Biology Paper 1- Main Focus Of Exam Flashcards
Do prokaryotes or eukaryotes have a nucleus?
Eukaryotes
What is an example of a prokaryote?
A bacterial cell
Where does a prokaryote store it’s genetic material?
In a single loop
What are 2 similarities in terms of sub- cellular structures, between prokaryotes and eukaryotes ?
They both have a cell membrane and cytoplasm
Do prokaryotes have plasmids?
Yes
Are prokaryotes or eukaryotes bigger?
Eukaryotes
By how much is every order of magnitude than the one before?
10X
Function of ribosomes
Function of protein synthesis
Function of nucleus
Controls activities and enclosed genetic material
Function of cytoplasm
Site of chemical reactions
Function of cell membrane
Controls what enters and exits the cell
Function of mitochondria
Respiration site
Which sub- cellular structures can only be seen through an electron microscope?
Mitochondria and ribosomes
Are ribosomes smaller than mitochondria?
Yes
Why type of shape do plant cells have?
Regular
Give 3 differences in terms of sub- cellular structures , between plant and animal cells
Plant cells have chloroplasts
Plant cells have a permanent vacuole
Plant cells have a cell wall
What does differentiation mean?
When cells become specialised
What is the job of a sperm cell?
Fertilise an egg cell
Give 3 features of a sperm cell
Head
Tail
Acrosome
What does the acrosome adaptation of a sperm cell give the cell?
Contains digestive enzymes needed to penetrate the egg cell
What does the head of a sperm cell contain?
Genetic info in its nucleus
What does a long tail give the sperm cell?
Used for cell motion and streamlined to swim to the ovum
Why is the middle section of a sperm cell filled with mitochondria?
Give it energy to swim to the ovum
What is the function of a nerve cell?
Send electrical impulses around the body
What does a long axon bring to the nerve cell?
Increases the distance for impulses to be carried
What does the myelin sheath act as?
An insulator- preventing any nerve signals leaking, increasing wooed of transmission
What do dendrites do?
Increase surface area and can connect to other nerve cells
What are muscle cells used for?
Contraction
What are 2 adaptations of a muscle cell?
Protein fibres
Mitochondria
What do proteins fibres bring to the muscle cell
Can change length
How is a muscle cell being packed with mitochondria an advantage?
Provide lots of energy for contraction
Give 3 adaptations of root hair cells
Hairs
Long projections
No chloroplasts
What do hairs on a root hair cell increase ?
Increases surface area for absorption
Why is having no chloroplasts relevant for a root hair cell?
It’s underground, so doesn’t photosynthesis
What do long projections bring to the root hair cell?
Increase surface area, therefore increase rate of absorption
Where are xylem cells found in a plant?
In the stwm
What do xylem cells transport?
Water and dissolved minerals
Give 2 adaptations of a xylem cell
Walls containing lignin
End walls broken
Why is login in an advantage for xylem cells?
Strengthens cell wall
What is having broken end walls advantageous for xylem cells?
Creates a long tube where water can flow through easily
Why sub cellular structures do xylem cells not have?
A nucleus, cytoplasm,
Vacuole
Or
Chloroplasts
What do phloem cells carry?
Dissolved sugars up and down the plant
Give 3 adaptations of phloem cells
Phloem vessel cell has no nucleus
End walls of vessel cells have pores
Companion cell has mitochondria
Why is the vessel cell having no nucleus and it’s end walls having pores advantageous?
Sieve plates, so
Sugar can move
Describe how you can observe a slide with a microscope
Place slide on stage
-use clips to hold in place
Select lowest power objective lens
- slowly turn coarse dial until it almost touches
Look down through eyepiece
-slowly turn coarse dial- increases distance r between lens and slide
Use fine dial to bring cells into clear focus
What is total magnification?
Eyepiece lens mag X objective lens mag
What are 2 Advantages of electron microscopes over light microscopes?
Higher resolution
Higher magnification
What is 2 advantages of light microscopes compared to electron microscopes?
