Biology Unit 1 Revision


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Define Metabolic rate?
The rate at which chemical reactions happen in your body
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What factors effect your metabolic rate?
Higher proportion of muscle to fat = high metabolic rate. Physically bigger people = high metabolic rate. Men = Higher. Regular exercise = boost metabolic rate
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Define Malnourished
Malnourised is different from starvation, which is not getting enough food of any sort. People's diet is badly out of balanced.
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What are the 2 main types of pathogens?
Bacteria and Viruses
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Are very small living cells (about 1/100th the size of your body size). They make you feel ill by damaging your cells and producing toxins.
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Not cells. about 1/100th the size of a bacteria. They replicate themselves by invading your cells and produce many copies of themselves and burst releasing all the new copies. This damages cells
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How do white blood cells work?
They travel around in your blood and crawl into every part of you, constantly patrolling for microbes. They engulf foreign cells and digest them. They produce antibodies (proteins). Produce antitoxins -counteract toxins produced by invading bacteria
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How do vaccinations work?
Vaccinations involve injecting small amounts of dead or inactive microorganisms which carry antigens meaning your body produces antibodies to attack them. But if live microorganisms appear, the white blood cells can rapidly reproduce.
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Advantages and Disadvantages of vaccinations
Pros = Helped control lots of infectious diseases that were once common in the UK/ Prevents big outbreak of diseases Cons= vaccines don't always work / can sometimes have a bad reaction
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How do painkillers work?
Are drugs that relieve pain. However they don't actually tackle the cause of the disease they just help to relieve the symptom
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How do anitbiotics work?
They actually kill (or prevent the growth of) the bacteria causing thr problem without kiling your own body cells. Different antibiotics kill different types of bacteria.
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How do bacteria become resistant to antibiotics?
The bacteria mutate and sometimes this mutation means that they're resistant to an antibiotic.The resistant bacteria will survive and reproduce and the population of the resistant stain will reproduce.
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Who made doctors wash their hands so that bacteria didn't spread between the wards?
Ignaz Semmelweis
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What happened when people started washing their hands before entering his ward in 1840s?
Death rate dropped from 12% to 2%. But he couldn't prove his method so it was dropped when he left
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What are receptors?
Cells that detect stimuli (changes to the environment)
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How are light receptors like most animal cells?
Have a nucleus, cytoplasm and cell membrane
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What is involved in a reflex action
Receptors - Sensory Neurone - Relay Neurone - Motor Neurone - Synapses - Effectors
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What happens at a synapse?
A nerve signal is transferred by chemicals which diffuse across the gap. These then set off an new electrical signal in the next neurone.
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Reflex Arc when a bee stings finger
1) Bee sting finger 2) Stimulation of the pain receptor 3) Impulses travel along the sensory neurone 4) Impulses are passed along a relay neurone, via a synapse 5) Impulses travel along a motor neurone 6) When impulses reach muscle it contracts
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How does the body control the water content of the body?
Water leaves the body via the lungs when we breathe out and via the skin when we sweat to cool us down and excess water is lost via the kidneys in the urine
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How does the body control the ion content of the body?
Ions are lost vis the skin when we sweat and excess ions are lost via the kidneys in the urine
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Why does the body control its temperature?
To maintain the temperature at which enzymes work best at
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Why does the body control the blood sugar levels?
To provide the cells with a constant supply of energy
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What coordinates the processes within the body?
Chemical substances called hormones. They are secreted by glands and are usually transported to their target organs by the bloodstream
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What do hormones regulate?
The functions of many organs and cells
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What hormones are involved in the menstrual cycle of a woman?
Follicle Stimulation Hormone (FSH) Luteinising Hormone (LH) Oestrogen
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What is FSH?
Its secreted by the pituitary gland and causes eggs to mature in the ovaries. It also stimulates the ovaries to produce hormones including oestrogen
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What is LH
Stimulates the release of eggs from the ovary
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What id Oestrogen?
Is secreted by the ovaries and inhibits further production of FSH
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Define a Hormone?
Are chemical messengers which travel in the blood to activate target cells
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What hormones do modern contraceptive pills include?
Lower amounts of oestrogen and higher levels of progesterone because oestrogen made people have headaches, nausea....
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How does the contraceptive pill work?
The hormones inhibit the production of FSH, which stops the egg maturing in the ovaries
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What happens if you increase the amount of FSH
More eggs mature, this means that women have an increased chance of becoming pregnant and too many eggs could be stimulated
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How does In Vitro Fertilisatioin (IVF) work?
FSH and LH are given before egg collection to stimulate egg production. Collecting eggs from the woman's ovaries and fertilising them in a lab using sperm. These then grow into embryos and transferred back into the urteus.
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What are plants sensitive to?
Light, Moisture and Gravity
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What is phototropism?
This is when plants grow towards the light. The shoot tip is exposed t light, more auxin accumulates on the side that's in the shade. Meaning cells grow faster on the shaded side,
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What happens to the shoots in plants?
Grow towards light and against the force of gravity
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What happens to the roots in plants?
Grow towards moisture and in the direction of the force of gravity
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What hormone do plants produce to coordinate and control growth/
Auxin controls phototropism and geotropism (gravitropism)
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How are plant growth hormones used in agriculture?
weed killers and as rooting hormones
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How are drugs tested before use?
Tested for toxicity, efficacy and does: it the laboratory (using cells, tissues and live animals). In clinical trails involving healthy volunteers and patients. Very low doses of the drug are given at the start of the clinical trial.
