Biology - AQA GCSE
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| What is a hormone? | A chemical substance produced by a gland delivered in the blood stream alters activity of target organs. |
| Describe all the glands and their functions. | Pituatary-Master gland controls other glands Thyroid-Produces thyroxine Adrena-Produces adreniline Pancreas-Produces insullin Testes-Produces testosterone Ovaries-Produce oestrogen |
| What are the main male hormone involved in puberty? | Tesotosterone-male-testes-sperm production |
| What are the 4 main hormones involved in the menstrual cycle and their roles and where they come from? | FSH-pituitary galnd-causes egg to mature in an ovary & ovaries to produce oestrogen Oestrogen-ovaries-stops FSH production (so only 1 egg produced) repairs, thickens, maintains uterus lining stimulates pituatary gland to release LH LH-pituatary gland-Triggers ovulation (release of a mature egg) Progesterone-ovaries,Placenta-maintains lining of uterus during middle of menstrual cycle and pregnancy |
| Describe the entire menstrual cycle? | 1)Day1-12 -oestrogen gradually increase peaks on day 12. Progestrerone, LH & FSH stay same and increase slightly from day 12 2)FSH & LH patterns similiar and peak on day 14 during ovulation, drop sharply on day 15 stay constant till day 28 3)Oestrogen drops on days 13-14, progesterone & oeastrogen increses to day 21then slow decrease. |
| Describe oral contraceptives. | Contains oestrogen and progesterone inhibiting production of FSH, eggs cant mature. Benifits - (1)if taken correctly 99% effective(2)reduce risk of certain cancers Risks - (1)possible side effects change in weight mood and blood pressure |
| Evaluate the 6 common physical contraceptions. | -Condoms (easy to use, but may rip) and diapraghms (left for several hours after) -IUDs prevent embry implantation/release of hormone (left up to years fitted by health proffesionals) -Spermasidical agents, disable sperm (some are allergic) -Abstaining from sex when egg in oviduct (timings must be accurate -Surgical methods e.g.vasectomy sperm duct tied (perminent) |
| Evaluate the use of 2 common infertility treatments. | Fertility drugs-contain FSH &LH stimulating egg to matuture in ovary risk of premature or underweight babies may lead to twins or triplets In Vitro Fertilisation (IVF) treatment-(1)mother gets FSH and LH stimulating mature of several eggs(1)egg and sperm collected and placed on dish in lab and fertilised(3)one or 2 embryos inserted in mothers uterus |
| What are the pros and cons of IVF? | Pros-(1)People that wouldnt be able to have babies can have them(2)safe track record since 1978(3)embryos screened for genetic diseases(4)unused eggs used in research/donation Cons-(1)if not funded by NHS then costs £5000(2)chance of pregnancy varies with age (32.2% under 35yrs)(1.9% over 44yrs)(3)risk of multiple births, danger to mother and babiese(4)risk of OHS ovarianhyper-stimulation where too many eggs developed(5)emotionally and physicaly stressful(6)low sucess rate(7)ethical issues, people may want babies with desirable qualities |
| What is a pathogen? | Microorganism enters body causes disease |
| Symbol equation for photosynthesis | 6CO2 + 6H2O --> C6H1206 + 602 |
| Describe the four molecules produced from glucose in biosynthesis? | Proriens - glucose + nitrates = amino acids. Lost of amino acids > protien Lipids - used for storage in seeds Starch - Lots of glucose molecules > starch, insolluble glucose stored Cellulose - Used to build and add strength to cell walls |
| Practical to investigate how light intensity effects photosynthesis | 1)Fill boiling tube 45cm^2 sodium hydrocarbonate soloution, leave for a few mins then shake air bubbles out. 2)Cut 8cm pondweed and place carefullt in boiling tube. 3)Place 10cm away from light source count n.o. bubbles for 5 minutes. 5)repeat at further distanes at interval of 5cm. 4)repeat 5 times and calculate average mean. |
| Give 4 extensions to the light intensity practical. | 1)Collect gas in syringe. 2)Use data logging equipment to mesure oxygen concetration. 3)Use acecate filters to mesure effects of different wavelengths. 4)Use veriegated plants (Type of leave with pale edges) - Drop veriegated leaf in boiling water to kill and preserve it. - Leave in hot ethanol for 10 minutes to remove chlorophyll. - Dip in boiling water to soften then spread in petri dish and cover with iodine. - Areas that had chlorophyl > blue/black, areas without remain pale. |
| What is Homeostasis? | HOMEOSTASIS Maintains optimal conditions for enzyme action throughout the body, as well as all cell functions. In the human body: - blood glucose concentration - body temperature - water levels |
| Nervous System | Made up of: - The CNS (brain and spinal cord) - peripheral nervous system (nerve cells that carry info to or from the CNS) |
