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282 Cards in this Set
- Front
- Back
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What does being healthy mean?
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Being free of any infections or diseases
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What does being fit mean?
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A measure of how well you can perform physical tasks, the ability
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What does fitness profiles measure?
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Strength, speed, agility, flexibility and stamina
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What is stamina a good indication of?
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Cardiovascular efficiency (the ability of the heart to supply the muscles with oxygen).
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How can cardiovascular efficiency be tested by?
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Measuring oxygen uptake during exercise and blood pressure
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How is blood pumped around the body?
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By the contractions of the heart which increase the pressure of the blood
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What happens when the blood is pumped around the body?
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The blood leaves the heart and flows through arteries. THese split into thousands of tiny capillaries which take blood to every cell in the body. The blood then flows back to the heart through veins. The pressure gets lower as the blood flows through the system
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What is systolic pressure?
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When the blood pressure is at its highest when the heart contracts
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What is diastolic pressure?
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When the heart relaxes, the pressure is at its lowest
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What is blood pressure measured in?
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mm of mercury mmHg
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What factors could increase blood pressure?
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Smoking, being overweight, drinking too much alcohol and being under lots of stress for a long time
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What can happen if there is high blood pressure?
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It can cause blood vessels to burst which can lead to strokes, brain damage and kidney damage
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How can high blood pressure be decreased?
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Lifestyle changes eg. eating a balanced diet or doing regular exercise
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What can happen if there is low blood pressure?
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Causes poor circulation and tissues don't get all the food and oxygen they need
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What chemicals are in fags?
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Carbon monoxide which combines with haemoglobin in red blood cells which reduces the amount of oxygen they can carry and nicotine which increases heart rate
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Saturated fats can cause a build up of Cholesterol, what is this?
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A fatty substance which is needed for making cell membranes. If you get too much it starts to build up in your arteries which forms plaques in the artery wall, which narrow the arteries. The plaques restrict the flow of blood, which can lead to a heart attack
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How is the heart muscle supplied with blood?
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By the coronary arteries
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What is thrombosis?
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A blood clot which could occur in an already narrow coronary artery which may lead to the flow to the heart blocked completely
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What are the nutrients required for different functions in the body?
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Carbohydrates, fats, proteins, vitamins, minerals, water and fibre
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What are essential amino acids?
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Where amino acids can't be made by the body so you have to get them from your diet
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What are first class proteins?
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Animal proteins
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What are second class proteins?
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Plant proteins
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How does the energy and nutrient needs vary because of age?
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Children and teens need more protein for growth. Older people need more calcium to protect against degenerative bone diseases like osteoporosis
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How does the energy and nutrient needs vary because of gender?
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Females need more iron to replace the iron lost in menstrual blood
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Why do some people choose to eat a different diet?
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Religious reasons, personal reasons such as vegetarians and medical reasons for example, some people are intolerant to certain foods
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What is Kwashiorkor?
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Eating too little protein which causes a swollen stomach
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How can you calculate a persons Estimated Average daily Requirement?
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EAR (g)= 0.6 x body mass (kg)
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What is a body mass index (BMI)
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Used as a guide to help decide whether someone is underweight, normal, overweight or obese
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What are pathogens and what are the types of pathogens?
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Microorganisms that cause disease. Fungi (athletes foot), bacteria (cholera), viruses (flu) and protozoa (dysentery)
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How are the symptoms of an infectious disease caused?
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Cell damage or by toxins produced by the pathogens
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What is malaria caused by?
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Malaria is caused by a protozoan
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What is a parasite?
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An organism that lives off another organism and often causes it harm
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What are vectors?
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Carry the disease without getting it themselves. They pick up the malarial parasite when they feed on an infected animal for example, in terms of malaria
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What happens once pathogens have entered your body?
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They'll reproduce rapidly unless they're destroyed. The immune system and white blood cells deals with the pathogens
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What do white blood cells do when they come across an invading microorganism?
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They can engulf foreign cells and digest them, antitoxins counter the effect of any poisons produced by the invading pathogens and when white blood cells come across a foreign antigen, they produce antibodies
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What are antigens?
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Every pathogen has unique molecules on the surface of its cells. No two pathogens have the same ones
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What do antibodies do?
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They lock on to and kill the new invading cells which are produced specifically to that pathogen
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What does immunisation do?
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Stops you getting infections. It involves injecting dead or inactive pathogens into the body which carry antigens, so even though they're harmless they still trigger an immune response
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What is active immunity?
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Where the immune system makes its own antibodies after being stimulated by a pathogen. It includes becoming naturally immune and artificially immune, usually permanent
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What is passive immunity?
