Eukaryotic and prokaryotic
Cytoplasm, cell membrane, cell wall, loop of DNA and plasmid
Cell membrane, cytoplasm and nucleus
Eukaryotes are larger and have a nucleus. Prokaryotes are smaller and have no nucleus.
Eukaryote: e.g. palisade cell, white blood cell, nerve cell etc. Prokaryote: bacteria.
Control the functions of the cell and is the location of chromosomes in eukaryotic cells.
Protein synthesis.
Site of aerobic respiration.
Site of photosynthesis.
The selective transport of substances in and out of the cell.
Supports the cell.
Involved with keeping plant cells turgid by osmosis.
A plant cell has a cell wall, chloroplasts and a vacuole in addition to the parts of an animal cell.
2
It is long to connect to the central nervous system. It is surrounded in fat to insulate the electrical signal.
The sperm cell has a tail to allow it to swim. It is packed with mitochondria to provide energy. The nucleus contains only half the chromosomes.
The muscle cells contain fibres to contract. It has many mitochondria to provide energy.
The root hair cell has thin projections which increase the surface area to volume ratio of the cell to allow efficient transport of water by osmosis.
Xylem consists of hollow tubes strengthened by lignin to allow the transport of water.
Phloem is composed of tubes of elongated cells with sieve plates. Cell sap can move from one phloem cell to another through the sieve plates in the end cell walls.
The cell will grow and increase the sub cellular structures such as ribosomes and mitochondria. The DNA will divide to form two copies of each chromosome. In mitosis the chromosome pairs are pulled apart to each end of the cell. The cytoplasm and cell membrane then divide to form two identical cells.
Mitosis is important in the growth and development of multicellular organisms.
Light microscopes allowed for the discovery of cells and electron microscopes allowed for the discovery of organelles within the cell.
electron microscopes have high magnification and high resolution (detail). Light microscopes have low resolution and low magnification.
Magnification = size of image / size of real object
Genetic material is made from DNA and organised in to chromosomes.
The cell will grow and increase the sub cellular structures such as ribosomes and mitochondria. The DNA will divide to form two copies of each chromosome. In mitosis the chromosome pairs are pulled apart to each end of the cell. The cytoplasm and cell membrane then divide to form two identical cells.
Mitosis is important in the growth and development of multicellular organisms.
It is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can develop by differentiation.
Stem cells from embryos can be cloned and made to differentiate into most different types of human cells
Stem cells from bone marrow can form many different types of cells including blood cells.
Meristems tissue is found in plants and can differentiate into any type of plant cell throughout the life of the plant.
Diabetes and paralysis
n embryo is produced with the same genes as the patient. The stem cells removed from the embryo will not be rejected by the patient’s body so may be used for medical treatment.
Risk of transfer of viral infections. Religious or ethical objections to using embryos for research.
Rare species can be cloned to protect from extinction and crop plants with special characteristics such as disease resistance or drought resistance, can be cloned to produce large numbers of identical plants for farmers.
The net movement of particles from an area of higher concentration to an area of lower concentration.
Gaseous exchange of carbon dioxide and oxygen in the lungs and muscles, the removal of urea from cells into the blood.
The difference in concentration (concentration gradient), the temperature and the surface area of the membrane.
A single cell organism has a large surface area to volume ratio. This allows the transport of substances in and out of the organism to meet its metabolic needs.
Small intestine, lungs, gills, roots and leaves.
Having a large surface area, a thin membrane (for a short diffusion path), an efficient blood supply (animals), being ventilated (animals for gaseous exchange).
Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
Water will move from inside the cell (dilute solution) to outside the cell (concentrated solution).
Water will move from outside the cell (dilute solution) to inside the cell (concentrated solution)
Water will move inside the cell by osmosis. The blood cell will swell up and burst.
Cut 5 pieces of potato to equal size. Weigh each piece of potato. Place a piece of potato in 5mL of the following solutions: 0M, 0.2M, 0.4M, 0.6M, 0.8M and1M. Incubate the solutions for 1hr. Remove each piece of potato, pat it dry with tissue paper and weigh. Calculate the change in mass of each potato. Calculate the percentage change in mass by dividing the change in mass by the mass of the potato at the start.