Can see living cells
Cheaper
What’s the equation for magnification?
Image size/actual size
Why do we use a low objective lens first?
Gives a bigger field of view and it is then easier to focus
how do bacteria multiply?
By binary fission- simple cell division
How often can bacteria carry out binary fission?
Every twenty minutes as long as they have enough nutrients and the temperature is suitable
What’s diffusion?
Spreading out of particles in a bet movement from an area of high concentration to an area of low concentration
How does oxygen diffuse?
From the lungs to bloodstream
How does urea diffuse?
Diffuse out of cells in blood
Plasma
What factors affect diffusion?
Concentration gradient
Temperature
Surface area
How does an increasing temperature increase the rate of diffusion?
Particles gain kinetic energy, so move faster
As organisms get larger, what happens to the surface area to volume ratio?
Decreases
How do fish gain oxygen?
Water passes into mouth, and flows over gills
The oxygen in the water is transported into the bloodstream
What are gills covered with that enable gases to pass in and out of the blood?
Fine filaments
What type of blood passes into the filament?
Deoxygenated blood
What are adaptations of fish filaments?
Huge surface area
Thin membrane
Rich blood supply
What is osmosis?
Diffusion of water from a dilute to a concentrated solution through a partially permeable membrane
What type of memebrane does osmosis require?
Partially permeable
What does a partially permeable membrane allow through?
Some smaller molecules(water) but not larger molecules(sugar)
Is the cytoplasm of cells relatively concentrated or dilute?
Concentrated
If we place an animal cell in a very concentrated solution, what will happen?
Water will move out by osmosis and the cell will shrink
If we place the cell in water, where will water move?
Outside to inside
What could happen to the cell when water moves in?
Expand and even burst
What happens when water moves into a plant cell?
Cell becomes turgid
Why doesn’t the plant cell burst when water enters it?
The cell wall prevents it
When water moves out a plant cell, what harkens you the cell?
It becomes flaccid
In the practical when investigating osmosis, why do we peel the potato?
Because the skin can affect osmosis
What do we add to the test tubes?
10cm3 of sugar solution at different concentrations(0.5,0.25etc)
Why do we use a test tube with distilled water?
Contains no dissolved ions that could affect osmosis
How do
We remove surface moisture when remove the potato cylinders?
Roll them on paper towl
How can we determine the concentration of sugar solution?
Plot a percentage change graph and find the value when the line crosses the x axis at 0%
Describe the potato practical
Peel potatoes
Use cork borer to produce 3 cylinder of potato
Use a scalpel to trim cylinders to same length
Measure length and mass
of each cylinder
Add 10cm3 of varying concentration into cylinder into a test tube
Remove and gentle roll on paper towel
Measure length and mass again
What is an independent variable in the potato practical?
Concentration of sugar solution
What is active transport?
Move substances from low to high concentration
Against concentration gradient
Requiring energy
Compare diffusion and active transport
In diffusion, particles move down the concentration gradient, whereas in active transport, particles move against it
Active transport requires energy from respiration, diffusion doesnt
Give 2 examples of active transport
Lumen of small intestine
Move ions into root hair cell from soil
What do root hair cells and lumen of small intestine have to provide it with energy for active transport?
Mitochondria
What is a tissue?
Groups of cells with a similar structure performing a specific function
Why do molecules like carbohydrates, protein and lipids have to be digested?
Because they are too large to be absorbed into the blood stream
What happens during digestion?
Large food molecules are broken down into small molecules by enzymes
What does the stomach contain that helps
Enzymes?
Hydrochloride acid to help digest proteins
What action of the stomach turns food into a fluid that increase surface area for enzymes to digest?
Churning
Describe the steps into digestion
Food chewed in mouth
Enzymes digest starch intk small sugar molecules
Pass into stomach- digest proteins
Stomach churns the food- turning it to a fluid
Fluid flows into small intestine - chemicals released from liver and pancreas
Pancreas releases enzymes- start digestion of lipids
What does bile dk?
