Biology Summary Notes (copy)
Unit 1 Characteristics and Classifications of Living Organisms
1.1 Characteristics
MRS. GREN
1.2 Classification
1.3 Features of Organisms
- Animals: Multicellular, Heterotrophs (energy from other organisms), Most reproduce sexually
- Plants: Multicellular, Autotrophs (energy from sun)
- Fungi: Unicellular , Saprotrophs (secreting digestive enzymes onto food outside the body, breaking down the food, absorbing it’s nutrients), Some fungi can be pathogens
- Protoctists: mainly unicellular, most have nothing to do with humans but some can cause diseases
- Bacteria: Most feed of off other organisms, live everywhere, some cause diseases
- Virus: depend on another organism to grow and reproduce, all are pathogens
1. 4 Vertebrates
Divided into 5 groups: fish, amphibians, reptiles, birds, mammals
1.5 Invertebrates
Crustaceans (crabs), myriapods (centipedes), insects (bees), arachnids (spider)
1.6 Ferns and flowering Plants
Unit 2 Organisation of the Organism
2.1 Structure of Cells:
smallest unit of life that can replicate independently
Parts:
Cell membrane: controls which substances can pass in and out of the cell
Nucleus: contains DNA
Cytoplasm: where chemical reactions take place
Mitochondria: provides energy
Ribosomes: site of protein synthesis
Plant cells also have:
Cell wall: support and structure
Vacuole: contains cell sap
Chloroplasts: for photosynthesis (contains chlorophyll)
Microscopy:
Magnification= image size/ object size
2.3 Specialised cells
Specific roles in the body, adapted to fulfil that role
- Ciliated Cell, Root Hair Cell, Xylem Vessels, Neurones, RBC, Palisade Mesophyll cells, Sperm cells, Egg cells
Differentiation: The process that makes cells specialised, changing the shape, structure and combination of organelles.
Stem Cells
- Divides by mitosis to form more cells
- Able to differentiate
Zygote→ Mitosis→ embryonic stem cells→ differentiates into any type of cell→ Adult → Has different stem cells that can differentiate into smaller cells (to replace damaged cells)
Plant Stem Cells:
Meristems: Shoots and roots that are growing
2.4 Levels of Organisation in the body
Tissues→ Organs→ Organ systems→ Body
Unit 3 Movement into and out of cells
3.1 Diffusion
Net movement of particles from an area of high concentration to an area of low concentration
Factors:
- Concentration gradient: larger concentration gradient → higher rate of diffusion
- Temperature: gives the particle more energy→ they diffuse faster
- Surface Area: larger→ higher rate of diffusion
3.2 Osmosis
Movement of water molecules across a partially permeable membrane from a region of higher water concentration to lower water concentration
3.4 Active Transport
Movement of water molecules against the concentration gradient from a region of lower concentration to a higher concentration requiring energy from cellular respiration
eg: Root hair cells use active transport to absorb mineral ions→ adaptations : large surface area and lot’s of mitochondria
Unit 4 Biological Molecules
Carbohydrates: energy source
Lipids (fats, oils): Long term energy store, insulator, protecting organs
Proteins: Grow, repair damaged tissue, energy
Vitamins: Organic molecules
- Vitamin A: leafy vegetables, liver→ good vision, healthy skin and hair
- Vitamin C: citrus fruits→ prevents scurvy
- Vitamin D: sun, egg→ absorb calcium
Minerals: Inorganic molecules
- Calcium: milk→strong bones
- Iron: red meat, nuts→ anaemia (less RBC)
Fibre: helps food move through intestines (prevents diorrhoea, constipation)
Water: Needed for chemical reaction, replacing the water lost in the body
4.2 Food Tests
Benedict’s test: Reducing sugar
- Set 10 drops of Benedict’s solution containing the food water solution and place in water bath for 6 minutes
- Safety: Test tube holder, point test tube away from you
- Not Present: stays blue
- Present: Green→ yellow→ Brick red
Iodine Test: Carbohydrate: Iodine Solution
- Add Iodine to test tube
- Present: blue/black
- Not present: Brown/orange
Biuret Test: Proteins
