Biology Core AQA

What is needed for a balanced diet?
Carbohydrates, Proteins, Vitamins, Minerals, Fibre, Fat and Water
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What happens if an individual's diet becomes unbalanced?
The person becomes malnourished
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What is metabolic rate?
The rate at which the reactions of your body take place, particularly within cells
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What are the factors that affect metabolic rate?
Proportion of muscle to fat in your body, amount of exercise you do and inherited factors
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What happens when the energy taken in is less than the energy used?
You lose mass
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What happens if more energy is taken in than is used?
You gain mass
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People who are very fat are said to be...
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Give an example of a health problem that obesity can cause
Type 2 Diabetes, Heart disease, etc...
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What can too little food (starvation) lead to?
Deficiency diseases due to a lack of vitamins and minerals. Person may also find it difficult to walk around
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What can inheritance affect?
Metabolic rate and cholesterol levels
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What is "good" cholesterol/HDL used for?
Cell membranes and production of vital substances/hormones
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What do high levels of "bad" cholesterol/LDL lead to?
Heart disease
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What can increase cholesterol levels?
Foods high in saturated fats
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How can someone increase metabolic rate and lower cholesterol levels?
By exercising regularly
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What are pathogens?
Microorganisms that cause disease
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What are the main two types of pathogen?
Bacteria and viruses
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What happens if pathogens are inside your body?
They reproduce rapidly and produce toxins [that make you ill]
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Where do viruses reproduce?
Inside the body's cells
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What can happen to the cells if a virus reproduces in them?
It becomes damaged
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What can washing hands do?
Remove pathogens from them
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Who was Semmelweiss?
A doctor who realised infection could be transferred from person to person in a hospital. He told his staff to wash their hands between treating patients
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What does the skin do?
It prevents pathogens from getting into the body
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What does the mucus do?
Traps pathogens
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What does the stomach acid do?
Kills pathogens
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What three things do white blood cells do?
Ingest pathogens, produce antibodies to destroy particular pathogens, produce antitoxins to counteract toxins that pathogens produce
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What do antibiotics do?
Kill infective bacteria in the body
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Why are viruses difficult to kill?
They reproduce inside the body's cells so any treatment could also damage the cells
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What do painkillers do?
Relieve symptoms of a disease but do not kill the pathogen
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Where can be bacteria be grown?
On agar jelly in a petri dish
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Why must all materials and equipment be sterilised before investigation?
To ensure that unwanted microorganisms do not infect the culture
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What can uncontaminated cultures be used for?
To investigate the effect of antibiotics and disinfectants on the bacteria
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How can a bacterial culture be kept pure?
The microorganisms from the air must be killed or prevented from entering the culture
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What happens if a pathogen changes by mutation? Why?
A new strain may spread rapidly because not many people are immune to it
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What is an epidemic?
When diseases spread within a country and more cases are being recorded than expected
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What is a pandemic?
When diseases spread across countries
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How have bacteria developed resistance to antibiotics?
Through natural selection
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What is MRSA?
MRSA (Methicillin-Resistant Staphylococcus Aureus) is an antibiotic-resistant bacterium
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Explain the process of bacteria becoming resistant through natural selection
Antibiotics kill pathogens of non-resistant strain, resistant bacteria survive and reproduce, a whole population of a resistant strain develops
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Why should antibiotics not be used for mild infections?
To slow down the rate of development of resistant strains
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What do vaccines contain?
Dead or inactive forms of the pathogen
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What can vaccines protect against?
Both bacterial and viral pathogens
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What does the vaccine encourage your white blood cells to do?
To produce antibodies that will recognise the antigen on the pathogen
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What does this help to do in future?
It allows your body to be immune to future infections of this particular pathogen because your body can respond rapidly as if you had already had this disease
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What does the MMR vaccine protect against?
Mumps, Measles and Rubella
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What do receptors in the nervous system detect?
External stimuli
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Where are the receptors found?
In the sense organs (the eyes, ear, nose, tongue and skin)
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How does the brain coordinate responses to stimuli?
Receptors stimulated, electrical impulses pass to the brain along neurons (nerve cells), brain coordinates response to the stimuli
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What makes up the CNS (Central Nervous System)?
Brain and Spinal Chord
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What are motor neurons?
Neurons that carry impulses from the CNS to the effector organs
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What is an effector organ?
A muscle or gland that responds to impulses from the nervous system
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How do the muscles and glands respond to the impulses from the central nervous system?
Muscles contract, glands secrete chemicals
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What are the steps involved in reflex actions?
Receptor detects stimuli, sensory neuron transmits impulse to CNS, relay neuron passes impulse on, motor neuron stimulated, impulse passes to an effect (muscle/gland), action is taken
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What is a synapse?
A gap between neurons where the transmission of information is chemical rather than electrical
