder for enough substances to be exchanged to supply their entire volume
What do multi-cellular organisms have because they cannot match the demand of substances?
Efficient exchange surfaces and mass transport systems
What are the three factors that affect the rate of diffusion?
Distance, concentration difference and surface area
Why does distance affect the rate of diffusion?
Substances diffuse more quickly when they haven’t got as far to move
Why does concentration difference affect the rate of diffusion?
Substances diffuse faster when there are more particles on a certain side
Why does surface area affect the rate of diffusion?
The more surface there is available for molecules to move across, the faster they can get from one side to the other
What is the job of the lungs?
To transfer oxygen to the blood and to remove waste carbon dioxide
True or false? The lungs have 2 aveoli, one for each side
False, in fact, there are millions of them
Where has the blood that reaches the lungs just came from?
The rest of the body (just came from the heart)
Why is the diffusion of oxygen and carbon dioxide within the alveoli fast?
Lots of the alveoli, so large SA:V
Close distance between alveoli and the circulation system
High concentration difference between alveoli and circulation system
Why do the alveoli have high concentration difference?
Just came from heart so low oxygen, high carbon dioxide
How are the alveoli specialised?
Moist lining
Good blood supply to maintain the concentration gradient
Very thin walls to minimise the distance that the gases have to move
An enormous surface area
What is ficks law?
Rate of diffusion ∝ surface area × concentration difference thickness / thickness of membrane
Is the surface area directly or inversely proportionate to the rate of diffusion?
Directly
Is the concentration difference directly or inversely proportionate to the rate of diffusion?
Directly
Is the thickness of membrane directly or inversely proportionate to the rate of diffusion?
Inversely
If the surface area doubles, what will happen to the rate of diffusion?
It will double aswell
If the concentration difference doubles, what will happen to the rate of diffusion?
It will double aswell
If the thickness of membrane doubles, what will happen to the rate of diffusion?
It will halve
What is the role of an erythrocyte?
To carry oxygen from the lungs to all the cells in the body
How is an erythrocyte specialised?
No nucleus - more space for oxygen
Biconcave disc - increase surface area
Contains haemoglobin - allows oxygen to bind to the erythrocyte
What do white blood cells defend against?
Infections
What are the two types of white blood cells?
Phagocytes and lymphocytes
How do phagocytes defend against infection?
They change shape to engulf microorganisms
How do lymphocytes defend against infection?
They produce antibodies or antitoxins against microogranisms
What will a blood test show a high amount of, if the body has an infection?
A high amount of white blood cells, to fight the infection
What do platelets help blood do?
Clot
What are platelets?
Fragments of cells
What do platelets not have?
A nucleus
Why does the blood clot?
To stop all your blood pouring out and to stop microorganisms getting in
What can lack of platelets cause?
Excessive bleeding and bruising
What is plasmas role in the blood?
To carry everything
What does plasma carry?
Red and white blood cells Platelets Urea Nutrients (glucose and amino acids) Carbon Dioxide Urea Hormones Proteins Antibodies and antitoxins
What do the arteries do?
Carry the blood away from the heart
What do the capillaries do?
Carry the blood so they can exchange the materials with the local tissue
What do the veins do?
Carry the blood to the heart
Why are artery walls strong and elastic?
The heart pumps the blood out at high pressure so the walls must be able to withstand the high pressure
Why do arteries contain thick layers of muscle?
To make them strong and to allow them to stretch and spring back
True or false? Capillaries are really tiny - too small to see?
True, this is to allow them to squeeze into small gaps between cells
Why do capillaries have permeable walls?
So substances can diffuse in and out
What do capillaries supply and take to and from cells?
Food, oxygen and carbon dioxide
Why are capillaries usually one cell thick?
To increase the rate of diffusion (ficks law)
Why are the vein walls less thick than artery walls?
The blood is at lower pressure
Why do veins have a bigger luman than artery walls?
To help the blood flow
What do veins have to keep the blood flowing in the right direction
Valves
What type of circulatory system do mammals have?
A double circulatory system
What type of circulatory system do fish have?
A single circulatory system
What does the heart pump blood through?
Blood vessels
Where does the right atrium recieve its blood?
From the body (through the vena cava)
What type of blood does the right atrium recieve?
Deoxygenated blood
Where does the right ventricle move the blood to?