The movement of substances from a dilute solution to a more concentrated solution, against the concentration gradient. This process requires energy from respiration.
Active transport moves substances against the concentration gradient while diffusion moves substances down the concentration gradient. Active transport requires energy for the process, diffusion is a passive process and does not require energy.
Mineral ions are absorbed by root hair cells into the plant from low concentrations in the soil. Sugar are absorbed into the blood (which has a high concentration of sugar) from the small intestine (which has a lower concentration of sugar).
Cells
A group of cells with a similar structure and function
Organs are aggregations of tissues which perform a similar function
ribosome, mitochondria, nucleus, vacuole, palisade cell.
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus.
They have low kinetic energy and will rarely collide with substrate molecules which results in a low rate of reaction.
The enzyme loses its shape and the active site no longer binds to the substrate.
Optimal pH is the pH at which the rate of reaction is the fastest. In the stomach the protease enzymes work best at pH3.
Enzymes action depends on the shape of the active site (the lock) fitting to substrate (the key). When the enzyme and substrate are joined together the enzyme can breakdown the substrate. When the enzyme is denatures, the active site no longer fits the substrate.
Salivary glands, pancreas and small intestine.
Stomach, pancreas and small intestine.
Pancreas and small intestine.
Starch is broken down into glucose.
Protein is broken down into amino acids.
Lipids are broken down in fatty acids and glycerol
Liver
Gall bladder
It is alkaline to neutralise hydrochloride acid from the stomach. Bile emulsified fat to form small droplets which increases the surface area of lipid for quicker digestion.
Benedict’s test
Green, orange or red.
Iodine test
Blue/black
Biuret test
Lilac
Sudan III
A red layer
Vena cava and pulmonary vein
Pulmonary artery and aorta
Pulmonary vein and aorta.
Pulmonary artery and vena cava
Right ventricle
Left ventricle
The circulatory system consists of a deoxygenated loop which passes the the lungs and an oxygenated loop which passes through the body. Blood passes through the heart twice as it travels through each loop.
It is controlled by a group of cells in the right atrium which act as a pacemaker.
An artificial pacemaker is an electrical device used to correct irregularities in the heart.
Artery, vein and capillary.
Arteries have thick walls with large muscle layers. Veins have thinner walls but contain valves to ensure blood flows in one direction. Capillaries are much small than arteries and veins and are only a one cell thick. They have gaps in their walls to allow plasma to leak out.
Red blood cells, white blood cells, platelets and plasma.
Red blood cells
Platelets
Plasma
White blood cells
White blood cells
Platelets
Plasma
Red blood cells
A non-communicable disease
Layers of fatty material build up inside coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle.
Stents are inserted through veins into the coronary arteries. A ballon is then inflated to open the stent which keeps the coronary artery open.
Statins are drugs which reduce blood cholesterol levels and slow down the rate of fatty material deposit.
If heart failure occurs a heart can be transplanted. Sometimes an artificial heart can be used to keep patients alive while waiting for a transplant or to allow a heart to rest to aid recovery.
Stents lower the risk of coronary heart disease, are a long term solution and recovery from surgery is quick. The is a risk of infection from the surgery and for patients to develop a blood clot (thrombosis) near the stent. Statins reduce the risk of strokes, heart disease and heart attacks. Can cause negative side effects such as headaches, kidney failure and liver damage. It can take time for statins to have an effect.
Heart valves may not fully open or they may leak.
Blood does not circulate as effectively. Lack of oxygen in circulation around the body.
Replacement with biological valves (from humans or other animals or synthetic valves (made from metal and plastic).
Health is the state of physical and mental well being.
Diseases, diet, stress and life situations.
Communicable and non-communicable
Infectious disease
Cancer
Allergies such as skin rashes or cancer
Depression and other mental illness
Many millions of human die each year from non-communicable disease. Their short life span and lower quality of life will also have an impact on their families. Treating illness costs money to fund health services and research.