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Where you use antibodies made by another organism, only temporary
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What are antibiotics?
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Drugs that kill bacteria without killing your own body cells. They're very useful for clearing up bacterial infections that your body is having trouble with, however they don't kill viruses
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What are antivirals used for?
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Treating viral infections. They are drugs that stop viruses from reproducing
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What is cancer caused by?
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Body cells dividing out of control
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What is a Benign tumour?
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Where the tumour grows until there's no more room. The cells stay where they are. This type isn't normally dangerous
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What is a malignant tumour?
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Where the tumour grows and can spread to other sites in the body. They are dangerous and can be fatal
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How are drugs developed and tested?
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Computer models stimulate a human's response to a drug. They can identify promising drugs to be tested in the next stage. Then drugs are developed by testing on human tissues. The last step is to develop and test the drug using animals. The law in Britain states that any new drug must be tested on two different live mammals
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What are clinical trials?
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Where a patient in the study doesn't know whether they're getting the drug or the placebo. Its after the drug has been tested on animals and then tested on humans
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What are depressants and give examples?
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Decrease the activity of the brain which slows down the responses of the nervous system causing slow reactions and poor judgement of speed and distances. Alcohol, solvents and temazepam
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What are stimulants and give examples?
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They increase the activity of the brain which makes you feel more alert and awake. Nicotine, ecstasy and caffeine
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What are painkillers and give examples?
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Reduces the number of painful stimuli at the nerve endings near an injury. Aspirin and paracetamol
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What are performance enhancers and give examples?
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Builds muscle and allows the athletes to train harder. Anabolic steroids
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What are hallucinogens?
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Distort whats seen and heard by altering the pathways that the brain sends messages along. LSD
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What do class A drugs include?
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Heroin, LSD, ecstasy and cocaine
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What do class B drugs include?
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Cannabis and ampthetamines
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What do class C drugs include?
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Anabolic steroids and tarnquillisers
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What does alcohol do?
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causes dehydration and being drunk leads to impaired judgement, poor balance, poor coordination, slurred speech, blurred vision and sleepiness
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What is cirrhosis?
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Alcohol is broken down by enzymes in the liver and some of the products are toxic. If you drink too much over a long period of time these products can cause the death of liver cless forming scar tissure that stops blood reaching the liver
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How can you get heart disease from smoking?
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Carbon monoxide reduces the oxygen carrying capacity of the blood. If the heart muscle doesn't receive enough oxygen it can lead to a heart attack
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How can lung, throat, mouth and oesophageal cancer occur from smoking?
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Tar from smoke collects in the lungs which is full of toxic chemicals called carinogens. They make mutations in the DNA more likely and if this happens, cell division can go out of control and malignant tumours
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How can diseases like emphysema be caused by a smoker's cough?
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Smoking damages the cilia on the epithelial tissue lining the trachea, bronchi and bronchioles which encourages mucus to be produced. But excess mucus can't be cleared because the cilia are damaged so it sticks to air passages causing smoker's cough. The longs also lose their elasticity causing emphysema
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What does the cornea do?
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Refracts light into the eye
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What does the iris do?
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Controls how much light enters the pupil
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What does the lens do?
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Refracts light, focusing it onto the retina
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What does the retina do?
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Its the light sensitive part which is covered in receptors called rods and cones which detect light
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What are cones?
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Sensitive in dim light but can't sense colour
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What is the optic nerve?
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It carries impulses from the receptors to the brain
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What happens when you look at distant objects in terms of the eye?
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The ciliary muscle relaxes which allows the suspensory ligaments to pull tight. This pulls the lens into a lessrounded shape so light is refracted less
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What happens when you look at close objects in terms of the eye?
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The ciliary muscle contracts which slackens the suspensory ligaments. The lens becomes a more rounded shape, so light is refracted mroe
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Why are long sighted people unable to focus on near objects?
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The lens is the wrong shape and doesn't bend the light enough and the images of near objects are brought into focus behind the retina
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What does the central nervous system consist of?
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Brain and spinal cord. Its made up of sensory, relay and motor neurones
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What does the sensory neurones do?
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Carry the information from receptors when you detect a change in your environment
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What does the central nervous system do?
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Sends information to an effector along a motor neurone. The effector then respond accordingly
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What is the job of the central nervous system?
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To coordinate the information
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What are reflex actions?
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The revous system uses electrical impules to allow a very quick response. Reflexes are automatic
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How does reflex actions work?
