Biology Paper 1 Flashcards
Eukaryotic Cells
Plant and animal cells.
Genetic material enclosed in a nucleus.
Prokaryotic Cells
Smaller.
Bacterial cells.
A single DNA loop
Small rings of DNA called plasmids
No chloroplasts/ mitochondria.
Ribosomes, cytoplasm, cell membrane, dna, cell wall
Nucleus
Contains genetic material.
Controls activities of cells
Cytoplasm
Chemical reactions take place here.
Cell membrane
What goes in and out of cell
Mitochondria
Release energy by respiration.
Respiration occurs in mitochondria.
Ribosomes
Make proteins
Chloroplast
Photosynthesis takes place here.
Chlorophyll contains green substance, absorbs light needed.
Food vacuole
Contains cell sap to make cell turgid
Cell wall
Made of cellulose, supports and strengthens cell
Microscopes : Practical
- Cut an onion into pieces using a sharp knife.
- Peel off a thin layer of onion epidermis from one piece of onion.
- Place the onion epidermis onto a microscope slide in a single flat layer.
- Add three drops of iodine solution.
- Slowly lower a cover slip at an angle onto the onion epidermis.
- Place the slide on the stage of the microscope
Microscopes
Course adjustment knob- moves stage up and down
Fine adjustment knob- focuses the image
Objective lens-higher magnification
Sperm cells
Reproduction, Join with egg cell
Tail- for movement
Mitochondria- energy for movement
Nerve cells
Send electrical impulses from one body to another.
Axons to carry electrical impulses to be transmitted everywhere.
Dendrites to connect to other nerve cells
Root hair cells
Hairs increase surface area to absorb nutrients and water better.
Thin walls for shorter distance
Muscle cells
Mitochondria- provide energy for muscle contraction
contain special protein fibres which can change their length.
Xylem
Dead plant cells
Carry water (transpiration)
thick walls containing lignin to prevent collapse
Only up
No internal structures between cells to provide a continuous route for water to flow
metre to micrometer
1 m —-> 1 000 000 micrometer
Differentiation
cells are specialised
Phloem
Living plant cell
Carry simple sugars (translocation)
Have sieve plates let sugars/amino acids up and down the stem
Companion cells to provide energy needed for active transport
Purpose of cell division
Growth and development of cells
Repair of cells
Replacement of cells
Cell stages
First stage: Longest stage
Cell grows
DNA replicates
Each set of chromosomes are split to end of side of cells.
Nucleus splits
Cytoplasm and cell wall splits to 2 identical cells are formed
Stem cells
Undifferentiated cell that can be copied/changed into other cell types.
Human embryo
Fertilized egg
Can be differentiated into any cells
May be able to treat conditions like paralysis and diabetes
Adult cells
Found in bone marrow
Can be differentiated into blood cells.
Replace dead / damaged tissues
Meristem
Plants
Can differentiate to any plant cells
Can be cloned to protect from extinction
Cloned to produce many identical plants
Therapeutic cloning
Produces embryo with genes that are same to the patients
Not rejected by body
Transfer of infection, ethical religious objections
SURFACE AREA TO VOLUME
SA: 6a2
V: a x a x a
Chromosomes
Consist of DNA molecules
Each chromosome carry many genes, which control development of different characteristics eg hair color.
Smallest–>Largest
DNA
Gene
Chromosome
Nucleus
Cell
Diffusion
movement of particles from a higher concentration to lower concentration down a concentration gradient.
Examples of diffusion
Minerals and water diffuse into the plant through the roots.
Food molecules diffuse into the blood stream in small intestine.
Water molecules diffuse into the blood stream in the large intestine.
Oxygen passing from the alveoli to the blood.
Factors which affect the rate of diffusion:
-The difference in concentration gradient
-Temperature
- Surface Area
Factors affecting gas exchange:
-Large surface area
-A membrane that is thin - short diffusion path
- Efficient blood supply (alveoli)
-Access to air (Ventilation)
Osmosis
Diffusion of water particles from a dilute solution (high water concentration) to a concentrated
solution (low water concentration) through a partially permeable membrane.
Osmosis practical
- Weigh five pieces of carrot.
- Place each piece into a different tube.