The lungs (via the pulmonary artery)
What type of blood does the right ventricle move?
Deoxygenated blood
What type of blood does the left atrium recieve?
Oxygenated blood
Where does the left atrium recieve its blood?
From the lungs (through the pulmonary vein)
What type of blood does the left ventricle move?
Oxygenated blood
Where does the left ventricle move the blood to?
To the whole body (via the aorta)
What ventricle has a thicker wall?
The left
Why does the left ventricle have a thicker wall?
Because it needs more muscle to push the blood around the whole body at a high pressure
What is the role of the valves within the heart?
To prevent the backflow of blood in the heart
Name 3 different valves within the heart
Tricuspid valve, Bicuspid valve and semi-lunar valves
Where does the blood flow into the heart?
Vena cava or Pulmonary vein
Where does the blood flow out of the the heart?
Pulmonary artery or aorta
What connects from the vena cava?
Right atrium
What connects from the right atrium?
Right ventricle
Where does the pulmonary artery go to?
The lungs
Where does the pulmonary vein come from?
The lungs
What connects from the pulmonary vein?
Left atrium
What connects from the left atrium?
Left ventricle
What connects from the left ventricle?
Aorta
Where does the aorta go to?
The rest of the body
What is cardiac output?
The total volume of blood pumped by a ventricle every minute
What are the units for cardiac output?
cm^3/min^-1
What is the equation for cardiac output?
Cardiac output = Heart Rate x Stroke Volume
What is heart rate?
The number of beats per minute
What is stroke volume?
The volume of blood pumped by one ventricle each time it contracts
What type of reaction is respiration?
Exothermic
Name the two types of respiration
Anaerobic and aerobic respiration
What type of respiration occurs in abundance of oxygen?
Aerobic
State the word equation of aerobic respiration
Glucose + Oxygen -> Carbon Dioxide + Water
State the symbol equation of aerobic respiration
C6H1206 + 602 -> 6C02 + 6H20
What equation is the reverse of respiration?
Photosynthesis
What type of respiration occurs in no oxygen?
Anaerobic
What type of respiration transfers more energy?
Aerobic
What type of respiration produces lactic acid/ethanol?
Anaerobic
True or false? Anaerobic transfers more energy due to it having less reactants
False, aerobic transfers more energy
What does the build up of lactic acid lead to?
Pain and cramp
What is the word equation for anaerobic respiration?
Glucose -> Lactic Acid
In plants, what do they produce when they anaerobically respire?
C02 and Ethanol
What is the word equation for anaerobic respiration in a plant?
Glucose -> Carbon Dioxide + Ethanol
What piece of apparatus can you use to measure the rate of respiration?
Respirometer
What measurement must you gather to measure the rate of respiration?
Amount of oxygen consumed by organisms in a given time
What apparatus must you have to measure the rate of respiration?
Woodlice, water bath and respirometer
What must be added to the two test tubes?
Soda lime granules
Why are soda lime granules added to the test tubes?
To asorb the CO2 produced
What is placed as a replace of the organisms in the other test tube?
Glass beads of the same mass
How long is the apparatus left in the water bath for when measuring the rate of respiration?
A set time
Why does the volume of gas decrease when measuring rate of respiration?
Because the woodlice use up the oxygen in the tube, with the carbon dioxide being absorbed by the soda lime present
How is the distance moved in the respirometer used to calculate rate of respiration?
Volume of oxygen taken in / Time
What is the indepenedent variable in the rate of respiration experiment?
The temperature, this is because the whole point of the practical is to see how changing the temperature affects the rate of respiration
What issues arise when using live animals in experiments?
Ethical issues
What must you avoid when using live animals when investigating respiration?
Ensuring they don’t run out of oxygen and die
What do green plants and algae use to make glucose?
Energy from the sun
What is some of the glucose used for in plants?
Growth
What is biomass?
The mass of an organism
Where does photosynthesis take place?
Chloroplasts
What is found inside chloroplasts?
Chlorophyll
What does chlorophyll do?
Traps and absorbs lights
How is energy transferred to the chloroplasts?
By light
What is the word equation for photosynthesis?
Carbon Dioxide + Water -> Glucose + Oxygen
What is the symbol equation for photosynthesis?
