| species | a group of organisms that can reproduce to produce fertile offspring |
| means of classification | sequences of bases in DNA |
| main groups of vertebrates | mammals, birds, reptiles, amphibians, fish |
| main groups of arthropods | myriapods, insects, arachnids, crustaceans |
| five kingdoms | animal, plant, fungus, prokaryote, protoctist |
| asexual reproduction | process resulting in the production of genetically identical offspring from one parent |
| what asexual reproduction do bacteria use | binary fission |
| what asexual reproduction do fungi use | spores |
| what asexual reproduction do virisus use | hi-jack cells |
| ways for asexual reproduction in plants | tubers, vegetative, artificial |
| tubers | used for storing starch (potato), can grow new genetically identical plants |
| vegetative propagation | new bud near soil will grow into a genetically identical plant instead of a new branch |
| artificial propagation | Cuttings – The stem of a plant is taken just below a node. Then placed in water or moist soil to encourage root growth |
| tissue culture | A few cells of a plant are placed in a growing medium, hormones make it grow roots. |
| advantages of asexual reproduction in plants | quick colonization, acclimatized offspring will have good characteristics, no mate needed |
| disadvantages of asexual reproduction in plants | bad characteristics can be passed down, little variation, lack of disease resistance |
| sexual reproduction | process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other |
| fertilization | fusion of the nuclei of gametes |
| flower | flower |
| petals | attract pollinators |
| style | hold the stigma up and provide access to the ovary |
| ovary | where the ovule is found |
| ovule | contains the female gamete |
| anther | where the pollen is made |
| filament | holds the anther up |
| sepal | protect the petals |
| pollen | male gamete |
| pollination | this is the transfer of pollen from an anther to a stigma |
| how are flowers adapted for insect pollination | large colourful petals, scented, nectar, honey guides |
| how are wind pollinated flowers adapted for pollination | produce a lot of pollen, anthers hang outside the flower due to long filaments, stigma are feathery |
| self-pollination | transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant |
| cross-pollination | transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species |
| when does fertilization occur | when a pollen nucleus fuses with a nucleus in an ovule |
| male reproductive system | male reproductive system |
| function of the testes | production of male gametes (sperm) |
| function of the scrotum | sac that holds the testes outside the body |
| function of the sperm ducts | transfer sperm to the urethra |
| function of the prostate gland | secrete fluids for sperm to swim in forming semen |
| function of the urethra | carries urine and semen to vagina during sexual intercourse |
| function of the penis | transfers semen to vagina during sexual intercourse |
| female reproductive system | female reproductive system |
| function of the ovaries | release of female gametes (eggs) |
| function of the oviducts | transfers egg to uterus and the site of fertilization |
| function of the uterus | where the fetus develops |
| function of the cervix | ring of muscle at the opening of the uterus |
| function of the vagina | receives penis during sexual intercourse |
| fertilization | the fusion of the nuclei from a male gamete and a female gamete |
| adaptive feature of flagellum in sperm | generates movement to propel itself towards the egg |
| adaptive feature of nuclei in sperm | holds DNA of the cell |
| adaptive feature of mitochondria in sperm | produce energy for the movement of the sperm |
| adaptive feature of enzymes in sperm | help the sperm break through the cell membrane of an egg |
| adaptive feature of energy stores in egg cells | contain large energy stores – these provide nutrients for the embryo during early development. |
| adaptive feature of jelly coating in egg cells | after one sperm manages to penetrate, it changes to become impenetrable to more sperm |
| comparison of sperm and egg in terms of size | sperm - very small, ovum - very big (for a cell) |
| comparison of sperm and egg in terms of motility | sperm - mobile, can propel themselves with their tales, ovum - immobile, is passively moved through the oviduct by the fluid |
| can the fetus be affected | yes, some pathogens and toxins can pass across the placenta |
| role of testosterone with secondary sexual characteristics | voice breaking, muscular development, growth of facial and public hair |
| role of estrogen with secondary sexual characteristics | breasts develop, hips widen, growth of pubic hair |
