Science B1

Pregunta	Respuesta
What is blood pressure measured in?	Millimetres of Mercury (mmHg)
What are the 2 measurements of blood pressure?	Systolic - the maximum pressure the heart produces Diastolic - the blood pressure between heart beats
What cause a blood pressure to increase?	Stress High Alcohol Intake Smoking Being Overweight
What causes a blood pressure to decrease?	Regular Exercise Eating A Balanced Diet
What are the problems with high blood pressure?	Blood vessels can burst which can cause damage to the brain otherwise known as a 'stroke'. It can also cause damage to the kidneys.
What are the problems with low blood pressure?	Dizziness and fainting as the blood supply to the brain is reduced. Poor circulation to other areas such as the fingers and toes.
What is fitness?	The ability to do physical exercise
What is health?	Being free from diseases such as those caused by bacteria and viruses.
How is fitness measured?	Strength - by the amount of weights lifted Flexibility - by the amount of joint movement Stamina - by the time of sustained exercise Agility - by changing direction many times Speed - by a sprint race By your cardiovascular efficiency
How does smoking increase blood pressure?	Carbon monoxide in cigarettes smoke causes the blood to carry less oxygen meaning the heart rate increases so that the tissues receive enough oxygen. Nicotine in cigarette smoke directly increases heart rate. Carbon monoxide decreases the oxygen-carrying capacity of blood. It combines with haemoglobin, preventing it from combining with oxygen, so less oxygen is carried.
What causes heart disease?	Restricted blood flow to the heart muscle.
What increase the risk of getting heart disease?	A high level of saturated fat in the diet, which leads to a build up of cholesterol in arteries. High levels of salt, which can increase blood pressure.
To have good health, you must eat a balanced diet containing the correct amounts of the chemicals found in food. What are these chemicals?	Carbohydrates - which are made up of simple sugars such as glucose. Proteins - which are made up of amino acids. Fats - which are made up of fatty acids and glycerol.
What makes a balanced diet vary?	Age Gender Level of Activity Religion Being Vegetarian or Vegan Food Allergies
When you eat too much fat and carbohydrates, how are they stored in the body?	Carbohydrates are stored in the liver as glycogen or converted into fats. Fats are stored under the skin and around organs as adipose tissue.
How do you calculate the Estimated Average Daily Requirements (EAR)?	EAR in g = 0.6 x body mass in kg
What causes the condition 'Kwashiorkor'?	Too little protein in the diet. It is more common in developing countries due to overpopulation and lack of money to improve agriculture.
What are proteins from meat and fish called?	First-class Proteins. They collect all the essential amino acids that cannot be made by the human body.
What are proteins from plants called?	Second-class Proteins. This is because they do not contain all the essential amino acids.
How is Body Mass Index (BMI) calculated?	BMI = (mass in kg)÷(height in m)^2
What are the categories for BMI?	30+ - Obese 25-30 - Overweight 20-25 - Normal -20 - Underweight
What causes 'Malaria'?	A protozoan called 'Plasmodium' which feeds on human red blood cells.
What is a parasite?	An organism that feeds on another living organism (a host), causing it harm. 'Plasmodium' is a parasite and humans are its host.
How can we stop the spread of 'Malaria'?	By draining stagnant water Putting oil on water surface Spraying insecticide
How can we reduce the risk of some cancers?	Not smoking reduces the risk of lung cancer Using sunscreen reduces the risk of skin cancer
What is a benign tumour?	A benign tumour cell is a cell that divides slowly and is harmless, for example; warts.
What is a malignant tumour?	A malignant tumour cell is a cell that displays uncontrolled growth and may spread, for example; cancers
What are pathogens?	Disease-causing organisms
How do pathogens produce the symptoms of an infectious disease?	By damaging the body's cells or producing poisonous waste products called toxins.
How does the body protect itself from illness?	By producing antibodies, which lock antigens on the surface of pathogens such as bacterium. This kills the pathogen.
What is the difference between active and passive immunity?	Active immunity is when human white blood cells produce antibodies. This can be a slow process but has a long lasting effect. Passive immunity is when vaccinations use antibodies from another human or animal. This has a quick but short term effect.
