B3 Revision

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What is the cytoplasm?
The site where chemical reactions take place.
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What is a cell membrane?
The site which allows movement into and out of a cell.
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What is a nucleus?
The site which contains the genetic information ad controls the cell.
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What is the mitochondria?
The site of respiration in a cell.
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What are the ribosomes?
The site of protein synthesis.
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What do chromosomes do?
Carry genetic information in the form of genes.
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What are genes?
A region of chromosome that carries information and controls a particular inherited characteristic.
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What is the structure of DNA?
Long coiled strands of DNA coiled in a double helix.
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How many pairs of chromosomes do humans have?
23.
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What are gametes?
Sex cells that contain individual chromosomes, having exactly half the number for an average cell.
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What are the four bases?
A,T,G and C.
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What is complementary base pairing?
A to T, G to C
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Who first worked out the structure of DNA?
Watson and Crick, using information from other scientists.
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How many bases represent 1 amino acid in a protein chain?
3.
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What is the role of mRNA?
To transport the code needed for proteins to be made from the nucleus to the ribosomes.
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What type of protein is collagen?
Structural.
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What type of protein is insulin?
Hormone.
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What type of protein is haemoglobin?
Carrier.
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Wwhat results in different proteins?
Different numbers and sequences of amino acids.
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What are enzymes?
Proteins that act as biological catalysts.
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What is the role of an enzyme?
To speed up chemical reactions.
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How is enzyme activity impacted?
By pH level or temperature.
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What is the structure of an enzyme?
They have an active site that only a specific reactant can fit into.
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What happens when enzyme molecules are exposed to high temperatures or extremes of pH?
The shape of the active site denatures and no longer fits te specific reactant.
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What is the optimum temperature for an enzyme?
When the highest enzyme activity is present, but going past it will cause the shape to be denatured.
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What happens during a mutation?
The base sequence of DNA is changed, altering the shape and function of the protein or stopping its production.
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What is the equation for aerobic respiration?
Glucose + oxygen ----> carbon dioxide + water
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What is aerobic respiration?
The release of energy from glucose in the presence of oxygen.
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What happens during aerobic exercise to the body?
Muscles demand more energy and so respiration must increasem to deliver oxygen and glucose to muscles and remove carbon dioxide quickly.
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How is ATP formed?
By respiration.
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When does anaerobic respiration occur?
When not enough oxygen is delivered to the muscles, releasing energy with the incomplete breakdown of glucose.
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What is formed as a result of anaerobic respiration?
Lactic acid.
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How is lactic acid removed from the muscles?
After anaerobic respiration, heavy breathing and heart rate stays high to allow oxygen to break down the acid and transport it in the blood to the liver.
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What is the 'oxygen debt'?
When the body takes in the oxygen that wasn't available for aerobic respiration.
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What does diploid mean?
Cells which contain two sets of matching chromosomes.
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What does haploid mean?
Cells which contain one set of chromosomes.
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What is formed at fertilisation?
A diploid zygote.
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How does a sperm cell enter an egg?
The acrosome bursts and digests the cell's membrane.
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How are two identical DNA strands formed?
The DNA helix unzips, adding bases to form new strands which creates a new DNA molecule.
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What happens during mitosis?
Each chromosome replicates and moves to the centre of the cell, divides and moves to opposite poles - this creates 2 daughter cells with the same number of chromosomes.
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What is meiosis?
Cell division that occurs in the testes and ovaries.
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What is the process of meiosis?
When the cell divides for the first time after replicating its chromosomes, the copies separate and second cell division takes place to create 4 haploid cells.
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What are the four components of blood?
Platelets, plasma, white blood and red blood.
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What are platelets?
Broken cells that clump together to produce a clot in a damaged blood vessel.
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What is plasma?
Transports several substances around the body.
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What are white blood cells?
Cells that protect the body from disease.
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What is the structure of red blood cells?
The are small, flexile and don't have a nucleus so that they can be packed with a lot of oxygen.
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What are the advantages of having a double circulatory system?
Blood is pumped to the body at a higher pressure than the lungs, creating a greater flow to the body tissues.
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What is the structure of an artery?
They have a thick wall made of elastic muscle fibres to cope with high pressure.
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What is the structure of a vein?
A large lumen to carry low pressure blood and valves to prevent backflow.
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What is the role of the capillaries?
They have thin permeable walls to allow the exchange of substances between the cells and blood.