| changes in the uterus lining during the menstrual cycle | an egg is produced, the lining of the uterus thickens up, then pregnancy doesn't occur, the egg is absorbed back into the body and the thick lining in the uterus is shed, this is your period. Then the cycle begins all over again. |
| changes in the ovaries during the menstrual cycle | immature follicle cells start to complete a meiotic cell division, just before ovulation one follicle is fully matured to an egg, an egg is released and the corpus luteum/yellow body is formed, if the egg is fertilized the yellow body stays. If the egg is unfertilized it disappears |
| what secrets progesterone during the menstrual cycle | The yellow body/corpus luteum |
| what secrets progesterone during pregnancy | The yellow body/corpus luteum for a period of time, then the placenta |
| what secrets estrogen during the menstrual cycle | maturing follicles |
| what secrets estrogen during pregnancy | the placenta |
| STI | an infection that is transmitted through sexual contact |
| HIV | a pathogen that causes an STI, an HIV infection may lead to AIDS |
| methods of transmission of HIV | from an infected mother to fetus across placenta, unprotected sex, sharing needles while taking drugs, transfusion with unscreened blood |
| how the transmission of STIs are controlled | abstinence, use contraceptive methods/condoms NOT BIRTH CONTROL, wait and test, education, track and trace |
| chromosome | made of DNA which contains genetic information in the form of genes |
| gene | length of DNA that codes for a protein |
| allele | an alternative form of a gene |
| structure of a DNA molecule | two strands coiled together to form a double helix, each strand contains chemicals called bases, bonds between pairs of bases hold the strands together, the bases always pair up the same way - A & T, C & G |
| haploid nucleus | a nucleus containing a single set of chromosomes, there are 23 pairs |
| diploid nucleus | a nucleus containing two sets of chromosomes, there is a pair of each type of chromosome |
| sequences of bases | determines the sequence of amino acids used to make a specific protein, different sequences of amino acids give different shapes to protein molecules |
| what does DNA control | cell function by controlling the production of proteins including enzymes, membrane carriers and receptors for neurotransmitters |
| how is a protein made | the gene coding for the protein remains in the nucleus, mRNA is a copy of a gene, mRNA molecules are made in the nucleus and move to the cytoplasm, the mRNA passes through ribosomes, the ribosome assembles amino acids into protein molecules, the specific sequence of amino acids is determined by the sequence of bases in the mRNA |
| genes in body cells | most body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs |
| mitosis | nuclear division, giving rise to genetically identical cells |
| role of mitosis in growth | mitosis produces new cells |
| role of mitosis in repair | to replace damaged or dead cells |
| role of mitosis in asexual reproduction | mitosis produces offspring that are genetically identical to the parent |
| mitosis process | the exact replication of chromosomes occur before mitosis, during mitosis the copies of chromosomes separate maintaining the chromosome number in each daughter cell |
| stem cells | unspecialized cells that divide by mitosis to produce daughter cells that can become specialized for specific functions |
| meiosis | a reduction division in which the chromosome number is halved from diploid to haploid resulting in genetically different cells, involved in the production of gametes |
| inheritance | the transmission of genetic information from generation to generation |
| genotype | the genetic make-up of an organism, each pair of alleles represents the genotype of a specific gene (Bb, HH) |
| phenotype | the observable features of an organism |
| homozygous | having two identical alleles of a particular gene |
| heterozygous | having two different alleles of a particular gene |
| pure breeding | homozygous individuals that breed together will be pure-breeding, a heterozygous individual will not be pure-breed |
| dominant allele | an allele that is expressed if it is present in the genotype |
| recessive allele | an allele that is only expressed when there is no dominant allele of the gene present in the genotype |
| how to use a test cross to identify an unknown genotype | crossing two parents to see the phenotypic ratio of the offspring produced |
| co-dominance | a situation in which both alleles in heterozygous organisms contribute to the phenotype |
| sex - linked characteristic | a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other, such as red green colour blindness |
| variation | differences between individuals of the same species |
| continuous variation | results in a range of phenotypes between two extremes like body length and body mass |