Emulsifies fats and neutralises acid from stomach
Function of stomach
Contains HcL to help enzymes digest proteins
Churns food into a fluid
Function of pancreas in digestion
Release enzymes to
Digest starch and proteins and begin to digest lipids
Function of liver
Release bile and chemicals into small intestine
Function of large intestine
Absorb excess water
What are enzymes?
Large proteins that are biological catalysts
Why are enzymes specific ?
Substrate must fit perfectly into active site
Where do we find protease?
Stomach pancreas small intestine
When we digest proteins ,what does protease do?
Convert proteins into amino acids
What does amylase break down?
Starch
What do we produce when starch is digested?
Simple sugars
Where is amylase found?
Saliva and pancreas
What does a like
Molecules
Consist of?
A molecule of glycerol attached to 3 molecules of fatty acids
What are lipids digested by?
Lipase
Where do we find lipase?
Pancreas and small intestine
Why does enzyme activity increase when temperature increases?
Enzyme and substrate are moving faster so there are more collisions per second between the substrate and active site
What’s the name of the temperature when enzyme rate is maximal?
Optimum temperature
Why do enzymes denature at a very high temperature?
Enzyme molecules vibrates and shape of active site changes, so substrate no longer fits
Besides temperature, what other factor can affect enzyme activity?
pH
Describe how we carry out a food test
Take food sample and grind with distilled water using a mortar and pestle
Transfer paste to beaker and add more water- chemicals in food can dissolve
Filter solution - remove suspended particles
Describe how to test for starch, including a colour change
Add few drops of iodine
It will go blue-black
Describe how we test for sugars
Add 10Drops of Benedict’s solution into test tube
Place test tube into beaker and half fill with hot water
If sugars are present it could go brick red(if lots of sugars)
Describe how to test for proteins
Add 2cm3 of bitter solution
If protein present, if will go blue- purple
Unlike the other tests, what DONT we do for lipids?
Filter the solution
Why don’t we filter the solution when testing for lipids!
Lipid molecules can stick to filter paper
Describe how to test for lipids?
Add few drops of distilled water and ethanol
Gently shake solution
If lipids are present, a milky layer will form
What’s a safety concern for testing for lipids?
Make sure no naked flames are present as ethanol is flammable
What’s some adaptations of the small intestine?
Very long
Has villi
Villi have a rich blood supply
Thin membrane
Why is the small intestine very long?
Provide a large surface area for absorption
Why is the interior of the small intestine covered with villi?
Increase surface area for absorption and have microvilli
Rich blood supply- increases concentration gradient
Thin membrane- short diffusion distance
What’s the problem of a single circulatory system?
Blood loses pressure
What type of circulatory system do humans have?
Double
What does a double circulatory system mean?
Passes through the heart twice on each circuit
What’s the benefit of having a double circulatory system?
Blood can travel rapidly- deliver oxygen faster to cells
What does the vena cava bring?
Deoxygenated blood from the body
What does the pulmonary artery do?
Carry deoxygenated blood from heart to lungs
What does the pulmonary vein do?
Carry oxygenated blood to the heart
What does the aorta do?
Pump oxygenated blood from the heart to the rest of the body
Describe the pathway of blood
Vena cava- right atrium - ventricles- ventricles contract and force blood to pulmonary artery- lungs- pulmonary vein- left atrium- left ventricle - aorta- body
What do valves prevent?
The back flow of blood
Why does the left side of the heart have a thicker muscular wall than the right side?
Contracts to pump blood to rest of body
What do the coronary arteries do?
Provide oxygen to muscle cells in heart
What is the resting heart rate controlled by?
Group of cells in right atrium / pacemaker
Do arteries carry high or low pressure from the heart?
High pressure
What’s some adaptations of arteries?
Thicker muscular walls- withstands high pressure blood
Elastic fibres- stretch and change length when blood passes through
What’s some adaptations of capillaries?