| What does the Body Control System Consist of? | - receptor cells, detect stimuli (changes in environment) - coordination centre (brain/spinal cord/ pancreas), which processes info from receptors around the body - Effectors (muscle/glands), bring about responses(muscle contractions or hormone release), restore optimum levels |
| What are the functions of Nerve Cells, Receptors & Effectors? | 1) Nerve Cells - bundle of neurons, adapted to carry electrical impulses from place to place. 3 main neurons: sensory, motor & relay. Features: long fibre (axon), carry messages up and down body; tiny branches (dendrons) branch of as dendrites & receive incoming impulses from other neurons 2) Receptors - Detect stimuli and stimulate electrical impulses in response. Sense organs contain a group of receptors that respond to specific stimuli: skin - touch, temperature, pain; tongue - chemicals; nose - chemicals; eye - light; ear - sound & position of head 3) Effectors - (muscles/glands) produce specific response to a detected stimulus (e.g. muscle contracting to move an arm; a gland releasing hormone into blood) |
| What does the Eye Consist of? | 1) Cornea - Refracts light - bends it as it enters the eye 2) Iris - Controls how much light enters the pupil (Bright - radial muscle relaxed, circular muscle contracts, pupil contratcs, vice versa) 3) Lens- Further refracts light to focus it onto the retina 4) Retina - Contains the light receptors (rods (more sensitive) and cones) 5) Optic nerve - Carries impulses between the eye and the brain 6) Sclera - Tough white outer layer of the eye. It helps protect the eye from injury |
| What are the 3 other corrections for vision defects? | 1) Contact lens - work like spectacle lenses(refract light), float on cornea surface 2) Laser Surgery - reshapes cornea surgically. Common for Myopia 3) Replacement lens - artificial lens implant (placed in front of original lens), corrects eye defect |
| What are the 3 other corrections for vision defects? | 1) Contact lens - work like spectacle lenses(refract light), float on cornea surface 2) Laser Surgery - reshapes cornea surgically. Common for Myopia 3) Replacement lens - artificial lens implant (placed in front of original lens), corrects eye defect |
| What are the 3 other corrections for vision defects? | 1) Contact lens - work like spectacle lenses(refract light), float on cornea surface 2) Laser Surgery - reshapes cornea surgically. Common for Myopia 3) Replacement lens - artificial lens implant (placed in front of original lens), corrects eye defect |
| How does the Reflex Arc Work? | 1. Receptor in skin detects a stimulus 2. Sensory neurone sends electric impulse to relay neurone (in spinal cord) 3. Motor neurone sends electric impulse to an effector 4. Effector produces response (muscle contraction...) |
| PRACTICAL: Ruler Drop Test (7 Stages) | 1) Person A holds out their hand with a gap between their thumb and first finger. 2) Person B holds the ruler with the zero at the top of person A's thumb 3) Person B drops the ruler without telling Person A and they must catch it. 4) The number level with the top of person A's thumb is recorded in a suitable table. Repeat this ten times. 5) Swap places, and record another ten attempts. 6) You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch distance in cm 7) Repeat practical, this time with background noise or caffeine and compare results |
| What does the Brain Consist of? | 1) The cerebrum (the outer layer is called the cerebral cortex), is split into two hemispheres and is highly folded. It controls intelligence, personality, conscious thought and high-level functions, such as language and verbal memory. 2) The cerebellum, which controls balance, co-ordination of movement and muscular activity. 3) The medulla, which controls unconscious activities such as heart rate and breathing rate, 4) The hypothalamus, which is the regulating centre for temperature and water balance within the body |
| How is the Brain Examined (3 Methods & Risks)? | 1) BRAIN DAMAGE: 1848, Phineas Gage, when laying railway tracks, an iron rod went through his skull. Survived but his personality changed losing his inhibitions socially and emotionally. This allowed scientists to examine the effect on injuries on his brain activity 2) ELECTRICAL STIMULATION: Scientists stimulate parts of the brain w/ a weak electrical current, patients describe what they experience. If motor area is stimulated, patient makes an involuntary movement. visual area stimulate - may see a flash of colour. Electroencephalograms can be created and studied, to observe the electrical activity in the brain 3) MRI BRAIN SCANS: use strong magnetic fields and radio waves to show details of brain structure and function. Patients perform various tasks, by looking at scan, scientist can see which parts of the brain are active 4) RISKS: Brain surgery may be needed to remove the tumour or excess fluid like blood. Due to complexity & delicacy of the brain, treating and investigating is very difficult. Surgery can cause more damage/side effects |