6C02 + 6H20 -> C6H1206 + 602
What type of reaction is photosynthesis?
Endothermic
What are the three factors of photosynthesis?
Concentration of carbon dioxide, light intensity and temperatire
What type of aquatic plant is used to measure the effect of light intensity of the rate of photosynthesis?
Canadian pond weed
True or False? The gas syringe should be full before used to investigate the rate of photosynthesis?
False, it needs to be empty
What gas is measured when investigating the rate of photosynthesis?
Oxygen
What light should be used when investigating the rate of photosynthesis?
White light
What is the independent variable when investigating the rate of photosynthesis??
Distance from white light and canadian pondweed
How do you calculate the rate of oxygen production when investigating the rate of photosynthesis?
Volume produced / Time taken
What variables should be controlled when investigating the rate of photosynthesis?
Temperature and Carbon dioxide concentration
What does not enough light do to the rate of photosynthesis?
Slows down the rate
What does light do for photosynthesis?
It transfers the energy needed
Describe the graph when increasing the light level and measuring the rate of photosynthesis?
At first, steady increase
But beyond that, no difference as the limiting factor will now be either carbon dioxide level or temperature
Why does the light level graph when measuring the rate of photosynthesis level off?
The limiting factor is no longer light level, it is now either carbon dioxide level or temperature
Why is the distance from the light and light intensity inversely proportional?
Because as distance increases, the light intensity decreases
What is the equation for light intensity and distance?
Light intensity ∝ 1 / distance²
If distance was to halve, what would happen to the light intensity?
It would be multiplied by 4
What does too little carbon dioxide do to the rate of photosynthesis?
Slows it down
Describe the graph when increasing the carbon dioxide level and measuring the rate of photosynthesis?
At first, steady increase
But beyond that, no difference as the limiting factor will now be either light level or temperature
Why does the temperature have to be just right when increasing the rate of photosynthesis?
Enzymes are present, too high of temperature will denature the enzymes
What temperature do the enzymes in photosynthesis need to be to denature?
Around 45°C
What do root hairs take in?
Minerals and Water
What sticks out of root hair cells?
Hairs which stick into the soil
What gives the root hair cells a large surface area?
They branch off to millions of microscopic hairs
Why do root hairs cells have a large surface area?
So they can absorb water and mineral ions more
What occurs alot in root hair cells?
Active transport
Why does active transport occur in root hair cells?
The concentration of mineral ions is usually higher in the cell than in the soil
Energy is needed to move the minerals up the concentration gradient
Why do the root hair cells have loads of mitochondria?
Because they undergo alot of active transport
Active transport is an active process so it requires energy
Mitochondria releases energy via respiration
More mitochondria means more efficient active transport
What do pholem tubes transport?
Food
What are pholem tubes made up of?
Elongated living cells
Why do pholem tubes have small pores?
To allow stuff to flow through
What are the two uses of the food that the pholem tube transports?
Immediate use (eg. growing) or storage for later use
What is the name of the process that occurs in the pholem tubes?
Translocation
Which directions does translocation occur?
Both directions
What do xylem tubes transport?
Water
What are xylem tubes made up of?
Dead cells joined end to end with no end walls between them
What substance is used to strengthen the xylem tubes?
Lignin
What and where do the xylem tubes transport?
Water and mineral ions from the roots to the stems/leaves
What is the name of the process that occurs in the xylem tubes?
Transpiration
Which directions does transpiration occur?
Only one, up and out of the leaves
What is transpiration?
The loss of water from plants
What causes transpiration?
Evaporation and diffusion
Where does transpiration occur most?
At the leaves
What does the loss of water due to transpiration cause?
More water to be absorbed up the xylem vessel due to lower concentration within plant
What is also dissolved in the water that is part of the transpiration stream?
Mineral ions
What are stomata needed for?
Gas Exchange
What are stomata?
Tiny pores on the surface of a plant
What do stomata allow to diffuse directly into the leaf?
Carbon Dioxide and Oxygen
True or False? Transpiration is really just a side-effect of the way leaves are adapted to photosynthesis?
True, thats because the stomata are there for gas exchange, the water simply diffuses out because theres a higher concentration within the plant
What are the three factors that affect the transpiration rate?
Light Intensity, Temperature and Airflow
Why does light intensity affect transpiration rate?