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The sensory neurone connects to a relay neurone in the spinal cord which links directly to the right motor neurone
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Where are electrical impulses passed along?
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The axon of the cell
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What do the branched endings of a neurone do?
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They connect with lots of other neurones
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What are sheaths?
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They are along the axon and act as an electrical insulator which speeds up the electrical impuls
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What is a synapse?
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The connection between two neurones
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How do neurones travel?
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The electrical impulse triggers the release of transmitter chemicals which diffuse across the gap. These chemicals bind to receptor molecules in the membrane of the next neurone which sets off a new electrical impulse
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What is homeostasis?
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Maintaining a constant internal environment
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What is negative feedback in terms of homeostasis?
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Changes in the environment trigger a response that counteracts the changes. This means that the internal environment tends to stay around a norm, the level at which the cells work best
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What is the optimum temperature of enzymes in a human body?
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37 degrees celcius
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What does the thermoregulatory center in the brain do?
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It contains receptors that are sensitive to the blood temperature in the brain and it receives impulses from the skin that provide information about skin temperature. The brain can respond to this information and bring about changes in the body's temperature using the nervous and hormonal systems to initiate temperature control mechanisms
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What happens to the body when you're too hot?
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Hair lies flat, lots of sweat is produced and blood vessels close to the surface of the skin widen
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What happens to the body when you're too cold?
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Hairs stand on end to trap an insulating layer of air which keeps you warm, very little sweat is produced, you shiver and blood vessels near the surface constrict
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What does eating foods containing carbohydrate do?
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Puts glucose into the blood from the gut
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What removes glucose from the blood?
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Respiration and vigorous exercise
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If blood glucose level is too high, what happens to the insulin?
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It is added
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If the blood glucose level is too low, what happens to the insulin?
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No insulin is added
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What is insulin?
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A hormone that travels in the blood so it can take a while for them to get where they're needed i.e. their target oran. Electrical impulses snet along the nerves travel much faster
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What is type 1 diabetes?
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Where the pancreas produces little or no insulin
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What is Type 2 diabetes?
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Where a person becomes resistant to insulin
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How is type 1 diabetes controlled?
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By injecting insulin into the blood at mealtimes
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How is type 2 diabetes controlled?
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By avoiding foods rich in simple carbohydrates i.e. sugars
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What are auxins?
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Plant homrones which control growth at the tips of shoots and roots, they move through the plant in solution
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Where is auxin produced?
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In the tips and diffuses backwards to stimulate the cell elongation process which occurs in the cells behind the tips
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What happens when shoots are positively photo tropic?
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When a shoot tip is exposed to light it accumulates more auxin on the side that's in the shade which makes the cells grow faster on that side so the shoot bends towards the light
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What happens when roots are negatively geotropic?
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When a shoot is grown sideways gravity produces an unequal distribution of auxin in the tip with more auxin on the lower side which causes tat side to grow faster bending the shoot upwards
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What happens if roods are positively geotropic?
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In a root the extra auxin inhibits growth which means the cells on top elongate faster and the root bends downwards
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What happens when roots are negatively photo tropic?
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If a root starts being exposed to some light, more auxin accumulates on the shaded side which makes the root bend downards
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What does the nucleus of cells in your body contain?
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Your genetic material in the form of chromosomes
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How many pairs of chromosomes are in a human body cell?
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23 pairs
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What do chromosomes carry?
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Genes which control the development of different characteristics
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What is an allele?
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A different version of the smae gene
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What are gametes?
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Sperm and egg cells
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What is fertilisation?
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When the sperm and the egg join to forma new cell with the full 46 chromosomes
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What are mutations?
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CHanges to the genetic cod which can create new characteristics increasing variation
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How is health, intelligence and sporting ability determine features?
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Some people are more likely to get certain diseases because of their genes, maximum IQ might be determined by your genes whether you get to it depends on your environment and genes determine your potential
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What does homozygous mean?
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For a trait if you have two alleles the same for that particular gene e.g. CC or cc
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What does heterozygous mean?
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For a trait if you have two different alleles for that particular gene e.g. Cc
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What do chromosomes control?
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Whether you're male or female
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All men have what chromosomes?
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X and Y. The Y chromosome causes male characteristics
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All women have what chromosomes?
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Two X chromosomes
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Plant hormones can be used to do what?
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Selective weedkillers, growing from cuttings with rooting powder, controlling the ripening of fruit and controlling dormancy
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What is classification?
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Organising living organisms into groups
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Why are classification systems important?
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They help us to understand how organisms are related and how they interact with each other
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What are natural classification systems?