| Compare what happens when focusing on near and far objects? | FOCUS ON NEAR OBJECT: 1) Ciliary muscle - Contract 2) Suspensory ligaments - slacken 3) Muscle tension - low 4) Lens shape - thickens 5) Light refraction - strong FOCUS ON DISTANT OBJECT: 1) Ciliary muscle - relax 2) Suspensory ligaments - stretched 3) Muscle tension - high 4) Lens shape - thin 5) Light refraction - slight |
| Causes of short sight, long sight & what are some other corrections that can be used to correct vision defects | SHORT SIGHT(Myopia): can't focus on distant object properly. Caused by: - Eyeball being elongated, distance between lens and retina is too great - Lens being too thick & curved, light is focused in front of retina Corrected by: Concave lens )( shape LONG SIGHT(Hyperopia): can't focus on near object properly. Caused by: - Eyeball being too short, distance between lens and retina is too small - loss of elasticity in the lens - it cannot become thick enough to focus (which is often age-related) Corrected by: Convex lens () shape OTHER CORRECTIONS: 1) Contact lens - work like spectacle lenses(refract light), float on cornea surface 2) Laser Surgery - reshapes cornea surgically. Common for Myopia 3) Replacement lens - artificial lens implant (placed in front of original lens), corrects eye defect |
| What is The Nervous System? | NERVOUS SYSTEM: - The CNS (brain and spinal cord) - peripheral nervous system (nerve cells that carry info to or from the CNS) |
| How is an impulse sent across a neurone? | Over a synapse: SYNAPSE - small gap where 2 neurons meet 1. An electrical impulse travels along the first axon: 2. This triggers the nerve-ending of a neurone to release neurotransmitters (chemical messengers ) 3. These chemicals diffuse across the synapse & bind with receptor molecules on the membrane of the second neurone 4. The receptor molecules on the second neurone bind to the specific neurotransmitters released from the first neurone. This stimulates the second neurone to transmit the electrical impulse |
| What are the causes of short sight & how can it be corrected? | SHORT SIGHT(Myopia): can't focus on distant object properly. Caused by: - Eyeball being elongated, distance between lens and retina is too great - Lens being too thick & curved, light is focused in front of retina Corrected by: Concave lens )( shape |
| What are the causes of Long sight & how can it be corrected? | LONG SIGHT(Hyperopia): can't focus on near object properly. Caused by: - Eyeball being too short, distance between lens and retina is too small - loss of elasticity in the lens - it cannot become thick enough to focus (which is often age-related) Corrected by: Convex lens () shape |
| How does Asexual Reproduction work (& Examples) | - Only one parent is needed - no fusion of gametes so genetic material does not mix, which means that the offspring produced through this process are genetically identical clones to the parent EXAMPLES: - bacteria - production of spores by fungi - some plants, such as strawberries, use runners - formation of tubers in potatoes and bulbs in daffodils |
| Sexual Reproduction, Meiosis & Fertilisation | SEXUAL REPRODUCTION: - Gametes in: animals - sperm and eggs; flowering plants - pollen & eggs - Offspring in sexual reproduction are genetically different to each other and the parents, resulting in variation as genetic info mixes MEIOSIS: Sexual reproduction uses the process of meiosis, which creates gametes, it happens in the male and female reproductive organs. As a cell divides to form gametes: - copies of the genetic information is made - the cell divides twice to form four gametes, each with a single set of chromosomes (haploid) - all gametes are genetically different from each other FERTILISATION: - The fusion of the nucleus of a male gamete with the nucleus of a female gamete - 23 chromosomes in a gamete - a haploid. When 2 gametes combine, they merge the 2 sets of chromosomes to have 46 - a diploid - This produces a new cell called a zygote, which matures into an embryo, the no. of cells increase by mitosis & the cells begin to differentiate as the embryo develops |
| Dis/advantages of Sexual Reproduction | ADVANTAGES: - Produces variation in the offspring - The species can adapt to new environments due to variation, which gives them a survival advantage - A disease is less likely to affect all the individuals in a population - Humans can speed up natural selection through selective breeding, which can increase food production DISADVANTAGES: - time and energy are needed to find a mate - it is not possible for an isolated individual |