- Into each tube add 20 cm3 of water or one of the sugar solutions as shown in Figure 1
- Leave the apparatus for 2 hours.
- Remove the carrot and dry each piece on paper towel.
- Reweigh each piece.
- Calculate the percentage (%) change in mass of each piece.
Isotonic
Concentrations of outside and inside solutions are the same.
No change
Hypertonic
Concentration of inside solution is less.
Concentration of outside solution is more.
Moves inside, swollen, turns turgid
Describe what would happen if red blood cells are put in a hypotonic solution.
water enters the cells (by osmosis)
they burst / lyse / lysis occurs
water leaves and cell shrinks
animal cells have no cell wall or plant cells have a cell wall
cell wall prevents lysis / bursting / allows turgidity
Hypotonic
Concentration of inside solution is more.
Concentration of outside is less.
Moves outside, shrinks, turns flaccid
Active Transport
The movement of particles from an area of low concentration to an area of higher concentration against concentration gradient using energy.
Examples of Active transport
Active transport allows mineral ions to be absorbed into plant by root hairs for healthy growth.
Cells, Tissues, Organs, Organ systems
Cells are the basic building blocks of all living organisms.
A tissue is a group of cells with a similar structure and function.
Organs are group of tissues performing specific functions.
Organ systems work together to form organisms.
Tissues
Muscular- churns up the food
Glandular- makes digestive juices to digest food.
Epithelial- covers inside and out of stomach.
Salivary glands
produces amylase in saliva
Stomach
-produces protease
-produces hydrochloric acid, which kills bacteria and right pH for protease to work
Liver
Where bile is produced.
Bile neutralises stomach acids, so enzymes work more efficiently, and emulsifies fats, for larger surface area.
Alkaline,
Gallbladder
Bile is stored here
Pancreas
Produces protease, amylase, and lipase.
Small intestine
absorbs nutrients for the body
makes protease, amylase, lipase.
Large intestine
absorbs excess water from food.
Rectum
Faeces are released here.
Substrate
Molecules which the enzymes break down
Enzymes
biological catalysts which speed up the reaction without being used up.
Lock and Key
Enzymes have a specific active site which only fits one substrate.
Optinum pH
6, 7, fastest for reactions to take place.
If too high/low, enzyme will denature and substrate won’t fit active site.
Protease- acidic
Lipase- alkaline
Optinum temperature
37 C, human body temperature, as it worked the fastest.
If too high/low, enzyme will denature and substrate won’t fit active site.
Amylase
Converts starch to simple sugars.
Made in salivary glands and pancreas
Works in mouth and small intestine
Protease
Converts protein to amino acids.
Made in stomach, pancreas and small intestine.
Works in stomach, small intestine.
Lipase
Converts lipids into fatty acids and glycerol.
Made in pancreas, small intestine.
Works in small intestine.
Starch
Iodine
Turns black/blue
Sugars
Benedicts
Prepare water bath, add the solution with foot sample for 5 mins.
Turns brick red.
Protein
Biuret
Turns purple.
Lipids
Ethanol
Turns cloudy emulsion
Sudan III
Layer turns bright red.
The effect of pH on the rate of reaction of amylase
enzyme
Put iodine solution in every spotting tile.
In 1 test tube, 2 cm3 starch
In 2 test tube, 2cm3 amylase solution
In 3 test tube, 2cm3 buffer solution (pH 5)
Place all 3 test tubes in water bath at 30 degrees, for 10 mins to reach temperature.
Now combine all 3 solutions into 1 test tube and stir.
Immediately put back into waterbath and start stopwatch.
After 30 secs use stirring rod and transfer solution to spotting tile with iodine.
Iodine should turn blue-black, if starch is present.
Now repeat with different ph buffers , 6,7,8
Villi in small intestine
Increase surface area for absorption of molecules
Thin membrane- short diffusion path
Double circulatory system
passes through the heart twice.
Heart
-The right ventricle pumps blood to the lungs .
-The left ventricle pumps blood around the rest of the body
Diagram of heart
Blood from body comes to Vena cava , to right atrium, then right ventricle to Pulmonary artery to take deoxygenated blood to lungs.
Blood from lungs come to pulmonary vein to left atrium then left ventricle to aorta to take oxygenated blood to body
How is heart rate controlled?
