loopyw
Flashcards by , created almost 6 years ago

Biology (BY4) Flashcards on BY4, created by loopyw on 12/04/2013.

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loopyw
Created by loopyw almost 6 years ago
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Question Answer
Explain the reason for the lag phase during population growth This is a period of preperation for growth and enzymes are produced by protein synthesis
What is meant by the tem 'carrying capacity'? The maximum population size that can be supported by the available resources
Distinguish between density dependent and density independent factors Density dependent = the effect depends on the population size Density independant = effect is the same no matter what the population size
List three density dependant factors that limit the population growth Lack of food Toxic waste Predation Parasitism
List the properties of an organism used for biological control of a pest Species highly specific Long term No environmental contamination
A parasitic wasp may be used to control whitefly populations in a glasshouse. State two reasons why it would be inappropriate to use both a chemical and biological control method at the same time Chemicals are non specific and would kill the wasps Waste of money
Explain why plants require nitrate Nitrate is combined with the products of phpotosynthesis to form amino acids which are converted to proteions which are required for growth
Give the term for the process of converting ammonium ions to nitrate ions Nitrification
What stage in the nitrogen cycle is this: Dead plants and animals are decomposed into ammonium ions Putrefaction
What is nitrogen fixation? Ammonia -> nitrites Nitrites -> nitrates
Give an example of free living bacteria Azotobacter
What is Rhizobium? A nitrogen fixing bacteria
Which releases more energy, fat or carbohydrate? Fat
What is the difference between an absorption spectrum and action spectrum? Action spectrum = rate of photosynthesis Absorption spectrum = how much light a particular pigment absorbs at each wavelength
Which pigment is found at the reaction centre? Chlorophyll a
What is the source of replacement electrons for photosystem 2? photolysis of water
State two differences between cyclic and non - cyclic photophosphorylation Cyclic only involves PS1 and the source of electrons is PS1 Non - cyclic involves both photosystems and the souce of electrons is from water INCLUDE BOTH SIDES
Why is it essential to regenerate ribulose bisphosphate? So that it can accept additional C02, otherwise the cycle wouldn't continue
Name the three shapes of bacteria Bacillus = rod shaped Cocci = spherical Spirillium = corkscrew shaped
What additional chemical is present in the cell wall of gram negative bacteria? Lipopolysaccharide
What colour would gram negative bacteria stain in the gram stain test? Red Positive = Purple (P&P)
Apart from oxygen, list three other requirements for microbial growth Suitable temperature Suitable pH Carbon source/glucose Nitrogen source
Define a pathogen a disease causing microbe
What assumption is made when counting bacterial colonies? Each colony developed from a single bacterium
By what process does one cell give rise to a colony? Asexual reproduction
State three advantages of using industrial fermenters - More efficient due to high yield -Carried out at lower temperatures -Rapid rate of growth
Why is ammonia included as one of the nutrients in fermentation? Ammonia contains nitrogen which is needed to synthesise proteins
Why is the cooling jacket essential to the process of fermentation? To prevent overheating which would denature the enzymes
Define a secondary metabolite A chemical which is not necessary for the growth of the fungus and is produced after the exponential phase of growth is completed, when glucose is depleted
Name a cell type with a large number of mitochondria Muscle, liver
Where do the following occur: -Glycolysis -Krebs cycle Cytoplasm Matrix
Explain the role of oxygen in the electron transport chain Oxygen is the final electron acceptor. Without it electrons would accumulate and the reaction would stop