| Dis/advantages of Asexual Reproduction | ADVANTAGES: - the population can increase rapidly when the conditions are favourable - only one parent is needed - it is more time and energy efficient as you don't need a mate - it is faster than sexual reproduction DISADVANTAGES: - it does not lead to variation in a population - the species may only be suited to one habitat - disease may affect all the individuals in a population |
| Organisms Which use Asexual & Sexual Reproduction | SEXUAL REPRODUCTION: - Fungi reproduce sexually to generate variation - Plants use sexual reproduction to produce seeds - Malarial parasites reproduce sexually in the host mosquito ASEXUAL REPRODUCTION: - Fungi release spores by asexual reproduction - Plants such as strawberries reproduce asexually by sending out runners, or daffodils when their bulbs divide - Malarial parasites reproduce asexually in the human host |
| What are DNA, Chromosomes & Genes | DNA - The genetic material in the nucleus of a cell is composed of a chemical called DNA - DNA is a polymer, a large and complex molecule - It is made up of two strands forming a twisted ladder structure called a double helix - It carries the genetic code, which determines the characteristics of a living organism CHROMOSOMES: Contained in cell nucleus, long threads of DNA which are made up of genes GENES: Small section of DNA in a chromosome. Each gene codes for a particular sequence of amino acids in order to make a specific protein. It is the unit of heredity, and may be copied and passed on to the next generation |
| The Human Genome & Disease ascociated genes | HUMAN GENOME: The genome of an organism is the entire genetic material of that organism. The human genome has great importance in medicine. It enables us to: - search for genes linked to different types of disease - understand inherited disorders and their treatment - trace human migration patterns from the past DISEASE ASCOCIATED GENES: - Scientists are searching for disease associated genes. One example was those that can contribute to breast cancer, which are known as BRCA1 and BRCA2. - Mutations in these genes account for approximately 10% of all inherited breast cancer cases detected. Scientists studied families where it was known to be inherited and were able to create a pedigree analysis, which is similar to a family tree diagram that showed the close relationship of those affected and unaffected within the family, differences in DNA can be analysed. - It is now possible to detect the presence of the genes by having a simple blood test |
| DNA Strucure | - James Watson and Francis Crick worked out the structure of DNA in 1953. By using data from other scientists they were able to build a model of DNA. The X-ray crystallography data they used showed that DNA consists of two strands coiled into a double helix - DNA is a polymer made from four different nucleotides. These repeat. Each nucleotide consists of alternating sugar and phosphate sections with one of the four different bases attached to the sugar BASE PAIRS(Each strand of DNA is made of chemicals called bases): - thymine, T - adenine, A - guanine, G - cytosine, C There are chemical cross-links between the two strands in DNA, formed by pairs of bases. A sequence of three bases is the code for a particular amino acid - known as a triplet or the triplet code. The order of the bases controls the order in which amino acids are assembled to produce a particular protein |
| 7 Facts in relation to Protein Synthesis | 1- The DNA code for the protein remains in the nucleus, but a copy, called mRNA, moves from the nucleus to the ribosomes where proteins are synthesised in the cytoplasm. 2- Amino acids are connected together in a specific order at the ribosome (see diagram) to create a specific protein molecule 3- The protein produced depends on the template used, and if this sequence changes a different protein will be made 4- Carrier molecules bring specific amino acids to add to the growing protein in the correct order (there's about 20 different naturally-occurring amino acids) 5- DNA structure determines the protein synthesised. If this changes a different protein will be made 6- Each protein molecule has hundreds, or even thousands, of amino acids joined together in a unique sequence. It is then folded into the correct unique shape. This allows the protein to do their jobs, such as enzymes or hormones and it can form structures within the body, such as collagen 7- Not all parts of the DNA code for proteins, there is a coding and non-coding part of DNA, which can switch genes on and off, so variations in these areas may affect gene expression, and if the correct protein is synthesised or not |