What is the process of immunisation/vaccination?	It starts with injecting a harmless pathogen carrying antigens. The antigens trigger a response by white blood cells, producing the correct antibodies. Memory cells remain in the body, providing long lasting immunity to that disease.
What do antibiotics fight against?	Bacteria and Fungi
What do antiviral drugs fight against?	Viruses
What is the difference between antibiotics and antiviral drugs?	An antibiotic destroys a pathogen. An antiviral drug slows down the pathogen's development.
What is a placebo?	A harmless pill. Placebos are used as a comparison in drug testing so the effect of a new drug can be assessed.
What happens in a Blind Trial?	The patient does not know whether they are receiving a new drug or a placebo.
What happens in a Double Blind Trial?	Neither the patient nor the doctor know which treatment is being used.
Why do we use blind and double blind trials?	To avoid a 'feel good factor' and a biased opinion.
What can excessive use of antibiotics result in?	Resistant forms of bacteria being more common than non-resistant forms.
What are light rays refracted by?	The cornea and lens.
What does binocular vision do?	Helps to judge distance by comparing the images from each eye; the more different they are, the nearer the object
What is accommodation?	When the eye can focus light from distant or near objects by altering the shape of the lens.
How does the eye focus on distant objects?	The ciliary muscles relax and the suspensory ligaments tighten, so the lens has a less rounded shape.
How does the lens focus on near objects?	The ciliary muscles contract and the suspensory ligaments slacken, so the lens regains a more rounded shape due to its elasticity.
What do the ciliary muscles do?	Control suspensory ligaments.
What does the outer cornea do?	Refracts light rays.
What does the pupil do?	Allows light rays to enter the eye.
What does the coloured iris do?	Controls the amount of light entering the eye.
What do the suspensory ligaments do?	Alter the shape of the lens in focusing.
What does the optic nerve do?	Carries nerve impulses to the brain.
What happens on the retina?	A focused image is formed which is sensitive to light.
What does the convex lens do?	Refracts light rays and focuses light onto the retina.
What causes red-green colour blindness?	A lack of specialised cells in the retina.
What causes long and short sight?	The eyeball or lens being the wrong shape. In long sight, the eyeball is too short or the lens is too thin, so the image is focused behind the retina. In short sight, the eyeball is too long or the lens is too rounded, so the lens refracts light too much, so the image is focused in front of the retina.
How is long and short sight corrected?	Corneal Surgery A lens in glasses Contact Lenses A convex lens is used to correct long sight. A concave lens is used to correct short sight.
What are nerve cells called?	Neurones.
What do nerve impulses pass along?	The axon
How do you show what happens in a reflex action?	By using a reflex arc.
What are the links in a reflex arc?	Stimulus Receptor Sensory Neurone Central Nervous System Motor Neurone Effector Response
What is the pathway for a spinal reflex?	Receptor Sensory Neurone Relay Neurone Motor Neurone Effector
How are neurones adapted?	By being long By having branched endings called dendrites to pick up impulses By having an insulator sheath
What is a synapse?	The gap between neurones. The arrival of an impulse triggers the release of a transmitter substance, which diffuses across the synapse. The transmitter substance binds with receptor molecules in the membrane of the next neurone causing the impulse to continue.
What are the classes of drugs?	Class A drugs are the most dangerous and have the heaviest penalties. Class C drugs are the least dangerous and have the lightest penalties.
What are the different types of drugs?	Depressants - alcohol, solvents, temazepam Painkillers - aspirin, paracetamol Stimulants - nicotine, MDMA (ecstasy), caffeine Performance Enhancers - anabolic steroids Hallucinogens - LSD
What do depressants do?	Block the transmission of nerve impulses across synapses by binding with receptor molecules in the membrane of the receiving neurone.
What do stimulants do?	Cause more neurotransmitter substances to cross synapses.
What are cilia and where are they found?	Cilia are tiny hairs which are found in the epithelial lining of the trachea, bronchi and bronchioles. Cigarette smoke contains many chemicals that stop cilia moving.