Diet, alcohol and smoking.
Diet, smoking and lack of exercise.
Obesity.
Alcohol.
Smoking.
Smoking and alcohol.
Carcinogens (in chemicals) and ionising radiation.
Cancer is a result of changes (mutations) in cells which lead to uncontrolled growth and division.
Growths of abnormal cells that are contained in one area usually within a membrane. They do not move to other parts of the body.
Malignant tumour cells are cancerous. They invade neighbouring tissue and spread to different parts of the body through the blood where they grow to form secondary tumours.
Epidermal, palisade mesophyll, spongy mesophyll, xylem, phloem and meristem
Leaf
Waxy cuticle (not a tissue), upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis (containing guard cells).
Root hairs cells take up water from the soil by osmosis. Xylem vessels transport the water up the plant to the leaves. Water evaporates from the stomata of leaves. It is the evaporation which pulls water up through the plant. The movement of water through the plant is called the transpiration stream.
Increasing the temperature and air movement will increase the rate of transpiration in a plant (more water evaporates from the stomata). Increasing humidity will decrease the rate of transpiration (less water evaporates from the stomata). The stomata open during the day (transpiration) but close at night (no transpiration)
Use a potometer. To look at the effect of wind set up the potometer and measure how far the bubble travels in 15 minutes. Use a hair drier on low power setting without the heater and blow plant for 15 minutes. Measure how far the bubble travels. Use the hair drier on the highest power setting and blow plant for 15 minutes. Record how far the bubble travels.
Stomata are located in the lower epidermis of the leaf in most terrestrial plants. Water lily leaves float on water, so their stomata are on the upper epidermis of the leaf.
Xylem (water and mineral ions) and phloem (sugar)
This is the process where phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage.
Stomata are located in the lower epidermis of the leaf in most terrestrial plants. Water lily leaves float on water, so their stomata are on the upper epidermis of the leaf.
Root hair cells have a long thread like structure which increases the surface area to volume ratio of the cell. This allows for the efficient uptake of water and mineral ions.
Phloem is composed of tubes of elongated cells with sieve plates. Cell sap can move from one phloem cell to another through the sieve plates in the end cell walls.
Hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream
Water is absorbed by osmosis and mineral ions are absorbed by active transport.
Pathogens are microorganisms that cause infectious disease.
Viruses, bacteria, protists and fungi.
Direct contact, by water or by air.
They reproduce rapidly inside the body. They may produce toxins (poison) that damage tissue and cause illness.
They live and reproduce inside cells, causing cell damage.
Measles, HIV and tobacco mosaic virus.
Fever and a red skin rash.
Measles can be fatal if there are complications.
Inhalation of droplets from coughing and sneezing.
Vaccination of young children.
Flu-like illness.
The virus attacks and destroys the cells of the body’s immune system.What is AIDS? The late stage of HIV when the body’s immune system is so badly damaged it can no longer cope with other infections or cancers.
The late stage of HIV when the body’s immune system is so badly damaged it can no longer cope with other infections or cancers.
HIV is spread by sexual contact or the exchange of body fluids (e.g. blood when drug users share needles)
By the use of antiretroviral drugs which slow down the replication of the virus.
Many species of plants, including tomatoes.
A distinctive mosaic pattern of discolouration on the leaves.
TMV affects the growth of a plant due to the lack of photosynthesis.
Salmonella food poisoning and gonorrhoea.
Fever, abdominal cramps, vomiting and diarrhoea.
The bacteria and the toxins they produce.
By ingesting contaminated food or on food prepared in unhygienic conditions (dirty hands and surfaces).
In the UK poultry (chickens) are vaccinated against salmonella.
A thick yellow or green discharge from the vagina or penis and pain when urinating.
Gonorrhoea is a sexually transmitted disease (STD).
Gonorrhoea is treated with antibiotics. The risk of transmission can be reduced by using barrier methods of contraception such as condoms.
Many antibiotic resistant strains have appeared.
Rose black spot.
Purple or black spots develop on leaves which turn yellow and drop early.
The growth of plants is affected as photosynthesis is reduced.