| What are Mutations, How do they work? | Mutation - a change in a gene or chromosome. It is a rare, random change in the genetic material and it can be inherited. It's continuous and can be spontaneous, also happens due to: - ionising radiation - chemical mutagens - such as tar from cigarette smoke 1) Ionising radiation includes gamma rays, X-rays and ultraviolet rays. The greater the dose of radiation a cell gets, the greater the chance of a mutation 2) Mutations could cause different genes to be switched on or off, and this could create a different or faulty protein to be synthesised. For example, if the protein is an important enzyme, the specific substrate might not fit into the substrate binding site. If it is a structural protein such as collagen, it might lose its strength 3) However, most DNA mutations do not alter a protein, they only alter it slightly so its appearance or function is not changed 4) These mutations may change the activity of a protein, in a coding part of the DNA, or it might change how the genes are expressed if the change is in a non-coding section of DNA/. May result in a serious consequence, such as genetic disease such as cystic fibrosis 5) Different types of gene mutation(self-explanatory): Substitution, insertion, deletion, inversion |
| 4 Steps of Mitosis | MITOSIS: 1) Chromosomes in nucleus - copied 2) Chromosomes & their copies pulled apart & move towards poles 3) Chromosomes separate 4) Cells divide into2 genetically identical daughter cells |
| How does Sexual Reproduction | SEXUAL REPRODUCTION: - Gametes in: animals - sperm and eggs; flowering plants - pollen & eggs - Offspring in sexual reproduction are genetically different to each other and the parents, resulting in variation as genetic info mixes |
| What are the 5 Animal cell Sub-cellular structures? | 1) Nucleus - contains genetic material that controls cells activities 2) Mitochondria - where most reactions for aerobic respiration happens 3) Cytoplasm - gel-like substance where most chemical reactions happen contains enzymes (that control chemical reactions) 4) Cell membrane - Holds cell together, controls what goes in and out 5) Ribosomes - where proteins are made |
| What are Prokaryote & Eukaryote Cells? | Prokaryote - single celled organisms (bacteria cells) Eukaryote - organisms made up of eukaryotic cells (animal, plant cells) |
| What are the 3 (Additional) Plant Cell sub-cellular structures? | 1) Rigid Cell wall - Made of cellulose, supports & strengthens the cell 2) Chloroplasts - Where photosynthesis happens, contain (green) chlorophyll which absorb light 3) Permanent Vacuole - Contains cell sap, weak solution of sugar & salts |
| What are the 5 Bacteria Cell sub-cellular structures? | 1)Cell membrane 2)Cell wall 3) Cytoplasm 4)Circular DNA strand 5)Plasmid |
| PRACTICAL: (Microscopy) Plant / Animal Cell | PRACTICAL: (Microscopy) Plant / Animal Cell |
| PRACTICAL: How to use a microscope | 1) Clip slide onto stage 2) Select lowest power objective lens 3) Use coarse adjustment knob (to move stage just below objective lens) 4) Look down eye piece, use coarse adjustment knob to lower stage until image's in rough focus 5)Adjust focus w/ fine adjustment knob to get a clear image of whats on slide 6) If you need a greater magnification, swap to a higher objective lens and refocus |
| 1- Function and Features: Sperm Cells | FUNCTION: get male DNA to Female DNA - long tail and streamlined head to help it swim - Lots of mitochondria to provide energy - Enzymes in its head, help it digest into egg cell membrane |
| 2- Function and Features: Nerve Cells | FUNCTION: carry electrical signals from one part of the body to another - Are long, to carry more distance -Have branched connections at their ends to connect to other nerve cells |
| 3- Function and Features: Muscle Cells | FUNCTION: contract quickly - Are long, so have space to contract - contain lots of mitochondria, to provide energy needed to contract |
| 4- Function and Features: Root Hair Cells | FUNCTION: absorb water and mineral ions - Are long, giving plant big surface area to absorb water and mineral ions from soil |
| 5- Function and Features: Phloem & Xylem Cells | FUNCTION: transport substances like food and water around the plant - Are long and joined end to end to form tubes - Xylem are hollow in centre, so water can flow through - Phloem have few sub-cellular structures, so food can flow through |
| Embryonic and Adult Stem cells | EMBRYONIC STEM CELLS: 1) An embryo develops from a fertilised egg (at the early stage of development the cells in the embryo are stem cells) 2) Cells are then removed from the embryo - Embryonic stem cells (they'll differentiate into any type of cell 3) Difficult to obtain and raise ethical challenges ADULT STEM CELLS: 1) Found in: brain, eyes, blood, heart, liver, bone marrow, skin and muscle 2) Can only differentiate into related cell types (e.g. bone marrow cells can differentiate into blood cells and cells of the immune system) (3) Use patients own stem cells, therefore they're genetically identical and less likely to get rejected |
