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Bio Paper 2 - Final Exams - Coggle Diagram
Bio Paper 2 - Final Exams
B5
L1 - Homeostasis
Homeostasis is the regulation of a constant internal environment in cells to maintain an optimum conditions for enzymes to function in response to changes in external conditions.
Conditions that need to be maintained in the body:
Temperature.
Water levels.
Hormone levels.
Blood glucose.
L2 - The Nervous System
The central nervous system consists of the brain and the spinal cord. It is linked to sensory neurons which form the peripheral nervous system. The nervous system sends fast but short-lived responses.
The endocrine system is slow and lasting, is uses chemical messengers and is carried to all organs but affects the target organ only.
Parts of a nerve:
Cell body - Contains genetic information.
Axons - Transmit electrical impulses.
Dendrites - Receives impulses from other neurons.
Myelin Sheath - Acts as an insulator to prevent the electrical impulse from being lost.
Synapses:
Presynaptic neuron delivers the impulse.
Neurotransmitters allow for the transfer of an electrical impulse over the synapse.
Receptor molecules receive the neurotransmitters and convert the chemical to electrical signals.
Reflex arc: Stimulus -> Receptor -> Coordinator -> Effector -> Response.
L3 - Req Prac
Use weaker hand for experiment.
Place forearm of weaker arm on the table with hand overhanging the edge of the table.
Ruler held at the 0cm mark.
Other participant will tell you when to prepare to catch the ruler.
Ruler is dropped.
Ruler caught and mark at top of thumb recorded and converted to reaction time.
Have a short rest and repeat with independent changed.
L4 - The Brain
Parts of the Brain:
Cerebral cortex: Largest part of the brain, responsible for though and action.
Medulla: Responsible for involuntary movements such as breathing, circulation and digestion.
Cerebellum: Responsible for voluntary movements such as posture, balance, coordination and speech.
Hypothalamus: Responsible for temperature regulation.
Pituitary gland: Master gland, releases hormones that causes other glands to secrete hormones.
L5 - The Eye 1
The eye contains two types of receptors: rods (light intensity) and cones (colour perception).
Parts of the Eye:
Cornea: Begins to focus light rays.
Pupil: A whole within the iris allows for light to pass through.
Lens: Focuses light rays onto the retina (it changes shape to allow for this).
Retina: Contains receptor cells that allow for the detection of light and colour.
Sclera: Tough and fibrous outer structure to protect the eye.
Suspensory ligaments: Connects the ciliary muscles to the lens.
L6 - The Eye 2
Hyperopia is when light converges behind the retina, myopia occurs when light converges in front of the retina.
When an object is
close
, the
ciliary
muscles
contract
.
L7 - Temp Control
Body temperature is monitored by the hypothalamus. The temp regulatory centre contains receptor cells sensitive to blood temperature. The skin also contains temperature receptors.
When body temperature increases, the body perspires (removes heat energy when sweat evaporates off skin), vasodilation occurs (blood is moves closer to the skin so heat can be radiated from the body easier).
L8 - Endocrine System
Rapid:
Insulin: Lowers.
Adrenaline: Fi or Fl
Thyroid Gland:
Controls metabolic rate in the body.
When thyroxine is low, the pituitary gland releases TSH which stimulates the thyroid to release thyroxine.
Pancreas:
Glucagon increases blood glucose levels while insulin decreases blood glucose levels.
L9 - Diabetes
Insulin causes liver and muscles to store excess glucose as glycogen.
L10 - The Kidneys
Water is lost through exhalation, sweating (with sodium ions and urea also) and in urination.
Blood enters the kidneys through an artery, the kidney removes all urea, all excess ion and all excess water. It reabsorbs all glucose (selective reabsorption). Urine is stored in the bladder and blood leaves the kidneys through a vein.
Excess amino acids are broken down in the liver to produce ammonia and then urea.
L13 - Plant Hormones
Photo- and geo- trophism
Auxin is produced at the very tip of shoots; here, it triggers cell growth. Auxin will concentrate on the darker side of a shoot tip, causing it to grow faster.