Thin walls- short diffusion distance
Rich blood supply- steep concentration gradient
What’s some adaptations of veins?
Valves- prevent back flow of blood
Thin wall- low pressure
Wide lumen- low pressure blood
Are cardiovascular diseases communicable?
No, they are non- communicable
In coronary heart disease, what builds up inside the coronary arteries?
Layers of fatty material
What does the build up of fatty deposit in the coronary arteries cause?
Then to narrow and thus reduce blood flow through the arteries- lack of oxygen to heart- heart attack
What are statins?
Drugs which reduce the level of cholesterol levels in the blood
What does reduced chlorestrol levels slow down?
Rate that fatty materials build up in the arteries
What are 2 advantages of statins(besides reducing Cholesterol levels)?
Reduce strokes
Effective
What are 2 disadvantages of statins?
Unwanted side effects
Drugs must be taken regularly
What is a stent?
A tube inserted into the artery to keep it open
What’s an advantage of inserting a stent?
Blood can flow normally
What are some advantages of stents?
No anaesthetic
Cheap
Doesn’t corrode
What are some disadvantages of stents?
Irritate lining of blood vessel
Need to take anti-cougulant drugs
What can leaky valves cause the patient to feel?
Weak and tired
What are 2 types of valves we can use to replace leaky valves?
Mechanical and biological
What is an advantage and disadvantage of a mechanical valve?
Last a lifetime
Increase risk of blood clot
What’s an advantage and disadvantage of biological valves?
Don’t need to take drugs
Often need to be replaced
What’s some disadvantages of having a donor heart if your heart is failing?
Shortage of donors
Patient must take anti rejection drugs
What do artificial hearts increase the risk of?
Risk of blood clotting
What does the trachea contain to prevent it collapsing?
Rings of cartilage
What are alveoli the sites of?
Gas exchange
What’s some adaptations of alveoli?
Huge surface area
Thin membrane
Rich blood supply
What’s an example of a communicable disease?
Measles
Where can communicable diseases be spread from?
Person to person
What are communicable diseases spread by?
Pathogens
What’s the definition of health?
State of physical and mental well being
What’s a risk factor for lung cancer?
Smoking
Does a correlation prove a cause?
No
What are carcinogens?
Chemicals that damage DNA and increase the risk of cancer
What’s an issue of epidermiology?
Sampling could be biased
How can we solve the problem of sampling?
Take a larger sample+ make it random
What are some risk factors for cardiovascular disease?
High fat diet
High salt diet
Smoking
What does a high fat diet increase?
Levels of cholesterol- increases fatty material build up
What do a high salt diet increase?
Blood pressure
What is the main risk factor for lung cancer?
Smoking
Why can smoking cause lung cancer?
Smoke contains carcinogens
What can smoking when pregnant cause?
Miscarriage and premature birth
What can drinking alcohol when pregnant cause?
Feral alcohol syndrome- physical problems
Adults who drink alcohol excessively increase their risk of what?
Liver cirrhosis and cancer
Affect brain- memory loss
What’s the main risk factor for type 2 diabetes?
Obesity
What’s an environmental factor that increase your risk on developing lung cancer?
Exposure to radon gas
What cells make up the top and bottom of a cross section of a leaf?
Epidermal cells
What’s the role of the epidermis?
Protect surface of leaf
What’s are 2 adaptations of the upper epidermis and why is it that way?
Transparent- allow light to pass through to photosynthetic cells below
Covered with a waxy cuticle- reduces water loss
What does the lower epidermis have?
Stomata
What do stomata allow?
Carbon dioxide to enter and oxygen to leave the leaf
Besides the exchange of gases, what else can stomata control?
Water vapour passing out of leaf
What’s under the upper epidermis?
Palisade mesophyll
What’s an adaptation for the palisade mesophyll that allows it to carry out its function ?
Packed with chloroplasts for photosynthesis
What’s an adaptation of the spongy mesophyll?