Group of cells in right atrium, which act as pacemaker.
Gas exchange
Alveoli——>tiny air sacs, where gas exchange takes place.
Ribcage—-> protect the lungs
Intercostal muscles—->Move the ribcage.
Diaphragm—–> helps with breathing, seperates from rest of the body.
Bronchioles—-> Deliver air to alveoli.
Passage of air into lungs
Air enters the body and is warmed as it travels through the mouth and nose.
It then enters the trachea.
Trachea has rings of cartilage to prevent collapse during inhalation.
The trachea divides into two bronchi.
Each bronchi branches out into smaller tubes called bronchioles.
Air travels through these bronchioles.
At the end of the bronchioles, the air enters one of the many millions of alveoli where gaseous exchange takes place.
Alveoli are where gases diffuse in and out of blood stream.
Adaptations of alveoli
millions of alveoli mean that the lungs have a large surface area
They have good blood supply
Blood vessels
Arteries, Veins, Capilaries
Arteries
Arteries carry oxygenated blood away from the heart and to the rest of the body.
They have thick walls containing muscle and elastic fibres to help withstand the high pressure created by pumping blood.
This stops the walls from bursting.
Veins
Veins carry deoxygenated blood towards the heart.
The lumen is wide to allow the low pressure blood to flow through.
Veins have valves to stop the backflow of blood and ensure it flows in the right direction.
Capillaries
Connect arteries and veins, carry blood really close to every cell.
One cell thick walls to allow exchange of molecules between blood and cells
They have permeable walls so substances can move across them.
Blood
WBC
Plasma
RBC
Platelets
WBC
Helps defend the body from pathogens.
Produces antibodies to fight microorganisms.
Contains nucleus, DNA, for instructions to do their job
Plasma
Transports all blood cells, like nutrients eg glucose.
Carries urea out of your body.
RBC
Contain red pigment, hemoglobin that binds with oxygen
No nucleus meaning more room to carry oxygen
Biconcave increases surface area. ( doughnut ), so blood diffuses in and out quickly
Platelets
Helps blood clot at sight of a wound.
Stops pathogens from entering
Coronary Heart Disease
When arteries become blocked with cholesterol ( fatty materials) meaning less blood flowing to heart, less oxygen supply, increasing heart attack
Stents
Metal mesh tubes inserted into arteries to keep it open so blood can flow.
Advantages- Lowering the risk of a heart attack.
-Recovery time is quick.
Disadvantages- Blood clots can form near the stent.
- Risk of heart attack during the procedure
-Infection
Statins
Drug that decreases the levels of bad cholesterol.
Advantages- Increase the levels of good cholesterol.
- Reduce the risk of CHD/ stroke
Disadvatages- Need to be taken continuously and for long term
- Can produce side effects, takes time.
Faulty valves
When a valve hardens or becomes damaged it begins to leak meaning the blood flows in the wrong direction meaning its not as efficient.
Leaky or hardened valves
Replacing it with a biological valve (pig or cattle).
Advantages- Works very well
Disadvantages- Only lasts 12-15 years.
Replacing it with a mechanical valve (manmade)
Advantages-Lasts for a long time
Disadvantages- Needs constant medication to stop blood clotting around the valve
Heart failure (If irregular heartbeat)
Artificial pacemaker
Requires a donor who recently died, artificial.
Electrical device that produces signals making heart beat at normal speed.
Advantages-Less likely to be rejected by the body and immune system
Disadvantages-Surgery temporarily leave the body open to infection.
- Blood clots could form leading to stroke
Health
A state of physical, mental and social well being .
Communicable disease
Can be passed from one individual to another.
Caused by pathogens (bacteria, viruses, fungi, protist)
Non - communicable disease
A disease that cannot be passed from one individual (Cancer, Diabetes, Cardiovascular disease)
How do diet, stress and life situations affect health
Diet- Too little food, lack of nutrition, vitamin deficiency. Too much food, unhealthy food, obesity Type 2 diabetes.
Stress- health problems, cancer, mental health affect.
Life situations- location, status, can impact a persons mental and physical health.
Examples how health problems interact
-Viruses living in cells can be the trigger for cancers.
-Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
-Severe physical ill health can lead to depression and other mental illness.