The fungal spores are spread by water or wind.
It can be treated using fungicides and by removing and destroying (by burning) the affected leaves.
Malaria
Recurrent episodes of fever.
It can be fatal.
An organism that transports the pathogen from one host to another.
It is spread from host to host by a mosquito.
By targeting the mosquito. This is achieved by disrupting its habitat (draining swamps), disrupting its breeding and using mosquito nets to prevent being bitten.
Skin, nose, trachea and bronchi and stomach.
A layer of dead cells which cannot be infected.
Hairs and mucus prevent pathogens entering the lungs.
Cilia and mucus, in the trachea and bronchi, trap then remove pathogens.
The acid in the stomach kills pathogens.
The immune system detects and destroys pathogens that enter the blood and tissues.
phagocytosis, antibody production and antitoxin production.
Vaccination involves the introduction of dead or inactive pathogens into an organism which stimulates the white blood cells to produce antibodies. If the organism is reinfected by a live pathogen it will activate the antibodies to eradicate the pathogens quickly and so prevent infection.
Vaccination on a global scale has helped to eradicate a number of diseases. This only happens when the majority of the population is vaccinated.
Antibiotics are medicines used to treat bacterial infections by killing the bacteria inside the body.
The overall effect of antibiotics has been to significantly reduce death from infections. However misuse of antibiotics has lead to the emergence of resistant strains.
They target bacteria (prokaryotic cells) only. They do not kill viruses.
A type of drug that treats symptoms of a disease but does not affect the pathogens themselves.
Viruses live inside cells so any treatment can also damage host cells as well.
Digitalis, aspirin and penicillin.
Alexander Fleming.
Most pharmaceuticals (drugs) are synthesised by chemists in laboratories.
Drugs are tested to ensure that they are safe and effective.
Drugs are tested for toxicity (side effects), efficacy (effectiveness) and dose (most effective amount which balances maximum efficacy with minimal toxicity.
Preclinical testing occurs in the laboratory and can use cells, tissues and live animals.
Clinical trials are carried out in healthy volunteers and patients. Low doses are given at the start of testing to ensure toxicity is low. Further trials are then carried out at different doses to find out the optimum dose of the drug. To check if a drug is effective a double blind trial will be used. In this case half the patients receive the drug and the other half will be given a placebo. The results of trials are published after peer review.
Phloem is composed of tubes of elongated cells with sieve plates. Cell sap can move from one phloem cell to another through the sieve plates in the end cell walls.
Carbon dioxide + water → glucose + oxygen
CO2
H2O
O2
C6H12O6
6CO2 + 6H2O → C6H12O6 + 6O2
Photosynthesis is an endothermic reaction in which energy from sunlight is transferred to chloroplasts.
Temperature, light intensity, carbon dioxide concentration and chlorophyll.
Photosynthesis is controlled by enzymes. Temperature affects the rate of collisions between the enzymes and the substrates. If the temperature is too high the enzymes will denature and no longer bind to the substrate.
Carbon dioxide is required to make the glucose. If the carbon dioxide concentration is too low the amount of glucose that can be produce is reduced.
Light transfers energy to the chloroplasts for the reactions. A reduction in light intensity will reduce the energy available for the reaction.
Pondweed is placed in a beaker of water at a constant temperature. Sodium carbonate is added to the water to ensure there is enough dissolved carbon dioxide. The plant is left for ten minutes to acclimatise. A glass filter funnel is placed over the plant. Any oxygen given off is collected in a graduated test tube placed on top of the funnel. A light source is placed at 100cm from the plant. A glass plate is placed between the light source and the plant. This prevents the water from heating up from the light. The light is turned on and the volume of gas collected over 5 minutes is measured. The experiment is repeated at 90cm, 80cm, 70cm, 60cm, 40cm, 30cm, 20cm and 10cm. A graph is plotted of distance vs volume of oxygen collected.
A limiting factor is a resource or environmental factor whose absence prevents an increase in the rate of a reaction. If the limiting factor is increased, the rate of reaction will increase as well.
ight intensity = 1 / 102 : light intensity = 0.01 au (arbitrary units)
if you halve the distance the light intensity will be four times greater.