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They are based on the evolutionary relationships and genetic similarities between organisms
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What are artificial classification systems?
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They are based on appearance rather than genes .They're used to identify organsims
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What are living things divided into?
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Kingdoms that are subdivided into smaller groups
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What are the smaller groups that kingdoms are subdivided into?
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Phylum, class, order, family, genus, species
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What do evolutionary trees show?
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They show how closely related different species are to each other. They show common ancestors and relationships between species
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Define the word species?
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A species is a group of organisms which can interbreed to produce fertile offspring
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What is asexual reproduction?
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Where an organism reproduces by making a copy of itself, such as bacteria
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What are hybrids?
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Where you interbreed a male from one species with a female from a different species. They are usually infertile and it's difficult to classify them
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What does the binomial system do?
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Gives everything a two part name
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What does each bar on a pyramid of biomass show?
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The mass of living material at that stage of the food chain
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What does each bar on a pyramid of numbers show?
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The number of organisms at that stage of the food chain, not their mass
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Why is the 'aphids' bar on a number pyramid longer than the 'pear tree' bar?
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One pear tree can feed a huge number of aphids
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How is energy lost?
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Energy from the sun is the source. Plants use a small percentage of the light energy for photosynthesis, the energy lost at each stage is used for staying alive i.e respiration, most of this energy is lost to surroundings as heat, material and energy are lost from the food chain as waste products and those waste products can become starting points for other food chains
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How do you work out efficiency of energy transfer?
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Energy available to the next level divided by energy that was available to the previous level, x 100
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What is a species ecological niche and what does it depend on?
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How it fits in to its ecosystem, it depends on things like where the individuals live and what they feed on
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What is interspecific competition?
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Where organisms compete for resources against individuals of another species
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What is intraspecific competition?
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Where organisms compete for resources against individuals of the same species
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Why does intraspecific competition have a bigger impact on organisms than interspecific competition?
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Because individuals of the same species have the same needs
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What is mutualism and give an example?
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A relationship where both organisms benefit such as plants are pollinated by insects, allowing them to reproduce. In return, the insects get a sip of sweet, sugary nectar.
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What are specialists organisms and give an example?
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Organisms which are highly adapted to survive in a specific habitat for example giant pandas are adapted to eat just bamboo
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What are generalists organisms and give an example?
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Organisms which are adapted to survive in a range of different habitats for example black rats are able to survive in forests, cities and farmlands
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What happens to the specialists and generalists if conditions in the habitat change?
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Specialists will be out-competed by generalists as they won't be adapted to the new conditions
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Give 2 examples of organisms adaptations?
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Extremophile bacteria that live in very hot environments have enzymes that work best at a much higher optimum temperature. They are able to function normally at temperatures that would denature enzymes from other organisms. Organisms that live in the cold have antifreeze proteins which interfere with the formation and growth of ice crystals in cells, stopping the cells from being damaged by ice
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What are anatomical adaptations?
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Features of an organisms' anatomy that help it to survive
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What do anatomical adaptations include?
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Having a thick coat to insulate the body or having a large size and compact body shape to give a small surface area to volume ratio
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How do penguins keep their feet warm?
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Blood vessels going to and from the feet carry blood that flows in opposite directions. They pass close to each other allowing heat to transfer between them
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How can you increase heat loss and reduce heat gain in hot environments?
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Animals spend the day in the shade to minimise the amount of heat their body gains from their surroundings. They are active at night and they bathe in water which means the water evaporates and transfers heat from the skin to the surroundings, cooling the animal down
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What anatomical adaptations increase heat loss?
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Animals that are small give them a large surface area to volume ration which allows them to lose more body heat. Having large hears can increase the surface area to volume ratio which also allows more blood to flow near the surface of the skin if they're thin ears. Some animals store fat which stops the rest of the body being too insulated
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How have some desert plants adapted to living in dry environments?
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Rounded shape giving them a small surface area to volume ration, thick waxy layer called a cuticle and spines instead of leaves to further reduce water loss, store water in their stems and have shallow roots to ensure water is absorbed quickly over a large area
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How have some desert animals adapted to living in dry environments?
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Specialized kidneys that allow them to produce very concentrated urine, no sweat glands and spend lots of time in underground burrows where the air contains more moisture than on the surface
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What is natural selection?
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Where organisms have to compete for limited resources in an ecosystem
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How is reproductive isolation caused by geographic isolation?