In roots, auxin inhibits cell growth so concentrates on the lower side.
Gibberellins are important in initiating seed germination, seed dormancy and flowering. It can be used to increase fruit size also.
Ethene - Ripen and div
L11 - Dialysis
If the blood becomes too concentrated, the pituitary gland releases the ADH hormone. This causes the kidney tubules to become more permeable to water. More water can be reabsorbed now.
Dialysis fluid contains the normal concentrations of water and ions with no urea. Dialysis fluid is constantly refreshed to maintain a high concentration gradient.
Disadvantages of dialysis:
Controlled diet must be followed.
Long periods of time are spent connected to the machine.
You feel tired and unwell as the next dialysis period approaches.
Substances are harder to regulate as you get older.
L12 - IVF
IVF can be used when the oviducts are damaged or blocked by infection and a donor egg has to be used.
FSH - Produced by the pituitary gland, causes an egg to mature in the ovaries and oestrogen to be released.
LH - Triggers ovulation (release of an egg).
Progesterone - Maintains the uterus lining during pregnancy and during the middle of a cycle.
Oestrogen - Stops FSH from being produced so that only one egg is released.
First treated with FSH and LH in drug form, causing several eggs to mature.
Eggs are collected and sperm from the father is used to fertilise the eggs.
The fertilised eggs develop into embryos and are inserted into the uterus.
While IVF treatment allows a woman to have a baby of her own, success rates are not high. Also, the treatment is physically and emotionally draining. + Multiple births + Some destroyed + Expense
B6
L1 - Sexual and Asexual
Sexual reproduction involves the fusion of two gametes (sperm and egg / pollen and egg).
In sexual reproduction, the mixing of genetic information leads to variation in offspring. Asexual reproduction involves one parent: this creates genetically identical offspring.
The gametes involved in sexual reproduction are formed through meiosis; the zygote develops through mitosis.
When a diploid cell divides to form gametes, all genetic information is copied, the cell divides into two cells with 23 pairs of chromosomes and then each of these cells divides again to form 4 varying gametes with 23 single chromosomes.
L2 - DNA and the Genome
Chromosomes contain the molecule DNA which determines our inherited features.
A gene is a small section of DNA on a chromosome; each gene encodes for a specific amino acids to produce a specific protein.
The genome is the entire genetic make-up of an organism. Understanding the human genome has allowed us to: observe genes that are linked to disease, understand how to treat inherited disorders and trace human migration patterns (ancestry).
L3 - DNA Structure
DNA is a polymer formed from nucleotide molecules. These nucleotides contain a base (ATCG), a phosphate group and a deoxyribose sugar molecule. A is always linked to T and C is always linked to G. The two strands are complementary.
A cell reads a stand of DNA in triplets of bases.
Stage 1 (Transcription):
(In the nucleus)
DNA uncoils at the gene.
Base sequence of gene is copied into a single stranded molecule template (mRNA).
The mRNA moves out of the nucleus and into the cytoplasm.
Stage 2 (Translation):
mRNA attaches to a ribosome and amino acids are brought to this ribosome by tRNA molecules .
The ribosome reads the triplets of bases on the mRNA and assembles the correct amino acids in the correct order.
The protein chain then folds into its unique shape.
Humans contain 20 different amino acids.
L4 - Mutations
A mutation is a change to a base. Most mutations do not have a significant effect on the function of a protein as different base triplets can sometimes encode the same amino acids.
Non-coding sections of DNA can also experience mutations. This may result in a gene producing proteins at unsuitable times. An example of this includes uncontrolled mitosis.
L5 - Alleles
Alleles are specific versions of genes. The genotype of a person tells us the alleles present. The phenotype of a person tells us the characteristics caused by this genotype.
L6 - Cystic Fibrosis
Cystic fibrosis is a disorder of cell membranes caused by a single gene. The allele for defective cell membranes is recessive.
L7 - Polydactyly
Caused by a dominant allele. You cannot be a carrier of the polydactyly allele.