| discontinuous variation | results in a limited number of phenotypes with no intermediates like ABO blood groups |
| what is continuous variation usually caused by | genes and the environment |
| what is discontinuous variation usually caused by | genes only |
| mutation | is a genetic change, the way in which new alleles are formed |
| what increases the rate of mutation | ionizing radiation and some chemicals |
| gene mutation | a random change in the base sequence of DNA |
| sources of genetic variation in populations | mutation, meiosis, random mating, random fertilization |
| adaptive feature | inherited feature that helps an organism to survived and reproduce in its environment |
| adaptive features of a xerophyte | have deep roots to seek out water, some roots spread a long way sideways from where the plant is growing, have leaves with small surface area to reduce water loss but this also slows down photosynthesis, hairy leaves to trap water vapor, have spikes so other animals cant take the water |
| process of natural selection | genetic variation within populations, production of many offspring, struggle for survival, including competition for resources, a greater chance of reproduction by individuals that are better adapted to the
environment than others, these individuals pass on their alleles to the
next generation |
| process of selective breeding | selection by humans of individuals with desirable features, crossing these individuals to produce the next generation, selection of offspring showing the desirable features |
| adaptation | the process, resulting from natural selection, by which populations
become more suited to their environment over many generations |
| development of strains of antibiotic resistant bacteria | an example of natural selection, when bacteria are initially exposed to an antibiotic, those most susceptible to the antibiotic will die quickly, leaving any surviving bacteria to pass on their resistant features to succeeding generations. |
| the differences between natural and artificial selection | Natural selection is any selective process that occurs due to the fitness of an organism to its environment. Whereas artificial selection is the selective breeding, imposed by an outside entity, typically humans, in order to increase the frequency of desired traits |
| sustainable resource | one which is produced as rapidly as it is removed from the environment so that it does not run out, some resources can be conserved and managed sustainably like forests and fish stocks |
| why organisms become endangered or extinct | climate change, habitat destruction, hunting |
| how endangered species can be conserved | monitoring and protecting species and habitats, education, captive breeding programs |
| how can forests be conserved | education, protected areas, quotas and replanting |
| how can fish stocks be conserved | education, protected areas, quotas |
| reasons for conservation programs | maintaining or increasing biodiversity, reducing extinction, protecting vulnerable ecosystems |
| reasons for conservation programs with maintaining ecosystem functions | resource provision such as
Food - making sure we have enough for the population
Drugs - having access to plants for plant-based remedies
Genes - so the gene pool remains wide and variety exists in all species |
| use of artificial insemination in captive breeding programs | this allows large numbers of offspring to be produced without the need for conventional sexual intercourse between males and females |
| use of artificial insemination and IVF in captive breeding programs | this allows gametes with known alleles to be used in ensuring the next generation remains biodiverse |
| risks to a species if its population size decreases | reductions in genetic diversity, limited ability to adapt to environmental change which increases the risk of extinction |
| why are bacteria are useful in biotechnology and genetic modification | few ethical concerns, presence of plasmids makes it easy to separate then remove and manipulate it |
| genetic modification | changing the genetic material of an organism by removing, changing or inserting individual genes |
| the process of genetic modification using bacterial production of a human protein | isolation of the DNA making up a human
gene using restriction enzymes, forming
sticky ends
(b) cutting of bacterial plasmid DNA with
the same restriction enzymes, forming
complementary sticky ends
(c) insertion of human DNA into bacterial
plasmid DNA using DNA ligase to form a
recombinant plasmid
(d) insertion of recombinant plasmids into
bacteria (specific details are not required)
(e) multiplication of bacteria containing
recombinant plasmids
(f) expression in bacteria of the human gene to
make the human protein |
