B3 revision

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Explain why liver and muscle cells have large numbers of mitochondira
Because they require a lot of energy as liver carries out many functions and muscle cells need to contract
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Describe the shape of a DNA molecule
Two strands coiled to form a double helix, each strand containing chemicals called bases, of which there are four different types, with cross links between the strands formed by pairs of bases
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Explain why enzymes are specific
Because its active site has a specific shape
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Describe the effect of temperature on enzyme action
At low temperatures, enzyme reactions are slow. They speed up as the temperature rises until an optimum temperature is reached. After this point the reaction will slow down and eventually stop.
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Recall the symbol equation for aerobic respiration
C6H12 + 6O2 -> 6CO2 + 6H20
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Explain why anaerobic respiration occurs during exercise
The muscles often do not recieve sufficient oxygen
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Explain some advantages of being multi cellular
It allows an organism to become larger and more complex, it allows different cells to take on different jobs
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Recall the uses of mitosis and meiosis in mammals
Mitosis is produces new cells for growth and Meiosis is cell division that produces gametes
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Explain how a red blood cell is adapted to its function
Small size: They can pass through the smallest blood vessels | Shaped like biconcave discs: Have a large surface area to exchange oxygen quicker | Contain haemoglobin: Combines with oxygen and makes cell red | No nucleus: So more haemoglobin can fit
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Recall the function of stem cells
Can be made to differentiate to form different types of cell, such as nerve cells.
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Explain potential benefits and risks of genetic engineering
Benefits: Organisms with desired characteristics can be produced | Risks: Inserted genes may have unexpected harmful side effects
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Describe some possible uses of cloning animals
Mass produce animals with desirable characteristics, produce animals that have been genetically engineered to provide human products, produce human embryos to supply stem cells for therapy
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What is meant by nuclear transfer
Cloning
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Describe the position and function of ribosomes in a cell
Ribosomes are in the cytoplasm and are the site of protein synthesis
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Explain how the bases in DNA code for protein
the base sequence determines amino acid sequence • each amino acid is coded for by a sequence (order) of 3 bases
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Explain how changes to genes can alter proteins
Gene mutations alter or prevent the production of the protein normally made, because the change the base code of DNA, so change the order of amino acids in the protein
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Recall the function of ATP
Provides the energy for many different processes in living organisms
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Explain what is meant by oxygen debt
The incomplete break down of glucose that results in a build up of lactic acid
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Describe the main stages in mitosis
Each chromosome is copied, line up along the centre of the cell • they then divide • the copies move to opposite poles of the cell
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What is meant by haploids
Cells that contain one chromosome from each pair
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Explain how haemoglobin transports oyxgen
Haemoglobin reacts with oxygen, forming oxyhaemoglobin, when oxyhaemoglobin reaches the tissues, the oxygen is released
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Explain how the main types of blood vessels are adapted for their functions
Arteries: Thick muscular and elastic wall to resist high pressure | Veins: Large lumen and valves to try and keep blood moving back to the heart | Capillaries: Permeable walls so substances can be transferred between blood and tissues
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Explain the advantages and disadvantages of different measures of growth
Measuring length: Easy but only measures growth in one direction | Measuring wet mass: Hard to do for some organisms | Measuring dry mass: Growth of the whole organism is given but involves killing organism and driving off the water.
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Explain the difference between adult and embroynic stem cells
Embryonic cells can form a greater range of cell types and are easier to find
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Explain some consequences of inbreeding
Health problems can occur as it reduces the variety of alleles in the gene pool which can lead to an increased risk of harmful recessive characteristics and reduction in variation so populations cannot adapt to change easily.
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Describe the main stages in genetic engineering
Desired characteristics are selected, the genes responsible are indentifed and removed, the genes are inserted into other organisms, the organisms are allowed to reproduce
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Describe the cloning technique used to produce dolly the sheep
Donor egg cell had its nucleus removed, egg cell nucleus was replaced with the nucleus from an udder cell of another sheep, the egg cell was then given an electric shock to make it divide, the embryo was implanted into a surrogate mother sheep
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Explain why cloning plants is easier than cloning animals
It is easier because many plant cells retain the ability to differentiate.
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Other cards in this set

Card 2

Front

Describe the shape of a DNA molecule

Back

Two strands coiled to form a double helix, each strand containing chemicals called bases, of which there are four different types, with cross links between the strands formed by pairs of bases

Card 3

Front

Explain why enzymes are specific

Back

Preview of the front of card 3

Card 4

Front

Describe the effect of temperature on enzyme action

Back

Preview of the front of card 4

Card 5

Front

Recall the symbol equation for aerobic respiration

Back

Preview of the front of card 5
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