Biology GCSE, B1 (OCR)

Pregunta	Respuesta
What temperature do enzymes work best at?	37 degrees (celsius)
If the body's temperature is too high: a) How does the body lower the temperature? b) What are the dangers?	a) The blood vessels widen (vasodilation) so the blood flows nearer to the skin and heat is transferred to the environment. Sweating works because when the water evaporates, heat is drawn from the skin. b) Dehydration
If the body's temperature is too low: a) How does the body raise the temperature? b) What are the dangers?	a) The blood vessels constrict (vasoconstriction) so blood flow near the skin is reduced. b) Hypothermia (when body temperature is below 35 degrees (celsius).
What are shivers, and why do we get them?	Tiny muscle contractions, to generate heat energy.
What are the differences between the two types of diabetes?	Type I is where the pancreas doesn't produce insulin, so you have to be injected with it. Type II is when the cells that respond to insulin become desensitised, so injecting insulin is useless. It's treated by diet.
What is insulin?	Insulin is a hormone released by the pancreas to control blood sugar levels. It converts glucose in the blood to glycogen in the liver.
What are hormones?	Hormones are chemical messages released into the blood stream. They travel much slower than nerve impulses.
How does the heart pump blood around your body?	The heart relaxes to fill with blood, then contracts to squeeze the blood out into the arteries.
Name a purpose of the circulatory system, other than pumping blood.	It carries oxygen and glucose in your blood to the body's cells, so that energy can be released through aerobic respiration.
What is the definition of 'health'?	Being free from infection.
What is the definition of 'fitness'?	How much physical activity you're capable of doing, and how quickly your body recovers afterwards.
How is cardiovascular efficiency measured?	How well your heart copes with aerobic excercise, and how quickly it recovers afterwards.
What are the aspects of fitness that can be measured?	Cardiovascular efficiency, flexibility, stamina, strength, agility, speed.
How is blood pressure measured?	In mmHg (milimetres of mercury). It's shown by 2 measurements, systolic and diastolic. i.e. 120/80 mmHg.
What is blood pressure?	A measure of the force of blood per unit area as it flows through the arteries.
What does homeostasis try to keep balanced?	CO2 levels in the blood, water levels, temperature.
What is the definition of 'homeostasis'?	The body's automatic control system to keep a constant internal environment.
What is the purpose of homeostasis?	To ensure that cells can function efficiently.
Name the three drug classes, from most dangerous to least, and give an example for each.	Class A (heroin), Class B (speed), Class C (steroids).
Other than drug classes, how else can you classify drugs?	Beneficial/harmful, legal/illegal, etc.
What are the 4 categories of drugs, and how do they work?	Painkillers (block nerve impulses), depressants (decrease brain activity), hallucinogens, stimulants (cause more transmitters to cross the synapses).
What is the definition of a drug?	A chemical that alters your mind or body.
What is the definition of an addiction?	Psychological or physical need for a drug.
Name the 4 main withdrawal symptoms.	Cravings, sweating, shaking, nausea.
What is the definition of rehabilitation? (in the context of addictions)	Learning to live without the drug.
What are the short-term effects of drinking alcohol?	Lack of balance and muscle control, blurred vision and slurred speech, poor judgement, drowsiness, vasodilation.
What are the long-term effects of drinking alcohol?	Liver damage (working too hard to removing the toxins), brain damage (dehydration).
What do cigarettes contain?	The tar contains irritants and carcinogens. Nicotine, carbon monoxide.
What can smoking lead to?	emphysema (damaged alveoli), bronchities, heart disease, cancer (mouth, throat, lungs, oesophagus).
What are most inherited diseases caused by?	Recessive faulty alleles.
Give an example of an inherited disease.	Sickle cell anemia, red-green colour blindness, cystic fibrosis.
What is our gender determined by?	Sex chromosomes (X and Y).
Which chromosomes do the gametes carry?	Egg cells have an X chromosome; 50% of sperm cells carry Y, the other half carry X.