| Plant Stem cells | 1) Found in the meristem region if the plant (mainly near the shoot tip and the root tip) 2) Can differentiate into any cell at anytime during the plants life 3) In a growing shoot new cells are being produced near the tip but as they become older and further away from the tip they become differentiated - and enlarge and develop vacuoles |
| What happens when a cell becomes cancerous? | When a cell becomes cancerous, it begins to grow and divide uncontrollably. New cells are produced – even if the body does not need them - A group of cancerous cells produces a growth called a tumour. - Cancer cells are undifferentiated – they do not carry out their normal function |
| What Factors effect Enzymes | - PH, different enzymes work best at different pH values - Temperature (work best at 37°C) |
| Where are the Digestive Enzymes Found? | 1) Proteases catalyse the breakdown of proteins into amino acids in the stomach and small intestine 2) Lipases catalyse the breakdown of fats and oils into fatty acids and glycerol in the small intestine 3) Amylase catalyses the breakdown of starch into maltose in the mouth and small intestine 4) Maltase catalyses the breakdown of maltose into glucose in the small intestine |
| What are Enzymes (involved in Chemical Digestion) | Enzymes are Biological Catalysts. They break down nutrients into small, soluble molecules that can be absorbed. |
| Embryonic and Adult Stem cells | EMBRYONIC STEM CELLS: 1) An embryo develops from a fertilised egg (at the early stage of development the cells in the embryo are stem cells) 2) Cells are then removed from the embryo - Embryonic stem cells (they'll differentiate into any type of cell 3) Difficult to obtain and raise ethical challenges ADULT STEM CELLS: 1) Found in: brain, eyes, blood, heart, liver, bone marrow, skin and muscle 2) Can only differentiate into related cell types (e.g. bone marrow cells can differentiate into blood cells and cells of the immune system) (3) Use patients own stem cells, therefore they're genetically identical and less likely to get rejected |
| Plant Stem cells | 1) Found in the meristem region if the plant (mainly near the shoot tip and the root tip) 2) Can differentiate into any cell at anytime during the plants life 3) In a growing shoot new cells are being produced near the tip but as they become older and further away from the tip they become differentiated - and enlarge and develop vacuoles |
| Cloning in Plants | 1) Meristematic cells are removed from a plant and grown in a tissue culture 2) Cells are grown in a culture medium that contains agar - which provides support support and water for the growing cells - along with nutrients and plant hormones to stimulate growth and cell division. - Plant cloning produces plants quickly and economically - Its prevents plants from being endangered - Clones will be genetically identical to the original plant. Its useful to provide desirable characteristics like disease resistance Also Cloning in Plants also occurs naturally - e.g. in runners in strawberries (farmers take away cuttings) |
| Human Stem Cell Uses | 1) Adult/Embryonic Stem Cells: can be used to replace damaged or destroyed cells: - in type 1 diabetes - in cases of multiple sclerosis (which can lead to paralysis) - in cases of spinal cord or brain injury (that have lead to paralysis) 3) Adult Stem cells: Differentiate in to a narrower range of cell types - E.g. Bone marrow transplants are carried out: in case of blood cell cancer (like leukaemia and lymphoma) or when blood cells have been destroyed by cancer treatment |
| Give 7 Specialised cells in animals | 1)Circualtorty system - Transport substances, defend the body and regulate temperature 2)Excretory system - Remove waste products and unwanted substances and regulate water content 3)Muscular system - Bring about movement 4)Nervous system - Respond to external and internal stimuli and conditions, carry messages from the body work as a coordinated whole 5)Respiritory system - Deliver oxygen for respiration and remove waste 6)Reproductive system - Bring about firtilisation to produce new offspring 7)Skeletal system - Help bring about movement, support and protect internal structures, produce blood, store and release calcium |
| Give 4 specialised cells in plants. | 1)Leaf - Palisade mesophyl - carry out photosynthesis - Spongey mesophyll - Allows gases to circulate for gas exchange, carry some photosynthesis - Guard cells - Open and close to control the exchange of gasses - Co2, H2O vapour, O2 2)Phloem -Sieve tubes - Transport products of photosysnthesis, sugars and amino acids from leaf to where theyre needed -Companion cells - Provide energy required for transporting substances in sieve tubes 3)Xylem - xylem vessels - Transport water and dissolved minerals from roots, up plant 4)Growing points - Merristem - Produce new cells as they divide |