| examples of genetic modification | the insertion of human genes into bacteria to produce human proteins, the insertion of genes into crop plants to confer resistance to herbicides OR insect pests OR to improve nutritional qualities |
| advantages of genetically modifying crops | less use of pesticides, more nutritious food, increased supply of food with reduced cost |
| disadvantages of genetically modifying crops | antibiotic resistance, toxic chemicals, allergic reaction |
| magnification calculation | magnification = image size/actual size |
| when plant cells are in a dilute solution with higher water potential | water enters by osmosis, increasing turgor pressure and making the cells turgid |
| in a concentrated solution water leaves plant cells by osmosis | making them flaccid and potentially affecting the plant's support. Under a microscope, these cells may appear plasmolyzed, with the cell membrane pulling away from the cell wall. |
| limiting factors of photosynthesis | light intensity, CO2 concentration and temperature |
| tooth structure | tooth structure |
| enamel | hard outer layer of the crown, the hardest substance in the body |
| dentine | not as hard as enamel, it forms the bulk of the tooth, if there are gaps in the enamel that expose the dentine to the outside, or enamel is very thin, your teeth will be sensitive |
| pulp | soft tissue, contains blood capillaries and nerve supply to the tooth |
| cementum | also known as cement, the layer of bone-like tissue covering the root, not as hard as enamel |
| gums | soft tissue that immediately surrounds the teeth and bone, protects the bone and roots of the teeth, provides an easily lubricated surface |
| teeth structure | teeth structure |
| incisors | sharp and are used for cutting food into small chewable pieces |
| canines | at corners, and are even sharper – they’re also used to bite into and tear food |
| premolars and molars | these have a flat surface, and are used to chew and grind food |
| role of bile | through emulsification, bile acids break down large lipid droplets into smaller ones, increasing the surface area for digestive enzymes |
| amylase | breaks down starch to maltose |
| maltase | breaks down maltose to glucose on the membranes of the epithelium lining the small intestine |
| pepsin | breaks down protein in the acidic conditions of the stomach |
| where is water absorbed | from the small intestine but some is also absorbed from the colon |
| significance of villi and microvilli | to increase the surface area, so each villus can absorb the maximum amount of nutrients |
| roles of capillaries and lacteals in villi | the blood capillaries absorb most nutrients, but the fats and fat-soluble vitamins are absorbed by the lacteals |
| circulatory system | a system of blood vessels with a pump and valves to ensure one-way flow of blood |
| single circulation of a fish | blood flows through the heart once every complete circuit, two heart chambers, blood absorbs oxygen in the gills in lower-pressure, released in body cells then back to the heart |
| double circulation of a mammal | four heart chambers, blood passes through the heart twice every complete circuit, oxygenated in the lungs to the heart to the body and back to the heart |
| advantages of double circulation | - preventing the mixing of oxygenated and deoxygenated blood
- raises its pressure, allowing it to deliver oxygen and glucose to cells more quickly and frequently for respiration
- blood can be retuned to the heart faster, like during exercise |
| heart structure | heart structure |
| thickness of the left muscular wall vs right | the left ventricular wall is thicker than the right ventricular wall as it forces blood out of the heart round the body at higher pressure than blood pumped into the lungs by the right ventricle which is at a lower pressure to protect the lungs and because it is a shorter distance |
| thickness of atria vs ventricle | the atria have thinner muscular walls than ventricles as blood moves into the ventricles helped by gravity and the low pressure pull by the empty ventricle so it requires less contraction by the atria |
| septum function | the septum separates oxygenated and deoxygenated blood from the right side and left side of the heart |
| how can the activity of the heart be monitored | ECG, pulse rate, listening to the sound of valves closing with a stethoscope |
| effect of physical activity on the heart rate | - resting heart rate affected by age (after in young), sex (faster in women) and fitness (slower if fitter)
- the heart rate increases with exercise as more oxygen is needed by the muscles for respiration
- recovery time is time needed for heart rate to return to normal-faster if fitter |
| coronary heart disease | - caused by the narrowing and blockage of coronary arteries as a result of fatty plaque and the formation of blood clots.
- the narrowing causes angina (chest pain on exertion)
- blockage causes a heart attack or cardiac arrest.