- 2cm^3 of solution mixed with 2cm^3 Biuret solution
- Present: Pink/Purple
- Not present: Blue
Emulsion Test: Lipids: Ethanol
- add 2cm^3 of Ethanol + 2cm^3 of distilled water
- Present: Cloudy white colour
- Not present: stays the same
DCPIP: Vitamin C
- add drops of DCPIP into the solution
- DCPIP loses its blue black colour when it comes in contact with vitamin C
Unit 5 Enzymes
Speed up the process of chemical reactions
- Lock and Key model
- Induced fit: active site changing it’s shape slightly to fit the model
5.2 Factors:
- Temperature: works best at optimum temperature because too high will change the shape of the active site
- pH: needs optimum pH else the shape of the active site changes and the substrate will no longer fit
Calculating rate of reaction= How much the product or reactant changes by/ the time it took to change
Unit 6 Plant Nutrition
carbon dioxide + water → glucose + oxygen
6CO2 + 6H20 → C6H12O6 + 6O2
Plant needs: light, chlorophyll, carbon dioxide, water
Product of Photosynthesis: glucose (makes starch and cellulose, converted to amino acid to make protein), oxygen as a by product
Rate of Photosynthesis: Light intensity, temperature, concentration of carbon dioxide
Glasshouse production: gives the ability to control everything the plant needs
Leaves have: large surface area, thin shape, many chloroplast, veins
Palisade Mesophyll: packed tightly to maximise absorption of sunlight, has chloroplasts
Stomata: opens to allow carbon dioxide to diffuse into the cell
Space between the spongy mesophyll so that carbon dioxide can diffuse at all mesophyll cells
Xylem: brings water and ions to mesophyll cells
Open during the day, closed at night
Mineral Requirements: nitrate to make amino acids, magnesium to make chlorophyll
Unit 7 Human Nutrition
7.3 Deficiency Diseases:
Vitamin C: citrus: tissue repair, resistance to disease: bleeding gums (scurvy)
Vitamin D: sun, milk, fish oil: strengthens bones and teeth: rickets, soft bones, osteomalacia
Iron: liver, meat: RBC for O2 transport: tiredness, anaemia
Calcium: milk, fish, green vegetables: strengthens bones and teeth: rickets, muscle weakness, cramps
Digestive Enzymes
Made in Pancreas, Small intestine
Carbohydrates: Starch
- Broken down by Amylase→ to Maltose
- Also made in Salivary Glands
Proteins:
- Broken down by Protease→ Amino acids
- Made in: Stomach (pepsin)
Fats (lipids)
- Broken down by Lipase→ Glycerol
7.5 Teeth
Incisors: biting cutting, Canines: piercing tearing, Premolars, molars: grinding and chewing
Enamel: Hard layer that covers dentine
7.6 Digestive System
To break down the food to be absorbed into the blood
Chewing: physical breakdown
Saliva: Salivary Amlylase that breaks down carbohydrates, mucus lubricates passage of bolus down the throat
Gullet (oesophagus): peristalsis, wave of muscle contractions that squeeze the food down the bolus
Stomach: Contracts muscular walls, produces pepsin (breaks down protein), produces hydrochloric acid that kills bacteria
Small Intestine: Produces enzymes to aid digestion, food absorbed into the lining of the intestine into the blood stream
Adaptations:
- Villi: Finger like projections that increases the surface area of the small intestine so digested food can be absorbed into the blood stream quickly
- Villi has only a single layer of surface cells so nutrients have to diffuse a short distance
- Good blood supply that maintains the concentration gradient
Pancreas: pushes digestive enzymes (amylase, protease, lipase) into the small intestine in pancreatic juice
Gall Bladder: Releases Bile that neutralises acid in the stomach, emulsifying fats
Large Intestine: absorbs excess water
Rectum: removal of waste
Unit 8 Transport in Plants
8.1 Transport systems
Xylem: transports water and mineral ions from the root to stem to leaf by osmosis
- strengthened by lignin
- Cohesion: water molecules sticking together to move upwards, Adhesion: water molecules sticking to side of xylem vessels reducing the chance that the columns will break