| How does cloning in plants happen? | 1)Tissue sample is scraped from parent plant 2)Meristematic cells are removed and grown in tissue culture - the culture medium contains: agar to provide support and water for growing cells, nutrients and plant hormones to stimulate growth and cell division 3)Samples develop into plantlets to be transferred into compost -A simpler way is to take cuttings |
| Why is plant cloning good? | 1)Identical plants quickly and economically, easier than sowing seeds 2)Increase production of disease resistant plant |
| Human Stem Cell Uses | 1) Adult/Embryonic Stem Cells: can be used to replace damaged or destroyed cells: - in type 1 diabetes - in cases of multiple sclerosis (which can lead to paralysis) - in cases of spinal cord or brain injury (that have lead to paralysis) 3) Adult Stem cells: Differentiate in to a narrower range of cell types - E.g. Bone marrow transplants are carried out: in case of blood cell cancer (like leukaemia and lymphoma) or when blood cells have been destroyed by cancer treatment |
| How does therapuetic cloning work? | 1)Human egg cell extracted from donor 2)Nucleus removed and discarded swapped with patients egg cell nucleus 3)The cell is stimulated to divide so developes into an embryo 4)After 4-5 days stem cells are removed 5)Stem cells from embryo are cultured for therapuric use |
| Benefits of Stem Cells in Medicine | Stem cells have great potential, in treating patients with currently untreatable conditions, growing organs for transplants, and research |
| CLINICAL ISSUES of Stem Cells in Medicine | - Difficult to find suitable donors - Difficult to obtain & store - Cultured stem cells could be contaminated with viruses |
| ETHICAL ISSUES of Stem Cells in Medicine | - Is it right to create embryos for therapy, and destroy them? - Embryos can be viewed as commodities, and not as an embryo that could develop into a person - At what stage of its development should an embryo be regarded as, and treated as a person |
| SOCIAL ISSUES of Stem Cells in Medicine | - Educating the public about what stem cells can, and can't do, is important - Whether the benefits of stem cell use outweigh the objections - Patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their developmental stages |
| What is the definition of osmosis? | Osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane |
| Osmosis in: Plant Cells | - Root hair cells, if the soil is wet or moist, will also take up water by osmosis - Leaf cells of land plants, unless it is raining or the humidity is high, will have a tendency to lose water - Plant cells have a strong cellulose cell wall which is fully permeable and supports the cell, stopping it from bursting as it gains water - Aquatic, freshwater plants placed in the sea, or a seaweed in a rock pool where the water evaporated in the Sun, would also lose water by osmosis |
| Osmosis in: Animal Cells | 1) Animal cells also take in and lose water by osmosis. They do not have a cell wall, so will change size and shape when put into solutions that are at a different concentration to the cell contents. Red Blood cells can: - lose water and shrink - gain water, swell and burst in a more dilute solution 2) In animals, the concentration of body fluids – blood plasma and tissue fluid – must be kept within strict limits, if cells lose or gain too much water by osmosis, they do not function efficiently |
| PRACTICAL: Osmosis | 1) Prepare a range of sucrose (sugar) solutions - could be sodium chloride (salt). Measured in 'mol dm-3'. E.g. 0.2 mol dm-3 to 1.0 mol dm-3. 2) Set up a series of boiling tubes with each of these solutions. 1 will contain distilled water (0.0 mol dm-3 of sucrose) - it'll act as the control in the experiment. Make sure each tubes concentration is labelled 3) Prepare blank results table. Make sure potatoes mass' are not mixed up when recording them. Each cylinder will have a different mass before and after investigation 4) For each sucrose concentration, repeat the investigation for several potato cylinders - makes experiment repeatable as not all potatoes behave in the same way, also means anomalies can be identified and ignored when calculating mean |
| Give 4 ways alvioli are adapted for exchanging substances? | 1)High surface area to volume ratio (more points of entry for gases compared to capacity or organism) 2)Moist lining 3)one cell thick minnimising distance gases have to diffuse 4)good blood supply |
| Give 3 ways villi are adapted for exchanging surfaces | 1)High surface area to volume ratio 2)single layer of surface cells minnimising distance gases have to diffuse 3)good blood supply |
| What key thing would happen if a plant didnt have guard cells? | The plant would wilt. |