What does gender depend on?	Whether the egg is fertilised by an X or Y carrying sperm.
What is variation?	Differences between individuals of the same species.
Why do genetic variations occur?	We inherit different combinations of genes.
What can variations be caused by?	Mutations, the random nature of fertilisation, environmental causes, differences between individual gametes.
What are alleles?	Different versions of a gene.
What is a gene?	A section of a chromosome that is coded for an inherited characteristic.
What are the scientific names for dominant and recessive alleles?	Dominant = homozygous, Recessive = heterozygous.
What do plant hormones control?	The growth of shoots and roots, the flowering and ripening of fruits.
How do auxins move through a plant?	In solution.
Where are auxins made?	In the shoot tip.
How is the auxins distribution throughout the plant determined?	By light. When light shines on a root: 1. Hormones in direct sunlight are destroyed. 2. Hormones on the shaded side continue to elongate. 3. Shoot leans towards the light.
Auxins affect the plant growth by responding to... (2 things)	Geotropism (gravity), phototropism (light).
Roots grow with... (2 things)	Negative phototropism (away from the light), positive geotropism (with gravity).
Shoots grow with... (2 things)	Positive phototropism (towards light), negative geotropism (against gravity).
Name 2 commercial uses of plant hormones, and how they work.	Control of dormancy (speed up/slow down plant growth and bud development), fruit-ripening hormone (can be accelerated or delayed), rooting powder (encourages root development in cuttings), selective weed killers (disrupt the growth patterns of some plants but not others).
What does food give us?	Energy and nutrients.
Why must a balanced diet contain meats?	They provide energy.
What are fats made of?	Fatty acids and glycerol.
Why must a balanced diet contain protein?	Energy if low on carbohydrates, repair of tissues, growth.
What are proteins made of?	Amino acids.
Why must a balanced diet contain carbohydrates?	They provide energy.
What are carbohydrates made of?	Simple sugars.
Where are carbohydrates stored?	In the liver as glucose, under the skin/around organs (when converted to fats).
What do you need to keep the body healthy?	Minerals, vitamins, fibre, water.
What does protein deficiency lead to?	Kwashiokor.
When might you need more protein than normal?	Pregnancy, teenagers. (Growth)
What is the difference between essential and non-essential animo acids?	Essential amino acids have to be eaten in, non-essential acids are produced in the body.
Describe 1st and 2nd class proteins.	1st class proteins are from animal origins and contain essential amino acids. 2nd class proteins are from plant origins.
Describe EAR.	Estimated Average Daily Requirement, EAR = 0.6xbody mass (kg), varies depending on ages and pregnancy.
What does the amount of energy you need depend on?	Age, gender, activity levels.
To retain a healthy body mass, what do you need to do?	Balance the amount of energy you take in with the amount you use.
Describe BMI.	Body Mass Index, BMI = mass (kg) [divided by] height[squared] (m).
What can obesity lead to?	Arthritis, heart disease, cancer, Type II diabetes.
What are the consequences of eating disorders?	Body doesn't get the energy and nutrients it needs, can damage bones and reproductive organs.
What can cause eating disorders?	Bad self-image, a desire for perfection, low self-esteem.
Name an eating disorder.	Anorexia nervosa, bulimia nervosa.
What are the 2 nervous systems?	Peripheral Nervous System (PNS), receptors and neurones. Central Nervous System (CNS), brain and spinal cord.
What is the point of the nervous system?	Allows us to react to our surroundings, allows us to coordinate our behaviour.
What are receptors, and where do we have them?	Specialised nevre endings that generate nerve impulses. Skin, nose, tongue, ears, eyes.
What are neurones?	Specially adapted cells that carry a nerve impulse.
What are the 3 types of neurones, and their purposes?	Relay (brain and spinal cord), motor (brain to muscles and glands), sensory (receptors to brain).
What are nerve impulses?	Electrical messages carried along the axon of the neurones.
