Biology questions

A genetc code is degenerate, what does this mean?
One amino acid can be coded for by more than one triplet
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What is a codon?
A base triplet in DNA or mRNA that codes for an amino acid
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Role of RNA polymerase during transcription
RNA polymerase joins nucleotides together to form mRNA
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What is a palindromic recognition sequnce?
The sequence is the same when one strand is read left to right and the other strand from right to left
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Role of tropomyosin in muscle contraction
Moves out of the way of the binding site, allowing the myosin head to bind to the action, when calcium ions bind to it
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Role of myosin in muscle contraction
Head of the myosin binds to the actin and slides the actin past. The head of the myosin detaches from the actin and moves further slong the actin, process uses ATP
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How does progesterone prevent ovulation?
Progesterone inhibits secretion of FSH/LH, FSH stimulates follicle development and LH stimulates ovulation
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What does a transcriptional factor do in terms of protein synthesis?
Bind to the DNA at a specific base sequence and either stimulate or prevent transcription
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How is the genetic code universal?
The triplet codes for the same amino acids
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What is the maximum number of different DNA triplets that can be made using these four bases?
64 (4³)
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What does splicing do?
It removes the base sequence (introns) from pre-mRNA to form mRNA
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What is a transcriptional factor?
A protein that moves from the cytopladm to the DNA and binds to RNA polymerase which leads to or blocks mRNA production
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Methods which can be used to find the base sequence of a gene
Restriction mapping and DNA/base sequencing of fragements
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During contraction what happens to the I-band?
It becomes narrower
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During contraction what happens to the A-band?
It stays the same
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How can progesterone prevent fertilisation?
It inhibits the production of FSH so a follicle is not stimulated and it also inhibits the production of LH so ovulation is prevented
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Signs that a animal/human is not pregnant?
Progesterone levels fall
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Why do scientists use control groups?
To ensure the result is due to the changed factor and not something else and it acts as a placebo in some cases so there is no psychological effect producing bias results
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What is the back bone of pre-mRNA made from?
Ribose and phosphate
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A DNA sequence is GATACCGTA, what is the pre-mRNA sequence produced by transcription?
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How does mRNA differ from tRNA?
mRNA contains codons and has no amino acid binding site
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How does IAA move from the plant shoot to other tissues?
By diffusion
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When does ovulation occur?
When oestrogen levels fall and progesterone levels increase
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How is the realtionship between oestrogen and LH an example of positive ffedback?
Positive feedback means more is produced, when there is an increase in oestrogen levelsthis stimulates LH production
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Taxis is what type of behaviour?
Directional movement towards the stimulus
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DNA, mRNA and tRNA, which of these contain hydrogen bonds?
DNA and tRNA
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What indicates that LH in the blood is controlled by negative feedback?
LH rises this stimulates progesterone production which causes progesterone levels to rise, progesterone inhibts LH production causing LH levels to fall
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What would indicate that ovulation took place?
An increase in oestogen which is associated with follicle development and increase in LH before ovulation as LH stimulates ovulation as well as an increase in progesterone levels after ovulation took place
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Two characteristics of stem cells
Keep dividing/replicate and can develop into other cells (totipotent)
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Role of restriction endonuclease
To cut the DNA
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Role of electrophoresis
To seperate the pieces of DNA
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What is a population?
All organisms of one species in a habitat/area at one time
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Which processes in aerobic respiration produce carbon dioxide?
Krebs cycle and Link reaction
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How does the light in the light-independent reaction produce ATP?
Light energy excites electrons in the chlorophyll, electrons are passed down the ecelctor transport chain, electrons reduce the carriers in a series of redox reactions, energy is released and ATP is generated from ADP and phosphate (phosphorylation)
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How does the efficiency of energy transfer differ at different stages of transfer?
Light energy may be reflected or the wrong wavelength, low efficiency of photosynthesis in plants, respiratory loss/excretion, loss of energy as heat, efficiency of transfer to consumers is greater than transfer of producers
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How does intensive rearing of livestock increase net productivity?
Saughtered when still growing so more energy is transferred to biomass, fed on concentrate so a higher proprtion of food is absorbed, restricted movement reduces repiratory losses as less energy used & kept inside as no predatos & less heat loss
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What does the Hardy-Weinberg principle predict?
The frequency of alleles, which will stay constant from one generation to another and there is no migration, selection or migration as well as a large population size with random mating
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How does carbon dioxide concentrations change in 24 hours?
High CO₂ concentrations are linked to night, thre is no photosynthesis at night as it requires light, in the dark plants repire (produce CO₂) and in the light there is net utake of CO₂ by plants (use more than produce)
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How does the carbon in CO₂ become the carbon in triose phosphate?
CO₂ combines with RuBP to produce two GP, which is then reduced to form TP (requires reduced NADP and energy from ATP)
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What are the microorganisms that make carbon available to plants from the conversion of decomposing dead matter?
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How do microorganisms make carbon contained in dead matter available to plants?
Saproptrophs secrete enymes onto the dead tissue (extracellular digestion), they absorb the products of digestion. When the microorganisms respire they release CO₂ into the atmosphere, CO₂ is then taken into the leaves though the stomata
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Does photosynthesis involve a electron transport chain?
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What are the properties of ATP that make it a suitable source of energy?
It is a small molecule so it is easily broken down, it is soluble, it involves a single/simple reaction and energy is release in small/suitable amounts
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What is the equation for net productivity?
Net productivity = Gross productivity - Respiratory losses
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Define birth rate
The number of births per 1,000 people per year
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What is meant by a recessive allele?
It is not expressed unless both alleles are recessive (homozygous)
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What is meant by codominance
Both alleles are expressed in the phenotype of an organism
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What is the equation for the gross rate of photosynthesis?
Gross rate of photosynthesis = Net rate of photosynthesis + respiratory losses
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How does succession occur?
A pioneer species colonises, it changes the environment enabling other species to colonise and survive, this causes a change in biodiversity and increase in the regions stability so the environment is less hostile. Climax community established
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Advantages of using biological agents to control pests
Specific, only one application needed, maintains low population, no resistance and no bioaccumulation
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Disadvantages of using biological agents to control pests
Does not eradicate pest, becomes the pest itself and slow acting
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Define community
All the species living in the same area
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What is an abiotic factor?
A non-living factor
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What is a dominant allele?
It is an allele which is always expressed in the phenotype of an organism
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What is meant by the term phenotype?
The genes that are expressed
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Other cards in this set

Card 2


What is a codon?


A base triplet in DNA or mRNA that codes for an amino acid

Card 3


Role of RNA polymerase during transcription


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Card 4


What is a palindromic recognition sequnce?


Preview of the front of card 4

Card 5


Role of tropomyosin in muscle contraction


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