Full of air spaces- allow carbon dioxide to diffuse from stomata to
Palisade cells
What’s the main function of the spongy mesophyll?
Diffusion
What’s translocation?
Movement of sugars through the phloem tissue
What does xylem tissue transport?
Water from roots to stem/leaves
What does phloem tissue transport?
Dissolved sugars from leaves to the rest of plant
Where does the xylem tissue transport the water?
From roots to the stem/leaves
Where does the phloem tissue transport it’s sugars?
From leaves to rest of plant
Where can we find the meristem tissue?
Growing tips of shoots
What does the meristem tissue contain?
Stem cells
What’s transpiration?
Evaporation of water from a plant
Why is the transpiration stream important ?
Brings water to leaves for photosynthesis
Transport dissolved minerals
Evaporation of water cools the leaf down in hot conditions
Why is the rate of transpiration high at greater temperatures?
Evaporation is faster as particles have more kinetic energy, so move faster
Why is transpiration faster during dry conditions?
Fewer water particles in the air, so a steep concentration gradient
Why does the rate of transpiration increase in windy conditions?
Wind removes water vapour
Why does the rate of transpiration increase with high light intensity?
This increases the rate of photosynthesis- so the stomata open
If the stomata are closed, what can’t the plant do?
Photosynthesise
Give 2 examples of how infection by pathogens can cause other r health problems
Viruses-ineffective cells of body can cause cancer
Immune reactions- trigger allergies
Why do most plants have more stomata on the bottom than the top?
The bottom is shaded and cooler, so less water is lost
Why will a person with heart failure have an artificial heart fitted?
Keep them allow until transplant is available
Help them recover and rest their heart
What are pathogens?
Microorganisms that cause infectious disease
How can bacteria make us ill?
Once inside body, they reproduce very rapidly
Release toxins
-
Damage tissues and make us feel ill
Where can viruses only reproduce?
Inside a host cell
What can viruses cause cells to Do?
Burst opens and die
How can viruses cause cells to burst and eventually die?
Invade cell
Reproduce inside host cell
= damaging
How do pathogens spread?
Air
Water
Direct contact
How can we reduce the spread of pathogens?
Wash hands- sanitation Clean drinking water Condom during sexual contact- reduce HIV Isolation Vaccination
What type of disease is measles and HIV?
Viral
Can viruses be killed by antibiotics?
No
What’s the symptoms of measles?
Fever
Red skin rash
How is measles spread?
In air droplets
What’s a long term impact of measles?
Damage to breathing system and the brain
What’s a symptom of HIV?
Flu like illness
Why can people with HIV struggle to fight off other infections?
Because the patients immune system becomes so badly damaged
How can you treat HIV?
Take antiretroviral drugs- stop virus multiplying
How can we treat measles?
Vaccination
How is HIV transmitted?
Through the exchange of fluids between humans
What are 2 examples of bacterial diseases?
Salmonella and gonorrhoea
Can bacteria be killed using antibiotics?
Yes
How are the bacteria that cause salmonella food poisoning spread by?
Ingesting infected food
What cause the symptoms of salmonella?
Bacteria that secrete toxins
What are some symptoms of salmonella?
Fever
Abdominal cramps
Vomiting
Diarrhoea
How can salmonella in chickens be controlled?
Vaccinate the chickens
What type of disease is gonorrhoea(not referring to bacterial)
STD
What are symptoms of gonorrhoea?
Thick yellow discharge from penis/vagina
Pain when urinating
How can we stop the spread of gonorrhoea?
Use a condom during sex
People who have unprotected sexual should be tested for it- treat with antibiotics
What is the malaria pathogen an example of?
A protist
What are symptoms of malaria?
Fever
How can a person get malaria?
Person is bitten by mosquito
Pathogen passes into mosquito
Mosquito bites another person and passes pathogen to them
What is a mosquito?
A vector
What does a vector mean?