What causes a smokers cough?	Dust and particulates in cigarette smoke collecting and irritating the epithelial lining Mucus not being moved by the cilia
What is the alcohol content of alcoholic drinks measured in?	Units of Alcohol
What does drinking alcohol do?	Increases the time taken to react and therefore increases the risk of accidents.
What is cirrhosis of the liver?	When the liver is damaged when it breaks down toxic chemicals such as alcohol.
What is homeostasis?	Keeping a constant internal environment.
What does homeostasis involve?	Balancing bodily inputs and outputs.
What can high temperature cause?	Heat Stroke - skin becomes cold and clammy and pulse is rapid and weak Dehydration - loss of too much water Both are fatal if untreated.
How does the body avoid overheating?	Sweating increases heat transfer from the body to the environment.
What can a very low temperature cause?	Hypothermia - slow pulse rate, violent shivering Fatal if untreated.
What is blood temperature monitored by?	The hypothalamus gland in the brain.
What controls reaction to temperature extremes?	The nervous and hormonal systems which trigger vasoconstriction or vasodilation.
What is vasoconstriction?	When the body is too cold the small blood vessels in the skin constrict. This causes less blood flow and less heat transfer.
What is vasodilation?	When the body is too hot, small blood vessels in the skin dilate. This causes more blood flow near the skin surface resulting in more heat transfer.
What hormone controls blood sugar levels?	Insulin
What is type 1 diabetes caused by and how is it treated?	The pancreas not producing any insulin, so must be treated by doses of insulin.
What is type 2 diabetes caused by and how is it controlled?	Caused either by the body producing too little insulin or the body not reacting to it. Can be controlled through diet.
What does insulin do?	Converts excess glucose in the blood into glycogen, which is stored in the liver. This regulates the blood sugar level.
What is phototropism?	A plant's growth response to light.
What is geotropism?	A plant's growth response to gravity.
How do different parts of a plant respond?	Shoots are positively phototropic (they grow towards the light) and negatively geotropic (they grow away from the pull of gravity). Roots are negatively phototropic (they grow away from light) and positively geotropic ( they grow with the pull of gravity).
What are auxins?	A group of plant hormones. They move through the plant in solution and are involved in phototropism and geotropism.
Where is a higher amount of auxin found and what does it do ?	More auxin is found in the shady part of shoots. A higher amount of auxin will increase the length of cells. Therefore the increase in cell length on the shady side of the shoot causes curvature of the shoot towards the light.
What are some commercial uses of plant hormones?	As selective weed killers, which kill specific weeds and increase crop yields. As rooting powder to increase root growth of cuttings. To delay or accelerate fruit ripening to meet market demands. To control dormancy in seeds
What are alleles?	Different versions of the same gene.
How are some human characteristics, such as facial features, received?	They can be inherited. They can be dominant or recessive.
What do dominant and recessive characteristics depend on?	Dominant and recessive alleles.
What is the difference between dominant and recessive alleles?	Dominant alleles are expressed when present but recessive alleles are expressed only in the absence of the dominant allele.
What does the number of chromosomes depend on?	The species of organism. Most body cells have the same number of chromosomes. Human cells have 23 pairs.
What do sex chromosomes determine?	The sex in mammals. Females have identical sex chromosomes called XX. Males have different sex chromosomes called XY.
What sex chromosomes do the sperm and egg carry?	A sperm will carry either an X or a Y chromosome. All eggs carry an X chromosome.
What is genetic variation caused by?	Mutations - which are random changes in genes or chromosomes. Rearrangement of genes during the formation of gametes. Fertilisation - which results in a zygote with alleles from the father and mother.
What does homozygous mean?	Having identical alleles.
What does heterozygous mean?	Having different alleles.
What does a monohybrid cross involve?	Only one pair of characteristics controlled by a single gene, one allele being dominant and one recessive.
What is a person's genotype?	Their genetic make-up.
What is a person's phenotype?	Which alleles are expressed.
What are inherited disorders caused by?	Faulty genes.
How can you predict the probability of inheriting an inherited disorder?	Using a genetic diagram.

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