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A physical barrier divides a population of a species where the two new populations are unable to mix. Different mutations create different new features in the two groups of organisms. Since conditions on each side of the barrier will be slightly different, the features that are beneficial will be different for each population. Eventually, individuals from the two populations will have such different features that they won't be able to breed together to produce fertile offspring. They'll have to become reproductively isolated and the two groups will be separate species
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Why was Darwin's theory of evolution by natural selection controversial?
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The theory was against religious beliefs, he couldn't explain why new, useful characteristics appeared and there wasn't enough evidence to convince many scientists
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What was Lamarck's idea of evolution?
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If a characteristic was used a lot by an animal then it would become more developed. People concluded that they don't have a genetic basis so his theory was rejected
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What is the carbon cycle powered by?
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Photosynthesis
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What happens in photosynthesis in the carbon cycle?
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Plants convert the carbon from co2 in the air into sugars which plants then incorporate into other carbohydrates as well as fats and proteins
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Why does the recycling of carbon take longer in waterlogged soils than in well-drained soils?
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Because the bacteria and fungi that decompose organic material usually need oxygen to respire and produce energy
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Why does nutrient recycling take longer in highly acidic soils than in neutral soils?
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Because extremes of pH slow down the reproduction of decomposers or kill them outright
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What are carbon sinks?
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Where oceans can absorb large amounts of co2 acting as huge stores of carbon called carbon sinks
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How much nitrogen gas is contained in the atmosphere?
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78%
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Where do plants get their nitrogen from?
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The soil so nitrogen in the air has to be turned into nitrates before plants can use it
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What do decomposers do?
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Break down proteins in rotting plants and animals and urea in animal waste into ammonia
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What is nitrogen fixation?
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Turning N2 from the air into nitrogen compounds in the soil which plants can use
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How can nitrogen fixation occur?
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Lightning which makes nitrogen react with oxygen in the air to give nitrates and nitrogen fixing bacteria in roots and oil
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What are the four different types of bacteria involved in the nitrogen cycle?
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Decomposers, nitrifying bacteria which turns ammonia in decaying matter into nitrates, nitrogen fixing bacteria and denitrifying bacteria which turns nitrates back into N2 gas
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Where does nitrogen fixing bacteria live?
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In the soil or in nodules on the roots of legume plants
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What is increasing amounts of pollution cause?
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Global warming, acid rain and ozone depletion
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What are lichens?
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They are used to monitor air quality but are damaged by pollution. The cleaner the air, the greater the diversity of lichens that survive
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What are mayfly larvae?
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They are used to monitor water quality, they cant survive in polluted water
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How can pollution level be measured?
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Surveys to see if species are present or absent or counting the number of times an indicator species occurs in an area. Sensitive instruments which measure the concentrations of chemical pollutants or satellite data
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What are the advantages of using living methods to measure pollution level?
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Quick, cheap and easy way of saying whether an area is polluted or not
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What are the disadvantages of using living methods to measure pollution level?
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Factors other than pollution can influence the survival of indicator species so living methods aren't always reliable
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What are the advantages of using nonliving methods to measure pollution level?
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Directly measuring the pollutants give reliable, numerical data that's easy to compare
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What are the disadvantages of using nonliving methods to measure pollution level?
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Expensive equipment and trained workers than methods that use indicator species
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How are species at risk of extinction?
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The number of habitats is low, the number of individuals is low and genetic variation which is the number of different alleles in a population is low, meaning it is less likely to adapt to changes
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What are conservation programmes designed for?
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To save endangered plants and animals. They protect habitats and create artificial environments and captive breeding
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How can you evaluate how successful a conservation programme is?
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Genetic variation, viability of populations, available habitats and interaction between species
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What is sustainable development?
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Providing for the needs of today's increasing population without harming the environment
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What are fishin quotas?
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They prevent types of fish from becoming extinct
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Why are whales endangered?
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Commercial value, tourist attraction, whale meat and oil can be used and cosmetics can be made from a waxy substance in their intestines
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How are people stopping whales from being endangered?
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The international whaling commission try to stop whaling by captivity and captive breeding programmes
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What is a nucleus?
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Contains DNA in the form of chromosomes
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What is a cell membrane?
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Holds the cell together and controls what goes in and out
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What is a ribosome?
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Where proteins are synthesised
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What is cytoplasm?
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Gel-like substance where most of the cell's chemical reactions happen
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What is mitochondria?
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Mitochondria where most of the reactions ivolved in respiration take place
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What does respiration provide for cells?
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Energy for cell processes
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What are chloroplasts?
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Where photosynthesis happens
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What is a cell wall?
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Made of cellulose which supports the cell
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What is a vacuole?