Greenhouses control light intensity (artificial light), temperature (heating) and carbon dioxide concentration (ventilation). The cost effectiveness of each factor is related to the maximum growth rate.
Carbon dioxide
Respiration, converted to starch for storage, converted to fat or oil for storage, converted to cellulose to make the cell wall, used to make amino acids for protein synthesis.
Plants absorb nitrate ions from the soil which are used to make proteins.
Cellular respiration is an exothermic reaction which is continually happening inside all living cells.
Aerobic respiration.
Anaerobic respiration.
Glucose + oxygen → carbon dioxide + water
C6H12O6 + 6O2 → 6CO2 + 6H2O
Glucose → lactic acid
Glucose → ethanol and carbon dioxide
Fermentation
Chemical reactions to synthesise large molecules (eg proteins).
Aerobic respiration requires oxygen, anaerobic respiration does not require oxygen.
Anaerobic respiration will produce lactic acid in humans or ethanol and carbon dioxide in yeast. Aerobic respiration produces carbon dioxide and water.
Aerobic respiration produces large amounts of energy slowly, from a molecule of glucose. Anaerobic respiration produces a small amount of energy quickly, from a molecule of glucose.
Anaerobic respiration is important in the manufacture of bread and alcoholic drinks.
Heart rate, breathing rate and breath volume.
Anaerobic respiration will take place in muscles.
Incomplete oxidation of glucose will lead to a build up of lactic acid in the muscles and creates an oxygen debt.
The muscles will become fatigued and will stop contracting efficiently.
Lactic acid is removed from the muscles and transported via the circulatory system to the liver. The liver converts the lactic acid back to glucose.
Oxygen debt is the amount of extra oxygen the liver uses after exercise to convert lactic acid back to glucose.
The sum of all the reactions in a cell or organism.
The energy transferred by respiration, is used by a cell or organism for enzyme controlled processes of metabolism that synthesise new molecules.
Starch and cellulose in plants and glycogen in humans.
One molecule of glycerol and three molecules of fatty acids.
Glucose and nitrate ions.
From amino acids.
They are broken down to form urea which is removed by excretion.
Glucose.
Amino acids.
Glycerol and fatty acids.
Homeostasis is the regulation of the internal environment of an organism to maintain optimal conditions for life processes (e.g. enzyme action).
Blood glucose concentration, body temperature and water levels.
Receptors, coordination centres and effectors
To detect stimuli (a change in the internal or external environment)
Brain, spinal cord and pancreas
To receive and process information from receptors.
Muscles and glands
To bring about responses which restore the internal environment to optimal levels.
To enable organisms to react to changes in the environment and to coordinate their behaviour.
Neurones and central nervous system (CNS)
Brain and spinal cord
To process information form receptors and coordinate responses by the effectors (e.g. contracting muscles or glands secreting hormones).
A protective nervous pathway.
Sensory neurone.
Motor neurone.
In the spinal cord.
The relay neurone.
The relay neurone.
The sensory neurone and the motor neurone.
Synapses
By the release of chemicals called neurotransmitters.
They are rapid and automatic. They are involuntary (they do not involve the conscious part of the brain)
Select a subject. Ensure the subject does not drink caffeine for 24 hours prior to the test. Hold a ruler above the subjects hand. When you release the ruler the subject will grab it. Measure the distance the ruler falls. Repeat the test 10 times and calculate the average distance the ruler fell. Give the subject a known amount of caffeine in a drink. Allow 30 minutes for the caffeine to be absorbed. Repeat the experiment. Compare the effect of caffeine on the distance the ruler falls. The experiment can be repeated with more subjects but they should be the same sex, height and weight to ensure the results can be compared.
Stimulus→Receptor→Coordinator
→Effector→Response
The endocrine system is made up of different glands which release chemical messengers called hormones into the blood.
The target organ is the organ where the hormone has an effect.
The endocrine system is slower than the nervous system but it has a longer lasting effect.
The pituitary.
The brain.