Phloem: transports sucrose made in leaves to other parts of the plant
8.3 Transpiration
Transpiration: evaporation of water at surfaces of mesophyll cells followed by diffusion of water vapour through the stomata into the atmosphere
Measuring transpiration: Potometer
Factors that affect transpiration: light intensity→ increases, temperature and wind speed→ increases, Humidity→ decreases
8.5 Translocation
Movement of sucrose and amino acids from the leaves to regions of respiration, growth, storage (called sinks)
Aphids: insects that feed on sap of phloem by piercing their stylets into the surface of the stem, the pressure of sap in the phloem causes it to pass to the stylet and provide the aphid with food
Unit 9 Transport in Humans
Circulatory System
Double circulation: prevents oxygenated and deoxygenated blood from mixing
The heart:
Pacemaker: in the right atrium causing small electrical impulses to ensure the heart beats properly
Blood Vessels:
Artery:
- carries blood away from the heart
- Strong and elastic muscle tissue
- Arterioles: small subdivisions of arteries
Capillaries:
- exchanges nutrients and oxygen with tissues
- Very small
- Permeable
Vein:
- carries blood to the heart
- Large
- Thin walls with small layers of elastic fibres and smooth muscles
- Has valves which prevents back flow of blood
- Venules: collects blood from capillary beds, unites to form veins
Shunt Vessel:
- Links the artery directly to the vein
- Controls blood flow by constriction and dilation
Blood
RBC:
- Carry oxygen from the lungs to body tissues for cellular respiration
- Has haemoglobin which combines with oxygen to make oxyhaemoglobin
- No Nucleus
- Biconcave disc gives large surface area for oxygen absorption
WBC:
- Phagocytosis: engulf pathogens
- Lymphocytes makes antibodies
- Antibodies attack by making pathogens stick together (agglutinate), dissolving their cell membranes, neutralising toxins
- Antibodies: bind onto pathogens and help destroy them
- Antitoxins: neutralise any toxins
Platelets:
- Help in blood clotting by thickening the blood and preventing blood from leaving the body and preventing pathogens from entering
Plasma:
- Makes the blood watery so it can flow
- Carries glucose, amino acids, hormones, proteins, urea
9.3 Heart and exercise
Electrocardiogram: traces, pulse rate and sounds of valves closing to monitor heart activity
Physical activity: increases heart rate, increases blood flow to muscles, supplying more oxygen and glucose and removing CO2
9.5 Coronary Heart Disease
Atherosclerosis: cholesterol sticking to the walls narrowing the artery and restricting flow of blood
Thrombosis: rough artery walls causing the blood to clot and block the vessel
Angina: coronary artery gets partially block esp if activity or emotion makes the heart work harder
Heart attack: total blockage, or thrombosis causes heart attack
Cardiac Arrest: heart stops beating
Risk factors: age, sex→ men, genes, smoking
Ways to reduce risk: exercise → makes circulatory system more efficient, Diet→ have saturated fats, less salt, no sugar
Unit 10 Disease and Immunity
Methods of transmission of pathogens: through air, contaminated food and drink, direct contact, indirect contact, insect vectors, body fluid, sexual activity
Defences against disease:
- Mechanical barriers: skin and hairs in the nose
- Chemical barriers: hydrochloric acid, mucus
Blood Defences: phagocytes, lymphocytes
10.2 Defences against disease
- Antibodies lock onto antigens which kill pathogens
- Each pathogen has a specific antigen that fits the shape of the specific antibody
- Active immunity is a defence against a pathogen by antibody production in the body
- Memory cells remember each pathogen so the body becomes immune to the pathogens
10.3 Vaccines
Exposure to pathogens and the immunity the body gets without getting the disease
- Weakened diseases so they are not strong enough to cause a disease, but they still have the same antigens so the body still responds to it and makes antibodies → Immunity!