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A large structure that contains cell sap, a weak solution of sugar and salts
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What is different about bacterial cells?
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They don't have chloroplasts or mitochondria and they don't have a nucleus instead they have a strand of DNA that floats freely in the cytoplasm
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What are the two DNA strands made up of?
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LOts of small groups called nucleotides
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What does nucleotides contain?
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A small molecule called a base
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What bases pair with which and what is this called?
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A pairs with T and G pairs with C. This is called complementary base pairing
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What data did scientists use to help them understand the structure of DNA?
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Xray data showing that DNA is a double helix formed from two chains wound together
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What does DNA do?
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It replicates itself every time a cell divides so that each new cell still has the full amount of DNA. The DNA unzips then new nucleotides then join on using complementary base pairing which makes an exact copy of the DNA on the other strand. This creates two double stranded molecules of DNA that are identical
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What does DNA control?
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The production of proteins in a cell
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What are proteins made up of?
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Chains of molecules called amino acids which join together to make proteins following the order of the bases in the gene
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What does mRNA carry?
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The code to the ribosomes. The mRNA acts as a messenger between the DNA and the ribosome
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How does DNA control a cell?
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By controlling protein production
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What are the functions of proteins?
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Enzymes, carrier molecules used to transport smaller molecules, hormones used to carry messages around the body and structural proteins which are physically strong
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What do enzymes control and what do they act like?
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Cell reactions such as respiration, photosynthesis and protein synthesis. They act as bilogical catalysts
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What do chemical reactions usually involve in terms of enzymes?
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Being split apart or joined together. The substrate is the molecule changed in the reaction and every enzyme has an active site which is the part where it joins on to its substrate to catalyse the reaction
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How does temperature effect the rate of an enzyme-catalysed reaction?
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Low temperatures slower the reaction and if it gets too hot some of the bonds holding the enzyme will break which makes the enzyme lose its shape. Its active site doesn't fit the shape of the substrate any more which means it can't catalyse the reaction
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What is an enzymes optimum temperature?
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37 degrees Celsius where the reaction goes fastest
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How does a pH level affect an enzyme?
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If it is too high or too low it interferes with the bonds holding it together which changes the shape of the active site and denatures the enzyme
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What does Q10 show?
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How much the rate changes when the temperature is raised by 10 degrees Celcius
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What is a gene mutation?
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A change in the DNA base sequence, if it occurs within a gene it could stop the production of the protein
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How is the chance of a mutation increased?
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If you're exposed ionising radiation including x rays and ultraviolet light and certain chemicals which are known to cause mutations. Such chemicals are called mutagens
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What are the advantages of being multicellular?
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You can be bigger which means you can travel further and get your nutrients in different ways. It allows for cell differentiation and organisms can be more complex
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Being multicellular means that an organism also has to have specialised organ systems including what?
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A system to communicate between different cells (nervous system), a system to supply cells with the nutrients they need (circulatory system) and a system that controls the exchange of substances with the environment (respiratory system)
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What is mitosis?
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When a cell reproduces itself by splitting to form two identical offspring
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What are the stages of mitosis?
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Before it starts, DNA in the cell is replicated. THen the DNA coils into double armed chromosomes which are exact copies of each other. THe chromosomes line up at the centre of the cell and then divide as cell fibres pull them apart. The two arms of each chromosome go to opposite poles of one cell. Membranes form around each of these two different sets. Then, the cytoplasm divides and you get two new cells
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What is formed by meiosis?
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Gametes in the ovaries and testes. They are haploid meaning they only have one copy of each chromosome
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What are the body cells of mammals?
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Diploid which means that each of the organism's body cells has two copies of each chromosome in its nucleus, one from the mum and dad
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What does meiosis involve?
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Two divisions. It replicates then the chromosomes arrange into pairs. The pairs split up then each chromosome splits in half and one arm ends up in each new cell ending up with 4 new cells
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What is fertilisation and what does fertilisation create?
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Where male and female gametes combine to form a diploid cell called a zygote which are controlled by genes on its chromosomes. It creates genetic variation
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What is a sperm's function?
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To transport the male's DNA to the female's egg
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What are sperm cells like?
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They are small and have long tails so they can swim to the egg. They have lots of mitochondria to provide the energy needed to swim this distance and they have an acrosome at the front of the head which can release the enzymes they need to digest their way through the membrane of the egg cell
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What is differentiation?
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The process by which a cell changes to become specialised for its job
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What does undifferentiated mean and what are they called in terms of plants?
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They can develop into different types of cells, tissues and organs depending on what instructions they're given. These cells are called stem cells
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In terms of growth, what does the method 'length' involve and what are its advantages and disadvantages?
