Biology Additional Science Revision Notes

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  • Created by: Anna Lucy
  • Created on: 06-11-12 22:19
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Enzymes and Digestion
Enzymes are important in digestion. Digestion is the breakdown of carbohydrates, proteins
and fats into small soluble substances that can be absorbed into the blood.
Lipases and proteases are used in biological detergents, and enzymes are used in the
manufacture of food and drink.
Salivary glands, pancreas, small intestine
Stomach, pancreas, small intestine
Used to pre-digest proteins during the manufacture of baby foods
Pancreas, small intestine
Used together with protease - in biological detergents to break down - digest - the
substances in stains into smaller, water soluble substances
The small intestines and the Pancreas make ALL of the enzymes but food is NOT digested in
the pancreas and it does not enter it, the pancreas secrets the enzymes into the small

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Homeostasis is the process where the body maintains a constant internal environment.
This includes constant temperature, pH, water content, glucose content, ion content and
Carbon dioxide is a waste product of respiration; it is excreted through the lungs.
Some of the amino acids we take in are not used. They are converted into urea by
the liver and excreted by the kidneys in the urine. Urine can be stored in the bladder.
The water and ion content of cells must be carefully controlled.…read more

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If there is too much sugar in our blood the pancreas produces insulin which stores
excess sugar in the liver as glycogen. If insulin is not produces the blood sugar
level may become fatally high.
If the pancreas is not producing enough insulin this is known as diabetes. It can
sometimes be controlled by diet or the person may need insulin injections.…read more

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Photosynthesis is the chemical change which happens in the leaves of green plants.…read more

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Glucose is soluble and so cannot be stored, because of this glucose is converted into starch
which is insoluble.
The veins in a leaf contain to vessels.
Xylem: carries water from the roots to the leaves
Phloem: carries glucose to other parts of the plant from the leaves.
The test for starch is iodine. If it goes from orange to black, starch is
present.…read more

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Pairs of chromosomes are called homologous pairs. They have the same genes in the same
position but may have different alleles.
o Chromosomes are in the cells nucleus and are made from long DNA
o Are large and complex molecules. They carry the genetic code that
determines the characteristics of a living thing.
o A gene is a short section of DNA. Each gene codes for a specific protein by
specifying the order in which amino acids must be joined together.…read more

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Everyone has two alleles for each gene, if the alleles for a characteristic in a homologous pair
are the same, the organism is said to be homozygous for that characteristic.
If the alleles for a characteristic in a homologous pair are different, the organism is said to be
heterozygous for that characteristic.
Variation within a species is the way that two animals of the same species display different
characteristics and/or behaviour.…read more

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People who are against embryonic stem cell research say stem cell research say adult
stem cell research should be taken further
They believe life starts at conception and so it is destroying life by killing unborn
They are worried that stem cells may be used to gain profit
Advantages of Stem Cell Research
It provides medical benefits.
It provides great potential for discovering treatments and cures to diseases including
Parkinson's disease, Alzheimer's disease, cancer, spinal cord injuries, diabetes and
many more.…read more

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Green is a dominant allele
DNA Fingerprinting
Unless you have an identical twin, your DNA is unique to you. Other members of your family
will have strong similarities in DAN, but each individual will has their own unique blue print.
Only identical twins have the same DNA because they were both developed from the same
original cell. Therefore DNA fingerprinting is enormously useful in solving crimes and is also
used to show who the biological father of a child is.…read more

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For example, the allele for brown eyes is dominant, while the allele for blue eyes is recessive.
An individual who inherits one or two alleles for brown eyes will have brown eyes. An
individual will only have blue eyes if they inherit two copies of the allele for blue eyes.…read more


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