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What is a reflex arc?
The sequence that brings about the reflex
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What do reflexes do?
Protect us from damage
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Where is FSH (Follicle Stimulating Hormone) made?
In the pituitary gland
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What does FSH do?
Causes eggs to mature and oestrogen to be produced
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Where is oestrogen produced?
In the ovaries
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What does oestrogen do?
Inhibits the production of FSH and stimulated the production of LH. Also stimulates the womb lining to develop to receive the fertilised egg
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Where is LH (Luteinising Hormone) produced?
In the pituitary gland
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What does LH do?
Stimulates thee mature egg to be released from the ovary (ovulation)
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How long is the menstural cycle and when does ovulation take place?
The menstrual cycle takes 28 days, with ovulation about 14 days into the cycle
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What do contraceptive pills contain?
They may contain oestrogen and progesterone
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What does the pill do?
Inhibits the production of FSH so no eggs can mature
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Why are FSH and LH given to women who cannot produce mature eggs?
To help her to produce mature eggs - FSH causes the egg to mature and LH stimulates ovulation
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What are the advantages to contraceptive pills?
Help reduce family size which has reduced poverty in some areas, allows women to plan pregnancies
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What are the disadvantages to contraceptive pills?
Can cause side effects, some people object to its use for ethical or religious reasons
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What are the advantages of fertility treatment?
Can help infertile couples who are having IVF, IVF helps couples to have a baby
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What are the disadvantages of fertility treatment?
Expensive, some people think its unethical, extra embryos prdouced may be stored or destroyed
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What internal conditions are controlled?
Water content, ion content, temperature and blood sugar level
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Why must we keep our temperature constant?
Because otherwise the enzymes in the body will not work properly or will stop working
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How is the level of sugar in our body controlled?
By the pancreas
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What is phototropism?
The response of a plant to light, controlled by auxin
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What is gravitropism?
The response of a plant to the force of gravity controlled by auxin
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Where do shoot grow towards?
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Where do roots grow towards?
Gravity and water
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What is auxin?
The hormone that controls phototropism and gravitropism
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What can plant growth hormones be used as?
Weed killers and to stimulate root growth
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What happens if plant hormones are used incorrectly?
They can cause damage to the environment. e.g. weed killers may harm other more useful plants
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What are the test subjects when developing new medicines?
First tests are on cells and tissues or organs, then animals, then healthy human volunteers and then patients
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Why are healthy people given very low doses of the drug?
To find out whether it is safe or not
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What is a placebo?
A substance used in the clinical trials which does not contain the drug at all
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Why are placebos used?
To see if the drug being tested really has an effect on the patient
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What is a double-blind trial?
Where neither the doctor nor patient knows who is given a drug
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What was thalidomide orignally developed as?
A sleeping drug
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Why was thalidomide given to pregnant women?
To control morning sickness
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What happened to some babies as a result of taking the thalidomide?
They were born with limb abnormalities
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What is thalidomide now used for?
Treating leprosy
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What are statins?
Drugs that lower the amount of "bad" cholesterol carried in the blood
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What do statins help reduce the risk of?
Heart and circulatory diseases
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What are drugs?
Chemicals which alter the body's chemistry
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What can happen as a result of taking drugs?
You can become addicted to it
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What can cannabis cause?
Mental illness
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Why can cannabis lead to hard drugs?
Because it must be bought from drug dealers, meaning usesers can be put into contact with hard drugs
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What are steroids?
Drugs used to build up muscle mass
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Why is the use of performance-enhancing drugs unethical for most people?
Because it gives an unfair advantage to the athletes who use them
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What are adaptations?
Special features that makes an organism particularly well suited to an environment where it lives
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What is an extremophile?
Microorganisms that are adapted to live in conditions where enzymes won't usually work because they would denature
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Why may coat colour of an animal change?
It provides year-round camouflage
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Which animals have a large surface area:volume ratio?
Animals in hot dry areas
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Which animals have a small surface area:volume ratio and are usually large?
Animals in cold areas
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How have plants adapted to live in dry conditions?
Reduced leaf surface area, tissues which store water, extensive root systems
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What do animals compete for?
Water, food, space, mates and breeding sites
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Give some examples of how animals may be adapted to compete and survive
Warning colours, camouflage, speed, horns, etc.
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Why do plants spread their seeds across a wide area?
So that they don't compete with themselves
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How do plants spread their seeds?
Through animals (animals eat the plant's fruit/seeds), by using the wind
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What affects the distribution of living organisms?
Changes in the environment
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What can these changes be caused by?
Living and non-living factors