Causal mechanism ( 1 factor affects another)
-The effects of diet, smoking and exercise on cardiovascular disease.
-Obesity as a risk factor for Type 2 diabetes.
-The effect of alcohol on the liver and brain function.
-The effect of smoking on lung disease and lung cancer.
-The effects of smoking and alcohol on unborn babies.
Drugs
-Optimal dose
-Effectiveness
-Safety ( non toxic)
Digitalis —- originated fromFoxgloves
Aspirin —– Willow Trees
Pencillin —- Mould
Alcohol
Can affect brain function
Causes liver cancer
Smoking
Damages walls of arteries
Nicotine- increases heart rate
Tar- damages lung tissue
Carbon monoxide- Poisonous, takes place of oxygen in blood.
Can lead to lightweight/ premature babies.
Cancer
Caused by uncontrolled growth, division.
Risks of Cancer
Smoking
Obesity
UV light
Genes
Radiotherapy
Chemotherapy
Surgery
Tumor
When DNA in cell becomes damaged
Cells divide uncontrollably and form a mass of cells
Benign
- Contained in 1 area
-They do not invade other parts of the body.
Malignant
-Not contained in 1 place
-They invade other tissues.
Epidermal tissue
Covers entire plant.
Has waxy cuticle which helps reduce water loss.
Palisade mesophyll
Photosynthesis, as contains many chloroplasts.
Spongy mesophyll
Many air spaces which allow gases in and out.
Xylem
Made up of dead cells for continuous hollow tube.
Strengthened by lignin, making vessels strong
Phloem
Sieve plates as they allow organelles to transform
Meristem
Differentiate into many different cell types allowing plant to grow.
Guard cells
Control opening and closing of stomata
Translocation
Movement of dissolved sugars from leaves to the plant
Transpiration
movement of water from roots / root hairs (up stem) via xylem to the leaves
(water) evaporates, via stomata
Factors affecting rate of transpiration
Temperature
Humidity
Wind
Light intensity
Temperature
Increasing temp, increase rate of transpiration.
More kinetic energy, diffuse faster.
Light intensity
Increases light, increases rate of transpiration.
Stomata is triggered to open, more water leaves.
Humidity
More humidity, less rate of transpiration
Less water will evaporate
Wind
Increases wind, increases rate of transpiration
As wind removes boundary layer, more water will evaporate.
Pathogen
disease causing microorganism eg fungi, protist, bacteria, virus
How do bacteria cause disease?
Once inside the body, they divide rapidly.
Kill cells and produce harmful toxins
How do viruses cause disease?
Invade and reproduce inside body cells, leading to cell damage.
Fungi
grow and penetrate human skin and surface of plants.
Protist
Live inside other organisms and can cause damage.
3 ways pathogens can be spread
By air
By water
By direct contact
Ways pathogens can be reduced
Being hygienic
Destroying vectors
Isolating from infected ppl
Vaccination
Measles
Virus
Cause blindness and brain damage.
Symptoms are fever and red skin rash.
Spread through by air, coughs and sneezes
HIV
Virus
Attacks and damages immune system.
Spread by exchange of bodily fluids and sexual contact.
To prevent use condoms, no sharing needles
Tobacco mosaic virus
Virus.
Infects many plants some maybe discoloured, can’t photosynthesise and affects growth.
Yellow spots
Spread by contact of infected and healthy plants
Salmonella
Bacteria.
Causes food poisoning.
Symptoms are fever, vomiting, cramps etc.
To avoid vaccinate animals, disinfect hands.
Gonorrhoea
Bacteria.
Causes by unprotected sex with an infected individual.
Symptoms are yellow/green discharge.
To prevent use condoms, antibiotics.
Rose black spots
Fungi
Causes purple or black spots on rose leaves.
Reduces photosynthesis.
Spread by wind and water.
To prevent, destroy infected leave
Malaria
Protist.
Carried from host to host by mosquitoes, and they enter human blood when they feed.
Symptoms like fever, shaking.
To prevent, use insect nets, repellent.
How does the skin prevent pathogens from entering?
Skin acts as a physical barrier.