- Vaccination techniques:
- Killed organism used
- Live non virulent strain of the organism used
- Antigens separated from the organism used
- Toxin produced by organism may be chemically modified so that it is no longer toxic but still has the same antigens
- Genetically modified cells
- Pros: Herd Immunity: Control of common diseases, prevents outbreaks even with those who are not vaccinated
- Cons: Don’t always grant full immunity, side effects
10.4 Aspects of Immunity
Passive Immunity: Short term defence against pathogens using antibodies from another individual (breast milk, placenta), no memory cells
Diabetes
Insulin → absorbs excess glucose turning it into glycogen regulating bood glucose
Inability to regulate blood glucose
Type 1
- Pancreas stops producing insulin
- Symptoms: thirst, weight loss, tiredness
- Treatment: Insulin Injections
- Avoid sugary food, exercise regularly
Type 2
- Cells become resistant to insulin
- So the cells don’t take glucose from the blood stream
- Treatment: Healthy, low sugar diet and regular exercise
10.5 Controlling Spread of Disease
Personal Hygiene, Hygienic food preparation, proper waste disposal, sewage treatment, drinking water treatment
Cholera: drinking contaminated food and water causing diarrhoea which leads to loss of ions and water from blood
10.6 Drugs
Drug: substance taken into the body that influences chemical reactions in the body
Antibodies: destroy pathogens
Antibiotics: live inside host cells and take over their metabolic processes
Unit 11 Gas Exchange
Alveolus:
- Thin so co2 and o2 can diffuse quickly across
- Moist allows gases to dissolve increasing rate of diffusion, large surface area to volume ratio, permeable, diffusion gradient
- External intercostal muscles raise the ribs, internal intercostal muscles lower the ribs
- Goblet cells: produce mucus which traps dust particles and pathogens in the air and cilia to remove mucus from the airways
Unit 12 Respiration
An exothermic reaction that transfers energy from glucose in all living things
How energy is used:
- Buildup of larger molecules from smaller ones
- Muscular contractions
- Maintaining body temperature
Metabolism: all chemical processes that occur within a living organism in order to maintain life
Aerobic Respiration
Glucose + oxygen → Carbon dioxide + Water
C6H12 + 6O2 → 6CO2 + 6H2O
Takes place when there’s oxygen
Anaerobic Respiration
Glucose → Lactic Acid
- Incomplete breakdown of glucose molecule because no oxygen
- Lactic Acid buildup gives burning sensation in muscles → body gets rid of lactic acid by using oxygen which creates oxygen debt
Fermentation: yeast, plants
Glucose → ethanol + Carbon Dioxide
Exercise and Oxygen Debt
Cellular Respiration→ requires energy→ so rate of breathing and heart rate increases
Excretory System
Kidney
Filtration of blood and removal of urea
Regulate the levels of glucose, ions, water
Filtration:
Glomerulus absorbing water, glucose, amino acids and urea
Selective Absorption:
Glucose gets reabsorbed
Water based on how much needed
Kidney
Remove waste products
Regulate the amount of ions
Regulate the amount of water in the blood
Unit 14 Coordination and Response
Central Nervous system: brain, spinal cord
Peripheral Nervous system: cranial, spinal nerves
<<stimulus→ receptor→ coordinator→ effector→ response<<
14.3 Synapses
- Contains mitochondria and vesicles that contain neurotransmitter molecules
- Uni Directional movement of impulses
- Nuerones don’t touch, the synapses in between them release chemical transmitter substances which triggers an impulse in the second nuerone.
14.4 Eye
Cornea: transparent, light enters through it
Pupil: hole in the centre of the iris, light passes through it
Iris: pigmented, controls the intensity of light entering the pupil
Retina: back of the eye, tissue with sensitive light receptor cells
- Rod cells that work in dim light
- Cone cells detect colour and details
Transparent layer at the front of the eye: provides protection
- Contains tear glands that wash your eye clean every time you blink
- Tears contain lysozyme, that kills bacteria
Ciliary muscles: elastic tissue that can be stretched, changes the thickness of the lens when focusing
Suspensory ligaments: holds the lens in place
Optic nerve: carries nerve impulses to the brain
Pupil Reflex: simple reflex
- Bright light > pupils decrease in size > radial muscles relax and pupil constricts > letting less light into the eyes to protect retina from damage
- No light > pupils increase in size > radial muscles constrict and pupil dilates> letting more light pass into the eye so you can still see
Looking at a distant object:
- Ciliary muscles relax , Pressure inside the eye pulls the suspensory ligaments tight (or taut) so the lens is pulled into an elliptical shape
Looking at a near object:
- Ciliary muscles contract to counteract the pressure inside the eye, Suspensory ligaments becomes slack so the elastic tissue around the lens recoils and the lens becomes spherical
14.6 Hormones
Adrenaline:
- Adrenal Gland
- Increasing breathing rate, pulse rate, widening of pupils
- Increasing oxygen and glucose supply to the muscles
Homeostasis: maintaining the body functions, temperature, pH, CO2, water, O2
Negative feedback:
Pancreas: Makes insulin that decreases blood sugar by turning glucose into glycogen
Makes glucagon that increases blood sugar by turning glycogen into glucose
14.8 Controlling body temperature
Skin: stops pathogens from entering, protects body from damage, prevents too much water loss, detects changes in temperature, detects pressure, loses heat by conduction, convection, radiation, evaporation
Sweating: loses heat
Shivering: Generates heat
Vasoconstriction: narrowing of blood vessels so that the blood moves slowly keeping body warmer and losing less energy, cells use energy for ATP that generates heat
Vasodilation: Blood vessels widen so more energy is transferred to the surroundings by convection and radiation
14.9 Tropic Responses
Gravitropism: response to gravity, roots are positively gravitropic, shoots are negatively gravitropic
Phototropism: response to light, roots are negatively phototropic, shoots are positively gravitropic
Auxins: hormones that control growth, goes on shaded side so that side elongates making plant go in direction of light
Unit 15 Reproduction
15.1 Asexual
- Genetically identical offspring
- Binary Fission, spore production, tuber formation
- produce individuals rapidly, no variation, no resistance to disease, competition of resources
Sexual
- fusion of male and female nuclei to form a zygote producing genetically different offspring
- slow production of individuals, variation, resistance to disease, no competition of resources
15.2 Flower
Insect Pollinated:
- Sepals to protect the flower
- Bright petals
- Stamen has anther and filament
- Each carpel is made of stigma style ovary
- Produces sticky spiky pollen to attract insects
Wind Pollinated
- inconspicous flowers
- feathery stigmas and anthers that hang outside the flower
- light smooth pollen so it can be carried by the wind
15.3 Pollination
Transfer of pollen grains from anther to stigma
Self pollination: transfer of pollen from anther to stigma of same flower, no variation, advantage if there are no insects or plant is growing in isolation
Cross Pollination: transfer of pollen from anther to stigma of a different plant, variation
15.4 Fertilisation
- Fusion of male and female gamete
- Pollen tube grows to move the male gamete to the female
- Fertilised egg grows into embryo inside the ovule which forms a seed
Germinating seeds require: water, oxygen, warm temperature
15.5 Male Reproductive System
testes, scrotum, sperm duct, prostate gland, urethra, penis
Sperm small in size so it can swim to the egg
15.6 Female Reproductive system
Ovaries: make eggs released into oviducts. at ovulation
Oviducts: fertilisation occurs, sperm must reach oviduct
Uterus: organ where embryo develops
Cervix: ring of muscle separating the uterus from the vagina
Zygote→ embryo which implants into the uterus lining
15.8 Pregnancy
- Fetus develops in the uterus
- Umbilical cord attaches fetus to placenta: site of exchange of substances between mother and fetus, acts as barrier for pathogens
- Amniotic fluid: protects fetus from mechanical damage
15.9 Sex Hormones
Testosterone, Oestrogen
15.10 Menstrual Cycle
FSH: development of follicles inside the ovary, secretion of oestrogen
LH: Stimulates ovulation and formation of yellow body from the remains of the follicle
Day 1 to 4: Menstruation
10 days: Uterus lining build up
Day 14: Ovulation
Day 15 to 28: maintaining the uterus lining
Day 28: Menstruation
15.11 STI
- passed via body fluids during sexual contact
- Sharing of needles, unprotected sex, breast milk
- leads to AIDS over time
- destroys lymphocytes that weakens the immune system making body susceptible to many diseases
- ART AntiRetroviral Treatment, zidovudine and other drugs
Unit 16 Inheritance
DNA
A pairs with T
C pairs with G
46 chromosomes→ 23 different types
23rd chromosome- sex chromosome XX XY
Gene: section that codes for a protein
Genome: entire set of genetic material in an organism
Mitosis: produces genetically identical daughter cells
Meiosis: reduction division in which the chromosome is halved from diploid to haploid resulting in genetically different cells
Alleles: different versions of the same gene
Homozygous: 2 of the same allele
Heterozygous: 2 different alleles
Dominant: get expressed
Recessive: doesn’t get expressed when there’s a dominant allele
Genotype: entire collection fo alleles we have
Phenotype: characteristics you get from the genotype
Variation
Natural selection:
Evolution: Inheritance of certain characteristics in a population could lead to changes in a whole species
Mutations
Change in DNA base sequence
Genetic Diagrams
Punnett square
Family Trees
Unit 17 Variation and Selection
Variation: Differences between individuals of the same species
Genetic Variation: Differences in genotype
Phenotypic variation: differences in external and internal appearance
Continuous variation: influenced by genes, environment
Discontinuous variation: small number of phenotypes, no intermediates, caused by genes alone
Natural Selection: only individuals better adapted than others will survive to breed and pass their alleles to offspring
Selective Breeding: humans finding organisms with desirable features, crossing them and selecting the best from the next generation, high yield crops, cattles that produce more milk