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What is a double-blind trial?
Some patients are given a placebo, which doesn't contain the drug. Neither the doctors nor the patients know who has received a placebo and who has received the drug until the trial is complete
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What is used to lower the risk of heart and circulatory diseases/
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Thailomide is a drug that was developed as a sleeping pill. What was it also developed for?
Relieving morning sickness in pregnant women.
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What was the problem with thailomide?
Not been tested for use in pregnant women. Unfortunately, many babies were born with severe limb abnormalities. The drug was then banned. Drug testing since has been much more vigorous.
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Name 3 illegal drugs
Ecstasy, cannabis and heroin
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What is the issue with cannabis?
Cannabis smoke contains chemicals which may cause mental illness in some people
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Why is the overall impact of legal drugs on health much greater than the impact of illegal drugs, why?
Far more poeple use them
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What do drugs do?
Change the chemical processes in peoples' bodies so that they may become dependent or addicted to the drug and suffer withdrawal symptoms without them
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Name the different types of drugs athletes can take to enhance the performance of the body
Stimulants that boost bodily function such as heart rate and anabolic steroids which stimulate muscle growth
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What do animals often compete with each other for?
Food, mates and territory
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What do plants often compete with each other for?
Light, space, water and nutrients from the soil
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What is an extremophile?
An organism that lives in an extreme environment. They may be tolerant to high levels of salt, high temperatures or high pressure
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How have animals adapted to survive in dry and arctic conditions?
Changes to surface area, Thickness of insulating coat, Amount of body fat, Camouflage
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How have plants adapted to survive in dry environments?
Changes to surface area - particularly to the leaves, Water-storage tissues, Extensive root systems
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What living organisms can be used to indicate pollution levels?
Linchens can be used as air pollution indicators, particularly of the concentrations of sulfur dioxide in the atmosphere. Invertebrate animals can be used as water pollution indicators and are used as indicators of the concentration of oxygen
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What non-living indicators can be used to measure environmental changes?
Satellites -> temperature of the sea surface. Rain gauges -> Rainfall. Dissolved Oxygen meters -> Dissolved oxygen in the water and how the water pollution is changing
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What is the main source of energy for most communities of living organisms/
Radiation from the sun
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When does the transfer from light energy to chemical energy occur?
During photosynthesis
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Why is the amount of material and energy contained in the biomass of organisms reduced at each stage?
Some material and energy are always lost in the organisms' waste materials. Respiration supplies all the energy needed for living processes, much of this energy is eventually transferred to the surrouundings
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What happens when something decays?
They are broken down by microorganisms.
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What conditions do microorganisms work best?
Microorganisms are more active and digest materials faster in warm, moist and aerobic conditions
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What are sex cells called
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What does the nucleus contain?
Chromosomes. These carry genes that control the characteristics of the body
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Differences in the characterisics of different individuals of the same kind may be due to differences in?
-The genes that they have inherited -The conditions in which they have developed (or a combination of both)
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How many pairs of chromosomes does a human cell contain?
23 pairs
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What is an allele
The different versions of the same gene
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Define Sexual Reproduction
The joining (fusion) of male and female gametes. The mixture of the genetic information from two parents leads to variety in the offspring
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Define Asexual Reproduction
No fusion of gametes and only one individual in needed as the parent. There is no mixing of genetic information and so no genetic variation in the offspring. These genetically identical individuals are known as clones
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What is the difference in the cloning techniques of tissue culture and embryo transplants?
Tissue culture uses small groups of cells from part of a plant. Embryo Transplants splits cells apart from a developing animal embryo before they become specialised, then transplanting the identical embryos into host mothers
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What is adult cell cloning?
The nucleus is removed from an unfertillised egg cell. The nucleus from an adult body cell is then inserted into the egg cell. An electric shock then causes the egg cell to begin to divide to form embryo cells.
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What are genetically modified crops?
Crops that have had their genes modified. For example crops that are resistant to insect attack or herbicides
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What are the concerns for GM crops?
Effect on populations of wild flowers and insects and uncertainty about the effects of eating GM crops on human health
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What was Darwin's theory of evolution?
Natural Selection. All species of living things have evolved from simple life form that 1st developed more than 3 billion years ago
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Why was Darwin's theory only gradually accepted?
The theory challenged the idea that God made all the animals and plants that live on Earth. There was insufficient evidence. The mechanism of inheritance and variation was not known until 50 years after the theory
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What were the other theories based on? (Lamarck's)
The idea that changes that occur in an organism during its lifetime can be inherited. We now know that in the vast majority of cases this type of inheritance cannot occur
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How does evolution occur via natural selection?
Individual organisms within a particular species may show a wide range of variation because of differences in genes. Individuals with characteristics more suited to the environment are more likely to survive to breed successfully and these genes are
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What may happen if new forms of a gene result in a mutation?
Relatively rapid change in species in the environment changes
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What factors effect your metabolic rate?


Higher proportion of muscle to fat = high metabolic rate. Physically bigger people = high metabolic rate. Men = Higher. Regular exercise = boost metabolic rate

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Define Malnourished


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What are the 2 main types of pathogens?


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