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What are the four main chambers of the heart?
Left and right atria/ventricles.
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What is the role of the ventricles?
To pump blood out of the heart.
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What is the role of the atria?
To receive blood coming back to the heart through the veins.
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What are the three valve types of the heart?
Semilunar, tricuspid and bicuspid.
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What delivers blood to the lungs?
The pulmonary artery.
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What delivers blood from the lungs?
The pulmonary vein.
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What delivers blood from the body?
The vena cava.
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What delivers blood to the body?
The aorta.
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Where do bacteria keep their DNA?
Floating around as circular strands.
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What do plant cells contain?
Cell wall, cytoplasm, vacuole, cell membrane, chloroplasts, nucleus and ribosomes.
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What is the role of the vacuole?
To support the cell.
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What are the two types of growth?
Cell division and cell differentiation.
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What is cell enlargement?
The main method by which plants gain height.
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How is growth measured?
As an increase in height or mass.
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What is the advantage of measuring length/height to measure growth?
It is easy and quick to measure.
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What is the disadvantage of measuring length/height to measure growth?
An increase in mass might occur with no length/height.
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What is the advantage of measuring wet mass to measure growth?
It is not destructve and is relatively easy.
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What is the disadvantage of measuring wet mass to measure growth?
The water content of living tissue can be very variable and may give a distorted view.
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What is the advantage of measuring dry mass to measure growth?
It is the most accurate method.
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What is the disadvantage of measuring dry mass to measure growth?
It is destructive as removal of water kills organisms.
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What are stem cells?
Undifferentiated animal cells that can specialise into different types of cells, tissues and organs.
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How can stem cells be obtained?
From embryonic tissue.
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What is the difference between embryonic stem cells and adult stem cells?
The embryonic cells can become any type of body cell, whereas adult stem cells are limited to cell types of their tissue origin.
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What are the risks of selective breeding?
Inbreeding, reduction of the gene pool, less variaton.
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What is genetic engineering?
The artificial transfer of genes from one organism to another.
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What are the reasons for genetic engineering?
To improve crop resistance, to improve quality of food, to produce a required substance.
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What are the ethical considerations of genetic engineering?
GM plants may cross-breed, GM foods may not be safe to eat in the long term, babies being modified, unborn babies could be aborted with genetic faults, insurance companies could refuse people with increased risk.
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What are the benefits of genetic engineering?
Producing disease-resistance crops and higher yields could feed more of the world's population, easier to plant crops in poor soil, replacing faulty genes.
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What is the method for genetic engineering?
The desired gene is isolated using an enzyme and is inserted into the cell of another organism.
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What is gene therapy?
Changing someone's genes in an attempt to cure genetic disorders.
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Why can gene therapy be controversial in sex cells?
The genetic changes affect all future generations, meaning they don't get a say in the treatment.
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What is asexual reproduction?
The reproduction of an identical copy without the prescence of fertilisation.
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What is the process of cuttings?
Cuttings are taken from a plant and placed in damp atmosphere to grow identical plants.
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What are the advantages of commercial plant clones?
They will be genetically identical so all characteristics are known and mass production is available.
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What are disadvantages of commercial cloning of plants?
Any weakness to disease or environment will impact all plants and the reduction of gene variation reduces potential selective breeding.
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What is cloning by tissue culture?
Selecting a parent plant with desired characteristics and scraping off a lot of small pieces into beakers containing nutrients/hormones aseptically.
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What are the uses of cloning?
Cloned human embryos can provide stem cells for medicine, mass production of animals with desired characteristics and animals can be produced for human products.
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What are the ethical dilemmas of cloning?
Cloning is unreliable, clones have limited life spans, effect on mental stability is unknown, religious views, tampering with human embryos is controversial.
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What is the process of cloning?
A nucleus is taken from an egg cell of a desired animal, and put into an empty egg cell of another. This is given a shock to cause division and placed inside a surrogate.
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What are the benefits of cloning?
Sex and birth time of animals can be controlled and genetically identical cloned animal will have the same characteristics.
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What are the risks of cloning?
Reduction of genetic variation, one diease could wipe them out, clones may not be as healthy as normal animals.
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What are the concerns of using animal organ donors?
Infections may be passed from animals to humans and ethical issures concerning welfare and rights.
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Other cards in this set

Card 2

Front

What is a cell membrane?

Back

The site which allows movement into and out of a cell.

Card 3

Front

What is a nucleus?

Back

Preview of the front of card 3

Card 4

Front

What is the mitochondria?

Back

Preview of the front of card 4

Card 5

Front

What are the ribosomes?

Back

Preview of the front of card 5
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