As it gets lighter, the stomata opens more and more to ensure more gas exchange to match the demand of photosynthesis which also increases the rate water leaves
Why does temperature affect transpiration rate?
The warmer it is, the more energy to evaporate and diffuse out the stomata
Why does air flow affect transpiration rate?
The more the air flow, the less water vapour outside a plant, therefore, the concentration difference becomes even more steeper increasing the rate of diffusion
What apparatus must you use to estimate the transpiration rate?
A potometer
What measurement do you measure to estimate the transpiration rate?
The amount the air bubble has moved
What is the equation to calculate the transpiration rate@
Distance moved / Time taken
Why are leaves broad?
To have a large surface area, so theres more area exposed to light which is needed for photosynthesis
What is the name of the layer that has lots of chloroplasts?
The palisade layer
Why does the palisade layer have loads of chloroplasts?
Because its at the top
The top is where the most light is
Photosynthesis requires light
Why is the upper epidermis transparent?
To allow light to pass through to the palisade layer
What do the xylem and phloem tubes move?
Water and glucose
How are the tissues of leaves adapted?
Lots of stomata, to allow carbon dioxide to diffuse directly in to the leaf
The spongy mesophyll tissue contains air spaces which increases the rate of diffusion of gases into and out of the leaf’s cells
What do plant adaptations tend to affect?
Size and shape of it’s leaves, it’s cuticle and the number and position of its stomata
What adaptations do cacti have to survive in desert locations?
Small leaves - reduces surface area so less water loss
Curled leaves - reduces air flow, reducing diffusion
Thick waxy cuticle - reduce water loss by evaporation
Thick fleshy stem - to store water
Fewer stomata - reduce water loss
Stomata sunken - reduces water loss as less air flow
What are auxins?
Growth hormones within a plant
True or False? Auxins move through the plant in solution?
True
Where is auxin produced?
The tips
Why and where does auxin diffuse to?
Backwards to stimulate cell elongation
What does auxin promote?
Growth in the shoot
What does auxin inhibit?
Growth in the root
What is photoropism?
The response to a stimulus of light
What is gravitropism?
The response to a stimulus of gravity
How do shoots react to light?
They are positively phototropic which means they grow towards light
Explain how a shoot reacts to light
When a shoot is exposed to light, it accumulates more auxin on the side that’s in the shade than the side that’s in the light
This makes the cells grow faster on the shaded side, bending the shoot
Why does a shoot bend towards the light?
To absorb more light for photosynthesis
What is the appearance of a shoot growing in the dark?
Tall and spindly
How do shoots react to gravity?
They are negatively gravitropic which means they grow away from gravity
Explain how a shoot reacts to gravity
When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip, with more auxin being on the lower side
This makes the cell grow faster on the lower side, bending upwards
How do roots react to gravity?
They are positively gravitropic which means they grow towards gravity
Explain how roots react to gravity
A root growing sideways will have more auxin on it’s lower side
But in a root the extra auxin inhibits growth
This means the cells on top elongate faster, bending the root downwards
How do roots react to light?
They are negatively phototropic which means they grow away from light
Explain how roots react to light
If a root is exposed to light, it accumulates more auxin on the side that’s on the more shaded side
The auxin inhibits cell elongation on the shaded side which leads to the root bending downwards
What seeds are used to investigate plant growth responses?
Cress Seeds
Where do you put the cress seeds when investigating plant growth responses?
In a petri dish with moist filter paper
What do you surround the petri dish with when investigating plant growth responses?
Black paper, leaving only one hole
What do you do through the hole when investigating plant growth responses?
Shine a light
How long do you leave the seeds when investigating plant growth responses?
One week
What should you find after one week of investigating plant growth responses?
The seedlings grow towards the light
Name examples of commercial uses of plant hormones
Weed killers, rooting powder, controlling fruit and flower formation, seedless fruit formation, controlling the ripening of fruits and seed germination
What kind of leaved are weeds growing in fields?
Broad-leaved
What have selective weed killers been developed from?
Auxins which only affect broad-leaved plants
How do weed killers actually work?
They totally disrupt their normal growth pattern which eventually kills them
True or false? Once weed killers are administered, all the weeds are killed leaving the crops and grass?
True
Why do weed killers only “target” broad-leaved plants?