Carries pathogen from person to person
How can we stop the spread of malaria
Drain still water(in ponds) - stop breeding
Use mosquito nets
Spray surfaces with insecticide
What is the skin an example of?
A non specific defence system
How does skin prevent microorganisms entering?
Outer layer has dead cells- pathogen can’t penetrate
Produces oily substance called sebum- kills bacteria
How does the nose stop pathogens entering?
Hair and mucus- trap pathogens
How are the trachea and bronchi adapted to prevent pathogens entering the lungs?
Covered with cilia- covered in mucus
Cilia wafts the mucus upwards towards the throat where it is swallowed
What does the stomach prevents pathogens entering?
Produce hydrochloric acid- kill pathogens
What’s the 2 main functions of the immune system?
Destroy pathogens and toxins
Protect us from the same pathogen if it invaded us again
What’s the first white blood cell function?
Ingest and destroy the pathogen
How can the white blood cell ingest the pathogen?
It detects chemicals released from the pathogen and moves towards it.
White blood cell releases enzymes that break down the pathogen
What’s the second function of the white blood cells?
Produce antibodies
How do antibodies destroy
Pathogens?
They attach onto specific antigens on the surface of the pathogen , triggering them to
Be destroyed
Besides ingesting the pathogen and producing antibodies, what else can white blood cells produce?
Antitoxins
How do antitoxins work?
They stick to toxins and counter act them- prevent them from damaging cells
What type of disease is the plant disease TMV?
Viral
What type of disease is the plant disease rose black spot?
Fungal
What does TMV do to the plant?
Discolour it- in a mosaic pattern
Why is the growth of the plant reduced if it has TMV?
Discolouration- less photosynthesis- less glucose and protein
What does rose black spot cause the leaves to develop?
Black spots
How can rose black spot be spread?
By water or by wind
How can we reduce the spread of rose black spot
Spray plants with fungicides
Remove infected leaves
What does vaccination involve?
Introducing small quantities of inactive forms of a pathogen in the body
How does the body react to the inactive pathogen?
White blood cells make antibodies
These attach to antigens and destroy the pathogen
After the body has killed the pathogen, what is different about the white blood cells?
They remember how to make the specific antibodies
What happens when the body encounters a live form of the pathogen?
White blood cells produce the antibodies rapidly, preventing infection
What is it called when people who have vaccinated also protect unvaccinated people!
Herd immunity
What are antibodies produced by?
White blood cells called lymphocytes
Describe how we make monoclonal antibodies
Inject mouse with antigen, lymphocytes will produce antibodies against the antigen- collect lymphocytes
Fuse lymphocytes with a tumour cell
We form a hybridoma cell
Select a single hybridoma producing the antibody we want
Allow cell to divide by mitosis- producing clones of hybridoma cells
Antibodies produced by cells are called monoclonal antibodies
Simply, how are monoclonal antibodies produced?
From a single clone of hybridoma cells
What’s a benefit of monoclonal antibodies being specific to one binding site on one antigen?
Can target a specific chemical or cells in body
What is a use of monoclonal antibodies in diagnosis?
Pregnancy testing
In pregnancy testing, what are monoclonal antibodies used to detect?
A specific hormone - produces by placenta in fetus
How else can we use monoclonal antibodies in lab testing?
Measure levels of hormones in blood and detect pathogens
What’s an an advantage of using monoclonal antibodies when measure hormone levels or detecting pathogens in the blood?
They are specific
What’s an Advantage of using monoclonal antibodies in pregnancy testing?
Cheap and easy to use
What’s another use of monoclonal antibodies?
Locate or identify molecules in a cell- eg attach to fluorescent dyes , these stick to specific molecules
What’s a final use of monoclonal antibodies for treating disease?
Make antibodies specific to cancer cells
Attach toxic drug to antibody
Antibody attaches to cancer cell
This stops cancer cells from growing
What’s an advantage of using monoclonal antibodies on a toxic drug?