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Just measure the length of a plant or animal. It is easy to measure but doesn't tell you about changes in width, diameter or number of branches, etc.
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In terms of growth, what does the method 'wet mass' involve and what are its advantages and disadvantages?
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Weigh the plant or animal and you have the wet mass. It is easy to measure but it is very changeable
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In terms of growth, what does the method 'dry mass' involve and what are its advantages and disadvantages?
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Dry out the organism before weighing it. It's not affected by the amount of water in a plant or animal but you have to kill the organism to work it out
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What is the best measure of growth in plants and animals?
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Dry mass because it's not affected by changes in water content and tells you the size of the whole organism
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What are the five main phases of growth in humans?
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Infancy, childhood, adolescence, maturity and old age
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What is respiration?
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The process of releasing energy from glucose and goes on in every cell in your body
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What does ATP act as?
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The energy source for many cell processes and transports energy to where it's needed in a cell
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What is respiration controlled by and what does this mean?
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Controlled by enzymes and the rate of respiration is affected by both temperature and pH
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What is aerobic respiration?
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When there's plenty of oxygen available
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What is the word and chemical equation for aerobic respiration?
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Glucose + oxygen -> carbon dioxide + water // c6h12o6 +602 -> 6h20
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When respiration rate increases what else increases?
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Oxygen consumption and carbon dioxide production
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What can the rate of oxygen consumption be used to estimate?
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The metabolic rate
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What is anaerobic respiration?
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Without oxygen
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What happens in anaerobic respiration?
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THe glucose is only partially broken down and lactic acid is produced which builds up in the msucles
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What is the word equation for anaerobic respiration?
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Glucose -> lactic acid
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What is the respiratory quotient?
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It tells you whether someone is respiring aerobically or anaerobically
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What is plasma and what does it carry?
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A liquid bit of blood which carries reed and white blood cells, water, digested food products like glucose, carbon dioxide from body cells to lungs, urea from liver to kidneys, hormones and antibodies
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What do red blood cells do?
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Transport oxygen from the lungs to all cells in the body
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What is the structure of a red blood cell?
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Small and have a biconcave shape to give a large surface area to volume ratio for absorbing and releasing oxygen. They contain haemoglobin, don't have a nucleus and they are flexible
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What are the three different types of blood vessel?
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Arteries which carry the blood away from the heart, capillaries which are involved in the exchange of materials at the tissues and veins which carry blood to heart
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Describe arteries?
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The heart pumps the blood out at high pressure so the artery walls are strong and elastic. They are thick and contain thick layers of muscle to make them strong
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Describe capillaries?
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Arteries branch into capillaries. THey are tiny and carry blood really close to every cell in body to exchange substances with them. They have permeable walls so substances can diffuse in and out and they supply food and oxygen and take away wastes like co2
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Describe veins?
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Capillaries join up to form veins, the have a bigger lumen than arteries to help blood flow despite lower pressures and they also have valves to help keep blood flowing in the right direction
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What is a double circulatory system?
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The first system connects the heart to the lungs and deoxygenated blood is pumped to the lungs to take in oxygen, the blood then returns to the heart. The second system connects the heart to the rest of the body. The oxygenated blood in the heart is pumped out to the body and gives up its oxygen and then the dexoxygenated blood returns to the heart to be pumped out again
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What are the advantages of mammals having a double circulatory system?
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Returning the blood to the heart means it can be pumped out around the body at a much higher pressure. This increases the rate of blood flow to the tissues so more oxygen can be delivered to the cells
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What is selective breeding?
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When humans artificially select the plants or animals that are going to breed and have their genes remain in the population
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Why are organisms selectively bred?
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To develop the best features such as maximum yield of meat, milk or grain, good health and disease resistance and other qualities like temperament, speed and attractiveness
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What is the process involved in selective breeding?
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From your existing stock select the ones which have the best characteristics then breed them. Select the best offspring and breed them. Continue this process over several generations and the desirable trait gets stronger and stronger
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What is the main drawback in selective breeding?
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A reduction in the gene pool which is the number of different alleles in a population. This is because the farmer keeps breeding the best animals or plants which is closely related
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What can inbreeding cause?
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Health problems because there's more chance of the organisms developing harmful genetic disorders when the gene pool is limited. This is because lots of genetic conditions are recessive
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What is the flow chart steps of selective breeding problems?
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Selective breeding - Reduction in the number of different alleles - Less chance of any resistant alleles being present in the population
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What is genetic engineering?