Because the auxins used to develop them have been taken from plants which are broad-leaved
What is a cutting?
A part of a plant that has been cut off
Why is root powder used on cuttings?
Because cuttings usually cannot grow, however, with root powder you can use it to produce roots rapidly and start growing as new plants
What are gibberellins?
Plant hormones that stimulate seed germination, stem growth and flowering
What is seed germination?
The growth of a seed into a plant
How do gibberellins work?
Enables the plant to grow earlier and in conditions which they don’t usually flower
What can gibberellins be used for in the commercial aspect?
They can be used to reduce flower formation which can improve fruit quality
Where do fruits with seeds in the middle usually grow?
On flowering plants which haven’t been pollinated by insects
What plant hormone is applied to remove seeds in fruit?
Gibberellin
Why is it better to pick unriped fruit?
It is firmer and less easily damaged
What ripening hormone is added to the fruit to ripen it?
Ethene
What conditions will seeds not germinate in?
A period of cold and dryness
What hormone can seeds be treated with to enable them to germinate in poor conditions?
Gibberellins
What is another advantage of using gibberellins when germinating seeds?
All the seeds germinate at the same time
In terms of ecosystems, what is an individual?
A single organism
In terms of ecosystems, what is a population?
All the organisms of one species in a habitat
In terms of ecosystems, what is a community?
All the organisms of different species living in a habitat
What is an ecosystem?
A community of organisms along with all the non-living conditions
True or False? Organisms in a community are interdependent?
True
What do organisms depend on?
Shelter and food
Why do organisms need shelter and food?
To survive and reproduce
What is mutualism?
A relationship between two organisms from which both organisms benefit
Where do parasites live relative to their host?
In or on them
What does the parasite do?
Take’s what it needs to survive, whilst the host has no benefit
What does abiotic mean?
Non-living
What does biotic mean?
Living
List all the abiotic factors
Temperature, water amount, light intensity and levels of pollutants
List all the biotic factors
Competition and predation
Why does water amount have an affect on an ecosystem?
All organisms need water to survive, too little can cause death from dehydration
However, if plants become water logged they will die
Why does light intensity have an affect on an ecosystem?
Trees and plants require light to photosynthesise, too little light will not only increase the competition but also cause more deaths
Why does level of pollutants have an affect on an ecosystem?
If levels of air pollution is too high organisms will be unable to survive
Why does temperature have an affect on an ecosystem?
If temperature is too high or low organisms will be unable to survive, without adaptations
Why does competition have an affect on an ecosystem?
Organisms compete with other species for the same resources
If too much competition there will not be enough food for specific organisms causing high amounts of death
Why does predation have an affect on an ecosystem?
If the numbers of predators increase, the amount of living prey will decrease
What is a quadrat?
A square frame enclosing a known area
What is a quadrat used for?
To compare how common an organism is in two sample areas
True or False? You must place a quadrat at a random point?
True, if not, the results will be unreliable as the place chosen may undergo bias
One placed your quadrat at a random point, what must you do?
Count all the microorganisms you’re interested in
Once counted all the microorganisms in the quadrat, whats the next step?
Repeat several times, then work out the mean (Total number of organisms / Number of Quadrats)
How do you calculate the mean when using quadrats?
Total number of organisms / Number of Quadrats
How do you estimate the population size when using a quadrat?
Number of organisms in one quadrat x (Sample Area / Quadrat Area)
What do you use to study distribution along a gradient?
Belt Transects
What is an example of when a belt transect may be used?
How a species changes rarity from an area of shade to an area of light
Once marked out using a belt transect, what must you do next?
Collect the relevant data by either counting the total organisms of a species present or by estimating percentage cover
What could you do if your belt transect is long?
Measure every so often, instead of back to back to back
What else could you measure when using a belt transect?
Light intensity or height of the plants
What is the source of energy for nearly all life on Earth?
The Sun
How do plants use light?
They convert a small percentage of the light that falls on them into glucose, via photosynthesis
What do plants use glucose for?
Respiration or storage (which contributes directly into their biomass)
What is biomass?
The mass of living material that makes up an organism
List ways energy is lost to the food chain?
Respiration, heating, waste excretion and movement
How is energy that is stored as biomass lost?
Not all of the organism is eaten, for example bones. But also, not all the stuff eaten can be digested
Usually, how many trophic levels long is a food chain
Five
In terms of population, what do you find as you go up a food chain?