In response to changes in the body, the pituitary secretes a number of hormones into the blood. These hormones then stimulate other glands to release hormones and bring about other effects.
Pituitary, pancreas, thyroid, adrenal gland, ovary and testes
Pituitary - brain, pancreas - abdomen, thyroid - neck, adrenal gland - on top of kidney, ovary - female lower abdomen and testes - male scrotum.
Pancreas
Glucose and glycogen
Insulin and glucagon
Pancreas, liver and muscle.
Insulin.
Liver and muscle.
Insulin triggers the liver and muscle to take up the excess glucose in the blood.
The liver and muscle convert the glucose into glycogen for storage.
A disorder where the pancreas does not produce enough insulin.
High levels of blood glucose concentration.
Insulin injections.
A condition where the body cells (target organs) no longer respond to insulin.
A carbohydrate controlled diet and more exercise.
Obesity
Glucagon.
Liver and muscle.
It stimulates the liver and muscles cells to breakdown glycogen into glucose and release the glucose into the blood.
As a result of exercise blood glucose concentration will fall. The fall is detected by the pancreas which releases glucagon to counteract the lower levels of glucose. The target organs for the glucagon are liver and muscle. The liver and muscle respond to the glucagon by breaking down the glycogen they have stored and releasing the glucose into the blood. This causes the blood glucose concentration to return to normal.
To stimulate the development of the secondary sexual characteristics
Oestrogen.
Ovary.
Testosterone.
Testes.
The release of an egg cell from the ovary.
At puberty.
Approximately every 28 days.
Oestrogen, progesterone, Luteinising hormone and follicle stimulating hormone.
It causes the maturation of an egg cell from a follicle in the ovary.
It stimulates ovulation.
They are involved in stimulating and maintaining the thickness of the uterine lining.
FSH → oestrogen → LH → progesterone
A - oestrogen, B - LH, C - progesterone and D - FSH
Breakdown of the uterine lining (menstruation).
Ovulation.
Oestrogen
It stimulates the uterine lining to thicken.
LH
It maintains the thickness of the uterine lining.
Hormonal and non-hormonal
It contains progesterone which inhibits the production of FSH so no eggs can mature and be released.
These inhibit FSH and prevent eggs maturing for months or even years.
Condoms and the diaphragm
They prevent the sperm from reaching the egg.
They prevent the implantation of an embryo into the uterine lining.
They kill or disable sperm.
Couples refrain from sex during the most fertile days of the cycle.
Tubes which transport sperm or eggs are tied off or cut to prevent passage.
LH and FSH.
In vitro fertilisation
The prospective mother is given FSH and LH to stimulate the maturing of several eggs. The eggs are collected from the prospective mother and fertilised with spree from the prospective father in the laboratory. The fertilised eggs develop into embryos. Some of the developed embryos are selected and inserted into the prospective mothers uterus.
The success rate is not very high. It is very emotional and physical stressful for the prospective parents. It can lead to multiple births which are a risk to both the babies and the mother. The destruction of embryos inside and outside the body is considered unethical by religious groups.
The sum of all the reactions in the body when it is at rest.
Thyroid gland.
Stimulates the basal metabolic rate. Thyroxine also plays a role in growth and development.
Thyroxine levels are controlled by negative feedback.
Adrenal glands
It is produced at times of fear or stress (fight or flight response)
Adrenaline increases the heart rate and increases the oxygen and glucose delivered to the muscles.
Non identical cells.
Identical cells.
The fusing of male and female gametes.
Egg (female) and pollen (male).
Egg (female) and sperm (male).
During the formation of gametes by meiosis and the mixing of genetic material during sexual reproduction.
There is only one parent cell and the is no fusion of gametes. As a result there is no mixing of genetic information.
Meiosis halves the number of chromosomes during the formation of the gametes. During fertilisation the full number of chromosomes is restored in the fertilised egg.
By meiosis.
Genetic information is copied. The cell divides twice to form single cells with half the number of chromosomes. All the gametes are genetically different.