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To move genes from one organism to another so that it produces useful biological products
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What is the advantage and risk to genetic engineering?
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The advantage is that you can produce organisms with new and useful features very quickly. The risk is that the inserted gene might have unexpected harmful effects
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What are the stages of genetic engineering?
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The gene is selected then cut from the DNA using enzymes and isolated. The gene is inserted into the DNA of another organism and then it replicates
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What are the three examples of genetic engineering?
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It has allowed scientists to take a gene that controls beta-carotene production from carrot plants and put it into rice plants, the gene for human insulin production has been put into bacteria which are cultured in a fermenter and the human insulin is extracted as they produce it and finally some plants have resistance to things like herbicides. Genetic engineering can cut out the gene responsible and stick it into useful plants such as crops
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What does gene therapy involve?
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Altering a person's genes in an attempt to cure genetic disorders
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What are the two types of gene therapy?
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Changing the genes in body cells which are most affected by the disorder or changing the genes in the gametes which is illegal
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What are clones?
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Genetically identical organisms
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How do you clone an adult animal?
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The nucleus of a sheep's cell is removed then replaced by another which is diploid from an udder cell of a different sheep. The cell is given an electric shock so that it started dividing by mitosis, the dividing cell is implanted into the uterus of a surrogate mother sheep and the result is Dolly, a clone of the sheep
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How do you clone plants?
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Parent plant - cuttings are taken each with a new bud on - these cuttings are kept in moist conditions until thy're ready to plant - cloned plant
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What is tissue culture?
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Parent plant - tissue removed from the tip of plant - tissue placed on a medium containing growth hormones - hundreds of clones can be made from just one parent plant
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What are the pros and cons of commercial use?
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You can be fairly sure of the characteristics of the plant and its possible to mass produce plants that are hard to grow from seeds. But if the plants suffer from a disease they'll all have the same problems and there are problems with lack of genetic variation
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What is a population?
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All the organisms of one species in a habitat
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What is a community?
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Populations of different species in a habitat
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How do you use a quadrat to estimate population sizes?
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Count all the organisms in a 1m2 quadrat and multiply the number by the total area of the habitat
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What is distribution?
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Where organisms are found within a particular area
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How is the abundance of each organism shown in kite diagrams?
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THe thickness of the kit shape
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What is the distribution of organisms affected by?
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Abiotic factors such as light, temperature, water, oxygen, salinity and soil quality
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Why is the distribution of organisms affected by abiotic factors?
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Organisms are adapted to live in certain conditions which means they're more likely to survive and reproduce in areas with these conditions
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What is zonation?
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The gradual change in the distribution of species across a habitat
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What can a gradual change in abiotic factors lead to?
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The zonation of organisms in a habitat
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Explain zone 1 in zonation
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Few plants can grow because salinity is very high
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Explain zone 2 in zonation
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Lichens and mosses can grow and can out compete the marram grass because they're better adapted to the less saline conditions
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Explain zone 3 in zonation
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Shrubs such as heather can grown and they out compete the lichens and mosses because they're better adapted to the lower salinity and deeper soil further away from the shore
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Explain zone 4 in zonation
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Trees such as birch and oak can grow and they out compete the mosses because they're better adapted to the low salinity and deep soil
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What is biodiversity and what does it include?
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Measure of the variety of life in an area and includes variation between individuals of the same species in an area and number of different species and habitats in an area
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Why is biodiversity important?
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Because ecosystems with a high level of biodiversity are healthier than those without because more diverse ecosystems are able to cope with changes
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What has the higher biodiversity, native woodlands or forestry plantations?
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Native woodlands because there is a variety of tree species, the trees are different sizes and ages and there is a variety of plant species, habitats and animal species
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Why do lakes have a higher biodiversity than fish farms?
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There are many different fish species and a variety of plant species and animal species
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WHat is the photosynthesis process?
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IT uses energy from the sun to change carbon dioxide and water into glucose and oxygen. It takes place in chloroplasts in plant cells which contain pigments like chlorophyll that absorb light energy
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What is the symbol equation for photosynthesis?
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6CO2 + 6H20 -> C6H1206 + 602
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What are the two main stages in photosynthesis?
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Light energy is used to split water it no oxygen gas and hydrogen ions and then carvon dioxide gas combines with the hydrogen ions to make glucose and water
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What is glucose converted into?
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For respiration, stored in seeds, making proteins, making cell walls and stored as starch
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What is starch?
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It is an insoluble carbohydrate which makes it good for storing because it can't dissolve in water and doesn't affect the water concentration inside cells
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