There is a lower number of organisms this is because there is less biomass to go round
What do pyramids of biomass show?
How much the creatures at each level of a food chain would weigh if you put them together
As you go up a pyramid of biomass what do you see?
The mass of organisms goes down this is because most of the energy is lost and so does not become biomass in the next level
True or False? The first level of a pyramid of biomass is the last organism in the food chain?
False, the first level is always the producer
What type of organism goes on the first level of a pyramid of biomass?
The producer
How do you calculate efficiency of a pyramid of biomass?
Efficiency = Energy transferred to next level / Energy available at previous level
What is biodiversity?
The variet of living organisms in an ecosystem
Give an example on how humans have a positive impact on biodiversity?
Reforestation or conservation schemes
Give an example on how humans have a negative impact on biodiversity?
Eutrophication, fishing and the introduction of non-indigenous species
What fertilisers cause eutrophication?
Nitrates
What is eutrophication?
Excess of nutrients in water
What does the excess nitrates in the water cause?
Algae to grow fast and block out the light
Why does the algae grown from excess nitrate have a big impact?
The algae covers the light, which kills the plants as they can’t get light to photosynthesise
They then die and decompose
What does the decomposure of fish cause during eutrophication?
Due to more food being available microorganisms, that feed on the plants, grow in numbers and use up more oxygen
During eutrophication, what does the increase in the amount of microorganisms cause?
Fish death as less oxygen available because the microorganisms also need oxygen to survive
Give examples of how fish farms in the open can reduce biodiversity?
Eutrophication if waste and food leaked
Breeding grounds for parasites
Predators are attracted to the nets and become trapped
Farmed fish can escape into the wild and can cause problems for wild populations
What is a non-indigenous species?
A species that doesn’t naturally occur in an area
Give ways non-indigenous species are brought in intentionally
Food or hunting
Give ways non-indigenous species are brought in unintentionally
Stoaway or international cargo
What is an indigenous species?
A species that does naturally occur in an area
Why are non-indigenous species bad?
Sometimes, they outcompete the indigenous species for resources leading to a decrease in the indigenous species
They may also bring a disease which can infect and kill lots of the indigenous species
What does reforestation increase?
Biodiversity in deforested areas
Give an example of a way to increase the effectivity of reforestation
Replanting with a variety of tree species
What do conservation schemes do?
Protect at risk species
How do conservation schemes work?
By preventing species from dying out
Give some examples of conservation schemes
Protecting a species natural habitat
Protecting species in safe areas outside their natural habitat
Introducing captive breeding to increase numbers
Introducing seed banks to store and donate rare and endangered plants
Why should we maintain biodiversity?
To protect the human food supply To ensure minimal damage to food chains To provide future medicines To provide cultural aspects To provide ecotourism To provide new jobs
List biological factors affecting the level of food security
Increasing consumption of higher trophic level foods
Environmental changes due to human activity
Human population
New pests and pathogens
How does increasing consumption of higher trophic level foods affect the level of food security?
As you go up the food chain there becomes less and less biomass and energy available
Therefore, more of that organism is needed to provide the same amount as energy as the previous level
How does environmental changes due to human activity affect the level of food security?
Climate change and soil pollution will reduce the growth of crops
How does the increasing human population affect the level of food security?
More people, more food needed to feed same amount
More people, more energy needed, biofuel used
How do new pests and pathogens affect the level of food security?
They cause damage to livestock therefore too many of them can reduce crop yields
True or False? Materials are constantly recycled in an ecosystem?
True
For example, carbon, water and nitrogen
Provide a step by step explanation of how recyling works in an ecosystem
Living things take in elements from the environment
Turn these elements into complex compounds
Elements passed along food chains (producer -> consumer)
Elements recycled via decomposers decomposing waste products and dead organisms
In the carbon cycle, what is the one way carbon returns from the air?
Photosynthesis
What is the whole carbon cycle powered by?
Photosynthesis
How does the carbon get out the plants?
Via consumers
When the organisms are alive, how does the carbon get into the air?
Via respiration
When the organisms are dead, how does the carbon get into the air?
Via decomposers or burning of materials from the plants or animals
What powers the water cycle?
The sun
How does the water get into the air?