Gametes fuse during fertilisation and restore the normal number of chromosomes. The new cell divides by mitosis. This increases the number of cells. Once the cells differentiate an embryo is formed.
Nucleus.
DNA.
A polymer made of two strands forming a double helix.
Chromosomes.
A small section of DNA on a chromosome.
A sequence of amino acids which make a specific protein.
The entire genetic material of an organism.
Search for genes linked to disease, understanding and treating inherited diseases and tracing human migration patterns from the past.
A sex cell.
A long strand of DNA folded into structure.
A section of DNA that codes for a specific protein.
A different form of the same gene (e.g. blue and brown alleles for eye colour).
A dominant allele is always expressed in the phenotype even if only one copy is present.
A recessive allele is only expressed if two copies are present.
Two copies of the same allele.
Different copies of an allele.
The alleles present in an organism. e.g. TT or Tt.
The physical expression of the genotype. E.g. Tall or short.
Fur colour in mice and red-green colour blindness in humans.
Molecular level.
Polydactyl.
Cystic fibrosis.
Embryonic screening and gene therapy.
Embryonic screening can be used to terminate an unwanted foetus due to gender. E.g. some societies value male children more than female children for economic reasons. Many religious groups consider the termination of babies to be immoral.
46.
X and Y.
XX.
XY.
The difference of characteristics of individuals in a population.
Genes, the environment in which the individual developed or a combination of both.
There is usually extensive variation within a population of a species.
Mutation.
Most have no effect, some influence the phenotype and a small proportion determine the phenotype.
Continuously.
It will lead to a rapid change in the species.
A change in the inherited characteristics of a population over time.
Natural selection.
All species of living organisms have evolved from simple life forms that first developed 3 billion years ago.
By the selection of variants with phenotypes that are best suited to their environment.
A group of individuals which can interbreed and produce fertile offspring.
The phenotypes of a species may become so different that the population can no longer interbreed.
Artificial selection.
To select useful genetic characteristics.
Thousands of years.
Parents with the desired characteristics are bred together. The offspring which show the desired characteristics are then bred together. This happens over many generations until all the offspring show the desired characteristics.
Disease resistance in food crops, animals which produce more milk or meat, domestic dogs with a gentle nature and large or unusual flowers.
Problems can arise from inbreeding and lead to some breeds which are prone to disease or inherited defects.
The process of modifying the genome of an organism by introducing a gene from another organism to transfer a desired characteristic.
Disease resistant and to produce larger fruit.
Bacteria are used to produce human insulin to treat diabetes.
Genes are cut out of chromosomes and transferred to the cells of other organisms.
Crop plants (e.g. wheat or rice) which have had genes from other organisms transferred into them.
Resistant to insects, resistant to herbicides and increased yields.
Their effect on wild populations of animals, plants and insects. The effect of eating GM crops on human health.
To treat inherited disorders.
Enzymes are used to cut out the required gene. This gene is then inserted into a vector (a plasmid or virus). The vector then inserts the gene into the required cells. If this occurs in the early stage of an organisms development (e.g. fertilised egg) the organism will develop with the desired characteristics.
Fossils and antibiotic resistance in bacteria.
The remains of organisms from millions of years ago found buried in rocks.
From parts of organisms that have not decayed, when parts of organisms are replaced by minerals as they decay and as preserved traces of organisms such as footprints, burrows and rootlet traces.
Early forms of life where soft bodied which left behind few traces. Many of these traces where destroyed by geologic activity.
They inform us how organisms have changed or stayed the same as life has developed on earth.
Extinction occurs when there are no remaining individuals of a species still alive.
Changes to the environment over a long period of time, new predators, new diseases, competition or a single catastrophic event.
Because they reproduce rapidly (e.g. every 20 minutes).
A mutation to a non resistant bacteria could lead to resistance. The resistant strain is not killed by antibiotics but the non resistant strains are. The resistant strains survive and reproduce. The population of the resistant strain increases.
A strain of bacteria resistant to antibiotics.
Doctors should not prescribe antibiotics inappropriately, patients should complete their course of antibiotics and the agricultural use of antibiotics should be restricted.