Embryo screening involves the testing of embryos to see if they have alleles for inherited disorders; the embryos without these alleles are then implanted into the woman. Issues include expense, not all are implanted so healthy embryos destroyed and the concept of genetically engineering embryos to produce children with more desirable characteristics.
L8 - Family Trees
Female: XX
Male: XY
B7
L1 - Communities
Deforestation is typically done in hopes of freeing space for rice fields, the growth of biofuels and allowing cattle to graze.
In a stable community, populations of species remain fairly constant. Biodiversity is the variety of species on the Earth or in an ecosystem.
Plants compete for light, soil, space, water and mineral ions.
Community: only living parts.
Interdependence:
Bees spread pollen
Birds --> Seeds in faeces
Trees as shelter.
L2 - Abiotic and Biotic
Biotic:
Availability of food.
Arrival of new predators.
Competition between species.
New pathogens.
Abiotic:
Light intensity
Temp
Water
pH of soil
Wind intensity
Gas conc
L3 - Food Chains
All food chains begin with a producer. These producers can synthesise complex molecules (known as biomass).
Organisms that eat producers are known as primary consumers.
L4 - Carbon Cycle
Plants and algae take in carbon dioxide from the atmosphere; this carbon is used to make carbohydrates, fats and proteins (with some released back into respiration).
Plants and algae are eaten by animals, animals produce waste such as faeces. These animals eventually die.
Dead animals are digested by decomposers, releasing mineral ions into the soil and respiring.
Under certain conditions (such as a lack of oxygen), dead remains cannot be fully broken down by composers and fossil fuels are formed.
L5 - Water Cycle
Water on the surface of oceans evaporates and rises through convection, it then cools and precipitation falls.
This precipitation returns water to the surface, forming streams, rivers or aquifers.
Plants take up water in their roots through transpiration. Animals take in water through food and drink which is removed in exhalation, urine and faeces.
L6 - Decay Practical
Method:
Label a test tube "lipase" and add a given volume of lipase using a pipette.
Label another test tube "milk" and add 5 drops of indicator, 5cm^3 of milk and 7cm^3 of sodium carbonate.
Place a thermometer into the "milk" test tube and place this into an electric water bath.
Transfer 1cm^3 of lipase solution into the test tube and begin a timer; stop the timer when a colour change is observed.
L7 - Decomposition
Bacteria and fungi can decompose plant matter over time. This can form compost which is used as a fertiliser as it is rich in minerals.
Factors affecting rate of decomposition:
Temperature.
Moisture (chemical reactions involved in decay require water)
Oxygen availability (needed for cellular respiration).
Anaerobic decomposition produces a mixture of gasses (such a methane). This is known as biogas and can be burned to release energy. It cannot be stored and is often created in biogas generators.
L8 - Waste Management
Eutrophication process:
Nutrients from fertilisers enter the water and are used by plants.
Algae flourish and this decreases the amount of available oxygen in the water.
(Also block sun).
Plants die and decompose.
Peat is used to produce cheap compost or is burned to produce energy. Upon extracting this peat, it decomposes and produces carbon dioxide.
Peat bogs contains a large amount of dead plant matter that cannot decay due to the bog's conditions and so it contains a large amount of trapped carbon.
L9 - Farming Techniques
Methane is produced by bacteria in paddy fields or when cows pass wind.
There is less biomass available for free range chickens as biomass is used in respiration and maintaining body temperature.
Biodiversity can be maintained with breeding programmes, protection of rate habitats, introduction of field margins/hedgerows and passing legislation.
Intensive farming (given high protein diet):
More efficient + diets are controlled.
Diseases can be spread more easily.
Antibiotic resistance.
Ethical objections.
Fisheries can be made sustainable by:
Introducing strict quotas (num of fish caught for each species).
Introducing a limit on the size of nets (only catching larger fish).
L10 - Biotechnology
Golden rice is a GM crop with more vitamin A.
Mycoprotein is produced from the fusarium fungus placed in glucose syrup within a fermenter; the fungus is then harvested and purified. It is suitable for vegetarians and a large amount of it can be grown in a very small area.