Nose has hair and mucus which trap pathogens
Trachea an bronchi have mucus trap pathogens
Stomach produces hydrochloric acid which kills pathogens
White blood cells help to defend against pathogens by:
-phagocytosis–> WBCs engulf and digest pathogens They produce specific antibodies. antibodies attach to antigens
Antigen- produced by pathogen
Antibody- produced by body
Lympothis- produce antibodies, and they immobilizes antigen, so they don’t move
-antibody production–> protein molecules produced by WBC. Antibodies stick to pathogens a and triggers pathogens to be destroyed.
-antitoxin production–> WBCs release specific antitoxins to neutralise toxins
Antibodies
Protect you from unwanted substances entering
Antitoxins
Neutralise a specific toxin
Vaccination
Patient is injected with dead pathogens.
WBC produce antibodies, and bind to antigens.
If the same pathogen re-enters the body, the
WBC respond quickly and produce the correct antibody
This prevents infection.
Painkillers and antibodies
Antibiotics cannot kill viral pathogens.
Painkillers are used to treat symptoms, not to kill pathogens.
It is difficult to develop drugs that kill viruses without also damaging the body’s tissues.
Preclinical testing
Done in a laboratory using cells, tissues and live animals, not humans, as the drug can be very toxic.
Clinical testing
-Use healthy volunteers and patients.
-Very low doses of drug are given at start
-If the drug is found to be safe, more trials are carried out to find the optimal dose for the drug.
-Placebo- tablet or injection with no active drug in it, some people will get better, as they think they are getting treated, so they believe they are getting better.
Double-blind test
-The test group received the active drug.
-The placebo (control) group receive a dummy drug which looks exactly like the test drug but it’s got no active ingredient.
-In a double-blind trial neither the patients nor the doctors know which people are receiving the active drug and which are receiving the placebo that’s to stop bias in case the doctors pay closer attention to people receiving the active drug.
Photosynthesis
Endothermic
carbon dioxide + water—> glucose + oxygen
Limiting factors are:
Light
Carbon dioxide
Temperature
Chlorophyll
5 uses of glucose
Respiration
Converted to starch for storage.
Produce fat for storage
Produce cellulose for cell walls
Produce amino acids for protein
Respiration
Exothermic
Mitochondria
glucose + oxygen —-> carbon dioxide + water
Why organisms need energy?
-chemical reactions to build larger molecules
-movement
-keeping warm.
Anerobic respiration
Muscles:
glucose —> lactic acid
-built up of lactic acid
Plant and Yeast cells :
glucose —> ethanol + carbon dioxide
-called fermentation, as its important for bread rising and alcoholic drinks.
Glucose isn’t completely broken down, less energy is transferred.
Exercise
Heart rate increases
Breathing rate increases
Breath volume increases
What happens if you have insufficient oxygen?
Anaerobic respiration takes place in muscles.
The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt.
(amount of energy needed to remove lactic acid)
During many hours of activity, muscles become fatigued and stop contracting efficiently.
How can farmers use knowledge about limiting factors to increase profits?
Can control temp, light, CO2, to get fastest rate of photosynthesis , increasing yield.
How is lactic acid transported away from muscles?
Blood flows through muscles, transports the lactic acid to liver.
In liver its converted back to glucose
Metabolism
Sum of all reactions taken place in the body, eg glycerol/fatty acids to lipids, photosynthesis , respiration, excess protein into urea.
Metabolic rate
Rate at which reactions take place.
Practical: Photosynthesis
- measure the distance between the pondweed and the light source
- count the number of bubbles or measure the volume of oxygen / gas produced
- (measure oxygen / gas produced) in a set period of time
- change the distance between the light source and the pondweed or use a different power lamp
- control colour of light
- control temperature using a heat screen / water bath
- use the same pondweed
- use the same length / size of pondweed
- control carbon dioxide supply
- idea of allowing time for pondweed to equilibrate
- repeat each test two or more times
- calculate a mean
Obesity
Type 2 diabetes
Doesn’t respond to insulin
Struggles to control concentration of glucose
Virus and bacteria
Virus is smaller than bacteria
Mitosis
Produces diploid cells
Produces cells with 46 chromosomes
Produces genetically identical cells
One cell divison
Produces 2 daughter cells
Meiosis
Produces haploid cells
Produces cells with 23 chromosomes
Produces genetically different cells
2 cell divison
Produces 4 daughter cells