Evaporation from the land, sea and even plants (transpiration)
What happens to the water vapour within the water cycle?
It rises and begins to cool and condense to form clouds
What happens to the water vapour that has cooled and condensed?
It comes down as precipitation
What happens with the rain in the water cycle?
It provides for life and then eventually dries back into the sea and restarts the cycle
When does a drought occur?
When there’s not enough precipitation (rain)
How does desalination work?
Water is evapourated leaving salt behind, water then condenses in a separate contained leaving pure water
How does reverse osmosis work?
Any solids removed from water
Water is then pumped, at high pressure, into a container with a partially permeable membrane
The water molecules move across the membrane into pure water leaving the salt molecules
What is recycled in the nitrogen cycle?
Nitrogen
Why can’t nitrogen be used directly in animals?
Because it’s unreactive
What is nitrogen needed to make, in organisms?
Proteins
How does nitrogen enter the food chain?
By turning into a nitrate
How does the nitrogen leave the food chain?
Being part of a rotting plant, animal or waste that is being decomposed by decomposers (bacteria and fungi in the soil)
What is nitrogen fixation?
The process of turning nitrogen in the air into nitrogen-containing ions
How does lightning fixate nitrogen?
Lightning has enough energy to make nitrogen and oxygen react
How does nitrogen fixing bacteria fixate nitrogen?
Turn nitrogen gas into ammonia which then forms ammonium ions
What are the four different types of bacteria involved in the nitrogen cycle?
Decomposers
Nitrifying bacteria
Nitrogen-fixing bacteria
Denitryifying bacteria
How do decomposers contribute to the nitrogen cycle?
By turning the proteins and urea into ammonia
Ammonia then turns into ammonium ions which plants can use
How does nitrifying bacteria contribute to the nitrogen cycle?
Turns ammonia in decaying matter into nitrites and then into nitrates
How does nitrogen-fixing bacteria contribute to the nitrogen cycle?
Turns nitrogen gas into ammonia which then forms ammonium ions
How does denitrifying bacteria contribute to the nitrogen cycle?
Turns nitrates back into nitrogen gas
In the nitrogen cycle, what is the one way nitrogen returns to the air?
Denitrifying bacteria
List ways farmers can increase the amount of nitrates in the soil
Crop rotation and fertilisers
How does crop rotation increase the amount of nitrates in the soil?
Different crops are grown each year
One of the years introduces a nitrogen-fixing crop which puts nitrates back into the soil
State examples of nitrogen-fixing crops
Peas or beans
How do fertilisers increase the amount of nitrates in the soil?
The field recycles the nutrients left in the fertilisers through decomposition
What animals can be used to measure water pollution?
Stonefly larvae, freshwater shrimps, blood worms and sludgeworms
What do high amounts of stonefly larvae mean?
Low pollution
What do high amounts of blood worms or sludge worms mean?
High pollution
What are blood worms and sludge worms adapted to?
Polluted conditions
What are stonefly larvae and freshwater shrimps adapted to?
Non-polluted conditions
How can air pollution be measured?
Number of lichen and blackspot fungus
What does a high amount of lichen indicate?
Clean air
What does a high amount of blackspot fungus indicate?
Clean air
Give examples of non-living indicator methods
Dissolved oxygen meters and electronic meters
What are three factors of the rate of decay?
Temperature, water content and oxygen availability
How does temperature affect the rate of decay?
A higher temperature means the faster the rate of enzyme-controlled reactions in microbes
How does water content affect the rate of decay?
Decay takes place faster in moist conditions because they need water to survive
How does oxygen availability affect the rate of decay?
Decay takes place faster in high oxygen conditions because most decomposers need oxygen to respire
What are food preservation methods to reduce the rate of decay?
Storing food in fridge or freezer
Storing food in airtight containers
Steralising food
Drying food
How does drying food prevent the rate of decay?
Microorganisms need water to survive
How does steralising food prevent the rate of decay?
Steralising will kill any microorganisms present
How do airtight cans prevent the rate of decay?
It prevents microorganisms getting in
How does storing food in a fridge or freezer prevent the rate of decay?
By slowing down the rate of reproduction
What is compost?
Decayed organic matter
When is compost produced quickest?
Warm and moist conditions
How do you calculate the rate of decomposition?
Arbitary Units / Time