Antibody delivers substance specifically to cancer cells without harming healthy cells
What’s a problem of using monoclonal antibodies found in drug trials?
Produce harmful side effects
When doing the potato practical how can we make the investigation more repeatable?
Repeat investigation for each sugar find for several potato cylinders
What are some risks and solutions of the potato practical?
Care must be taken when using the scalpel
Wear eye protection when using chemical solutions
Make sure potato is placed ok ceramic tile when using cork borer
Describe the transport of water through a plant from roots to atmosphere
Transport in xylem
Water evaporates from leaves
Through stomata
Why does a person with a leaky valve experience difficulty exercising?
Backflow of blood occurs Less blood leaves heart Less oxygen supplied to muscles Less aerobic respiration Less energy released Less muscle contraction
Explain how diabetes can causes the body cells to lose more water
Blood is more concentrated and has less water
So water moves out of cells by osmosis
Through a partially permeable membrane
Why does having only one ventricle make the circulatory system less efficient than having 2 ventricles?
Oxygenated and deoxygenated blood mixes
Less oxygen reaches cells
Why might an axolotl die in water with a low concentration of oxygen?
Concentration gradient is shallower - out of axolotl Oxygen diffuses out of blood Less aerobic respiration Less energy released Less metabolism
Explain how pancreatic cancer may Cause a person to lose weight
Fewer enzymes released Food is not broken not fully Less glucose absorbed into blood Less amino acids absorbed Less proteins made for growth and repair
How can monoclonal antibodies treat pancreatic cancer?
Monoclonal antibody is attached to a cytotoxic drug
Anti overt will only attach onto the target cancer cells
Cytotoxic drugs will bind to target cells and stop them growing and dividing
Why might a person with AIDS take very long to recover from salmonella?
Immune system is weakened
White blood cells cannot kill bacteria as effectively
How could you modify the potato investigation for determine the concentration of solution inside each egg?
Use five different finds of sugar solution
Plot percentage change on graph
Determine concentration when line corsages x axis
What does magnesium deficiency result in(not stunted growth)?
Less chlorophyll
Why could indicstor in both tubes containing bile become colourless?
Lipase breaks down fat into fatty acids
Fatty acids lower the pH
When fatty acids Sadie the pH to be below 19, the indicstor becomes colourless
How does water move from roots to leaves(2 marks)
By the transpiration stream in the xylem cells
Why is less water loss an advantage of a plant?
So it doesn’t wilt
How can scientists use a plant that contains a TMV resistant gene to produce many plants with this resistant gene?
Take stem cells from meristem
Describe how glucose from small intestine is moved to a muscle cell
Glucose is absorbed by diffusion into blood
Blood delivers glucose to muscles in capillaaries
What 2 products does anaerobic respiration inyeast cells produce?
CO2 and ethanol
In the potato practical, why could you calculate the percentage change in mass as well as the change in grams?
Allow results to be compared
What are possible sources of error in the potato practical?
Drying of chips
Concentration of solutions
Accuracy of balance
How could an infection that is from an acid tolerant bacteria that damages the stomach mucus lining result in a stomach ulcer?
Bacteria isn’t killed by stomach so they damage mucus lining
So acid damages stomach tissue and cause an ulcer
Why could a person that has a disease that causes inflammation in the intestines and damages villi have poor growth?
Reduced surface area for absorption
Fewer amino acids and glucose absorbed
Less respiration
Fewer amino acids available to build new proteins
Why at some point Do bacteria stop multiplying by binary fission?
Shortage of nutrients so cells die
How does a pregnancy test strip work to show a positive result?
Urine passes through reaction zone
Hormone bonds to mobile antibody
Hormone binds to immobilised antibodies in results zone
Antibodies which don’t attach to hormone bind the antibodies in control zone
Blue dye apparatus in both control and results zone
What’s Happens in the 3 stages of the cell cycle?