- in the brain it can cause a stroke |
| coronary heart disease risk factors | lack of exercise, stress, smoking, genetic predisposition, age and sex |
| role of diet in reducing the risk of coronary heart disease | low in unsaturated fats reduce cholesterol, so reduce atheroma formation in coronary arteries. Also reduces obesity, which reduces blood pressure. |
| role of exercise in reducing the risk of coronary heart disease | reduces obesity, stress and blood pressure, which are all risk factors for coronary heart disease. Lowers resting heart rate and speeds up recovery time from exercise. |
| structure of arteries | very thick walls, no valves, small lumen |
| structure of capillaries | thin muscular walls, no valves, small lumen |
| structure of veins | thin muscular walls, contain valves, big lumen |
| function of capillaries | take waste products away from your tissues, exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues. |
| components of blood | red blood cells, white blood cells, platelets, plasma |
| red blood cells | transport oxygen around the body from the lungs to cells which require it for aerobic respiration. They carry the oxygen in the form of oxyhaemoglobin |
| white blood cells | defend the body against infection by pathogens by carrying out phagocytosis and antibody production |
| platelets | involved in helping the blood to clot |
| lymphocytes | antibody production |
| pathogen | a disease causing organism |
| transmissible disease | a disease in which the pathogen can be passed from one host to another |
| how pathogens are transmitted | direct contact - including through blood and other body fluids
indirectly - including from contaminated surfaces, food, animals and air |
| skin as the body's defence | covers almost all parts of your body to prevent infection from pathogens. If it is cut or grazed, it immediately begins to heal itself, often by forming a scab |
| nose hairs as the body's defence | these make it difficult for pathogens to get past them further up the nose so they are not inhaled into the lungs |
| mucus as the body's defence | made in various places in the body, pathogens get trapped in the mucus and can then be removed from the body (by coughing, blowing the nose, swallowing etc) |
| stomach acid as the body's defence | contains hydrochloric acid which is strong enough to kill any pathogens that have been caught in mucus in the airways and then swallowed or have been consumed in food or water |
| white blood cells as the body's defence | white blood cells work to prevent pathogens reaching areas of the body they can replicate in
By phagocytosis - engulfing and digesting pathogenic cells
By producing antibodies - which clump pathogenic cells together so they can’t move as easily (known as agglutination) and releasing chemicals that signal to other cells that they must be destroyed |
| hygienic food preparation | - cook food well to kill bacteria
- wash hands after using the bathroom before handling food
- cover food to prevent flies landing on it before eating |
| personal hygiene | - wash hands after using the bathroom
- use tissues to catch coughs and sneezes
- dispose of used pathogens as soon as possible as pathogens can still be alive |
| waste disposal | - all rubbish should be stored before collection away from human habitation
- rubbish bins should be covered and removed to the landfill for disposal or burning regularly
- waste food is a food source for flies that can act as vectors for transmissible diseases and so should be disposed of in a sealed container |
| sanitation | - homes and public places should have plumbing and drains to safely remove faeces and waste, which can carry pathogens
- raw sewage should be treated to remove solid waste and kill pathogens before being released into the environment |
| active immunity | - defence against a pathogen by antibody production in the body
- gained after an infection by a pathogen or by vaccination |
| pathogen | each pathogen has its own antigens which have specific shapes |
| antibodies | - proteins that bind to antigens, leading to the direct destruction of pathogens or marking of pathogens for destruction of phagocytes
- specific antibodies have complimentary shapes which fit specific antigens |
| platelets | used in clotting which is the conversion of fibrinogen to fibrin to form a mesh |
| plasma | the transport of blood cells, ions, nutrients, urea, hormones and carbon dioxide |
| blood clotting | preventing blood loss and the entry of pathogens |
| lymphocytes | antibody production |
| phagocytes | engulfing pathogens by phagocytosis |
| process of vaccination | - weakened pathogens or their antigens are put into the body
- the antigens stimulate an immune response by lymphocytes which produce antibodies
- memory cells are produced which give long term immunity |
| passive immunity | short term defence against pathogens by antibodies acquired from another individual including across the placenta and in breast milk, memory cells are not produced in passive immunity |
| testes | secrete testosterone |
| ovaries | secrete oestrogen |
| endocrine system | typically slow but long-lasting, uses the bloodstream |
| nervous system | fast and short lasting, uses electrical impulses |
| role of adrenaline in the control of metabolic activity | increasing the blood glucose concentration, increasing heart rate |
| hooray | hooray |