The development of new antibiotics is costly and slow.
Carl Linnaeus
Their structure and characteristics.
Kingdom, phylum, class, order, family, genus and species.
A system of naming organisms using their genus and species e.g. Homo sapiens.
An increase in our understanding of the internal structures of the cell and increased understanding of biochemical processes.
The three domain system.
Due to evidence from chemical analysis.
Archaea (primitive bacteria), Bacteria (true bacteria) and Eukaryota (includes protists, fungi, plants and animals).
A diagram used by scientists to show how organisms are thought to be related.
The non living parts of an environment.
The interaction of a community of living organisms with the non living parts of their environment.
An environment in which a particular species lives.
A supply of materials from their surroundings and from other living organisms living there.
Light, space, water and mineral ions.
Food, mates and territory.
A group of individuals from the same species living in an environment.
A group of populations living within the same environment.
Food, shelter, pollination and seed dispersal.
A community where the species and environmental factors are in balance so that population sizes remain fairly constant.
Light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity and direction, carbon dioxide levels (for plants) and oxygen levels (for aquatic animals).
Availability of food, new predators, new diseases and competition between species.
A feature that enables an organism to survive in the conditions they normally live.
Structural, behavioural and functional.
Spines in a cactus instead of leaves prevent water loss.
Mating rituals in birds such as peacock feathers in males to attract females.
Formation of venom in plants and animals such as nettles and snakes.
High temperature, pressure and salt concentration.
Extremophiles.
Bacteria living in deep sea vents (high temperature and pressure).
Photosynthetic organisms.
Food chains.
An organism that synthesises molecules.
Green plants and algae.
Distribution and abundance of a species in an ecosystem.
The average number (of species in ecosystem).
The value which appears the most often.
The value in the middle of a range of data.
Producers are eaten by primary consumers which in turn are eaten by secondary consumers which are then eaten by tertiary consumers.
Consumers that kill and eat other organisms.
Animals eaten by by other organisms.
A community where the numbers of predator and prey fall and rise in cycles.
One method is to assign a grid to the area of interest. Squares in the grid are randomly selected and the abundance of a species is noted. An alternate method is to use a transect square which is thrown randomly and the abundance of a species is counted. In each square a light meter is used to measure light intensity. The abundance of each square is then plotted against the light intensity to see if the is any relationship.
Photosynthesis.
Feeding.
Respiration.
By death and decay.
Fossilisation.
Combustion.
Evaporation and transpiration
The moment of water through the atmosphere, usually from over oceans to over land.
Condensation.
Rain, snow, sleet or hail.
The process by which water soaks in to the soil and rocks to form groundwater.
Deforestation reduces transpiration, the lack of soil reduces infiltration and increases the amount of run off.
The variety of different species of organisms in an ecosystem.
High biodiversity increases the the stability of ecosystems by reducing the dependence of one species on another.
Waste, deforestation and global warming.
Rapid growth in population and an increase in the standard of living.
In water from sewage, fertilisers and toxic chemicals. In air from smoke and acidic gases. On land from landfill and toxic chemicals.
Pollution kills plants and animals which reduces biodiversity.
Building, quarrying, farming and dumping waste.
Peat.
Reduces the area of peat bog and as a result it reduces the biodiversity of the habitat.
The decay or burning of peat release carbon dioxide into the atmosphere.
To provide land for cattle or rice fields and to grow crops for biofuels.
Burning of timber increases the carbon dioxide being released into the atmosphere. The destruction of trees leads to less photosynthesis removing carbon dioxide from the atmosphere.
The destruction of habitat reduces the number of species living in a habitat.
Deforestation reduces transpiration, the lack of soil reduces infiltration and increases the amount of run off.
Melting polar ice caps, rising sea levels, flooding and climate change (violent storms and extended droughts).
Carbon dioxide and methane.
Breeding programs.
Protection and regeneration
Reintroduction of field margins and hedgerows.
Legislate (make laws) to reduce deforestation and cut carbon dioxide emissions.
Legislate (make laws) to reduce deforestation and cut carbon dioxide emissions.