1- DNA and organelles replicate
2- chromosomes move to centre of cell then are pulled to opposite ends of cell
3- cytoplasm and cell membrane divide to form 2 identical cells
Explain the lock and key theory of enzyme action
Enzyme binds to substrate because they are complementary
Substrate is broken down into products
Products are released
What do you do to the Benedict’s solution before you observe the colour change?
Boil/heat it
Explain why a lead left in the cupboard with no light contains glucose but not starch
Starch converted to glucose
Glucose used for respiration and used to release energy
Because no light to make new glucose by photosynthesis
Besides a deficiency of nitrate ions, what 2 are reasons can be used to expansion reasons for yellow leaves and stunted growth?
Magnesium deficiency
Infected by a pathogen
Give 2 pieces of lab equipment you can use to prepare cells to view using a microscope
Stain and a slide
Why does a red blood cell burst but a plant cell doesn’t
Water enters by osmosis and the plant has a cell wall to stop tjis
What’s the financial impact of increasing number of people who are obese?
Costs hospitals more
How can We prepare an uncontaminated culture of bacterium in a petri dish (6)
Sterilise loop in Bunsen burner- kill harmful microbes
Dip loop into bacteria and streak across surface if agar and replace lid to prevent outside contamination
Seal lid- prevent microorganisms entering
Incubate at 25 degrees- safety
What’s the pro of embryonic stem cells?
Can turn into any type of cells- treat wide variety of diseases
What’s 2 disadvantages of using embryonic stem cells?
Killing an embryo is seen as unethical
Can’t give consent
What’s a pro of adult stem cell bs embryonic stem cells?
Well tried and tested, so more reliable
What are 2 disadvantages of adult stem cells?
Can only treat limited diseases
Painful
What’s the purpose of cell specialisation?
Cells differentiate and obtain new structural features enabling them to carry out specific functions
How can a student carry out the investigation to observe and label the viewable structures of an onion?(6)
Use tweezers to peel epidermal tissue from onion
Add drop of water to slide place epidermal tissue on slide and add iodine stain
Slowly Place cover slip over tissue
Place slide under microscope- with lowest powered objective lens
Adjust coarse focus until sun cellular structures become viewable
Look down through eyepiece and move to highest objective lens
Adjust fine focus until image of high resolution is produced
Why do we slowly place the cover slip of the epidermal tissue?
So no air bubbles are trapped
Why do we add iodine stain to the tissue on a slide?
Ensure structures can be observed
Describe how water moves from soil to the leaf
Water moves into the root via osmosis Water flows from the root hair cells to xylem cell by osmosis Water moves up the plant via the storm Evaporation of water from leaves Produces tension This is the transpiration stream
Why go large compels molecules Jones to be broken down into smaller simple molecules?
They can move into the bloodstream by active transport and then be transported to useful organs
Independent variable in potato practical
Sugar conc
Dependent variable in potato practical
Mass of potato
Describe a method that could be used to determine the rate of anaerobic respiration
Collect gas produced using a gas syringe
Compare volumes at different temperatures
Incubate mixture at diff temperatures
Why is it important that high proportions of populations are immune to specific diseases?
Cannot he spread from person to person and therefore cannot he spread across populations
Why would there be no change in ass if instead of potatoes m, boiled leeks were used?
Partially worn ranks membrane is damaged
How can you prepare the food sample when testing for proteins?
Break up good using a mortar and pestle
Transfer to a test tube and add distilled water
Mix good with water by stirring with glass rod
Filter mixture - use funnel and filter paper
How is the heart adapted for its function?
Ventricles have thick walls as they have to pump high pressure blood around the body
2 sets of valves- prevent back flow of blood
Coronary stereos supply heart tissue with oxygenated blood for aerobic respiration
Describe the process of inhalation in the lungs
Intercostal misled contract- ribcage moves up
Diaphragm contracts and flattens
Inverse relationship between pressure and volume
Air is drawn into lungs
How can HIV be spread ?
Direct sexual contact
Exchange of bodily fluids
Drug users that’s share infected needles