What are synapses?	Small gaps between neurones.
How do nerve impulses cross synapses?	Transmitter substance diffuses across the gap and binds with receptor molecules on the next neurone.
What is the difference between voluntary and reflex actions?	Voluntary: under conscious control of your brain. Reflex: bypasses your brain to give fast, automatic responses.
What is the purpose of reflex actions?	To protect us from harm.
Give an example of a reflex action.	Eyes restrict light coming in, etc...
What are the parts of the eye?	Iris, lens, retina, cornea.
Name 2 eye defects and their causes.	Colour blindness (specialised cells in the retina missing), long/short sight (eyeball/lens is the wrong shape).
How do we see?	Rays of light are refracted by the cornea, lens focuses them onto the retian so they converge at a single point. Receptor cells cause nerve impulse to pass onto the optic nerve in brain.
What are the two types of vision?	Monocular (eyes on the sides of the head), binocular (eyes close together on the front of the head).
Give an advantage for each type of vision.	Binocular: can judge speed and distance accurately. Monocular: each eye has a wide field of view.
Give a disadvantage for each type of vision.	Binocular: each eye has a limited field of view. Monocular: difficult to judge distance or speed.
How are disease symptoms caused by pathogens attacking the body?	They release toxins and damage cells.
Which 4 microorganisms are infectious diseases caused by? Give an example for each.	Protozoa (malaria), bacteria (cholera), fungi (athlete's foot), viruses (flu).
How are non-infectious diseases different to infectious ones?	No pathogens are involved, can't be caught from another person.
What causes non-infectious diseases?	Poor diet (skurvy), organ malfunction (diabetes), genetic inheritance (colour blindness), cells mutate (cancer).
What are tumours?	Cells divide uncontrollably forming lumps of cells.
What is the difference between benign and malignant tumours?	Benign: tumour that grows in one place. If cells break off and form secondary tumours it's malignant.
How can you reduce the risk of cancer?	Don't smoke, eat fibre, no excess alcohol, avoid sunburn.
Which pathogen is malaria caused by?	Protozoa.
How is malaria spread?	By vector.
How does the skin stop pathogens?	It acts as a barrier.
How does the stomach stop pathogens?	It produces hydrochloric acid which destroys microorganisms in food.
How does the respiratory system stop pathogens?	It produces mucus which traps the pathogens.
How does blood stop pathogens?	It clots at wounds to prevent pathogens from entering the bloodstream.
How do the two types of white blood cells deal with pathogens?	One type engulfs and then digests them. The other type creates antibodies that lock onto antigens on the surface of the pathogens, killing them. (Lock and key)
What is passive immunity?	When antibodies are put into the body, not created by it.
When is passive immunity needed?	Weak immune system, need a very quick response (snake bites).
What is a disadvantage of passive immunity?	No long-term immunity.
How do you get natural immunity?	When you're infected by a particular pathogen, your white blood cells make antibodies for them. These stay in the blood for years.
What is an advantage of natural immunity?	Can produce the needed antibodies more quickly the next time.
What does vaccination do?	Provides natural immunity from a disease without being infected with it.
What are the benefits of vaccination?	Diseases can be completely destroyed (smallpox), protects against potentially lethal diseases (polio).
What are the risks of vaccinations?	It's not 100% safe, could have a bad reaction.
Which pathogens can be killed by antibiotics?	Bacteria and fungi.
How do you kill viruses?	Antiviral drugs.
What happens if antibiotics are over-subscribed?	All the bacteria are killed except for the resistant ones which spread, creating super bugs (MRSA).
Why do we have to test new drugs?	To make sure they're safe and effective.
What is the advantage of using a blind trial when testing new drugs?	It eliminates psychological bias.
What is a double blind trial?	Neither the doctors or the volunteers know which volunteer has the placebo.
How can drugs be tested?	Computer models, animals, human tissue, healthy and infected volunteers.

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