| Descreibe the gaseous exchange in fish | 1)water enters the fish through the mouth and reaches the gills oxygen diffuses from the water into the blood and carbon dioxide diffuses from the blood |
| Give 4 ways gills are adapted for gaseous exchange? | 1)Each gill consistss of plates called gill filiament, each filliament covered in tiny structures called lamelle meaning the have very large surface area. 2)Lots of blood capiliaries speeding up diffusion. 3)Thin surface layer minnimising distance gases have to diffuse. 4)Blood and water travekin different directions maintaining high concentration gradient so as much oxygen diffuses as possible. |
| How can I test for reducing sugars? | 1)Place 5cm^3 food sample in test tube in 75c waterbath 2)Add 10 drops benidict soloution and leave 5 mins pointing away from you 3)Ascending sugar - Blue - Green - Orange - Brick Red |
| How can i test for starch? | 1)Place 5cm^3 in test tube 2)Add a few drops of iodine soloutuion gently shake 3)Brown/Orange (remains if no starch) to Blue black |
| How can i test for protiens? | 1)Place 2cm^3 in test tube 2)Add 2cm^3 biurett solution - gently shake 3)Blue (remains if no protien) to purple |
| How can I test for lipids? | 1)Prepare 5cm (dont need to filter) test tube 2)Add 3 drops sudan III stain soloution gently shake 3)Red seperate layer will form. |
| Give 3 ways red blood cells are adapted to carry out their function? | 1)Shaped as biconcave disc - large surface area 2)Contain red pigment - haemoglobin, binds with oxgen - oxyhaemoglobin 3)Have no nucleus |
| Give 2 ways white blood cells are adapted? | 1)Engulf microorganisms - phagacytosis 2)Produce antibodies to fight microorganisms and antitoxins to neutralise their toxins |
| Give 2 ways platelets are adapted? | 1)Small fragments of cells, have no nucleus 2)Help blood clot a wound preventing microorganisms getting in |
| Give 7 things plasma contain? | 1)Red and white blood cells and platelets 2)Nutrients - glucose and amino acids 3)Carbon dioxide 4)Urea 5)Hormones 6)Protiens 7)Antibodies and antitoxins produced by white blood cells |
| Where are the most chlorophyl found in a leaf? | Palliside mesophyl and spongey mesophyll. |
| 2 Types of Tumours | Benign- (1)Grows slowly (2)usually within a membrane so easy to remove (3)doesnt invade other parts of the body Melignant- (1)Grows quickly (2)not within a membrane (3)invades neighbouring tissues spreads to other parts of body (4)undergoes metastasis (forming of secondary tumors) |
| What happens when a cell becomes cancerous? | When a cell becomes cancerous, it begins to grow and divide uncontrollably. New cells are produced – even if the body does not need them - A group of cancerous cells produces a growth called a tumour. - Cancer cells are undifferentiated – they do not carry out their normal function |
| What are Carcinogens? | Chemical and other agents that can cause cancer - Carcinogens cause cancer by damaging DNA. - Carcinogens cause mutations to occur. A single mutation will not cause cancer – several are required. For this reason, we are more likely to develop cancer as we get older |
| State an Industrial and environmental factor at work that may cause Cancer | 1) exposure to ionising radiation increases the risk factor 2) exposure to carcinogens |
| Describe how Secondary Tumours form | 1) Tumour secretes chemicals 2) The chemicals stimulate the blood vessels to grow (the blood vessels grows around the tumour) 3) Cancer cells detach from the tumour and are transported in the blood 4) A malignant cell squeezes through a blood capillary wall 5) The cell divides - a secondary tumour starts to grow |
| State 3 Life Style Factors that may cause Cancer | 1) viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse 2) the chemical carcinogens in cigarette smoke increasing the risk of lung cancer 3) alcohol intake is linked with certain cancers 4) exposure to ultraviolet radiation, part of which is ionising, during sunbathing or outdoor activities, leading to the development of skin cancers 5) diet, including fat and salt intake, increases the risk of cancer |
| What are the 3 main Stages of Drug Testing? | 1) STAGE 1: Drugs are tested in Laboratories using computer models and skin cells grown using human stem cells. Tests: efficacy and possible side effects. Many substances fail this first test of a preclinical drug trial because they damage cells or do not seem to work 2) STAGE 2: New medicines tested on animals (In UK), illegal to test cosmetics and tobacco products on animals. Typically involves giving a known amount of substance and monitoring carefully for any side-effects 3) STAGE 3: Human clinical trials. Tested on healthy volunteers to check that they are safe, then tested on people with the illness to ensure that they are safe and that they work. Low doses of the drug are used initially, and if this is safe the dosage increases until the optimum dosage is identified |