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Examples of non-living factors
Temperature, rainfall, light levels, oxygen levels
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Examples of living factors
New predator, new disease, more food or habitats
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What can indicate air pollution?
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What can indicate water pollution?
Freshwater invertebrates
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What is biomass?
The mass of living material in plants and animals
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What do plants transfer light energy into?
Chemical energy that is passed along the food chain
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Does the biomass decrease or increase after the previous stage?
It decreases; the biomass at each stage in the food chain is less than at the previous stage
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Does energy decrease or increase as you go down the food chain?
It decreases because energy is being used by the organism and is transferred to the surroundings
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What are detritus feeders?
They are decomposers (such as some types of worm) that start the decay process by eating dead animals or plants
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What do the decomposers (such as bacteria and fungi) do after the animal and plants have been broken down?
They break down the waste material or the dead animal/plant further
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When is decay faster?
It is quicker in warm, moist, aerobic conditions
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How are waste/dead organisms recycled by nature?
They are returned as nutrients to the soil
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How can humans recycle waste?
In sewage treatment plants and compost heaps
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What is the constant cycling of carbon in nature called?
The Carbon Cycle
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What two processes does the recycling of carbon involve?
Photosynthesis and respiration
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Does photosynthesis add or remove carbon dioxide from the atmosphere?
It removes carbon dioxide from the atmosphere
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What returns carbon dioxide to the atmosphere?
Respiration of animals and plants as well as combustion
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What is a chromosome?
A thread-like structure carrying the genetic information found in the nucleus of a cell
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What are genes?
Short sections of DNA carrying genetic information found in the chromosomes
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What are gametes?
Sex cells which have half the chromosome number of an ordinary cell (they only have 23 chromosomes)
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What do the genes control?
The different characteristics of your body
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What doesn't asexual reproduction involve?
The joining/fusion of gametes as all genetic information comes from the one parent
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What are clones?
Identical copies of the parent organism produced through asexual reproduction
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How many parents does sexual reproduction involve?
Two parents
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What does sexual reproduction lead to (in relation to offspring)?
A variety in offspring
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What causes a difference in characteristics of individuals of the same species?
Inherited genes, the environment, or both
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How can plant clones be made?
By taking cuttings from mature plants
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What is tissue culture?
Using a small group of cells from a plant to make new plants. It is a newer method of cloning
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What artificial process is used to clone animals?
Embryo transplants
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What is genetic modification/engineering?
A technique for changing the genetic information of a cell
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Explain the process of adult cell cloning
The nucleus is removed from unfertilised egg cell, nucleus from skin cell is removed and placed into empty egg cell, new egg cell is given electric shock to cause it to divide, embryo is formed, after embryo develops, it is placed in host mother
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Benefits of adult cell cloning?
Can save animals from extinction, development of cloned animals which have been genetically engineered to produce valuable proteins in their milk can have uses in medicine
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Disadvantages of cell cloning?
Ethical concerns, limits variation in population which is a problem for natural selection if environment changed, concerns about using technique to clone humans in future
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What is genetic engineering used for?
Transferring a gene from one organism to another
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What is used to 'cut out' the gene from a human chromosome?
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Where is the gene inserted into?
A bacterial cell
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When can genes be transferred to the cells of animals/plants?
During early stages of development
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What was Lamarck's theory?
Characteristics which develop during an organism's lifetime can be passed on to the next generation
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What was Darwin's theory?
Small changes in organisms take place over a long time. All organisms in a species vary and are some are more likely to survive (natural selection). The best adapted breed and pass on its characteristics
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Why wasn't Darwin's theory accpeted at first?
It challenged the idea that God made all animals and plants that live on Earth, scientists weren't convinced because they think he had insufficient evidence
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What is the sequence for natural selection?
Mutation → Variation → Best adapted → Survival → Breed → Genes passed on to offspring
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What are the main 'kingdoms'?
Animal kingdom, plant kingdom, kingdoms which contain microorganisms
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What are evolutionary trees?
Models that can be drawn to show relationships between different groups of organisms
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What are evolutionary relationships?
Model of relationships between organisms which suggests how long ago they evolved away from each other and how closely related they are in evolutionary terms
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What do ecological relationships tell us?
How species have evolved together in an environment
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What is a species?
A group of organisms with many features in common which can breed successfully producing fertile offspring
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Card 2


What happens if an individual's diet becomes unbalanced?


The person becomes malnourished

Card 3


What is metabolic rate?


Preview of the front of card 3

Card 4


What are the factors that affect metabolic rate?


Preview of the front of card 4

Card 5


What happens when the energy taken in is less than the energy used?


Preview of the front of card 5
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